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The DeWitt Wallace Institute of Psychiatry: History, Policy, and the Arts at Weill Cornell Medical College in New York, was formerly known as The History of Psychiatry Section. Founded in 1958 by Dr. Eric T. Carlson, the institute is devoted to the study of the history of the mind-sciences and the preservation of resources on the history of psychology, psychiatry, psychoanalysis, neuroscience and other related disciplines. Its companion library, the Oskar Diethelm Library , houses over 50,000 titles on these subjects, with the earliest dating to the 14th century. The present Director is George Makari .
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https://en.wikipedia.org/wiki/DeWitt_Wallace_Institute_of_Psychiatry:_History,_Policy,_and_the_Arts
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De praestigiis daemonum , translated as On the Tricks of Demons , [ 1 ] is a book by medical doctor Johann Weyer , also known as Wier, first published in Basel in 1563. [ 2 ] [ 3 ] The book argues that witchcraft does not exist and that those who claim to practice it are suffering from delusions, which should be treated as mental illnesses, rather than punished as witchcraft. [ 4 ] It was influential in the abolishment of witchcraft trials in the Netherlands.
Weyer disagreed with certain contemporaries about the justification of witch-hunting . Weyer believed that most, probably all, cases of alleged witchcraft resulted from delusions of the alleged witch, rather than actual, voluntary cooperation with spiritual evil. In brief, Weyer claimed that cases of alleged witchcraft were psychological rather than supernatural in origin. [ 4 ]
The book contains a famous appendix also circulated independently as the Pseudomonarchia Daemonum , a listing of the names and titles of infernal spirits, and the powers alleged to be wielded by each of them. Weyer relates that his source for this intelligence was a book called Liber officiorum spirituum, seu liber dictus Empto Salomonis, de principibus et regibus demoniorum ("The book of the offices of spirits, or the book called Empto, by Solomon, about the princes and kings of demons). [ 5 ] Weyer's reason for presenting this material was not to instruct his readers in diabolism, but rather to "expose to all men" the pretensions of those who claimed to be able to work magic, men who "are not embarrassed to boast that they are mages, and their oddness, deceptions, vanity, folly, fakery, madness, absence of mind, and obvious lies, to put their hallucinations into the bright light of day." [ 6 ] Weyer's source claimed that Hell arranged itself hierarchically in an infernal court which is divided into princes, ministries and ambassadors. [ 7 ]
De Praestigiis has been translated into English, French, and German; it was one of the principal sources of Reginald Scot 's sceptical account of witchcraft, The Discoverie of Witchcraft . [ 8 ]
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https://en.wikipedia.org/wiki/De_praestigiis_daemonum
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Dead on arrival ( DOA ) indicates that a patient is unsalvageable, i.e. cannot be resuscitated, upon arrival at a medical facility. [ 1 ] Dead in the field , brought in dead ( BID ), and dead right there ( DRT ) are terms which similarly indicate that a patient was found to be already clinically dead upon the arrival of professional medical assistance, often in the form of first responders such as emergency medical technicians , paramedics , firefighters , or police . [ citation needed ]
In some jurisdictions, first responders must consult verbally with a physician before officially pronouncing a patient deceased, but once cardiopulmonary resuscitation (CPR) is initiated, it must be continued until a physician can pronounce the patient dead.
When presented with a patient, medical professionals are required to perform cardiopulmonary resuscitation (CPR) unless specific conditions are met that allow them to pronounce the patient as deceased. [ 2 ] In most places, these are examples of such criteria:
This list may not be a comprehensive picture of medical practice in all jurisdictions or conditions. For example, it may not represent the standard of care for patients with terminal diseases such as advanced cancer. In addition, jurisdictions such as Texas permit withdrawal of medical care from patients who are deemed unlikely to recover.
Regardless of the patient, a pronouncement of death must always be made with absolute certainty and only after it has been determined that the patient is not a candidate for resuscitation. This type of decision is rather sensitive and can be difficult to make.
Legal definitions of death vary from place to place; for example, irreversible brain-stem death, prolonged clinical death , etc.
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https://en.wikipedia.org/wiki/Dead_on_arrival
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Dead space is the volume of air that is inhaled that does not take part in the gas exchange, because it either remains in the conducting airways or reaches alveoli that are not perfused or poorly perfused . It means that not all the air in each breath is available for the exchange of oxygen and carbon dioxide . Mammals breathe in and out of their lungs, wasting that part of the inhalation which remains in the conducting airways where no gas exchange can occur.
Total dead space (also known as physiological dead space ) is the sum of the anatomical dead space and the alveolar dead space.
Benefits do accrue to a seemingly wasteful design for ventilation that includes dead space. [ 1 ]
In humans, about a third of every resting breath has no change in O 2 and CO 2 levels. In adults, it is usually in the range of 150 mL. [ 3 ]
Dead space can be increased (and better envisioned) by breathing through a long tube, such as a snorkel . Although one end of the snorkel is open to the air, when the wearer breathes in, they inhale a significant quantity of air that remained in the snorkel from the previous exhalation. Therefore, a snorkel increases the person's dead space by adding even more airway that does not participate in gas exchange.
Anatomical dead space is the volume of the conducting airways (from the nose , mouth and trachea to the terminal bronchioles). These conduct gas to the alveoli but no gas exchange occurs here. In healthy lungs where the alveolar dead space is small, Fowler's method accurately measures the anatomic dead space using a single breath nitrogen washout technique. [ 4 ] [ 5 ]
The normal value for dead space volume (in mL) is approximately the lean mass of the body (in pounds), and averages about a third of the resting tidal volume (450-500 mL). In Fowler's original study, the anatomic dead space was 156 ± 28 mL (n=45 males) or 26% of their tidal volume. [ 4 ] Despite the flexibility of the trachea and smaller conducting airways, their overall volume (i.e. the anatomic dead space) changes little with bronchoconstriction or when breathing hard during exercise. [ 4 ] [ 6 ]
As birds have a longer and wider trachea than mammals the same size, they have a disproportionately large anatomic dead space, reducing the airway resistance. This adaptation does not impact gas exchange because birds flow air through their lungs - they do not breathe in and out like mammals. [ 7 ]
Alveolar dead space is defined as the difference between the physiologic dead space and the anatomic dead space. It is contributed to by all the terminal respiratory units that are over-ventilated relative to their perfusion. Therefore it includes, firstly those units that are ventilated but not perfused, and secondly those units which have a ventilation-perfusion ratio greater than one.
Alveolar dead space is negligible in healthy individuals, but it can increase dramatically in some lung diseases due to ventilation-perfusion mismatch .
Just as dead space wastes a fraction of the inhaled breath, dead space dilutes alveolar air during exhalation. By quantifying this dilution, it is possible to measure physiological dead space, employing the concept of mass balance , as expressed by the Bohr equation . [ 8 ] [ 9 ]
The Bohr equation is used to measure physiological dead space. Unfortunately, the concentration of carbon dioxide (CO 2 ) in alveoli is required to use the equation but this is not a single value as the ventilation-perfusion ratio is different in different lung units both in health and in disease. In practice, the arterial partial pressure of CO 2 is used as an estimate of the average alveolar partial pressure of CO 2 , a modification introduced by Henrik Enghoff in 1938 (Enghoff H. Volumen inefficax. Bemerkungen zur Frage des schadlichen Raumes. Upsala Läkarefören Forhandl., 44:191-218, 1938). In effect, the single arterial pCO 2 value averages out the different pCO 2 values in the different alveoli, and so makes the Bohr equation useable.
The quantity of CO 2 exhaled from the healthy alveoli is diluted by the air in the conducting airways (anatomic dead space) and by gas from alveoli that are over-ventilated in relation to their perfusion. This dilution factor can be calculated once the mixed expired pCO 2 in the exhaled breath is determined (either by electronically monitoring the exhaled breath or by collecting the exhaled breath in a gas impermeant bag (a Douglas bag) and then measuring the pCO 2 of the mixed expired gas in the collection bag). Algebraically, this dilution factor will give us the physiological dead space as calculated by the Bohr equation:
The alveolar dead space is determined as the difference between the physiological dead space (measured using the Enghoff modification of the Bohr equation) and the anatomic dead space (measured using Fowler's single breath technique).
A clinical index of the size of the alveolar dead space is the difference between the arterial partial pressure of CO 2 and the end-tidal partial pressure of CO 2 .
A different maneuver is employed in measuring anatomic dead space: the test subject breathes all the way out, inhales deeply from a 0% nitrogen gas mixture (usually 100% oxygen) and then breathes out into equipment that measures nitrogen and gas volume. This final exhalation occurs in three phases. The first phase (phase 1) has no nitrogen as that is gas that is 100% oxygen in the anatomic dead space. The nitrogen concentration then rapidly increases during the brief second phase (phase 2) and finally reaches a plateau in the third phase (phase 3). The anatomic dead space is equal to the volume exhaled during the first phase plus the volume up to the mid-point of the transition from phase 1 to phase 3.
The depth and frequency of our breathing is determined by chemoreceptors and the brainstem, as modified by a number of subjective sensations. When mechanically ventilated using a mandatory mode, the patient breathes at a rate and tidal volume that is dictated by the machine.
Because of dead space, taking deep breaths more slowly (e.g. ten 500 ml breaths per minute) is more effective than taking shallow breaths quickly (e.g. twenty 250 ml breaths per minute). Although the amount of gas per minute is the same (5 L/min), a large proportion of the shallow breaths is dead space, which does not help oxygen to get into the blood. [ citation needed ]
Mechanical dead space or external dead space is volume in the passages of a breathing apparatus in which the breathing gas flows in both directions as the user breathes in and out, causing the last exhaled gas to be immediately inhaled on the next breath, increasing the necessary tidal volume and respiratory effort to get the same amount of usable air or breathing gas, and increasing the accumulation of carbon dioxide from shallow breaths. It is in effect an external extension of the physiological dead space. [ 10 ]
It can be reduced by:
Dead space reduces the amount of fresh breathing gas which reaches the alveoli during each breath. This reduces the oxygen available for gas exchange, and the amount of carbon dioxide that can be removed. The buildup of carbon dioxide is usually the more noticeable effect unless the breathing gas is hypoxic as occurs at high altitude. The body can compensate to some extent by increasing the volume of inspired gas, but this also increases work of breathing , and is only effective when the ratio of dead space to tidal volume is reduced sufficiently to compensate for the additional carbon dioxide load due to the increased work of breathing.
Continued buildup of carbon dioxide will lead to hypercapnia and respiratory distress .
In healthy people, V d is about one-third of V t at rest and decreases with exercise to about one-fifth mainly due to an increase in V t , as anatomic dead space does not change much and alveolar dead space should be negligible or very small. [ 12 ]
External dead space for a given breathing apparatus is usually fixed, and this volume must be added to tidal volume to provide equivalent effective ventilation at any given level of exertion.
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https://en.wikipedia.org/wiki/Dead_space_(physiology)
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Deafness has varying definitions in cultural and medical contexts. In medical contexts, the meaning of deafness is hearing loss that precludes a person from understanding spoken language, an audiological condition. [ 1 ] In this context it is written with a lower case d . It later came to be used in a cultural context to refer to those who primarily communicate with a deafness aid or through sign language regardless of hearing ability, often capitalized as Deaf and referred to as "big D Deaf" in speech and sign. [ 2 ] [ 3 ] The two definitions overlap but are not identical, as hearing loss includes cases that are not severe enough to impact spoken language comprehension, while cultural Deafness includes hearing people who use sign language, such as children of deaf adults .
In a medical context, deafness is defined as a degree of hearing difficulties such that a person is unable to understand speech, even in the presence of amplification. [ 1 ] In profound deafness, even the loudest sounds produced by an audiometer (an instrument used to measure hearing by producing pure tone sounds through a range of frequencies) may not be perceived by the person. In total deafness, no sounds at all, regardless of amplification or method of production, can be heard.
Neurologically, language is processed in the same areas of the brain whether one is deaf or hearing. The left hemisphere of the brain processes linguistic patterns whether by signed languages or by spoken languages. [ 5 ]
Deafness can be broken down into four different types of hearing loss:
All of these forms of hearing loss impair a person's hearing so they are not able to perceive or interpret sounds correctly. These different types of hearing loss occur in different parts of the ear, which make it difficult for the information being heard to get sent to the brain properly.
For each of these types, there are four different levels or amounts of hearing loss. The first level is mild hearing loss . This is when someone is still able to hear noises, but it is more difficult to hear the softer sounds. The second level is moderate hearing loss , and this is when someone can hear almost nothing when someone is talking to them at a normal volume. The next level is severe hearing loss. Severe hearing loss is when someone can not hear any sounds when they are being produced at a normal level, and they can only hear minimal sounds that are being produced at a loud level. The final level is profound hearing loss , which is when someone is not able to hear any sounds except for very loud ones. [ 6 ]
Millions of people globally live with deafness or hearing impairments. The 2005 Survey of Income and Program Participation (SIPP) indicated that fewer than 1 in 20 Americans are deaf or hard of hearing at a level that makes normal conversations difficult to hear; more than half of these people are over retirement age . [ 7 ]
Several solutions are available for many people with hearing impairments. Hearing aids are a common device. Additionally, people may use devices that use blinking lights instead of noises for alarm clocks or other notifications.
Cochlear implants are an option for children and adults with severe or profound hearing loss. Cochlear implants are surgically placed devices that stimulate the cochlear nerve in order to help the person hear. A cochlear implant is used instead of hearing aids in order to help when someone has difficulties understanding speech. [ 8 ] For children, the younger they are at the time of implantation, the better their auditory skill and perception. [ 9 ] Babies with confirmed bilateral profound sensorineural hearing loss may begin the surgical evaluation process for implantation as early as six months, with the US officially allowing the surgery to take place as early as nine months of age. [ 9 ] Children with other medical problems or other types of hearing loss may be considered at a slightly older age. [ 9 ] Parents sometimes have difficulty deciding to get cochlear implants for their child. Many felt a sense of urgency, and, in the end, most parents felt it was beneficial for their child. [ 10 ]
In a cultural context, Deaf culture refers to a tight-knit cultural group of people whose primary language is signed , and who practice social and cultural norms which are distinct from those of the surrounding hearing community. This community does not automatically include all those who are clinically or legally deaf, nor does it exclude every hearing person. According to Baker and Padden, it includes any person who "identifies him/herself as a member of the Deaf community, and other members accept that person as a part of the community", [ 11 ] an example being children of deaf adults with normal hearing ability.
It includes the set of social beliefs, behaviors, art, literary traditions, history, values, and shared institutions of communities that are influenced by deafness and which use sign languages as the main means of communication. [ 12 ] [ 13 ]
While deafness is often included within the umbrella of disability , members of the Deaf community tend to view deafness as a difference in human experience or itself as a language minority. [ 14 ] [ 15 ] [ 16 ]
Many non-disabled people continue to assume that deaf people have no autonomy and fail to provide people with support beyond hearing aids, which is something that must be addressed. Different non-governmental organizations around the world have created programs towards closing the gap between deaf and non-disabled people in developing countries.
As children, deaf people learn literacy differently than hearing children. They learn to speak and write, whereas hearing children naturally learn to speak and eventually learn to write later on. [ 17 ]
The Quota International organization, headquartered in the United States, provided immense educational support in the Philippines, where it began offering free education to deaf children in the Leganes Resource Center for the Deaf. The British organisation Sounds Seekers also supported deaf communities by offering audiology maintenance technology in hard-to-reach areas.
The Nippon Foundation supports deaf students at Gallaudet University and the National Technical Institute for the Deaf through international scholarship programmes to encourage them to become future leaders in the deaf community. The more aid these organisations give to deaf people, the more opportunities and resources marginalised people have to speak up about their struggles and aspirations. When more people understand how to leverage their privilege for marginalised groups, society can build a more inclusive and tolerant environment for future generations. [ 2 ] [ 3 ]
The first known record of sign language in history comes from Plato 's Cratylus , written in the fifth century BCE. In a dialogue on the "correctness of names", Socrates says, "Suppose that we had no voice or tongue, and wanted to communicate with one another, should we not, like the deaf and dumb, make signs with the hands and head and the rest of the body?" [ 18 ] His belief that deaf people possessed an innate intelligence for language put him at odds with his student Aristotle , who said, "Those who are born deaf all become senseless and incapable of reason", and that "it is impossible to reason without the ability to hear".
This pronouncement would reverberate through the ages and it was not until the 17th century when manual alphabets began to emerge, as did various treatises on deaf education , such as Reducción de las letras y arte para enseñar a hablar a los mudos ('Reduction of letters and art for teaching mute people to speak'), written by Juan Pablo Bonet in Madrid in 1620, and Didascalocophus, or, The deaf and dumb mans tutor , written by George Dalgarno in 1680.
In 1760, French philanthropic educator Charles-Michel de l'Épée opened the world's first free school for the deaf . The school won approval for government funding in 1791 and became known as the "Institution Nationale des Sourds-Muets à Paris". [ 19 ] The school inspired the opening of what is today known as the American School for the Deaf , the oldest permanent school for the deaf in the United States, and indirectly, Gallaudet University , the world's first school for the advanced education of the deaf and hard of hearing, and to date, the only higher education institution in which all programs and services are specifically designed to accommodate deaf and hard of hearing students.
Parents of deaf and hard-of-hearing children often encounter difficulties when choosing an educational setting for their child. They may consider the needs and abilities of the child, how the school can make accommodations for the child, and the school environment itself. [ 20 ] Both the child and the parent may benefit from trial and error with different schools, to identify the best available environment.
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https://en.wikipedia.org/wiki/Deafness
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Dean Turner Burk (March 21, 1904 – October 6, 1988) [ 2 ] was an American biochemist, medical researcher, and a cancer researcher at the Kaiser Wilhelm Institute and the National Cancer Institute . [ 3 ] In 1934, he developed the Lineweaver–Burk plot together with Hans Lineweaver . [ 4 ] Lineweaver and Burk collaborated with the eminent statistician W. Edwards Deming on the statistical analysis of their data: [ 5 ] they used the plot for illustrating the results, not for the analysis itself.
Dean Turner Burk was born on March 21, 1904, in Oakland in Alameda County . [ 6 ] Dean was the second of four sons born to Frederic Lister Burk , the founding President of the San Francisco Normal School, a preparatory school for teachers which eventually became San Francisco State University .
He entered the University of California, Davis at the age of 15. A year later, he transferred to the University of California, Berkeley , where he received his B.S. degree in Entomology in 1923. Four years later, he earned a Ph.D. in biochemistry. [ citation needed ]
Burk joined the Department of Agriculture in 1929 working in the Fixed Nitrogen Research Laboratory. [ 3 ] In 1939, he joined the Cancer Institute as a senior chemist. He was head of the cytochemistry laboratory when he retired in 1974. He also taught biochemistry at the Cornell University Medical School from 1939 to 1941. [ 3 ] He was a research master at George Washington University. Burk was a close friend and co-author with Otto Heinrich Warburg . [ 7 ] He was a co-developer of the prototype of the Magnetic Resonance Scanner . [ 3 ] [ 8 ] Burk published more than 250 scientific articles in his lifetime. [ 9 ] He later became head of the National Cancer Institute's Cytochemistry Sector in 1938, although he is often mistaken as leading the entire facility.
After retiring from the NCI in 1974, Dean Burk remained active. He devoted himself to his opposition to water fluoridation . [ 10 ] [ 11 ] [ better source needed ] He and a coauthor published an analysis of cancer mortality in 10 cities that fluoridated the drinking water supply and 10 that didn't. The paper was criticized for using overly broad grouping and making assumptions about variations in racial composition of cities. Epidemiologists from the National Cancer Institute analyzed the findings and found no significant increase in cancer mortality associated with fluoridation. [ 12 ] [ 13 ] Burk considered "fluoridation as "mass murder on a grand scale." [ 14 ] Dean Burk argued on Dutch television against a water fluoridation proposal which was before the Dutch Parliament in the Netherlands. [ 13 ] He also was an avid supporter of laetrile ; an alleged cancer treatment regarded by the medical community as ineffective and potentially dangerous. [ 15 ]
For his work on photosynthesis , Dean Burk received the Hillebrand Prize in 1952. Dean Burk and Otto Heinrich Warburg discovered the photosynthesis I-quantum reaction that splits CO 2 activated by respiration. [ 16 ] [ 17 ] For his techniques to distinguish between normal cells and those damaged by cancer, Dean Burk was awarded the Gerhard Domagk Prize in 1965. [ 18 ]
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https://en.wikipedia.org/wiki/Dean_Burk
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Harold Judd Noyes (1898–1968), often called "Dean Noyes", was an American orthodontist who graduated from Angle School of Orthodontia . He was the Chairman of the Orthodontic Department of the Northwestern University Dental School. He also served as the Dean of University of Oregon Dental School. [ 1 ]
He was the son of Frederick Bogue Noyes and grandson of Edmund Noyes , who both served as deans of American dental schools. He received his college degree from Beloit College . He received his dental degree in 1928 from University of Illinois College of Dentistry and received his medical degree in 1933 from Rush Medical School . His education was interrupted because of World War I in 1917 and 1919. He was married to Elizabeth Noyes and had a daughter, Loren N. Bates.
In his professional career, Dr. Noyes served as a pediatrician at Presbyterian Hospital, Children's Memorial in Chicago. He served as a consultant to Zoller Memorial Dental Clinic in Chicago in 1940. He was the Chairman of the Orthodontic Department of the Northwestern University Dental School from 1940 to 1946. He then served as the Dean of University of Oregon Dental School from 1946 until his death in 1967.
While being Dean at Oregon Health & Science University School of Dentistry , Dr. Noyes introduced the "Vertical Curriculum" for dental students. He allowed first-year dental students to construct full dentures and participate in exercise of tooth morphology. This made a profound impact in dental education, as this curriculum was widely accepted and implemented in other dental schools. [ 1 ]
He also co-authored a textbook with his father, Oral Histology and Embryology with Laboratory Directions .
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Death Risk Rankings was a website that approximated the likelihood of a European or American person dying within a twelve-month span. Using public data to do its calculations, the website also listed the possible causes of death, including illnesses or accidents .
Created by Carnegie Mellon University in Pittsburgh , Pennsylvania , Death Risk Rankings has been nicknamed the "death calculator".
Death Risk Rankings was created by researchers and students at Carnegie Mellon University in Pittsburgh , Pennsylvania . [ 1 ] The website was developed by Paul Fischbeck , a professor of Social and Decision Sciences and Engineering and Public Policy at Carnegie Mellon, and David Gerard, associate professor of Economics and Public Policy at Lawrence University in Appleton, Wisconsin . [ 2 ] Fischbeck believed that the website will provide lawmakers with ideas during the health care reform debate . [ 3 ]
Death Risk Rankings has been nicknamed the "death calculator" according to Kaytie Dowling of The Intelligencer & Wheeling News Register . [ 4 ]
On August 27, 2009, the day it was launched, Death Risk Rankings had about a million visitors per hour. [ 2 ] The website then crashed and was inaccessible for two hours due to server issues. [ 1 ] In twenty-four hours, the website had surpassed Carnegie Mellon University's bandwidth cap for one month. [ 2 ]
The website has not been available since mid 2011. [ 5 ]
The website based its results on the public information gathered by the Centers for Disease Control and Prevention (CDC) for data in the United States and Eurostat for data in Europe. [ 6 ]
Death Risk Rankings did not use genetics or an individual's way of living in its calculations. [ 2 ] However, the website was able to determine the possibility of death using information such as location, gender, and age. [ 7 ] After submitting the information, users were able to view their chance of dying that year of sixty-six different causes, such as murder , a number of illnesses, and accidents. [ 8 ]
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https://en.wikipedia.org/wiki/Death_Risk_Rankings
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In the United Kingdom , death by misadventure is the recorded manner of death for an accidental death caused by a risk taken voluntarily. [ 1 ]
Misadventure in English law , as recorded by coroners and on death certificates and associated documents, is a death that is primarily attributed to an accident that occurred due to a risk that was taken voluntarily. In contrast, when the manner of death is given as an accident , the coroner has determined that the decedent had taken no unreasonable willful risk. [ 1 ]
"Misadventure may be the right conclusion when a death arises from some deliberate human act which unexpectedly and unintentionally goes wrong." [ 2 ]
Legally defined manner of death : a way by which an actual cause of death (trauma, exposure, etc.) was allowed to occur. For example, a death caused by an illicit drug overdose may be ruled a death by misadventure, as the user took the risk of drug usage voluntarily. Misadventure is a form of unnatural death , a category that also includes accidental death , suicide , and homicide . [ 1 ]
In the case of R v Wolverhampton Coroner , [ 3 ] it was held that the coroner must establish death by misadventure on the balance of probabilities , commonly known as "more likely than not". This is opposed to beyond reasonable doubt , which is used elsewhere. [ 4 ]
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Deathcare (also death care, death-care or after-deathcare ) is the planning, provision, and improvement of post- death services, products, policy, and governance. Here, deathcare functions to describe the industry of deathcare workers, the policy and politics surrounding deathcare provision, and as an interdisciplinary field of academic study. [ 1 ]
Deathcare, from the point of clinical death , has a diverse timeline. The first point of care often involves immediate healthcare professionals and responders closest to the person who has died, including doctors, nurses, palliative and end-of-life care workers. [ 2 ] From here, the care of deceased individuals has a culturally, religious, and personal course. This can involve a range of people from religious figures, morticians, to grave keepers – all of these roles formulating to what can be known as deathcare workers. [ 3 ]
The word deathcare is a compound term from the words death and care . It can also take the form of death care, [ 4 ] however this is mostly used in the United States and Canada in the Anglosphere , where deathcare is a preferred variation elsewhere in the English speaking world reflecting on the preferred version of healthcare in places like the UK, Australia, India, etc. [ 5 ]
The provision of deathcare has historically [ 6 ] and often continues to be a highly decentralized and diverse practice combining multiple actors and stages. [ 7 ] [ 8 ] Nonetheless, trends in providers and purveyors of deathcare do exist throughout different eras: in the time prior to the American Civil War, for instance, the majority of care for the deceased was performed by one's own family members. Specifically, women in the family were expected, as a part of their domestic duties, to oversee and execute the sanitization, dressing, and ultimately burial of their families' corpses. [ 9 ] However, following the number of deaths during the Civil War, the practice of embalming became commonplace, as fallen soldiers had to be preserved before their bodies could be transported vast distances from the battlefield back to their hometowns. Following the war, it became the norm to have loved-ones bodies prepared and cared for by morticians, and spaces for services to be provided by funeral home directors. [ 10 ] Coinciding with the professionalization of the funeral industry, the advances of the medical field changed expectations around an infectious disease course. That is, rather than comfort care, medical providers began to offer life-saving, and thus life-changing measures, e.g. antibiotics. [ 11 ] This resulted in a change in the concentration of the placement of ill-people: rather than remaining at home, people began to rely increasingly on hospitals as a place of healing, especially in urban areas where hospitals were more accessible. [ 12 ] In areas that allowed for access to hospital systems, this inevitably resulted in a greater proportion of deaths occurring in hospitals rather than at home, thus bolstering the change from home-based care to professional, funeral home-based care of the deceased in the urban West. [ 9 ]
In other countries, the social practices around deathcare vary compared to the U.S. For instance, in Hindu culture, women have been barred from attending cremation rituals, and even from touching the deceased. [ 13 ] Before World War Two in Britain, women were "commonly responsible for laying-out the body", but following the war were barred from such a role given the expedient professionalization of the deathcare industry. [ 14 ]
Examples of government policy involvement include the impact of new burial methods like human composting [ 15 ] to pressures like COVID-19 placing on those involved with deathcare as well as their families. [ 16 ] [ 17 ] [ 18 ] In addition to government policy, the effects of COVID-19 have directly impacted those involved in deathcare: funeral directors were shown to have increased rates of burnout following the first wave of the pandemic. [ 19 ]
National and regional governments are often responsible for providing the legal framework for deathcare to operate within, including laws and guidance on what deathcare techniques, practices, and what individuals/ organisations are involved. However, this has a varying level of non-government organisations, third-sector, religious, and private organisations (such as funeral homes ) [ 20 ] take part in both providing and shaping deathcare policy and practice. [ 21 ] [ 22 ] However, most research on state interactions within deathcare is limited to the US, with further research needed elsewhere. [ 23 ]
Governments can also become a major focal point for deathcare services in specific situations, such as with deaths in the military, prisons, or in extraordinary events. COVID-19 is an example of global governmental intervention to provide mass fatality management to cope with high human fatality around the world. [ 23 ] This also brought up issues of inequality and inequity within deathcare as some deaths throughout the pandemic were treated as "more tragic" compared to others, highlighted as a public values failure as economic productivity and social worth overruled public health and humanity. [ 24 ]
Analysts have stated that the deathcare industry can be divided into three portions: the ceremony and tribute (funeral or memorial service); the disposition of remains through cremation or burial (interment); and memorialization in the form of monuments, marker inscriptions or memorial art. [ 25 ]
Deathcare industry is a multifactorial sector including, but not limited to: companies and organizations that provide services related to death memorials, funerals, and burials. Theses types of ceremonies includes service use of coffins, headstones, crematoriums, and funeral homes. Most of the death service industry has consisted of small businesses that have been consolidated as time has gone on. [ 26 ]
There is a global marketplace for deathcare in the produces, services, and insurance that surrounds someone's death. This is a market that has shown expanding fiscal growth in years 2020 to 2021 supported by a compound annual growth rate of 5.6%. The market is expected to continue to grow to a compound annual growth rate of 8% by year 2025 expecting to reach a value of 147.38 billion dollars up from 103.93 billion dollars in 2020. [ 27 ]
The deathcare process comes with multiple costs to allow for certain rituals to take place. Including to removal/transfer of remains to funeral homes (est $340), embalming (est $740), Hearse use ($340), metal burial casket (est $2500). The estimated median cost of funeral with burial and funeral was estimated by an NFDA news release to be $7640. [ 28 ]
Deathcare industrial complex (DIC) has been outlined as a concept, mirroring the military-industrial complex concept, in at least the US and potentially Western countries as an industry: "profit-driven, medicalised, de-ritualized and patriarchal [in] form, modern death care fundamentally distorts humans' relationship to mortality, and through it, nature". [ 29 ] The death care industry in the United States is deemed controversial due to high costs and negative environmental impacts. [ 4 ]
Localized efforts to reform and offer innovative deathcare practices can be seen in the natural deathcare movements such as human composting to natural burials. [ 9 ] [ 30 ]
Common funeral practices in Western society are associated with notable environmental impacts. [ 31 ] Metal caskets can deteriorate and release harmful toxins when buried, leading to contamination of land and water. [ 31 ] Cremation also uses a significant amount of fuel consumption, releasing chemicals and carbon emissions. [ 31 ]
With the threat of climate change, conversations about green death practices are becoming more prevalent. [ 31 ] Natural burial methods are being developed to promote eco-sustainability in deathcare. [ 31 ]
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Debakey forceps are a type of atraumatic tissue forceps used in vascular procedures to avoid tissue damage during manipulation. They are typically large (some examples are upwards of 12 inches (36 cm) long), and have a distinct coarsely ribbed grip panel, as opposed to the finer ribbing on most other tissue forceps. [ 1 ]
They were developed by Michael DeBakey , along with other innovations during his tenure at Baylor College of Medicine . [ 2 ]
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In dentistry, debridement refers to the removal by dental cleaning of accumulations of plaque and calculus (tartar) in order to maintain dental health. [ 1 ] Debridement may be performed using ultrasonic instruments, which fracture the calculus, thereby facilitating its removal, as well as hand tools, including periodontal scaler and curettes , or through the use of chemicals such as hydrogen peroxide .
Dental debridement is a procedure by which plaque and calculus (tartar) that have accumulated on the teeth is removed. [ 1 ] Debridement may be performed in the process of personal or professional teeth cleaning . Professional debridement techniques include the use of ultrasonic instruments (which fracture the calculus, thereby facilitating its removal), as well as the use of hand tools, including periodontal scaler and curettes . [ citation needed ] Debridement may also be performed using saline solution. [ citation needed ]
Periodontal Pockets
A periodontal pocket is formed from a disease process; it is defined as the apical extension of the gingiva, resulting in detachment of the periodontal ligament (PDL). [ 2 ] The PDL is a ligament that attaches the root of the tooth to the supporting alveolar bone. This ligament allows for occlusal force absorption. Plaque accumulates within the pocket initiating an inflammatory response due to an increased number of spirochetes. There are different types of bacteria that make up dental plaque. In cases of aggressive periodontitis three major species of bacteria have been identified within the periodontal pocket. [1] These bacteria include Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans. [ 2 ] Healthy gingiva consists of few microorganisms, mostly coccoid cells and straight rods. Diseased gingiva consists of increased numbers of spirochetes and mobile rods. Interactions between plaque and host inflammatory response determine the alterations in pocket depths. [ 3 ] Bacterial plaque initiates a nonspecific host inflammatory response with the intention of eliminating necrotic cells and harmful bacteria. During this process cytokines, proteinases, and prostaglandins are produced which can cause damage, or kill healthy tissues such as macrophages, fibroblasts, neutrophiles, and epithelial cells. [ 2 ] The exposure to connective tissue and blood capillaries, allows microorganisms to gain an entryway to the circulation. This suppresses host protection mechanisms, leading to further destruction of bone. [ 3 ]
Periodontal pockets may occur from either coronal swelling or apical migration. Pockets that occur due to coronal swelling with no clinical attachment loss are considered pseudopockets. There are two types of periodontal pockets that are determined by the type of bone loss present. A suprabony pocket occurs when there is horizontal bone loss, the bottom of the pocket is coronal to the alveolar bone. An infrabony pocket occurs when there is vertical bone loss where the bottom of the pocket is apical to the alveolar bone. [ 4 ]
Clinical signs of periodontal pockets include bluish-red, thickened gingiva, gingival bleeding, localized pain and in some cases exudate. Periodontal pockets can cause the loosening and loss of dentition due to destruction of supporting tissues including the alveolar bone, PDL and gingival tissue. Clinical diagnosis of periodontal pockets is achieved from full mouth periodontal probing performed by a dentist or dental hygienist. [ 2 ] [ 5 ]
Treatment of periodontal pocketing requires professional and at home intervention. At home treatment for periodontal pockets include meticulous and routine plaque removal by brushing and interproximal cleaning. Professional treatment includes routine dental visits for debridement, scaling and root planing. Clinical treatment goals are set to control the inflammatory disease by removal of coronal and subgingival plaque containing destructive pathogens. With the consistent and complete removal of biofilm, the infection can be arrested and healthy periodontium can be achieved. [ 6 ]
Another major risk factor of a periodontal pocket is smoking as it affects the severity and prevalence of pockets. Tobacco cessation is a necessary intervention to motivate patients to quit smoking and achieve periodontal health. [ 5 ] Smoking also delays the healing process once debridement, scaling, root planing and adequate home care has been completed.
Healing of periodontal pockets are shown by a reduction in pocket depth. Although pocket depths can be reduced by decreasing inflammation, large changes will not occur. Two ways in which periodontal pocket reduction can occur is by either non-surgical periodontal therapy (NSPT) or surgical periodontal therapy. NSPT includes but is not limited to initial debridement, scaling, root planing, antibiotic treatment, and oral health education. If periodontal pocket depths are not controlled and maintained with NSPT during a re-evaluation appointment then surgical periodontal therapy is necessary. [ 2 ] Surgical periodontal therapy creates a stable and maintainable environment for the patient by eliminating pathological changes in the pockets. The overall purpose of surgical therapy is to eliminate the pathogenic plaque in pocket walls to get a stable and easily maintainable state. This can promote periodontal regeneration. [ 2 ]
Periodontal Scalers
Professional periodontal therapy includes initial debridement, scaling and root planing with specific periodontal instruments. These instruments include files, curettes, after fives and mini fives used for mechanical debridement. The shank of periodontal instruments can either be rigid, which works better with heavy and tenacious calculus or flexible for fine tuning and light deposit. [ 7 ]
Periodontal files are used to crush larger, tenacious deposits to prepare them for further debridement with a scaler, curette or ultrasonic scaler. They have a series of blades on a base, therefore they are not suitable for root planing and fine scaling. [ 7 ] Universal curettes are double-ended instruments with paired mirror working ends and a rounded toe. These instruments can be used on all surfaces of the tooth including root surfaces in a periodontal pocket. [ 8 ] Gracey curettes have a stronger, rigid shank and angulated working blades that are area specific. They are best for subgingival scaling and root planing because the offset blade allowing for greater adaptation. [ 7 ] After fives are similar to gracey's except they have an extended shank to allow extension into deeper pockets (>5mm). They also have a thinner blade for heavy or tenacious calculus. [ 7 ] Mini fives are a modification of after fives as their blades are half the length to allow for easier insertion and adaptation into deep pockets, furcations, developmental grooves and line angles. They also contribute to a reduction in tissue trauma. [ 7 ] Ultrasonic scalers move in an elliptical motion and do not have a cutting edge. They operate at a frequency of 3,000–8,000 cycles per second and use magnetostrictive or piezo-electric technology, thus helping remove plaque and calculus while reducing operator wrist fatigue. [ 9 ]
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The decay-missing-filled ( DMF ) index or decayed, missing, and filled teeth ( DMFT ) index is one of the most common methods in oral epidemiology for assessing dental caries prevalence as well as dental treatment needs among populations and has been used for about 75 years. [ 1 ] This index is based on in-field clinical examination of individuals by using a probe, mirror and cotton rolls, and simply counts the number of decayed, missing (due to caries only) and restored teeth. Another version proposed in 1931 [ 1 ] counts each affected surface, yielding a decayed, missing, and filled surfaces ( DMFS ) index. Statistics are available per populations according to age (e.g., "DMF of 12-year old children"). Because the DMF index is done without X-ray imaging, it underestimates real caries prevalence and treatment needs. [ 2 ]
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Decellularized homografts are donated human heart valves which have been modified via tissue engineering . Several techniques exist for decellularization with the majority based on detergent or enzymatic protocols which aim to eliminate all donor cells while preserving the mechanical properties of the remaining matrix. [ 1 ]
Aortic valve disease affects the valve between the left ventricle and the aorta , and can be present as a congenital condition at birth or caused by other factors. Several therapeutic options are open to patients once the indication for aortic valve replacement has been confirmed. One option is replacement using a mechanical valve . [ citation needed ]
This, however, necessitates a strict lifelong anticoagulation regime to avoid cerebral thromboembolism . These blood thinners hold an inherent risk for severe bleeding episodes, which affects both professional and leisure activities and the majority of patients opt to not use mechanical valves for this reason. [ citation needed ]
Biological prostheses , i.e. pericardial heart valves of animal origin ( xenogenic ), offer a viable alternative. However, in particular for young patients, it has been found that xenogenic valves do not provide satisfactory durability and rapid valve degeneration can occur within months. [ 2 ]
A further avenue open to patients is a so-called Ross operation , an extensive surgical procedure in which the diseased aortic valve is replaced by the patient's pulmonary valve ( autograft ). The pulmonary valve then needs to be replaced by a heart valve prosthesis. A drawback of this method is that it can frequently result in a "two-valve" diseased heart, as almost all autografts are impaired by progressive dilatation in the long term, and the pulmonary valve prosthesis, often a conventional cryopreserved homograft , is subject to the same rate of degeneration as all biological valves. This can thereby lead to frequent reoperations [ 3 ] which have a substantially higher mortality rate due to postoperative adhesions. [ 4 ]
The lack of durable heart valve prostheses for young patients has driven forward research in tissue engineering approaches for valve replacement. Current tissue-engineering concepts are based on either artificial polymeric or biological scaffolds, derived from donated human tissue ( allogeneic ) or animals (xenogenic). While more readily available, there have been reports of dramatic failure in the use of xenogeneic matrices in paediatric patients, leading to scepticism regarding their application. [ 5 ]
Total artificial tissue-engineered heart valve concepts are currently under development and would solve many unmet clinical demands, such as the permanent availability of different sizes and lengths. These concepts have shown good results in the technical implementation of valved polymeric conduit production and have successfully been used for in vitro and in vivo seeding of different (stem) cell lines. However, preclinical testing in long-term animal models has yet to deliver satisfactory results due to a lack of mechanical, leading to early failure of the valvular function. [ 6 ]
Aortic valve replacement using a homograft in orthotopic position was first performed over 50 years ago on 24 July 1962 by Donald Ross at Guy's Hospital , London and has been assessed in prospective randomized studies, e.g. in comparison to the Ross procedure. [ 7 ] Aortic valve replacement using conventional cryopreserved homografts is currently performed only in about 3% of all patients, mostly to treat acute aortic valve endocarditis .1 Severe calcification of conventional homografts frequently occurs and is the main reason for its restrictive use, however, current guidelines confirm homografts as a valid alternative for young patients requiring anatomical reconstruction of the outflow tract. [ citation needed ]
DPH have been clinically implanted since 2002 in paediatric patients. [ 8 ] The indications mainly include patients with pulmonary diseases such as pulmonary valve stenosis, atresia or insufficiency. They have shown excellent early to midterm clinical performance, challenging conventional cryopreserved homografts as the "gold standard" for pulmonary valve replacement in congenital heart disease. [ 9 ] [ 10 ] Compared to cryopreserved homograft, decellularized pulmonary homografts have shown less degeneration and had to be explanted less. [ 11 ] The main limitation is the low availability of such homografts and the higher costs.
DAH developed at Hannover Medical School (MHH) have shown sufficient mechanical stability for the systemic circulation at the greatest possible extent of antigen elimination and have been validated in long-term animal models. [ 12 ] The first DAH was implanted in human in the year 2008. [ 13 ]
A multicenter european study of aortic valve replacement with the use of DAH in 106 pediatric patients published in 2020 showed outcome data comparable to Ross procedure and mechanical aortic valve implantation and better results compared to cryopreserved homografts. In comparison to Ross procedure, early mortality rates were lower in DAH patients (2,2% versus 4,2%), however this trend was not statistically significant. Complications due to coronary reimplantation during DAH implantation occurred in 3.8% and progressive valve degeneration in 10%. [ 14 ]
A multicenter european study in both pediatric and adult patients compared DAH with Ross procedure and showed almost identical results regarding valve degeneration and freedom from explantation. [ 13 ]
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Decentralized Trials & Research Alliance ( DTRA ) is a 501(c)(3) nonprofit organization in the United States that works to make research participation accessible for all. DTRA works to accelerate the adoption of innovative research methods, including decentralized elements, by collaborating with a community of global stakeholders.
. [ 1 ]
Dr. Amir Kalali, M.D. and Craig Lipset are the organization's co-chairs and launched the DTRA on December 10, 2020. They discussed the challenges that decentralized research can address in a piece published in STAT on January 29, 2021, where they confirmed that membership in the organization had reached over 100 collaborating organizations that share the mission of DTRA. [ 2 ]
Disadvantaged communities have traditionally been largely underrepresented in clinical trials . [ 3 ] Decentralized research that leverages available communications, telemedicine , artificial intelligence and other technologies has been proposed as a way to help recruit a more broadly representative patient population by gender, ethnicity, age, geography, income and more.
MedCity News highlighted decentralized trials as one of the strategies that would make 2021 a "banner year" for life science industries, and cited the DTRA as uniting "industry stakeholders with a singular mission to make clinical trial participation widely accessible by advancing policies, research practices and new technologies in decentralized clinical research". [ 4 ]
As a result of travel restrictions and the social distancing required to mitigate against the COVID-19 pandemic , clinical trials were affected worldwide. According to a study published in June 2020 by researchers at the University of Texas MD Anderson Cancer Center , of the 1,052 clinical trials that were suspended during the period from March 1 to April 26, 2020, at least 905 were suspended because of COVID-19. [ 5 ]
It has been noted that the impacts of COVID-19 may have set back clinical trial research several years [ 6 ] because of prospective patients' reluctance or inability to schedule physical visits at research locations. Decentralized clinical trials have emerged as an answer to that problem, as outlined in a report from Oracle Health Sciences. [ 7 ]
Kalali told MobiHealth News in December 2021, "The benefits of decentralized research methodologies have been apparent for some time, but adoption has been slow due to many factors including culture and the lack of a forum for stakeholders to collaborate. The COVID-19 pandemic has forced organizations to adopt decentralized methodologies, which have the potential to broadly accelerate drug development." [ 8 ]
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Decidualization is a process that results in significant changes to cells of the endometrium in preparation for, and during, pregnancy . This includes morphological and functional changes (the decidual reaction ) to endometrial stromal cells (ESCs), the presence of decidual white blood cells (leukocytes), and vascular changes to maternal arteries. The sum of these changes results in the endometrium changing into a structure called the decidua . In humans, the decidua is shed during childbirth . [ 1 ]
Decidualization plays an important role in promoting placenta formation between a mother and her fetus by mediating the invasiveness of trophoblast cells. It also triggers the production of cellular and molecular factors that result in structural changes, or remodeling, of maternal spiral arteries . Decidualization is required in some mammalian species where embryo implantation and trophoblast cell invasion of the endometrium occurs, also known as hemochorial placentation . This allows maternal blood to come into direct contact with the fetal chorion , a membrane between the fetal and maternal tissues, and allows for nutrient and gas exchange. However, decidualization-like reactions have also been observed in some species that don't display hemochorial placentation. [ 2 ]
In humans, decidualization occurs after ovulation during the menstrual cycle . After implantation of the embryo, the decidua further develops to mediate the process of placentation. In the event no embryo is implanted, the decidualized endometrial lining is shed or, as is the case with species that follow the estrous cycle , absorbed. [ 1 ] In menstruating species , decidualization is spontaneous and occurs as a result of maternal hormones. In non-menstruating species, decidualization is non-spontaneous, meaning it only happens after there are external signals from an implanted embryo. [ 3 ]
After ovulation, the high levels of progesterone initiate the molecular changes leading to decidualization. The process triggers an influx of decidual leukocytes along with morphological and functional changes of ESCs. The changes in the ESCs result in the endometrium developing a secretory lining that produces a variety of proteins, cytokines , and growth factors . These secreted factors will regulate the invasiveness of trophoblast cells that eventually form the placental connection if an embryo implants into the decidua. [ 4 ]
One of the identifying features of the decidua is the presence of large numbers of leukocytes that are mostly made up of specialized uterine natural killer (uNK) cells [ 5 ] and some dendritic cells . As the fetus consists of both maternal and paternal DNA , the decidual leukocytes play a role in suppressing the immune response of the mother to prevent treating the fetus as genetically foreign. Outside of their immune functions, the uNK cells and dendritic cells also act as regulators of maternal spiral artery remodeling and ESC differentiation. [ 6 ]
ESCs are the connective tissue cells of the endometrium that are fibroblastic in appearance. However, decidualization causes them to swell up and adopt an epithelial cell-like appearance due to the accumulation of glycogen and lipid droplets. Furthermore, they begin secreting cytokines, growth factors, and proteins like IGFBP1 and prolactin , along with extracellular matrix (ECM) proteins such as fibronectin and laminin . The increased production of these ECM proteins turns the endometrium into the dense structure known as the decidua, which produces factors that promote trophoblast attachment and inhibit overly aggressive invasion. [ 7 ]
The decidual reaction is seen in very early pregnancy in the generalized area where the blastocyst contacts the endometrial decidua . It consists of an increase in secretory functions of the endometrium at the area of implantation, as well as a surrounding stroma that becomes edematous . [ 8 ]
The decidual reaction occurs only in humans and a few other species. The decidual reaction and decidua are not required for implantation. Evidence can be taken from the fact that in ectopic pregnancies and hysterectomies , implantation can occur anywhere in the abdomino-pelvic cavity. [ 9 ]
Abnormalities in decidualization have been implicated in diseases such as endometriosis , in which impaired decidualization leads to ectopic uterine tissue growth. Lack of decidualization has also been linked to higher rates of miscarriage . [ 10 ]
Chronic deciduitis , a chronic inflammation of the decidua, has been linked with premature birth . [ 11 ]
The decidualization process is initiated by progesterone, but this requires cyclic adenosine monophosphate (cAMP) to act as the initial signalling molecule to sensitize endometrial cells to progesterone. Consequently, human ESCs have been decidualized in culture with chemical analogs of cAMP and progesterone together. In vitro decidualization results in similar morphological changes to the human ESCs as well as upregulated production of decidualization markers such as IGFBP1 and prolactin . [ 7 ]
Mouse models have been extensively used for the identification of the molecular factors required for and involved in decidualization. [ 12 ]
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In medicine , decompensation is the functional deterioration of a structure or system that had been previously working with the help of compensation. Decompensation may occur due to fatigue , stress , illness, or old age. When a system is "compensated," it is able to function despite stressors or defects. Decompensation describes an inability to compensate for these deficiencies. It is a general term commonly used in medicine to describe a variety of situations.
For example, cardiac decompensation may refer to the failure of the heart to maintain adequate blood circulation , after long-standing (previously compensated) vascular disease (see heart failure ). Short-term treatment of cardiac decompensation can be achieved through administration of dobutamine , resulting in an increase in heart contractility via an inotropic effect. [ 1 ]
Kidney failure can also occur following a slow degradation of kidney function due to an underlying untreated illness; the symptoms of the latter can then become much more severe due to the lack of efficient compensation by the kidney.
In psychology , the term refers to an individual's loss of healthy defense mechanisms in response to stress , resulting in personality disturbance or psychological imbalance. [ 2 ] [ 3 ] [ 4 ]
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In medicine, decompression refers to the removal or repositioning of any structure compressing any other structure. [ citation needed ]
Common examples include decompressive craniectomy (removal of part of the skull to relieve pressure on the brain), a spinal decompression to relieve pressure on nerve roots , and a nerve decompression for peripheral nerve entrapments . [ 1 ] [ 2 ]
This surgery article is a stub . You can help Wikipedia by expanding it .
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Deep brain stimulation ( DBS ) is a type of neurostimulation therapy in which an implantable pulse generator is surgically implanted below the skin of the chest and connected by leads to the brain to deliver controlled electrical impulses . These charges therapeutically disrupt and promote dysfunctional nervous system circuits bidirectionally in both ante- and retrograde directions. [ 1 ] Though first developed for Parkinsonian tremor, the technology has since been adapted to a wide variety of chronic neurologic disorders. [ 2 ]
The usage of electrical stimulation to treat neurologic disorders dates back thousands of years to ancient Greece and dynastic Egypt . The distinguishing feature of DBS, however, is that by taking advantage of the portability of lithium-ion battery technology, it is able to be used long term without the patient having to be hardwired to a stationary energy source . This has given it far more practical therapeutic application as compared its earlier non mobile predecessors. [ 3 ]
The exact mechanisms of DBS are complex and not fully understood, though it is thought to mimic the effects of lesioning by disrupting pathologically elevated and oversynchronized informational flow in misfiring brain networks. [ 4 ] [ 5 ] [ 6 ] As opposed to permanent ablation, the effect can be reversed by turning off the DBS device. [ 7 ] Common targets include the globus pallidus, ventral nuclear group of the thalamus , internal capsule and subthalamic nucleus . It is one of few neurosurgical procedures that allows blinded studies , [ 8 ] though most studies to date have not taken advantage of this discriminant. [ 9 ]
Since its introduction in the late 1980s, DBS has become the major research hotspot for surgical treatment of tremor in Parkinson's disease, [ 10 ] and the preferred surgical treatment for Parkinson's, essential tremor and dystonia. Its indications have since extended to include obsessive-compulsive disorder , refractory epilepsy , chronic pain, Tourette's syndrome , and cluster headache . [ 11 ] In the past three decades, more than 244,000 patients worldwide have
been implanted with DBS. [ 12 ] [ 13 ]
DBS has been approved by the Food and Drug Administration as a treatment for essential and Parkinsonian tremor since 1997 and for Parkinson's disease since 2002. [ 14 ] It was approved as a humanitarian device exemption for dystonia in 2003, [ 15 ] obsessive–compulsive disorder (OCD) in 2009 [ 16 ] and epilepsy in 2018. [ 17 ] [ 18 ] DBS has been studied in clinical trials as a potential treatment for chronic pain , affective disorders, depression , Alzheimer's disease and drug addiction , amongst others.
The DBS system consists of three components: a neurostimulator known as an implanted pulse generator (IPG), its leads and an extension. The neurostimulator has titanium housing and a battery that sends electrical pulses to the brain to interfere with neural activity through deafferentation .
The leads are two coiled wires insulated in polyurethane with four platinum-iridium electrodes that allow delivery of electric charge from the battery pack implanted in the chest wall. The battery is usually situated subcutaneously below the clavicle and rarely in the abdomen . The leads, in turn, are connected to the battery by an insulated extension wire which travels from the chest wall superiorly along the back of the neck below the skin, behind the ear, and finally enters the skull through a surgically made burr hole to terminate in the deep nuclei of the brain. [ 19 ] Microelectrodes (usually 1–5) are delivered through the burr holes. A combination of microelectrode recordings, microstimulation, macrostimulation, and neurophysiological mapping at the level of single neurons or local neuronal populations through local field potential analyses are used to increase specificity of placement for the most precise neurophysiologic effect possible. [ 2 ]
After surgery, battery dosage is titrated to individual symptoms, a process which requires repeat visits to a clinician for readjustment. [ 20 ]
DBS leads are placed in the brain according to the specific symptoms to be addresses and implantation may take place under local or general anesthesia. A hole about 14 mm in diameter is drilled in the skull and the probe electrode is inserted stereotactically , using either frame-based or frameless stereotaxis. [ 21 ] During the awake procedure with local anesthesia, feedback from the individual is used to determine the optimal placement of the permanent electrode. During the asleep procedure, intraoperative MRI is used to image the brain during device placement. [ 22 ] The installation of the IPG and extension leads occurs under general anesthesia. [ 23 ]
The surgery is utilized in Parkinson's to help with motor symptoms and reduce dopaminergic medication, but it does not usually help with axial non motor symptoms such as posture, gait instability, mechanical falls and can have adverse effects such as loss of cognitive function, depression, apathy, and suicide. [ 24 ]
Selection of the correct individual to have the procedure is a complicated process. Multiple clinical characteristics are taken into account, including identifying the most troubling symptoms, current medications and comorbidities . Surgery and aftercare are typically managed by multidisciplinary teams at specialized institutions. The right side of the brain is stimulated to address symptoms on the left side of the body and vice versa. [ 2 ]
The surgery is usually contraindicated in individuals who have dementia, suffer from depression or other psychiatric disorders, or who have frequent falls despite being in their best on-drug state. Systematic assessment of benign or even beneficial precursor symptoms of a hyperdopaminergic syndrome such as do-it-yourself activities, creativity, and nocturnal hyperactivity also help prevent the devastating behavioral addictions or impulse-control disorders that can occur after the procedure. [ 1 ]
Stereotactic MRI is used to localize the target nuclei, though it is more susceptible to anatomic field distortion than ventriculography , the latter is not done anymore as it is considered too invasive for its benefit with anatomic precision and the advent of high Tesla intraoperative MRIs. The awake variant of the surgery allows symptom testing in real time. Several motor symptoms, except gait, can be evaluated, but wrist rigidity is often done because it does not require the patient's active participation and can be scored in the operating room by use of a semi-quantitative scale. Speech and tremor can also be assessed in real time, though speech may be difficult to evaluate due to fatigue that occurs for the patient during the later hours of the procedure. When the best tract has been identified, the corresponding microelectrode is removed and replaced by a permanent lead. [ 25 ] Because of its larger size, the GPi does not necessarily require microrecording prior to placement of a chronic lead, leading to a reduced risk of hemorrhage or cognitive deficit. [ 26 ]
Post operative programming after DBS is complex and personalized, but poorly standardized across institutions despite decades of research. In practice, it is still an iterative trial and error based process. Parameters are initially set based on experience and then adjusted according to individual clinical response. Though this works for symptoms that respond quickly to stimulation such as tremor, for other symptoms with a more delayed or nuance response profile, it carries risk of chronic overstimulation leading to adverse events such as impairment of gait and speech. Inappropriate stimulation can also cause non-motor side effects such as impaired cognition or manic disinhibition. Such effects are usually energy-dependent and reversible with adjustment. [ 27 ] Though it is recognized that the most important parameter in stimulation is frequency over voltage or pulse-width, there is no global consensus about the initial parameters of DBS, nor is there a protocol for stimulation options in case of poor outcome. [ 26 ]
In distinction to DBS, although surgical lesions in the globus pallidus improve dyskinesias and Parkinsonian symptoms, they are irreversible and carry a risk of permanent neurologic deficit. Similarly, lesions of the STN improve parkinsonian symptoms, but can cause hemiballism. [ 28 ]
DBS is used to manage Parkinson's disease symptoms that are resistant to medication. [ 19 ] [ 29 ] The ideal candidate for DBS is one that does not have dementia, is not severely depressed, and who does not have falls while being in their best on-drug state, but who do have disabling motor fluctuations or dyskinesias that necessitate bilateral surgery. [ 1 ] It is treated by applying high-frequency (> 100 Hz) stimulation to target structures in the deep subcortical white matter of the basal ganglia. Frequently used targets include the subthalamic nucleus (STN), globus pallidus internus (GPi) and ventrointermediate nucleus of the thalamus (VIM). Neurostimulation can be considered for people who have Parkinson's with motor fluctuations and tremors inadequately controlled by medication, or to those who are intolerant to medication as long as they do not have severe neuropsychiatric problems. [ 30 ] A >30% degree of symptom responsiveness to dopamine is a strong predictor of a good response to DBS surgery, though it is not mandatory. This has led most centers to require evaluation both on and off dopamine prior to the procedure to increase the likelihood of success. [ 31 ] DBS is not currently considered to be a disease-modifying treatment . [ 32 ] Shorter disease duration pre-operatively tends to lead to better results after surgery. [ citation needed ] The response from DBS is only as good as the patient's best "on" time, with the exception of tremor, which may show greater improvement than that seen with medication. [ 33 ]
Initially, the STN was considered superior to the GPi for tremor reduction, rigidity, and bradykinesia as well as enabling greater reductions in dopaminergic medication following surgery and the GPi superior for reducing dyskinesia. [ 34 ] Longer term studies have found the two targets to be equivalent in motor symptoms, but both relatively ineffective for cognitive and axial motor symptoms of Parkinson's disease such as gait, posture and speech. [ 24 ]
Comparison of the STN and GPi in DBS is also inconsistent due to different medical centers tending to have better results with specific nuclei and studies focusing on short as opposed to long term results. The three most commonly studied targets to date are the globus pallidus internus (GPi), subthalamic nucleus (STN) and ventrointermediate nucleus (VIM). DBS has also been compared to infusion therapies such as intestinal levodopa and subcutaneous apomorphine. The vast majority of DBS research to date has been on the subthalamic nucleus. [ 1 ] [ 33 ]
A large inclusive meta analysis that compared the STN to the GPi between 6–12 months found the STN to be superior for motor symptoms and activities of daily living, but found studies to be too heterogenous or insufficient to compare the targets for dyskinesia, daily off time, quality of life, or levodopa reduction. [ 35 ]
In longer term studies, however, the impact of the two nuclei on motor symptoms equalizes, but the GPi becomes superior to the STN for improvement of activities of daily living and dyskinesia. Conversely, the STN is superior to the GPi for reduction of dopamine medication. Both short and long term analyses showed the targets to be equivalent as far as adverse events. [ 36 ]
A meta-regression showed that combined with levodopa, the GPi preserved postural instability and gait disability better than the STN. [ 37 ] Gait or dysarthria are often unaffected or even worsened by DBS, particularly in ON medication state. When comparing 60 vs 130 Hz, 60 Hz frequency substantially reduced gait freezing, but subsequent studies have not replicated this, often finding worsening motor symptoms and less gait benefit with lower frequencies. A recent retrospective study showed 64% of patients had subjective improvement of axial symptoms when switching from higher to lower frequency stimulation with increased voltage. [ 38 ]
An indirect systems analysis compared the DBS to the STN, DBS of the GPi, subthalamotomy, jejunal levodopa, and subcutaneous apomorphine, in the first 6 months. Different results were seen depending on dopamine responsivity and whether motor symptoms (UPDRS II) or activities of daily living (UPDRS III) were assessed: [ 39 ]
A Bayesian analysis utilizing the minimal clinically important difference (MCID) compared DBS (predominantly of the STN and to a lesser degree GPi) to infusions of intestinal dopamine, apomorphine, and medical therapy. The analysis was significantly limited because it followed dopamine prospectively only to 3 months but other therapies such as DBS to five years. There was also a 10-fold difference in the quantity of DBS patients as compared to other therapies. They found LCIG to be similar to DBS, though with a wider confidence interval for dopamine due to lower quantity of participants. In the non-prospective cohort groups, LCIG lost its benefit for activities of daily living after 2–3 years. Both therapies were superior to apomorphine and best medical therapy for activities of daily living and "on" time for dopamine responsiveness, while DBS had the highest rate of adverse effects, particularly surgical and neuropsychiatric. LCIG was similar to DBS in effect on quality of life, though the analysis for levodopa was again underpowered. [ 40 ]
A short term meta-analysis that primarily looked at changes within the first year found the STN to be better than the GPi for motor symptoms and activities of daily living, but they included studies that analyzed the targets separately. For activities of daily living (UPDRS II) with DBS during the dopamine unresponsive state, patients improved 50% with STN but only 20% with GPi. For motor symptoms (UPDRS III), there was a 50% with STN but only 30% with GPi-DBS. STN reduced dyskinesia by 64%, OFF time by 69%, improved QOL by 20%, Levodopa dose was reduced 50%. GPi insufficient data to assess for dyskinesia OFF time, and levodopa reduction. [ 35 ]
A meta analysis following 1148 patients for a year and with an equal distribution between groups found that both STN and GPi improved motor function, but in different ways. GPi preserved postural instability and gait disability better than STN. GPi did not produce any significant improvement over STN in motor symptoms during the on state, though a point estimate favored the use of GPi. Motor symptoms in the off state showed that STN did not produce any significant improvement over GPi, though again a point estimate favored the use of STN. STN had a larger dopamine reduction than GPi, while GPi improved depression more than STN after surgery. Compared to the GPi, the STN showed more improvement in off state motor symptoms and activities of daily living. Conversely, the GPi was better than the STN for on state motor symptoms and activities of daily living, [ 41 ] similar to data from the Netherlands NSTAPS study. [ 42 ]
In the longer term and with trials comparing targets head to head, STN and GPi were found to be equal for activities of daily living in the off state and for motor function in both the on and off state. GPi had less dyskinesia and improved activities of daily living in the on state for advanced Parkinson's disease. There was no significant difference between the STN and GPi for motor scores during the on medication phase. [ 36 ] The GPi reduces dyskinesia through a medication independent mechanism and has less neuropsychiatric effects (ie. depression, apathy, and suicide). [ 1 ] The long term duration of therapeutic benefit has not been clearly established, though reports suggest that individuals may have sustained clinical improvement for at least 10 years. [ 44 ]
There is usually a greater improvement in akinesia targeting the STN as compared to the pallidus, while there may be a wearing off of the initially excellent antiakinetic effect with pallidal stimulation after 5 years. [ 1 ] Conversely, deep brain stimulation of the GPi has consistently shown superior and sustained reduction in dyskinesia. [ 45 ] Although overall gait has been reported to improve consistently after DBS, postural instability, which can affect gait, is less likely to respond. A greater number of falls occur after surgery with DBS of the STN as compared to the GPi. [ 45 ]
GPi programming requires less-intensive monitoring of medication and stimulation adjustments in most patients. The STN has multiple motor, cognitive, and limbic pathways that are not completely anatomically segregated. In contrast, the larger size of the GPi motor region reduces the likelihood of the current spreading into adjacent functional areas or to the internal capsule, causing less neuropsychological side effects, [ 45 ] long term comorbidities [ 46 ] and global cognitive decline. [ 47 ] This could be due to the GPi being separate from the limbic component of the STN, the greater dopamine reduction allowed with STN stimulation, or that the vast preponderance of studies in the literature are about the STN, causing an inadvertent publication bias . [ 1 ] [ 33 ]
For individuals with unsatisfactory outcomes after DBS in Parkinson's, lead revision resulted in 30% improvement when leads were repositioned from the GPi to the STN, and no improvement when repositioned from the GPi to the STN. The cases in which improvement occurred were when there was clear evidence of lead mispositioning. [ 48 ]
A Bayesian analysis comparing DBS with intestinal levodopa, subcutaneous apomorphine and best medical therapy found DBS and intestinal levodopa to be the superior treatments, though it did not distinguish specific nuclei as DBS targets. In the setting of this limitation, they found intestinal levodopa being the best at improving quality of life more and DBS being the best at reducing off time. [ 49 ] A more specific Bayesian Monte Carlo analysis comparing individual nuclei found bilateral STN, GPi and intrajejunal levodopa to be better than either subcutaneous apomorphine or best medical therapy. Amongst the three, STN had the greatest likelihood of improvement, though it was not statistically significant. [ 39 ]
The overall rate of intracranial hemorrhage at surgery is 5%, with symptomatic hemorrhage in 2% and hemorrhage causing permanent deficit or death in 1%. Stroke occurred in 1%, infection in 8%, lead erosion without infection in 2%, lead fracture in 8%, lead migration in 10%, and death in 2%. [ 50 ] Additional adverse events include the need for revision in 5%, lead malposition 3%, surgical site complications 3%, hardware-related complications 2%, and seizure 2%. There was a significant non-linear increase with each additional track, for example in situations when leads needed to be repositioned or in multiple target procedures. [ 51 ]
In the short term, studies have reported a risk of cerebral hemorrhage of 1.4%, hardware infection 1.1%, post operative mental status change occurred in 4.6%, and seizure occurred in 1.4%; in the longer term adverse events include confusion at 3.9%, hardware infection at 4.5%, implantable pulse generator malfunction 1.4%. [ 31 ]
Image guided lead placement tends to have shorter surgical times and lower rates of intracranial hemorrhage. Combined methods that use both microelectrode recording and image guidance are not as brief in operating room time and have a higher risk of hemorrhage, but result in more accurate lead placement. [ 52 ]
More than half of caregivers rate DBS to the STN negatively at one year after surgery. Some of the symptoms caregivers were unhappy about included mania, apathy, depression, impulsivity, compulsivity, aggressiveness and disinhibition. Children of individuals with Parkinson's tended to be happier than spouses. Concerns raised by caregivers included dyskinesia impacting the physiognomy of their loved ones, leading to the inability to control movements and a glassy-eyed appearance. Family relationships changed between partners and children were also stressed because the empathy and self-awareness of patients diminished as they lost their sense of reality over time. The degree of dissatisfaction did not appear to correlate with the success of the surgery as far as motor symptoms, which generally improved. [ 53 ] Similar dissatisfaction persisted at two years in a separate analysis, with almost 60% of caregivers continuing to report dissatisfaction. [ 54 ]
Despite the high dissatisfaction rate of caregivers with surgery, additional measures such as caregiver burden, psychiatric and cognitive functioning and caregiver quality of life remained relatively stable. In addition, both patients and caregivers reported that they would opt for DBS again. [ 55 ]
DBS for the GPi has a direct effect on dyskinesia reduction and is more effective than DBS to the STN, with the latter being dependent on dopamine reduction. As such, pallidal surgery is indicated when dyskinesia is a dose-limiting factor preventing higher levels of needed dopaminergic therapy. STN stimulation can also induce persistent contralateral dyskinesia, and in some cases require a repeat surgery to implant GPi rescue leads. [ 56 ]
The effect on gait is inconsistent, with multiple studies showing worsening of gait, balance and speech as potential complications of DBS, [ 57 ] with DBS to the STN carrying a higher risk of gait dysfunction. [ 58 ] A study delineating adverse effects by time found that though DBS mitigated gait symptoms after surgery, postoperative postural instability and gait disorders worsened in the long term. [ 43 ]
When axial symptoms are responsive to dopaminergic medications, they are likely to improve with DBS. Several studies reported gait improvement with either STN or GPi DBS, including reduction in freezing of gait, though GPi is generally associated with preserved gait function compared with STN, [ 45 ] and generally more favorable for those with axial symptoms, gait issues, depression, and word fluency problems. [ 38 ]
Electromyography studies of the lower limbs in the study of gait have shown that dopaminergic medication increases distal lower limb muscle activity while STN DBS increases both proximal and distal lower limb muscle activity. [ 59 ]
In the context of chronic levodopa therapy, the most relevant effect of STN neurostimulation is improvement of motor function during the off state, the period during which symptoms are non responsive to dopamine. [ 60 ]
Benefit after STN DBS has been reported in nonmotor fluctuating symptoms, including urinary dysfunction, sialorrhea , sleep, PD-related pain, and off-period sweating. [ 45 ]
A meta analysis predominantly looking at DBS to the STN found it led to less urinary urgency, increased bladder capacity and maximum urinary flow rate. [ 61 ] Another meta analysis study further distinguished effects by target subgroups, finding that DBS of the GPi and STN have an inhibitory effect on detrusor function at the pelvic floor , leading to an increase in functional urine capacity and retention. DBS of the VIM has the opposite effect, leading to detrusor excitation and improved voiding. [ 62 ]
Long term mortality rates with DBS measure up to 17% with an average age at death of 71 years, [ 63 ] with the risk of mortality being more pronounced in cases of advanced disease. [ 64 ] DBS of the STN has a three-fold increased mortality compared to the GPi in Parkinson's patients, with most deaths being due to postoperative complications and not directly related to the stimulation itself. [ 65 ]
Neurologic side effects of deep-brain stimulation include cognitive impairment, memory deficits, difficulties with speech, disequilibrium , dysphagia , and motor and sensory disturbances. Potential psychological side effects include mania, depression, apathy, laughter, crying, panic, fear, anxiety, and suicidal ideation. It is important that individuals be screened before and after the procedure for suicidal ideation, impulsivity (e.g., gambling, impulsive shopping, hypersexuality, etc.), and dopamine dysregulation, an addiction-like syndrome associated with the use of levodopa. [ 44 ] The STN, at approximately 160 mm 3 , is one-third the size of the GPi (on average 480 mm 3 ) and has multiple nearby non-motor pathways, the inadvertent activation of which has been suggested to be the cause of emotional dysregulation that can be seen when it is targetted. [ 43 ]
Cognitively, decreased verbal fluency and an increased risk for dementia can occur due to the wire passing through the prefrontal cortex and caudate nucleus , a path more often seen with subthalamic stimulation than GPi due to its more inferomedial positioning. Long-term follow-up showed a more rapid decline in cognitive function with treatment targeting the subthalamic nucleus than that targeting the GPi. [ 44 ] Without surgery, the risk of developing dementia in Parkinson's is approximately 10% per year with a mean prevalence of 40% across the disease [ 66 ] and a lifetime incidence of 80%. [ 67 ] One large meta-analysis suggested the likelihood of dementia increases by 2.5 fold, though the subpopulation in the analysis was limited in quantity. [ 68 ] Another meta analysis suggested the incidence as the same. [ 67 ] Additional cognitive changes after STN in Parkinson's were mixed and included an improvement in reaction time , but also more errors in tasks involving response inhibition . [ 1 ]
Potential neuropsychiatric side effects in the short term can occur due to lesional effects, causing disinhibition, mania, hallucinations , hypersexuality , and euphoria. In the long term, this tendency inverts and can evolve into apathy , depression and even suicidal ideation. Some studies report a prevalence of apathy after surgery as high as 70%. [ 69 ] These effects can be due to misplacement of electrodes, miscalibration, or even well placed electrodes that inadvertently stimulate adjacent limbic circuits adjacent to the target nuclei. Though dopamine withdrawal syndrome due to the reduced dose of levodopa required after surgery (typically 70%) could contribute to these findings, it does not completely account for them. [ 70 ] [ 1 ]
The majority of studies indicate an increased risk of suicidal ideation and suicide attempts after treatment with DBS. [ 70 ] [ 71 ] Concerningly, though preoperative screening for depression and suicide are done to mitigate this risk, some studies have shown no evident difference in pre-operative depressive or cognitive status between suicidal and nonsuicidal individuals after surgery. [ 72 ] The risk of suicide is more pronounced with treatment to the STN than the pallidus, [ 70 ] [ 73 ] with studies as soon as 6 months showing increased proxy symptoms of suicide such as depression, isolation, tearfulness, anger, anxiety and hallucinations. [ 74 ] As with other neuropsychiatric effects that are more common with the STN, it is thought to be due to a combination of the levodopa dose reduction that occurs after surgery, adjacent subthalamic limbic circuit activation and disinhibition. [ 70 ]
Both depression [ 75 ] and euphoria [ 76 ] have been reported after DBS. Comparative studies between the STN and GPi have suggested higher depression rates for the STN. [ 45 ] With acute neurostimulation to the STN, depression can occur after left sided stimuation, whereas right sided stimulation can produce mirthful laughter. [ 77 ]
The improvement in motor symptoms but progressive deterioration of axial symptoms such as gait, vocal control, and neuropsychiatric side effects has led to a new phenotype of Parkinson's patient in the long term with mitigated or well controlled non axial motor symptoms, but with progressive worsening of axial motor symptoms (bradykinesia, dysarthria, postural instability, freezing of gait) and cognitive symptoms such as dementia and hallucinations. [ 24 ]
At baseline, the total lifetime risk of suicide in Parkinson's at baseline is 22% for ideation and 1% for attempts, with the general population at 13% ideation and 5% attempts. [ 78 ]
Parkinson's is often characterized by camptocormia , a classic stooped kyphotic posture that develops as the disease progresses as well as Pisa syndrome , characterized by a persistent tilted posture. The impact of DBS to the STN or GPi on posture in Parkinson's have been heterogenous and inconsistent at best. [ 79 ] Though some studies have shown positive effect, the quality of evidence is quite low. [ 80 ]
The pedunculopontine nucleus (PPN) is being studied as a target for postural instability and gait freezing , but clinical research is still in its early stages. [ 81 ] It is located in the mesopontine tegmentum next to the crossing of the superior cerebellar peduncle and is theorized to play a role in reflex reactions, sleep-wake cycles, posture and gait. [ 81 ] It is inhibited by the GPi while the STN excites it. [ 43 ] Freezing, as part of the pattern of akinesia, usually responds to levodopa. When freezing of gait persists, and is not improved by drugs, it is usually not improved by STN stimulation. [ 25 ] The loss of verbal fluency after PPN or VIM stimulation is greater than even that seen with the STN. [ 82 ]
A study comparing quality of life and adverse affects from patient perspective found that DBS had a more positive effect on quality of life than subcutaneous apomorphine, intestinal dopamine and best medical therapy, but also the highest rate of adverse effects. [ 40 ] DBS has been found to be superior to best medical therapy in impact on quality of life, though no study to date has shown to favor the GPi or STN specifically. [ 45 ] [ 83 ] A Bayesian analysis found intestinal dopamine has been shown to be superior to both DBS and best medical therapy for quality of life. [ 84 ] Younger age, early onset of Parkinson's, less dyskinesia, and higher quality of life before surgery predict higher quality of life following the procedure. [ 85 ]
The effects of DBS on sleep are heterogenous but it generally improves in quality over time. [ 86 ] There is an increase of complex behavior during REM sleep after surgery independent of DBS target, while REM sleep without atonia increases with STN and decreases with GPi. [ 87 ]
Almost 40% of patients develop speech impairment after DBS to the STN, with only 10% improving after reprogramming. [ 88 ] DBS to the GPi improves speech, in contrast to the STN, thalamus or zona incerta. [ 89 ] Up to 33% of patients can develop problems with speech after bilateral DBS to the STN, both by formal metrics [ 90 ] and as subjectively reported by individuals and their families. [ 91 ] This is less than that seen after thalamotomy (40%). The numbers are significantly lower for unilateral treatment, at 10-15%, but the symptomatic improvement with this is also one-sided, making it more appropriate for individuals with asymmetric disease. [ 90 ]
Speech impairment occurs in up to 20% of patients with DBS to the VIM of the thalamus. Focused ultrasound, by comparison, causes speech impairment in 15% of patients when done unilaterally and 40% when bilateral. [ 92 ]
Swallowing function after DBS can be impacted, analysis showing that it is either stable or improved after DBS to the GPi and has more variable effect after DBS to the STN, possibly worsening in on medication states, but stable or improved in off states. [ 93 ]
Speech disorders are more common after STN surgery, though dysphagia is more common after DBS to the GPi, an important finding because aspiration pneumonia is the most common cause of death in Parkinson's. The two nuclei have differing effects on the pedunculopontine nucleus, which in turn affects swallowing through the solitary nucleus . The GPi inhibits the PPN, while the STN excites it. [ 43 ]
For Parkinson's tremor alone, DBS has similar efficacy to MR guided focused ultrasound. [ 94 ] DBS of the VIM is more commonly done with tremor-dominant variants of Parkinson's and essential tremor . It can cause dysarthria in about 20% of patients. [ 77 ] A Bayesian meta-analysis comparing multiple targets found STN DBS to be best for motor symptoms over the GPi and caudal zona incerta, but DBS as similar in efficacy to MR guided focused ultrasound for essential tremor. [ 94 ] DBS of the subthalamic nucleus has a more sudden effect on tremor, while tremor reduction in GPi can be delayed. [ citation needed ]
A forest plot meta analysis found that DBS targeted at GPi and STN in the on-medication phase were similar; however, in the off-medication phase, Vim-targeted DBS was the superior target and could be a choice as a DBS target for tremor-dominant Parkinsonism. [ 95 ]
In trials on interventions, symptom scales such as the Unified Parkinson's Disease Rating Scale (UPDRS III) are typically used. These metrics measure motor function with a score from 0 to 108. Alternatively, the 39-item Parkinson's disease questionnaire (PDQ-39) has been utilized to measure disease specific quality of life with a score between 0 and 100. The effectiveness of an intervention is usually based on comparison of these scores in treatment and control groups . It has been pointed out that a statistically significant numerical difference in a scale or questionnaire does not necessarily translate to a clinically meaningful impact for the individual. [ 96 ] Beyond this, the scales can be subjective and susceptible to placebo effects and physician bias. [ 77 ] The minimal important difference (MID) or minimal clinically important difference (MCID) has been suggested as a more pragmatic metric to standardize the clinical impact of an intervention, though it has not yet been widely adopted. It is defined as the smallest difference in symptom scores that an individual would consider clinically meaningful. [ 97 ]
Essential tremor, the most common movement disorder, is a chronic condition characterized by involuntary and rhythmic shaking. [ 98 ] It was the first indication to be approved for DBS (alongside Parkinsonian tremor) and before DBS had a long history of being treated with ablative brain lesioning. [ 99 ]
Frequencies above 100 Hz are most effective for cessation of tremor, while lower frequencies have less effect. [ 100 ] In clinical practice, frequencies between 80 and 180 Hz are typically applied. DBS electrodes commonly target the ventrointermediate nucleus of the thalamus (VIM) or ventrally adjacent areas in the zona incerta or posterior thalamus. Multiple targets along the circuitry of the cerebellothalamic pathway (also referred to as the dentatorubrothalamic or dentatothalamic tract) have been shown to have similar therapeutic effect. [ 101 ] [ 102 ] [ 103 ]
Possible side effects of DBS for essential tremor include speech difficulties and paresthesia. Similar targets have previously been applied to treat essential tremor using surgical lesioning, for instance using MR-guided Focused Ultrasound , Gamma-Knife Radiosurgery or conventional radiofrequency lesioning . The annual volume of MRgFUS thalamotomies has overtaken DBS for treatment of tremor. [ 104 ]
DBS is also used to treat dystonia , a movement disorder characterized by sustained repetitive muscle contractions causing painful abnormal postures and involuntary movements. DBS is effective in treating primary generalized dystonia, and also used for focal variants such as cervical and task-specific dystonias. In studies targeting the GPi using high frequency DBS there were improvements of ~45% within the first six months of treatment. [ 105 ]
In contrast to some symptoms in Parkinson's disease or essential tremor, improvements in dystonia are appear over weeks to months. The delay is thought to be a consequence of the complexity of dystonic motor circuits and the time required for long-term neuroplastic remodeling. Despite its slower onset, many individuals experience lasting and meaningful improvements.
Recent large-scale mapping efforts have suggested slightly different optimal target sites for different kinds of dystonia. [ 106 ] [ 107 ] [ 108 ] [ 109 ]
DBS for OCD, [ 110 ] Tourette's Syndrome, [ 111 ] and dystonia were first completed in 1999. [ 112 ] The original target studied was the anterior limb of the internal capsule , [ 110 ] though multiple sites have been probed since then. Within the internal capsule, large probabilistic mapping trials have identified two therapeutic sites, [ 113 ] one thought to corresponding to the direct pathway in the basal ganglia [ 114 ] to the subthalamic nucleus and other midbrain regions, the other indirect .
A potential circuit structure that seems to combine most effective targets in both the ALIC and STN region has been identified and termed the OCD response tract, though multiple targets have been probed and found to have effect. [ 114 ] [ 115 ]
DBS for OCD received a humanitarian device exemption from the FDA in 2009. [ 116 ] In Europe, the CE Mark for Deep Brain Stimulation (DBS) for Obsessive-Compulsive Disorder (OCD) was active from 2009 to 2022 but not renewed due to a lack of government health coverage. [ 117 ] [ 118 ]
DBS has been studied for treatment resistant epilepsy with seizure foci not amenable to surgical resection or vagus nerve stimulation ; [ 119 ] almost 40% of individuals with the disease are inadequately treated with medication alone. [ 120 ]
Responsive neurostimulation is a form of adaptive brain stimulation that targets the anterior nucleus of the thalamus . The anterior nuclei of the thalamus is the only FDA approved target for epilepsy treatment, with some individuals achieving more than a 50% decrease in seizures. Other brain regions being studied as potential targets include:
DBS has been used experimentally for individuals with severe Tourette syndrome that do not respond to conventional treatment. Despite early successes, DBS remains a highly experimental procedure for the illness, with more study needed to fully understand its clinical effects. [ 123 ] [ 124 ] [ 125 ] [ 126 ] The procedure is well tolerated, but complications include "short battery life, abrupt symptom worsening upon cessation of stimulation, hypomanic or manic conversion, and the significant time and effort involved in optimizing stimulation parameters". [ 127 ] The first clinical use of DBS for Tourette's Syndrome was carried out in 1999 [ 111 ] in follow up to earlier studies on ablative lesions. [ 128 ]
The procedure is invasive and expensive and requires long-term expert care and its benefits for severe Tourette's are inconclusive. Tourette's is more common in children, tending to remit spontaneously in adulthood, limiting the applicability of surgery in these populations. It also may not always be obvious how to utilize DBS for a particular person because the diagnosis of Tourette's is based on a history of symptoms rather than an examination of neurological activity.
The Tourette Association of America recommends that the procedure be reserved for adults with severe debilitating treatment resistant variants of the disease, and without comorbidities such as substance abuse or personality disorders. [ 127 ]
Though depression can be a contraindication for electrostimulation of other chronic neurologic diseases in the basal ganglia, the therapy can also be used for treatment of severe depression. The target for electrostimulation in depression is more anterior and superficial at the frontal lobes, as opposed to other motor disorders where it is deeper in the basal ganglia. Beginning in the 1950s, treatment has been attempted in the subcallosal cingulate region [ 129 ] and the ventral capsule/ventral striatum [ 130 ] have shown mixed outcomes.
Diffusion-weighted imaging based tractography has led to the theoretical discovery of the so-called 'depression switch', [ 131 ] the intersection of four bundles that allowed more deliberate targeting of DBS in the subcallosal area and improved results in additional open-label studies. [ 132 ] While anatomical descriptions as well as supposed mechanisms for this target site have been debated, [ 133 ] [ 134 ] clinical effects of this DBS target in patients with TRD have been promising. [ 135 ]
Stimulation of the periaqueductal gray and periventricular gray for nociceptive pain , and the internal capsule , ventral posterolateral nucleus , and ventral posteromedial nucleus for neuropathic pain has produced impressive results with some people, but results vary. One study [ 136 ] of 17 people with intractable cancer pain found that 13 were virtually pain-free and only four required opioid analgesics on release from hospital after the intervention. Most ultimately did resort to opioids, usually in the last few weeks of life. [ 137 ] DBS has also been applied for phantom limb pain . [ 138 ]
The possible negative effects of DBS can be divided into two categories: short-term in the immediate post operative period, and long-term on the scale of months to years.
Hardware related compliations include bleeding inside the head (1–2%), infection (5%) skin erosion (0.5%), lead migration (1.5%), lead fracture (1.5%), IPG malfunction (1%), which may require repositioning or a stay in the neurological intensive care unit . Long term negative effects of the device include an increased risk of decreased mental function and dementia beyond that typically seen with chronic neurologic disorders. [ 139 ] Tourette's syndrome and epilepsy are more at risk of hardware related complications, with Parkinson's having the lowest rates, possibly due to abnormal mechanical positioning and picking behaviors associated with the former two conditions. [ 11 ] Delayed brain edema can occur after lead placement, but is usually self limited. [ 140 ]
Because the brain can shift slightly during surgery, the electrodes can become displaced or dislodged, though electrode misplacement can be suspected by lack of clinical effect when the leads are turned on and a sudden dramatic increase in electrode impedance . The displacement can be physically located using CT scan , which would then guide a repeat intervention for repositioning. After surgery, swelling of the brain tissue, mild disorientation, and sleepiness are normal. After 2–4 weeks, the sutures are removed and the neurostimulator is activated. [ 141 ]
Expectations can impact surgical outcomes, with individuals that had more positive expectations generally having better motor outcomes. Bradykinesia was in particular responsible to verbal suggestions. The placebo response rate in the Parkinson's population similar to other neurologic diseases at 16% (range 0-55%). Conversely, those that had unrealistic expectations surrounding surgery because they anticipated improvement and symptoms that are not typically addressed by neurostimulation, reported being unhappy about the outcome as well. With regards to particular symptoms, expectations of improvements in motor symptoms and medication reduction were mostly met, whereas expectations regarding non-motor issues such as speech, balance, and walking problems were not. [ 142 ]
MRIs can be obtained after the procedure when necessary, but they have to be done under strict guidelines due to risks such as heating of the leads and to a lesser degree lead migration. The current FDA approved manufacturer (Medtronic) recommendations are interrogation of the system prior to the MRI; assessment of impedance to rule out short or open circuits and compromise of system integrity; that the DBS be off, programmed at zero volts, bipolar mode with the magnetic switch disabled, only a 1.5-T MRI head transmit/receive coil with specific absorption rate of less than 0.1 W/kg in the head. Multiple centers have found these guidelines to be overly cautious. [ 143 ]
In early 2025, Medtronic achieved the CE mark as the first clinically available closed loop system in the world, and the technology is now being used in the European Union and the United Kingdom , though it has yet to receive FDA or Medicare approval in the United States. [ 144 ] Closed feedback loop systems deliver a lower total charge to the brain over time because their trigger for neurostimulation is based on a threshold signal from the individual themselves, rather than being assigned through external programming of the device by a clinician. [ 27 ] Studies have shown lower total electrical energy delivered with adaptive DBS and a 40% reduction in motor symptoms, though research thus far comparing adaptive and conventional DBS has suffered from publication bias. [ 145 ]
In both open and closed loop systems, there are a basic set of neurostimulator parameters can be modified such as choice of contact configuration (monopolar, bipolar , double monopolar, double bipolar), stimulation amplitude , pulse width , and frequency . Segmented leads were introduced in 2015, allowing the possibility of steering and orienting the stimulation horizontally. This led to both an increased specifity of treatment zone and an increase in time needed for device programming. Symptom specific and task-dependent neurostimulation, similar to rate adaptive cardiac pacemakers , is under development but not yet clinically available. [ 27 ]
Though a wide variety of sources have been studied as feedback loops to trigger neurostimulation, the two that have been clinically tested are electricocortical and kinetic. Electricocortical signals in the brain can be recorded by an unused DBS electrode contact via electrocorticography . Kinetic signals are triggered by wearable technology that detects tremor , usually a gyroscope or accelerometer . [ 146 ] Most electrocortically based feedback devices thus far have used beta activity as the primary feedback signal, though this does not always correlate with symptomatology. A minority have used wearable devices. [ 145 ] Besides tremor, wearables can be used to track other motor symptoms like bradykinesia, levodopa induced dyskinesia, freezing of gait, festination , and balance impairment. [ 27 ] Wireless nanoparticals, [ 147 ] neurochemical ionic changes, local neurotransmitter level, electrode-electrolyte interfaces, and impedance spectroscopy, amongst others, are currently being researched for adaptive systems. [ 27 ]
Microelectrodes can be used for local neuronal firing patterns while macroelectrodes can be used to detect local field potentials, whose detection correlates with time locked bursts of neuronal spikes from synchronous neural oscillations. [ 27 ]
A challenge of closed loop DBS is the obscuration of brain activity from artifact of the neurostimulation itself. By recording and stimulating in the same area, DBS devices capture the impulses of the delivered electric stimulation. While theoretically useful as a feedback signal, this artifact must be carefully filtered to prevent saturation of the sensing amplifiers and introduction of fictitious resonant information. This issue has been partially mitigated by advancements in wire insulation, but it still persists. An alternative input signal for aDBS that has been suggested is the evoked resonant neural activity, as it has a better signal to noise ratio than beta oscillations. [ 27 ]
New DBS systems are being developed with current steering that allows the application of current in a focal as opposed to a concentric ring around the activated contact. Future DBS electrodes also will have more than four contacts, allowing for finer control of the stimulation area. Segmented contacts have also been developed with each piece having the potential for its own individual stimulation. The manufacturer St Jude is already approved for this for this in Europe and it has FDA approval in the United States. Blinded intraoperative use of directional current with segmented electrodes has been found to have a higher therapeutic window (>41.3%) for STN PD and VIM in essential tremor, as compared to standard omnidirectional stimulation. Boston Scientific has developed leads with eight contacts, each with an independent current source, allowing separate manipulation of DBS parameters (amplitude, frequency, pulse width, and current) at each contact; these have already been approved for use in Europe. Directional current capabilities of the new technology could be more beneficial than simple monopolar settings because they may allow shielding of brain regions with current shaping and steering may be useful to lower the side effects. Potential negatives increased programming time with further programming alternatives, the degree of the programmer's accuracy in "steering" the electrical current to the needed areas and that the decreased surface area due to smaller contacts will increase impedances and increase battery drainage. In essential tremor that is poorly responsive to initial DBS, another set of electrodes was placed in close proximity so that current could be directed from one electrode to the other, has been used as "rescue" therapy for ET; two-electrode system provides greater volume of tissue activation, but more static damage due to second electrode. [ 38 ]
Optogenetics is a new technique that may allow activation of neurons using light rather than electricity. [ 146 ]
The exact mechanism of action of DBS is not completely understood. [ 148 ] The overlapping effects of anatomically distinct targets suggest that either there are as many different DBS mechanisms as there are effective targets or there is some common mechanism that is not unique to any particular target. This has led to viewing DBS from a systems perspective of circuit modulation rather than focusing only on its local effects. [ 149 ]
Clinical effects of DBS and lesioning are similar, which led to the initial hypothesis that DBS inhibited local neurons through deafferentation. Further investigations suggest its mechanism as more complex than simple inhibition of nuclei. For example, activity is increased in the downstream nuclei during stimulation. The apparent paradox of simultaneous cell body inhibition and axonal activation was explained in part by computational modeling studies demonstrating that under extracellular electrical stimulation, the action potential initiates in the axon. Not only does stimulation serve as an on–off switch for modulating circuit oscillations, but that it also induces synaptic reorganization and alters gene expression. [ 150 ]
Other studies have suggested that its benefit occurs through modulation of subcellular compartment processes (for example, the cell body versus its axon ) and to change in quality depending on time scale (milliseconds, seconds, days, weeks and months). Applying current to neural elements either activates or inhibits of the surrounding elements. The inhibition of neuronal activity may be secondary to depolarization, neurotransmitter depletion, hyperpolarization, or activation of inhibitory afferent projections. [ 2 ] Adjusting the frequency in DBS may also change neuronal discharge threshold, altering the relative population of neurons sending out action potentials. [ 38 ]
Mechanistic hypotheses include the following: [ 151 ] [ 152 ] [ 153 ]
Electrophysiological studies showed that cortico-basal circuits in chronic neurologic disease are tonically overactive with oversynchronization , irregular and rhythmic neuronal discharge, and loss of selectivity in response to peripheral sensitive stimulation. [ 1 ]
Phase amplitude coupling is a measure of how the amplitude of an oscillation in a given frequency band correlates with the phase of another frequency band, a normal process that occurs with functions such as memory, learning, and cognition. In Parkinson's there is an excessive beta-gamma coupling, which, when suppressed by DBS, correlates in magnitude to the degree of clinical improvement. [ 27 ]
There is little evidence to suggest that DBS in patients with movement disorders restores normal basal ganglia functions, for example, its roles in movement or learning. Instead, it appears that high-frequency DBS mitigates abnormal basal ganglia output into a more tolerable pattern, helping to restore downstream network function. In support of this theory is the observation that in a normal healthy brain, all basal ganglia connections are inhibitory except for those from the STN. [ 155 ]
The STN, the most common nucleus targeted in Parkinson's, integrates motor, cognitive, and emotional information to orchestrate complex behaviors. Furthermore, fMRI studies showed that the STN is involved in emotional processes such as amusement, disgust, sexual arousal, and maternal and romantic love. On fMRI STN-DBS reversed the hypometabolism in motor, associative, and limbic prefrontal areas observed in Parkinson's disease and the diffuse hypermetabolism of the prefrontal cortex. The functional deafferentation of the STN induced by DBS seems to improve executive functions, but reduction of reaction time hastens the decision, which could lead to impulsive and erroneous choices. [ 1 ]
Histopathologically, the brain parenchyma surrounding the leads develops gliosis over time, and occasionally a microglial infiltrate. [ 156 ]
When therapeutic target sites are near areas causing adverse effects, monopolar stimulation, in which the brain is the cathode and the neurostimulator the anode, can be modified to bipolar in which another electrode serves as the anode rather than the neurostimulator, yielding a narrower area of stimulation. [ 146 ]
The coordinated reset counteract pathological synchronization processes by providing an antikindling effect and retraining the neural network. [ 146 ]
Either there are as many different DBS mechanisms as there are effective targets or there is some common mechanism that is not unique to any particular target. This suggests that it may be profitable to view DBS from a systems perspective rather than just its local effects, an approach that here-to-fore has not been received much consideration. [ 149 ]
The electrical effects of clinically applied DBS are strongly influenced by the anisotropic nature of the tissue at the target site in relation to the electrode and can therefore cause heterogeneous electrophysiological, structural, molecular, and cellular reactions. DBS seems to uncouple STN neurons from its axons and cause a functional deafferentation from both efferent and afferent structures. [ 13 ]
Though DBS was developed in the 1980s, research on electric neurostimulation has a tumultuous history spanning thousands of years. Physicians in ancient Greece considered thunderbolts to be sacred and experimented with medical applications of electrical current. At the same time in dynastic Egypt, electric catfish of the Nile were used to treat migraines. In 46 A.D., Scribonius Largus wrote about the use of electric rays for the treatment of headache. [ 34 ]
In 1890, Horsley performed the first extirpation of the motor cortex for treatment of athetosis . Sixty years later, Spiegel described the first stereotactic frame and made lesions in patients with PD to interrupt pallidofugal fibers , causing improvement in bradykinesia, rigidity, and tremor. The 1950s were also when parkinsonism was first treated with ventrolateral thalamic lesions. While attempting to section the cerebral peduncle, a surgeon inadvertently disrupted the anterior choroidal artery and was forced to ligate it, leading to disappearance of rigidity and tremor with preserved motor and sensory function. [ 146 ]
In 1963, the first neurostimulation of the thalamic VIM at frequencies of 100–200 Hz improved tremor in patients with parkinsonism. Early pioneers included Carl-Wilhelm Sem-Jacobsen , Natalia Bekhtereva , José Delgado , Robert Heath and Irvine Cooper. [ 50 ] Sem-Jacobsen's work was funded by the United States military and criticized for ethical concerns. Similarly, Heath's research faced considerable controversy because of its lack of rigorous scientific method and ethical violations , particularly with regards to informed consent and attempts at conversion therapy . The associated negative publicity, along with the emerging effectiveness of levodopa for Parkinson's after its discovery in 1969, led to a general distaste for electrical neurostimulation and stereotactic surgery in the medical community that lasted until the 21st century. [ 157 ]
Alim Louis Benabid and Pierre Pollak heralded the modern era of DBS in 1987 when battery technology and public sentiment had evolved enough to allow manufacture of a portable neurostimulator variant, the addition of a lithium battery allowing it to maintain long term sustained charge. The first application of DBS was to the thalamus in individuals with a history of tremor and prior contralateral thalamotomy.
Though the inhibition of Parkinson's tremor from basal ganglia electrical stimulation had been reliably demonstrated decades before by Bekhtereva in the Soviet Union , Benabid and Pollak were reportedly unaware of this earlier work, with their own discovery of the phenomenon being incidental. They were using electrodes to map out the effects of a planned surgical lesioning for a patient with tremor related to a tumor in the basal ganglia and found that when they electrically stunned tissue around the tumor, the tremor would temporarily disappear.
The surgeons used this observation to construct a device powered by a lithium battery, allowing it to be small enough to be housed entirely within a subcutaneous chest wall pocket and charged by electromagnetic induction . The portability and relative longevity of the device led DBS to gain widespread adaptation.
In 1990, the first models of basal ganglia function were mapped out based on the segregated circuits in its thalamocortical network. During this time pallidotomies were reintroduced for individuals with advanced PD and severe levodopa induced dyskinesia. In 1998, neurostimulation to the STN was first attempted for PD and two years later to the GPi for dystonia. [ 146 ]
Over the past two decades, DBS has become the major research hotspot for surgical treatment of tremor in Parkinson's disease, with the United States being its dominant hub for research and Michael S. Okun at the University of Florida being the most productive author in the field over this time. [ 10 ] Their protocol has recommended the use of a 3T volumetric thin-slice, 1 mm thick MRI sequence, FGATIR (fast gray matter acquisition T1 inversion recovery), for sharper delineation of basal ganglia contour in an effort to minimize field distortion and recreate the anatomic precision formerly afforded by air based ventriculography. [ 158 ]
There are a number of different targets with the procedure, depending on the specific disease and symptomatology. The procedure is FDA approved or has FDA device exemptions for treatment of Parkinson's disease , dystonia , essential tremor , obsessive-compulsive disorder and epilepsy . In Europe, beyond these indications, a CE mark exists for treatment of Alzheimer's Disease. There was a past device exemption for OCD as well but this has not been renewed. [ 117 ] Other indications are considered investigational and require Institutional Review Board approval.
The table below summarizes DBS targets and their respective FDA approvals:
There are multiple major competitors in the current market for stimulators, including Boston Scientific , Medtronic and Abbott , and Newronika. Medtronic and Newronika are the first to develop a closed loop system based on automatic feedback, though it the technology will likely soon be available on all devices. It is still not approved for clinical usage, however. Abbott has designed a variant that allows remote programming for the patient at home. [ citation needed ]
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Deep hypothermic circulatory arrest ( DHCA ) is a surgical technique in which the temperature of the body falls significantly (between 20 °C (68 °F ) to 25 °C (77 °F)) and blood circulation is stopped for up to one hour. It is used when blood circulation to the brain must be stopped because of delicate surgery within the brain, or because of surgery on large blood vessels that lead to or from the brain. DHCA is used to provide a better visual field during surgery due to the cessation of blood flow. [ 1 ] DHCA is a form of carefully managed clinical death in which heartbeat and all brain activity cease.
When blood circulation stops at normal body temperature (37 °C), permanent damage occurs in only a few minutes. More damage occurs after circulation is restored. Reducing body temperature extends the time interval that such stoppage can be survived. [ 2 ] At a brain temperature of 14 °C, blood circulation can be safely stopped for 30 to 40 minutes. [ 3 ] There is an increased incidence of brain injury at times longer than 40 minutes, but sometimes circulatory arrest for up to 60 minutes is used if life-saving surgery requires it. [ 4 ] [ 5 ] Infants tolerate longer periods of DHCA than adults. [ 6 ]
Applications of DHCA include repairs of the aortic arch , repairs to head and neck great vessels, repair of large cerebral aneurysms , repair of cerebral arteriovenous malformations , pulmonary thromboendarterectomy , and resection of tumors that have invaded the vena cava . [ 7 ] [ 2 ]
The use of hypothermia for medical purposes dates back to Hippocrates, who advocated packing snow and ice into wounds to reduce hemorrhage. The origin of hypothermia and neuroprotection was also observed in infants who were exposed to cold due to abandonment and the prolonged viability of these infants. [ 8 ]
In the 1940s and 1950s, Canadian surgeon Wilfred Bigelow demonstrated in animal models that the length of time the brain could survive stopped blood circulation could be extended from 3 minutes to 10 minutes by cooling to 30 °C before circulation was stopped. [ 9 ] He found that this time could be extended to 15 to 24 minutes at temperatures below 20 °C. [ 10 ] He further found that at a temperature of 5 °C, groundhogs could endure two hours of stopped blood circulation without ill effects. [ 11 ] [ 12 ] This research was motivated by a desire to stop the heart from beating long enough to do surgery on the heart while it remained still. Since heart-lung machines, also known as cardiopulmonary bypass (CPB), had not been invented yet, stopping the heart meant stopping blood circulation to the whole body, including the brain.
The first heart surgery using hypothermia to provide a longer time that blood circulation through the whole body could be safely stopped was performed by F. John Lewis and Mansur Taufic at the University of Minnesota in 1952. [ 13 ] In this procedure, the first successful open heart surgery , Lewis repaired an atrial septal defect in a 5-year-old girl during 5 minutes of total circulatory arrest at 28 °C. Many similar procedures were performed by Soviet heart surgeon, Eugene Meshalkin, in Novosibirsk during the 1960s. [ 14 ] In these procedures, cooling was accomplished externally by applying cold water or melting ice to the surface of the body.
The advent of cardiopulmonary bypass in the United States during the 1950s allowed the heart to be stopped for surgery without having to stop circulation to the rest of the body. Cooling more than a few degrees was no longer needed for heart surgery. Thereafter, the only surgeries that required stopping blood circulation to the whole body ("total circulatory arrest") were surgeries involving blood supply to the brain. The only heart surgeries that continued to require total circulatory arrest were repairs to the aortic arch .
Cardiopulmonary bypass machines were essential to the development of deep hypothermic circulatory arrest (DHCA) in humans. [ 15 ] By 1959, it was known from the animal experiments of Bigelow, Andjus and Smith , Gollan, Lewis's colleague, Niazi, and others that temperatures near 0 °C could be survived by mammals, [ 16 ] [ 17 ] [ 18 ] and that colder temperature permitted the brain to survive longer circulatory arrest times, even beyond one hour. [ 19 ] Humans had survived cooling to 9 °C, and circulatory arrest of 45 minutes, using external cooling only. [ 20 ] However, reaching such low temperatures by external cooling was difficult and hazardous. At temperatures below 24 °C, the human heart is prone to fibrillation and stopping. [ 21 ] This can begin circulatory arrest before the brain has reached a safe temperature. Cardiopulmonary bypass machines allow blood circulation and cooling to continue below the temperature at which the heart stops working. By cooling blood directly, cardiopulmonary bypass also cools people faster than surface cooling, even if the heart is not functioning.
In 1959, using cardiopulmonary bypass (CPB), Barnes Woodhall and colleagues at Duke Medical Center performed the first brain surgery using DHCA, a tumor resection, at a brain temperature of 11 °C and esophageal temperature of 4 °C. [ 22 ] This was quickly followed by use of DHCA by Alfred Uihlein and other surgeons for treatment of large cerebral aneurysms , another neurosurgical procedure, for which DHCA is still used today. [ 23 ] In 1963, Christiaan Barnard and Velva Schrire were the first to use DHCA to repair an aortic aneurysm , cooling the patient to 10 °C. [ 13 ] Randall B. Griepp , in 1975, is generally credited with demonstrating DHCA as a safe and practical approach for aortic arch surgery. [ 24 ] [ 13 ]
Cells require energy to operate membrane ion pumps and other mechanisms of cellular homeostasis . Cold reduces the metabolic rate of cells, which conserves energy stores ( ATP ) and oxygen needed to produce energy. Cold therefore extends the length of time that cells can maintain homeostasis and avoid damaging hypoxia and anaerobic glycolysis by conserving local resources when blood circulation is stopped and unable to deliver fresh oxygen and glucose to make more energy. [ 25 ]
Normally 60% of brain oxygen utilization (CMRO2) consists of energy generation for the neuronal action potentials of brain electrical activity . [ 26 ]
A key principle of DHCA is total inactivation of the brain by cooling, as verified by "flatline" isoelectric EEG , also called electrocerebral silence (ECS). Instead of a continuous decrease in activity as the brain is cooled, electrical activity decreases in discontinuous steps. In the human brain, a type of reduced activity called burst suppression occurs at a mean temperature of 24 °C, and electrocerebral silence occurs at a mean temperature of 18 °C. [ 27 ] The achievement of measured electrocerebral silence has been called "a safe and reliable guide" for determining cooling required for individual patients, [ 28 ] and verification of electrocerebral silence is required prior to stopping blood circulation to begin a DHCA procedure. [ 29 ]
Secondary to conservation of local energy resources by metabolic slowing and brain inactivation, hypothermia also protects the brain from injury by other mechanisms during stopped blood circulation. These include reduction of free radicals and immune-inflammatory processes. [ 25 ]
Mild hypothermia (32 °C to 34 °C) and moderate hypothermia (26 °C to 31 °C) [ 30 ] are contraindicated for hypothermic circulatory arrest because 100% and 75% of people respectively will not achieve electrocerebral silence in these temperature ranges. [ 31 ] Consequently, safe circulatory arrest times for mild and moderate hypothermia are only 10 and 20 minutes respectively. [ 32 ] While moderate hypothermia may be satisfactory for short surgeries, deep hypothermia (20 °C to 25 °C) affords protection for times of 30 to 40 minutes at the bottom of this temperature range.
Profound hypothermia (< 14 °C) usually isn't used clinically. It is a subject of research in animals and human clinical trials. As of 2012, the lowest body temperature ever survived by a human being was 9 °C (48 °F ) as part of a hypothermic circulatory arrest experiment to treat cancer in 1957. [ 33 ] [ 34 ] This temperature was reached without surgery, using external cooling alone. Similar low temperatures are expected to be reached in emergency preservation and resuscitation (EPR) clinical trials described in the Research section of this article.
Since the benefits of hypothermia were discovered there have been numerous methods used to cool the body to desired temperatures. Hippocrates used snow and ice to surface cool wounded patients to prevent excessive bleeding. [ 8 ] This method would fall under conventional cooling techniques, in which cold saline and crushed ice are used to induce a state of hypothermia to the patient. These techniques are inexpensive but lack the precision needed to maintain target temperatures and require careful monitoring. [ 35 ] It has been proven to help prevent undesirable rewarming of the brain during DHCA. [ 30 ] Hospitals and emergency medical services commonly use surface cooling systems that circulate cold air or water around blankets or pads. Advantages of this method are accuracy of cooling due to auto-regulating temperature control, feedback probes, applicable in non-hospital settings, and non-complexity of use. [ 8 ] Drawbacks to surface cooling systems is skin irritation, shivering and rate of cooling. [ 36 ] Intravascular cooling systems regulate temperature from inside veins such as the femoral, sub-clavian, or internal jugular to reduce adverse effects that external cooling methods cause. This method is unparalleled in achieving and maintaining the target temperature desired. [ 8 ] The use of continuous renal replacement therapy (CRRT) has proven effective in the induction of hypothermia as an intravascular cooling system. [ 8 ]
People who are to undergo DHCA surgery are placed on cardiopulmonary bypass (CPB), a procedure that uses an external heart-lung machine that can artificially replace the function of the heart and lungs. [ 37 ] A portion of the circulating blood supply is removed and stored for later replacement, with the remaining blood diluted by added fluids with the objective of reducing viscosity and clotting tendencies at cold temperature. [ 38 ] [ 39 ] The remaining diluted blood is cooled by the heart-lung machine until hypothermia causes the heart to stop beating normally, after which the blood pump of the heart-lung machine continues blood circulation through the body. Corticosteroids are typically given 6–8 hours before surgery as it has shown to have neuroprotective properties to decrease risk of neurological dysfunction by decreasing the release of inflammatory cytokines. [ 2 ] Glucose is eliminated from all intravenous solutions to reduce the risk of hyperglycemia. [ 30 ] In order for accurate hemodynamic monitoring, arterial monitoring is typically placed in the femoral or radial artery. [ 2 ] Temperature taken from two separate sites, typically the bladder and nasopharynx, is used to estimate brain and body temperatures. [ 2 ] Cardioplegic drugs may be administered to ensure the heart stops beating completely ( asystole ), which is protective of both the heart and brain when circulation is later stopped. [ 40 ] Cooling continues until the brain is inactivated by the cold, and electrocerebral silence (flatline EEG) is attained. The blood pump is then switched off, and the interval of circulatory arrest begins. At this time more blood is drained to reduce residual blood pressure if surgery on a cerebral aneurysm is to be performed to help create a bloodless surgical field. [ 41 ]
After surgery is completed during the period of cold circulatory arrest, these steps are reversed. The brain and heart naturally resume activity as warming proceeds. The first activity of the warming heart is sometimes ventricular fibrillation requiring cardioversion to re-establish a normal beating rhythm. [ 42 ] Except for the period of complete inactivation just prior to and during the circulatory arrest interval, barbiturate infusion is used to keep the brain in a state of burst suppression for the entirety of the DHCA procedure until emergence from anesthesia. [ 43 ] Hypothermic perfusion is maintained for 10–20 minutes while on CPB before rewarming as to reduce the risk of increased intracranial pressure. [ 2 ] Warming must be done carefully to avoid overshooting normal body temperature. It is recommended that rewarming is stopped once the body is warmed to 37 °C. [ 30 ] Post-operative hyperthermia is associated with adverse outcomes. [ 44 ] Patients are completely rewarmed before discontinuing CPB, but temperature remain labile despite rewarming efforts which requires close monitoring in the ICU. [ 2 ]
The use of hypothermia following cardiac arrest shows increased likelihood of survival. It is the re-warming period that, if not controlled properly, can have detrimental effects. Hyperthermia during the re-warming period shows unfavorable neurologic outcomes. For each degree the body is warmed above 37 °C, there is an increased association with severe disability, coma, or vegetative states. [ 8 ] Excessive rewarming with temperatures above 37 °C can increase the risk of cerebral ischemia secondary to the increased oxygen demand that occurs with rapid rewarming. [ 2 ] Several theories have been proposed, with one being during re-warming, the body releases increasing catecholamines which increase heat production leading to a loss of thermoregulation. [ 8 ] Hyperthermia in the preperfusion period can also be caused by an increase in the production of oxygen radicals, which influences brain metabolism. [ 8 ] These oxygen radicals attack cell membranes, leading to a disruption of intracellular organelles and subsequent cellular death. [ 30 ]
Virtually all patients who undergo DHCA develop impaired glucose metabolism and require insulin to control blood sugars. [ 2 ] Thrombocytopenia and clotting factor deficiencies prove to be a significant cause of early death after DHCA. Careful monitoring intra-procedure and post-procedure is needed. [ 2 ]
Although DHCA is necessary for some procedures, the use of anesthesia can provide optimum operation time and organ protection but can also have serious impacts on cellular demand, brain cells, and serious systemic inflammatory results. [ 45 ] Possible disadvantages of DHCA includes alteration in organ functions of the liver, kidney, brain, pancreas, intestines and smooth muscles due to cellular damage. Permanent neurological injury has been seen in 3-12% of patients when using DHCA. [ 30 ] Cases of partial or complete limb motor loss, impaired language, visual defects, and cognitive decline have all been reported as consequences of DHCA. [ 45 ] Other neurological complications include increased risk for seizures postoperative due to delayed return of cellular blood flow to the brain. [ 1 ] When compared to Moderate Hypothermia (temperature dropped to 26-31 °C [ 30 ] ), there was less bleeding volume experienced during surgery thus leading to less use of packed red blood cells or plasma post surgery. [ 45 ] Longer recovery time postoperatively have been noted with DHCA as compared to Moderate Hypothermia, but the length of hospital stay and death has no correlated difference. [ 45 ] Most patients can tolerate 30 minutes of DHCA without significant neurological dysfunction or adverse effects, but after an extended period of 40 minutes or more, prevalence of increased brain injury have been noted. [ 2 ]
One of the anticipated medical uses of long circulatory arrest times, or so-called clinical suspended animation, is treatment of traumatic injury. In 1984 CPR pioneer Peter Safar and U.S. Army surgeon Ronald Bellamy proposed suspended animation by hypothermic circulatory arrest as a way of saving people who had exsanguinated from traumatic injuries to the trunk of the body. [ 46 ] Exsanguination is blood loss severe enough to cause death. Until the 1980s, it had been thought impossible to resuscitate people whose heart stopped because of blood loss, resulting in these people being declared dead when cardiac resuscitation failed. Traditional treatments such as CPR and fluid replacement or blood transfusion are not effective when cardiac arrest has already occurred and bleeding remains uncontrolled. [ 47 ] Safar and Bellamy proposed flushing cold solution through blood vessels of patients with deadly bleeding, and leaving them in a state of cold circulatory arrest with the heart stopped until the cause of bleeding could be surgically repaired to allow later resuscitation. In preclinical studies at the University of Pittsburgh during the 1990s, the process was called deep hypothermia for preservation and resuscitation , and then suspended animation for delayed resuscitation . [ 48 ]
The process of cooling people with fatal bleeding for surgical repair and later resuscitation was finally called Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma (EPR-CAT), or EPR. [ 49 ] [ 50 ] [ 51 ] [ 52 ] It is presently undergoing human clinical trials. [ 53 ] In the trials, patients who experience clinical death for less than five minutes duration from blood loss are being cooled from normal body temperature of 37 °C to less than 10 °C by pumping a large quantity of ice-cold saline into the largest blood vessel of the body ( aorta ). By remaining in circulatory arrest at temperatures below 10 °C (50 °F), it is believed that surgeons have one [ 54 ] to two hours [ 55 ] [ 56 ] to fix injuries before circulation must be restarted. Surgeons involved with this research have said that EPR changes the definition of death for victims of this type of trauma. [ 57 ]
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Deepak L. Bhatt is a US interventional cardiologist , researcher, and educator. He is known for novel clinical trials in cardiovascular prevention, intervention, and heart failure. As of 2024, he is the director of Mount Sinai Fuster Heart Hospital in New York City and the Dr. Valentin Fuster Professor of Cardiovascular Medicine at the Icahn School of Medicine at Mount Sinai Health System. [ 1 ] [ 2 ] Prior, he served as the executive director of Interventional Cardiovascular programs at Brigham and Women’s Hospital Heart and Vascular Center and a professor of medicine at Harvard Medical School . [ 3 ] [ 4 ] He was given the American College of Cardiology 's Distinguished Mentor Award in 2018, and in 2019, the American Heart Association presented him with its Distinguished Scientist award. [ 5 ] As of 2024, Google Scholar reports that he has been cited 294,036 times, has an h-index of 201, and an i10-index of 1,261.
Bhatt graduated Boston Latin School , earned his science degree as a National Merit Scholar from MIT , an MD from Cornell and an MPH from Harvard . [ 6 ] He received his Executive MBA from the University of Oxford in 2024. [ 7 ]
He trained in internal medicine and cardiology at the University of Pennsylvania and Cleveland Clinic , completing fellowships in interventional cardiology and cerebral and peripheral vascular intervention. He served as chief interventional fellow at Cleveland Clinic [ 8 ] where he worked as an interventional cardiologist, associate professor of medicine, director of the interventional cardiology fellowship, associate director of the cardiovascular medicine fellowship, and associate director of the cardiovascular coordinating center. [ 9 ]
Later, he became the Chief of Cardiology at the VA Boston Healthcare System and, subsequently, the Interventional Cardiovascular Programs executive director at Brigham and Women’s Hospital. Additionally, he was a Senior Investigator in the TIMI Study Group and Editor-in-Chief of the Harvard Heart Letter. [ 8 ] In 2012, he was appointed a professor of medicine at Harvard Medical School . [ 10 ]
As of 2024, Bhatt serves on the Board of Directors and Science and Technology Committee of Bristol Myers Squibb . [ 11 ] He is on the cardiovascular advisory board for McKinsey and is a consultant to Broadview Ventures. He had previously served on the Board of Directors of the Boston VA Research Institute and as a Trustee of the American College of Cardiology . [ 7 ] He serves on the Board of Directors of the American Heart Association New York City chapter. [ 12 ]
Bhatt focuses on several areas of cardiology, including interventional cardiology, heart attacks, stroke, prevention, and heart failure, as well as related areas such as high cholesterol, diabetes, and obesity. [ 13 ] AD Scientific Index ranks him as one of the top 3% of scientists worldwide in his field. [ 14 ]
Recent trials as of 2024 include:
Brigham and Women’s Hospital chose Bhatt in 2014 as the Eugene Braunwald Scholar and in 2016 presented him with the Research Mentor Award, and in 2017 he was awarded the Eugene Braunwald Teaching Award for Excellence in the Teaching of Clinical Cardiology. [ 6 ] He was given the American College of Cardiology’s Distinguished Mentor Award in 2018, [ 20 ] and in 2019, the American Heart Association’s Distinguished Scientist Award. [ 5 ] [ 21 ] He received NLA ’s Honorary Lifetime Membership Award in 2021, and the Society for Cardiovascular Angiography and Interventions’ Master Designation in 2022. [ 2 ] Also in 2022, Research.com recognized him with its Best Scientists award. [ 13 ] He was listed by the Web of Science Group as a Highly Cited Researcher from 2014 to 2024. [ 12 ] [ 22 ]
Bhatt is the Editor of the first and second editions of Cardiovascular Intervention: A Companion to Braunwald’s Heart Disease and of Opie's Cardiovascular Drugs: A Companion to Braunwald's Heart Disease . [ 23 ] He is one of the co-editors of Braunwald’s Heart Disease . [ 24 ] Elsevier credits him with a total of 11 titles as an author, chapter contributor, and editor. [ 25 ]
Bhatt was Senior Associate Editor for News and Clinical Trials for ACC .org, member of the Healio | Cardiology Today Editorial Board, [ 26 ] and Editor-in-Chief of the Journal of Invasive Cardiology, which also lists him as: [ 27 ]
As of 2024, Google Scholar reports that he has been cited 294,036 times, has an h-index of 201 and an i10-index of 1,261. [ 31 ]
Bhatt has authored or co-authored over 2,000 publications [ 32 ] and has been listed by the Web of Science Group as a highly cited researcher from 2014 to 2024. [ 33 ] [ 34 ] [ 35 ] [ 22 ]
Bhatt's most cited, peer-reviewed articles include:
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Aphantasia ( / ˌ eɪ f æ n ˈ t eɪ ʒ ə / ⓘ AY -fan- TAY -zhə , / ˌ æ f æ n ˈ t eɪ ʒ ə / AF -an- TAY -zhə ) is the inability to voluntarily visualize mental images. [ 1 ]
The phenomenon was first described by Francis Galton in 1880, [ 2 ] but has remained relatively unstudied. Interest in the phenomenon renewed after the publication of a study in 2015 conducted by a team led by Adam Zeman of the University of Exeter . [ 3 ] Zeman's team coined the term aphantasia , [ 4 ] derived from the ancient Greek word phantasia ( φαντασία ), which means "appearance/image", and the prefix a- ( ἀ- ), which means "without". [ 5 ] People with aphantasia are called aphantasics , [ 6 ] or less commonly aphants [ 7 ] or aphantasiacs . [ 8 ]
Aphantasia can be considered the opposite of hyperphantasia , the condition of having extremely vivid mental imagery. [ 9 ] [ 10 ]
The phenomenon was first described by Francis Galton in 1880 in a statistical study about mental imagery . [ 2 ] Galton wrote:
To my astonishment, I found that the great majority of the men of science to whom I first applied, protested that mental imagery was unknown to them, and they looked on me as fanciful and fantastic in supposing that the words "mental imagery" really expressed what I believed everybody supposed them to mean. They had no more notion of its true nature than a colour-blind man who has not discerned his defect has of the nature of colour. [ 2 ]
In 1897, Théodule-Armand Ribot reported a kind of "typographic visual type" imagination, consisting in mentally seeing ideas in the form of corresponding printed words. [ 11 ] As paraphrased by Jacques Hadamard ,
The first discovery of this by Ribot was the case of a man whom he mentions as a well-known physiologist. For that man, even the words "dog, animal" (while he was living among dogs and experimenting on them daily) were not accompanied by any image, but were seen by him as being printed. Similarly, when he heard the name of an intimate friend, he saw it printed and had to make an effort to see the image of this friend... Moreover, according to Ribot, men belonging to the typographic-visual type cannot conceive how other people's thought can proceed differently. [ 12 ]
The phenomenon remained largely unstudied until 2005, when Professor Adam Zeman of the University of Exeter was approached by a man who seemed to have lost the ability to visualize after undergoing minor surgery. [ 13 ] Following the publication of this patient's case in 2010, [ 14 ] a number of people approached Zeman reporting a lifelong inability to visualize. In 2015, Zeman's team published a paper on what they termed " congenital aphantasia"—a form of aphantasia in which individuals have never had the ability to generate voluntary mental images— [ 3 ] sparking renewed interest in the phenomenon. [ 4 ]
The idea of aphantasia was popularised on social media in 2020, through posts which asked the reader to imagine a red apple and rate their "mind's eye" depiction of it on a scale from 1 (photographic visualisation) through to 5 (no visualisation at all). Many were shocked to learn that their own ability or inability to visualise objects was not universal. [ 15 ]
Zeman's 2015 paper used the Vividness of Visual Imagery Questionnaire (VVIQ), developed by David Marks in 1973, to evaluate the quality of the mental image of 21 self-diagnosed and self-selected participants. He found that most aphantasics lack voluntary visualizations only; the majority of test subjects did report involuntary visualizations such as dreams . [ 3 ] Along with Zeman's reports of involuntary mental imagery occurring during dream states, a 2020 study found that individuals with aphantasia experience less control and fewer sensory emotions during dreams compared to those with a strong ability to generate voluntary mental images while awake. [ 16 ] The lack of intense emotions is thought to result from a functional trade-off [ 17 ] —competition between two neural systems—occurring between semantic information and sensory qualities, which is strongly associated with individuals who have low VVIQ scores. [ 16 ]
In 2017, a paper measured the sensory capacity of mental imagery using binocular-rivalry (BR) and imagery-based priming and found that when asked to imagine a stimulus, the self-reported aphantasics experienced almost no perceptual priming, compared to those who reported higher imagery scores where perceptual priming had an effect. [ 18 ] In 2020, Keogh and Pearson published another paper illustrating measurable differences correlated with visual imagery, this time by indirectly measuring cortical excitability in the primary visual cortex (V1). [ 19 ]
In 2018, a study analyzing the visual working memory of a person with aphantasia found that mental imagery has a "functional role in areas of visual cognition, one of which is high-precision working memory" and that the person with aphantasia performed significantly worse than controls on visual working memory trials requiring the highest degree of precision, and lacked metacognitive insight into their performance. [ 20 ]
A 2020 study concluded that those who experience aphantasia also experience reduced imagery in other senses, and have less vivid autobiographical memories . [ 16 ] In addition to deficits in autobiographical memories compared to people without aphantasia, people with aphantasia had significant differences in all aspects of memory when compared to the performance of people without aphantasia. [ 21 ] A 2021 study concluded that while those with aphantasia reported fewer objects in drawing recall, they showed high spatial memory concerning controls in drawings, with these differences only appearing during the recall stage of the study. [ 22 ]
In 2021, a study by Keogh, Wicken, and Pearson focusing on the role of visual imagery in visual working memory tasks specifically considered the strategies people with aphantasia use in these tasks. It found no significant differences in visual working memory task performances for those with aphantasia when compared to controls. However, significant differences were found in the reported strategies used by aphantasic individuals across the memory tasks. [ 23 ]
In 2021, a study that measured the perspiration (via skin conductance levels ) of participants in response to reading a frightening story and then viewing fear-inducing images found that participants with aphantasia, but not the general population, experienced a flat-line physiological response during the reading experiment, but found no difference in physiological responses between the groups when participants viewed fear-inducing images. The study concluded the evidence supported the emotional amplification theory of visual imagery. [ 24 ]
In 2021, a study found that people with aphantasia have slower reaction times than people without aphantasia in a visual search task in which they were presented with a target and a distractor. But both groups saw a similar reduction in reaction time when primed with the color of the target compared to if primed with the color of the distractor or a third color, suggesting that people with and without aphantasia were primed in the same way. The researchers hypothesized that this may be because the color of the prime is not relevant to the search task. To explore this, a follow-up experiment by the same researchers found people without aphantasia saw a greater reduction in reaction time when selecting the target from two images compared to from two words. At the same time, both people with and without aphantasia were faster in the image task than the word task. [ 25 ] A 2023 study explored more natural scenarios and found that aphantasics are slower at solving hidden object pictures . [ 26 ]
In 2021, a study relating aphantasia, synesthesia , and autism was published that found that people with aphantasia reported more autistic traits than people without aphantasia, with weaknesses in imagination and social skills. [ 27 ] [ 28 ]
In addition to congenital aphantasia, there have been cases reported of acquired aphantasia—characterized by new onset of diminished voluntary visual imagery—due either to brain injury or psychological causes. [ 29 ] [ 30 ] In 2021, a study reported on acquired aphantasia following a case of COVID-19. [ 31 ] [ 32 ]
A 2021 study aimed to provide insights into the correlation between auditory and visual imagery. The research, conducted on a sample of 128 participants, included 34 individuals who self-identified as having aphantasia. The study found a strong association between auditory imagery (measured using the Bucknell Auditory Imagery Scale-Vividness, BAIS-V) and visual imagery (measured using the Vividness of Visual Imagery Questionnaire-Modified, VVIQ-M). They found most people who self-reported having aphantasia also reported weak or entirely absent auditory imagery. Moreover, participants lacking auditory imagery tended to be aphantasic. The authors proposed a new term, "anauralia", to describe the absence of auditory imagery, particularly the lack of an "inner voice". [ 33 ] A subsequent study, corroborated this finding, showing that the majority of a sample of people recruited on the basis of visual aphantasia also reported having reduced auditory imagery. However, this self-reported reduction in auditory imagery was not evident in performance on tasks thought to require auditory imagery, including a musical pitch imagery and voice recognition task. [ 34 ]
A 2022 study estimated the prevalence of aphantasia among the general population by screening undergraduate students and people from an online crowdsourcing marketplace through the Vividness of Visual Imagery Questionnaire. They found that 0.8% of the population was unable to form visual mental images, and 3.9% of the population was either unable to form mental images or had dim or vague mental imagery. [ 35 ] Sitek and Konieczna have shown that its progressive form may be a harbinger of dementia. [ 36 ] A group of authors interviewed people with aphantasia about their lives and found that they generated fewer episodic details than controls for both past and future events, indicating that visual imagery is an important cognitive tool for dynamic retrieval and recombination of episodic details. [ 37 ]
There have been various approaches to find a general theory of aphantasia or incorporate it into current philosophical , psychological and linguistic research. Blomkvist [ 38 ] has suggested that aphantasia is best explained as a malfunction of processes in the episodic system and sees it as an episodic system condition. Nanay [ 39 ] has argued that at least some instances of this condition can be explained in terms of unconscious mental imagery. [ clarification needed ] Alternative explanations for aphantasia have also been proposed in the scientific literature. Lorenzatti [ 40 ] provides a summary of these views. Aphantasia also has been studied from philosophical perspectives. Šekrst [ 41 ] proposed that a gradual range of perceptions and mental images, from aphantasia to hyperphantasia, influences philosophical analysis of mental imagery from a fuzzy standpoint, along with influence on linguistics and semiotics . Whiteley [ 42 ] argues that a modified theory of dreaming has to incorporate aphantasia, by involving the claim that dreams are a non-voluntary form of imagination. Additionally, research by Boran [ 43 ] into romantic desire has shown a potential link between vividness of mental imagery and romantic feelings, suggesting that mental imagery may also play a role in emotional memory and relationships.
In 2024, a research team led by Jonathan Rhodes from the University of Plymouth assessed the imagery abilities of over 300 athletes finding a small sample of 27 who had aphantasia or low imagery abilities. The researchers developed a training program over six weeks to improve imagery ability, finding that it can be significantly improved for the majority of participants. [ 44 ] In addition, the research of Keogh and Pearson's [ 45 ] follow-up with over 50 participants further confirmed the absence of sensory imagery in aphantasia, adding evidence to the field of study. Zeman [ 46 ] also proposes that alterations in connectivity between the frontoparietal and visual networks may provide the neural substrate for extreme variations in visual imagery.
The interoceptive view of aphantasia, proposed in recent peer-reviewed publications [ 47 ] [ 48 ] by Juha Silvanto and Yoko Nagai, proposes that mental imagery is not purely a visual or sensory process, but rather a form of embodied simulation grounded in internal bodily states. According to this perspective, the inability to generate mental images in aphantasia arises from disruptions in interoception—the brain’s ability to detect, interpret, and integrate signals from the body, such as heart rate, respiration, and visceral sensations.
This model emphasizes that vivid imagery depends on more than just activity in visual regions; it also requires the integration of interoceptive information that imbues images with emotional tone, a sense of ownership, and volitional control. Brain areas such as the insula and anterior cingulate cortex play a key role in this process by combining bodily signals with top-down predictions about sensory experiences. When interoceptive precision is reduced—either through underdevelopment or adaptive suppression—this integration fails, leading to diminished imagery vividness or a complete lack of conscious imagery.
Congenital aphantasia may reflect a lifelong failure to develop the neural architecture required to integrate bodily and sensory signals. In contrast, acquired aphantasia may emerge as a protective mechanism, in which the brain dampens imagery and bodily simulation to cope with overwhelming autonomic input or emotional distress. This account aligns with predictive coding frameworks, which suggest that imprecise interoceptive predictions lead to insufficient gain on top-down signals, preventing imagery from reaching awareness.
This interoceptive disruption may also explain the high rates of alexithymia, emotional blunting, and depersonalization reported in some individuals with aphantasia. Rather than viewing aphantasia as a narrowly defined visual deficit, the interoceptive account reframes it as a broader disturbance of embodied mental simulation—a failure to integrate sensory and bodily signals into coherent internal experiences.
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Defibrillation is a treatment for life-threatening cardiac arrhythmias , specifically ventricular fibrillation (V-Fib) and non-perfusing ventricular tachycardia (V-Tach). [ 1 ] [ 2 ] A defibrillator delivers a dose of electric current (often called a counter-shock ) to the heart . Although not fully understood, this process depolarizes a large amount of the heart muscle , ending the arrhythmia. Subsequently, the body's natural pacemaker in the sinoatrial node of the heart is able to re-establish normal sinus rhythm . [ 3 ] A heart which is in asystole (flatline) cannot be restarted by a defibrillator; it would be treated only by cardiopulmonary resuscitation (CPR) and medication, and then by cardioversion or defibrillation if it converts into a shockable rhythm.
In contrast to defibrillation, synchronized electrical cardioversion is an electrical shock delivered in synchrony to the cardiac cycle . [ 4 ] Although the person may still be critically ill , cardioversion normally aims to end poorly perfusing cardiac arrhythmias , such as supraventricular tachycardia . [ 1 ] [ 2 ]
Defibrillators can be external, transvenous, or implanted ( implantable cardioverter-defibrillator ), depending on the type of device used or needed. [ 5 ] Some external units, known as automated external defibrillators (AEDs), automate the diagnosis of treatable rhythms, meaning that lay responders or bystanders are able to use them successfully with little or no training. [ 2 ]
Defibrillation is often an important step in cardiopulmonary resuscitation (CPR). [ 6 ] [ 7 ] CPR is an algorithm-based intervention aimed to restore cardiac and pulmonary function. [ 6 ] Defibrillation is indicated only in certain types of cardiac dysrhythmias , specifically ventricular fibrillation (VF) and pulseless ventricular tachycardia . [ 1 ] [ 2 ] If the heart has completely stopped, as in asystole or pulseless electrical activity (PEA) , defibrillation is not indicated. Defibrillation is also not indicated if the patient is conscious or has a pulse. Improperly given electrical shocks can cause dangerous dysrhythmias, such as ventricular fibrillation. [ 1 ]
A defibrillation device that is often available outside of medical centers is the automated external defibrillator (AED), [ 8 ] a portable machine that can be used with no previous training. That is possible because the machine produces pre-recorded voice instructions that guide the user. The device automatically checks the patient's condition and applies the correct electric shocks. There also exist written instructions that explain the procedure step-by-step. [ 9 ]
Survival rates for out-of-hospital cardiac arrests in North America are poor, often less than 10%. [ 10 ] Outcome for in-hospital cardiac arrests are higher at 20%. [ 10 ] Within the group of people presenting with cardiac arrest, the specific cardiac rhythm can significantly impact survival rates. Compared to people presenting with a non-shockable rhythm (such as asystole or PEA), people with a shockable rhythm (such as VF or pulseless ventricular tachycardia) have improved survival rates, ranging between 21 and 50%. [ 6 ] [ 11 ] [ 12 ]
Manual external defibrillators require the expertise of a healthcare professional. [ 13 ] [ 14 ] They are used in conjunction with an electrocardiogram , which can be separate or built-in. A healthcare provider first diagnoses the cardiac rhythm and then manually determine the voltage and timing for the electrical shock. These units are primarily found in hospitals and on some ambulances . For instance, every NHS ambulance in the United Kingdom is equipped with a manual defibrillator for use by the attending paramedics and technicians. [ citation needed ] In the United States , many advanced EMTs and all paramedics are trained to recognize lethal arrhythmias and deliver appropriate electrical therapy with a manual defibrillator when appropriate. [ citation needed ]
An internal defibrillator is often used to defibrillate the heart during or after cardiac surgery such as a heart bypass . The electrodes consist of round metal plates that come in direct contact with the myocardium. Manual internal defibrillators deliver the shock through paddles placed directly on the heart. [ 1 ] They are mostly used in the operating room and, in rare circumstances, in the emergency room during an open heart procedure .
Automated external defibrillators (AEDs) are designed for use by untrained or briefly trained laypersons. [ 15 ] [ 16 ] [ 17 ] AEDs contain technology for analysis of heart rhythms. As a result, it does not require a trained health provider to determine whether or not a rhythm is shockable. By making these units publicly available, AEDs have improved outcomes for sudden out-of-hospital cardiac arrests. [ 15 ] [ 16 ]
Trained health professionals have more limited use for AEDs than manual external defibrillators. [ 18 ] Recent studies show that AEDs does not improve outcome in patients with in-hospital cardiac arrests. [ 18 ] [ 19 ] AEDs have set voltages and does not allow the operator to vary voltage according to need. AEDs may also delay delivery of effective CPR. For diagnosis of rhythm, AEDs often require the stopping of chest compressions and rescue breathing. For these reasons, certain bodies, such as the European Resuscitation Council, recommend using manual external defibrillators over AEDs if manual external defibrillators are readily available. [ 19 ]
As early defibrillation can significantly improve VF outcomes, AEDs have become publicly available in many easily accessible areas. [ 18 ] [ 19 ] AEDs have been incorporated into the algorithm for basic life support (BLS). Many first responders , such as firefighters, police officers, and security guards, are equipped with them.
AEDs can be fully automatic or semi-automatic. [ 20 ] A semi-automatic AED automatically diagnoses heart rhythms and determines if a shock is necessary. If a shock is advised, the user must then push a button to administer the shock. A fully automated AED automatically diagnoses the heart rhythm and advises the user to stand back while the shock is automatically given. Some types of AEDs come with advanced features, such as a manual override or an ECG display.
Implantable cardioverter-defibrillators , also known as automatic internal cardiac defibrillator (AICD), are implants similar to pacemakers (and many can also perform the pacemaking function). They constantly monitor the patient's heart rhythm, and automatically administer shocks for various life-threatening arrhythmias, according to the device's programming. Many modern devices can distinguish between ventricular fibrillation , ventricular tachycardia , and more benign arrhythmias like supraventricular tachycardia and atrial fibrillation . Some devices may attempt overdrive pacing prior to synchronised cardioversion. When the life-threatening arrhythmia is ventricular fibrillation, the device is programmed to proceed immediately to an unsynchronized shock.
There are cases where the patient's ICD may fire constantly or inappropriately. This is considered a medical emergency , as it depletes the device's battery life, causes significant discomfort and anxiety to the patient, and in some cases may actually trigger life-threatening arrhythmias. Some emergency medical services personnel are now equipped with a ring magnet to place over the device, which effectively disables the shock function of the device while still allowing the pacemaker to function (if the device is so equipped). If the device is shocking frequently, but appropriately, EMS personnel may administer sedation.
A wearable cardioverter defibrillator is a portable external defibrillator that can be worn by at-risk patients. [ 21 ] The unit monitors the patient 24 hours a day and can automatically deliver a biphasic shock if VF or VT is detected. This device is mainly indicated in patients who are not immediate candidates for ICDs. [ 22 ]
The connection between the defibrillator and the patient consists of a pair of electrodes, each provided with electrically conductive gel in order to ensure a good connection and to minimize electrical resistance , also called chest impedance (despite the DC discharge) which would burn the patient. Gel may be either wet (similar in consistency to surgical lubricant ) or solid (similar to gummi candy ). Solid-gel is more convenient, because there is no need to clean the used gel off the person's skin after defibrillation. However, the use of solid-gel presents a higher risk of burns during defibrillation, since wet-gel electrodes more evenly conduct electricity into the body. Paddle electrodes, which were the first type developed, come without gel, and must have the gel applied in a separate step. Self-adhesive electrodes come prefitted with gel. There is a general division of opinion over which type of electrode is superior in hospital settings; the American Heart Association favors neither, and all modern manual defibrillators used in hospitals allow for swift switching between self-adhesive pads and traditional paddles. Each type of electrode has its merits and demerits.
The most well-known type of electrode (widely depicted in films and television) is the traditional metal "hard" paddle with an insulated (usually plastic) handle. This type must be held in place on the patient's skin with approximately 25 lbs (11.3 kg) of force while a shock or a series of shocks is delivered. Paddles offer a few advantages over self-adhesive pads. Many hospitals in the United States continue the use of paddles, with disposable gel pads attached in most cases, due to the inherent speed with which these electrodes can be placed and used. This is critical during cardiac arrest, as each second of nonperfusion means tissue loss. Modern paddles allow for monitoring ( electrocardiography ), though in hospital situations, separate monitoring leads are often already in place.
Paddles are reusable, being cleaned after use and stored for the next patient. Gel is therefore not preapplied, and must be added before these paddles are used on the patient. Paddles are generally only found on manual external units.
Newer types of resuscitation electrodes are designed as an adhesive pad, which includes either solid or wet gel. These are peeled off their backing and applied to the patient's chest when deemed necessary, much the same as any other sticker. The electrodes are then connected to a defibrillator, much as the paddles would be. If defibrillation is required, the machine is charged, and the shock is delivered, without any need to apply any additional gel or to retrieve and place any paddles. Most adhesive electrodes are designed to be used not only for defibrillation, but also for transcutaneous pacing and synchronized electrical cardioversion . These adhesive pads are found on most automated and semi-automated units and are replacing paddles entirely in non-hospital settings. In hospital, for cases where cardiac arrest is likely to occur (but has not yet), self-adhesive pads may be placed prophylactically.
Pads also offer an advantage to the untrained user, and to medics working in the sub-optimal conditions of the field. Pads do not require extra leads to be attached for monitoring, and they do not require any force to be applied as the shock is delivered. Thus, adhesive electrodes minimize the risk of the operator coming into physical (and thus electrical) contact with the patient as the shock is delivered by allowing the operator to be up to several feet away. (The risk of electrical shock to others remains unchanged, as does that of shock due to operator misuse.) Self-adhesive electrodes are single-use only. They may be used for multiple shocks in a single course of treatment, but are replaced if (or in case) the patient recovers then reenters cardiac arrest.
Special pads are used for children under the age of 8 or those under 55 lbs. (22 kg). [ 23 ]
Resuscitation electrodes are placed according to one of two schemes. The anterior-posterior scheme is the preferred scheme for long-term electrode placement. One electrode is placed over the left precordium (the lower part of the chest, in front of the heart). The other electrode is placed on the back, behind the heart in the region between the scapula. This placement is preferred because it is best for non-invasive pacing.
The anterior-apex scheme (anterior-lateral position) can be used when the anterior-posterior scheme is inconvenient or unnecessary. In this scheme, the anterior electrode is placed on the right, below the clavicle. The apex electrode is applied to the left side of the patient, just below and to the left of the pectoral muscle. This scheme works well for defibrillation and cardioversion, as well as for monitoring an ECG.
Researchers have created a software modeling system capable of mapping an individual's chest and determining the best position for an external or internal cardiac defibrillator. [ 24 ]
Defibrillation halts chaotic cardiac activity by forcibly depolarizing heart cells, disrupting re-entrant circuits, and allowing for the heart's natural pacemaker to take over. [ 25 ] [ 26 ]
Cardiac cells require a strong electrical stimulus to raise their transmembrane potential to the activation threshold. [ 25 ] [ 26 ] Only a small amount of electrical current enters the cell due to high membrane impedance. [ 25 ] The intracellular voltage of the cell remains uniform, while the extracellular voltage rapidly increases or decreases depending on proximity to the electrodes. [ 25 ] This creates a voltage gradient that alters the transmembrane potential of cells, potentially resetting irregular electrical activity to restore normal cardiac rhythm. [ 25 ] [ 26 ]
Irregular rhythms often result from re-entrant circuits, where electrical impulses circle within the heart tissue due to areas of slow conduction or unidirectional block. [ 27 ] The widespread depolarization from the shock interrupts these circuits, stopping the erratic propagation of electrical signals. [ 25 ] [ 26 ] [ 27 ]
After the cells depolarize, they enter a refractory period, during which they cannot be re-excited. [ 28 ] [ 29 ] This allows the heart's natural pacemaker, the sinoatrial node, to resume control of the rhythm. During this period, ion pumps actively restore the normal distribution of ions, re-establishing the resting membrane potential. [ 28 ] [ 29 ]
Defibrillators were first demonstrated in 1899 by Jean-Louis Prévost and Frédéric Batelli, two physiologists from the University of Geneva , Switzerland. They discovered that small electrical shocks could induce ventricular fibrillation in dogs, and that larger charges would reverse the condition. [ 30 ] [ 31 ]
In 1933, Dr. Albert Hyman , heart specialist at the Beth Davis Hospital of New York City, and C. Henry Hyman, an electrical engineer, looking for an alternative to injecting powerful drugs directly into the heart, came up with an invention that used an electrical shock in place of drug injection. This invention was called the Hyman Otor where a hollow needle is used to pass an insulated wire to the heart area to deliver the electrical shock. The hollow steel needle acted as one end of the circuit and the tip of the insulated wire the other end. Whether the Hyman Otor was a success is unknown. [ 32 ]
The external defibrillator, as it is known today, was invented by electrical engineer William Kouwenhoven in 1930. Kouwenhoven studied the relationship between electric shocks and their effects on the human heart when he was a student at Johns Hopkins University School of Engineering. His studies helped him invent a device to externally jump start the heart. He invented the defibrillator and tested it on a dog, like Prévost and Batelli. The first use on a human was in 1947 by Claude Beck , [ 33 ] professor of surgery at Case Western Reserve University .
Beck's theory was that ventricular fibrillation often occurred in hearts that were fundamentally healthy, in his terms "Hearts that are too good to die", and that there must be a way of saving them. Beck first used the technique successfully on a 14-year-old boy who was having his breastbone separated from his ribs because of a congenital growth disorder, causing breathing problems. The boy's chest was surgically opened, and manual cardiac massage was undertaken for 45 minutes until the arrival of the defibrillator. Beck used internal paddles on either side of the heart, along with procainamide , an antiarrhythmic drug, and achieved return of a perfusing cardiac rhythm. [ citation needed ]
These early defibrillators used the alternating current from a power socket, transformed from the 110–240 volts available in the line, up to between 300 and 1000 volts, to the exposed heart by way of "paddle" type electrodes. The technique was often ineffective in reverting VF while morphological studies showed damage to the cells of the heart muscle post-mortem. The nature of the AC machine with a large transformer also made these units very hard to transport, and they tended to be large units on wheels. [ citation needed ]
Until the early 1950s, defibrillation of the heart was possible only when the chest cavity was open during surgery. The technique used an alternating voltage from a 300 or greater volt source derived from standard AC power, delivered to the sides of the exposed heart by "paddle" electrodes where each electrode was a flat or slightly concave metal plate of about 40 mm diameter. The closed-chest defibrillator device which applied an alternating voltage of greater than 1000 volts, conducted by means of externally applied electrodes through the chest cage to the heart, was pioneered by Dr V. Eskin with assistance by A. Klimov in Frunze, USSR (today known as Bishkek , Kyrgyzstan ) in the mid-1950s. [ 34 ] The duration of AC shocks was typically in the range of 100–150 milliseconds. [ 35 ]
Early successful experiments of successful defibrillation by the discharge of a capacitor performed on animals were reported by N. L. Gurvich and G. S. Yunyev in 1939. [ 36 ] In 1947 their works were reported in western medical journals. [ 37 ] Serial production of Gurvich's pulse defibrillator started in 1952 at the electromechanical plant of the institute, and was designated model ИД-1-ВЭИ ( Импульсный Дефибриллятор 1, Всесоюзный Электротехнический Институт , or in English, Pulse Defibrillator 1, All-Union Electrotechnical Institute ). It is described in detail in Gurvich's 1957 book, Heart Fibrillation and Defibrillation . [ 38 ]
The first Czechoslovak "universal defibrillator Prema" was manufactured in 1957 by the company Prema, designed by Dr. Bohumil Peleška. In 1958 his device was awarded Grand Prix at Expo 58 . [ 39 ]
In 1958, US senator Hubert H. Humphrey visited Nikita Khrushchev and among other things he visited the Moscow Institute of Reanimatology, where, among others, he met with Gurvich. [ 40 ] Humphrey immediately recognized importance of reanimation research and after that a number of American doctors visited Gurvich. At the same time, Humphrey worked on establishing a federal program in the National Institute of Health in physiology and medicine, telling Congress: "Let's compete with U.S.S.R. in research on reversibility of death". [ 41 ]
In 1959 Bernard Lown commenced research in his animal laboratory in collaboration with engineer Barouh Berkovits into a technique which involved charging of a bank of capacitors to approximately 1000 volts with an energy content of 100–200 joules then delivering the charge through an inductance such as to produce a heavily damped sinusoidal wave of finite duration (~5 milliseconds ) to the heart by way of paddle electrodes. This team further developed an understanding of the optimal timing of shock delivery in the cardiac cycle, enabling the application of the device to arrhythmias such as atrial fibrillation , atrial flutter , and supraventricular tachycardias in the technique known as " cardioversion ".
The Lown-Berkovits waveform, as it was known, was the standard for defibrillation until the late 1980s. Earlier in the 1980s, the "MU lab" at the University of Missouri had pioneered numerous studies introducing a new waveform called a biphasic truncated waveform (BTE). In this waveform an exponentially decaying DC voltage is reversed in polarity about halfway through the shock time, then continues to decay for some time after which the voltage is cut off, or truncated. The studies showed that the biphasic truncated waveform could be more efficacious while requiring the delivery of lower levels of energy to produce defibrillation. [ 35 ] An added benefit was a significant reduction in weight of the machine. The BTE waveform, combined with automatic measurement of transthoracic impedance, is the basis for modern defibrillators. [ citation needed ]
A major breakthrough was the introduction of portable defibrillators used out of the hospital. Already Peleška's Prema defibrillator was designed to be more portable than original Gurvich's model. In Soviet Union, a portable version of Gurvich's defibrillator, model ДПА-3 (DPA-3), was reported in 1959. [ 42 ] In the west this was pioneered in the early 1960s by Prof. Frank Pantridge in Belfast . Today portable defibrillators are among the many very important tools carried by ambulances. They are the only proven way to resuscitate a person who has had a cardiac arrest unwitnessed by Emergency Medical Services (EMS) who is still in persistent ventricular fibrillation or ventricular tachycardia at the arrival of pre-hospital providers.
Gradual improvements in the design of defibrillators, partly based on the work developing implanted versions (see below), have led to the availability of Automated External Defibrillators. These devices can analyse the heart rhythm by themselves, diagnose the shockable rhythms, and charge to treat. This means that no clinical skill is required in their use, allowing lay people to respond to emergencies effectively.
Until the mid 1990s, external defibrillators delivered a Lown type waveform (see Bernard Lown ), a heavily damped sinusoidal impulse having a mainly uniphasic characteristic. Biphasic defibrillation alternates the direction of the pulses, completing one cycle in approximately 12 milliseconds. Biphasic defibrillation was originally developed and used for implantable cardioverter-defibrillators. When applied to external defibrillators, biphasic defibrillation significantly decreases the energy level necessary for successful defibrillation, decreasing the risk of burns and myocardial damage.
Ventricular fibrillation (VF) could be returned to sinus rhythm in 60% of cardiac arrest patients treated with a single shock from a monophasic defibrillator. Most biphasic defibrillators have a first shock success rate of greater than 90%. [ 43 ]
A further development in defibrillation came with the invention of the implantable device, known as an implantable cardioverter-defibrillator (or ICD). This was pioneered at Sinai Hospital in Baltimore by a team that included Stephen Heilman, Alois Langer, Jack Lattuca, Morton Mower , Michel Mirowski , and Mir Imran , with the help of industrial collaborator Intec Systems of Pittsburgh. [ 44 ] Mirowski teamed up with Mower and Staewen, and together they commenced their research in 1969. However, it was 11 years before they treated their first patient. Similar developmental work was carried out by Schuder and colleagues at the University of Missouri .
The work was commenced, despite doubts amongst leading experts in the field of arrhythmias and sudden death. There was doubt that their ideas would ever become a clinical reality. In 1962 Bernard Lown introduced the external DC defibrillator. This device applied a direct current from a discharging capacitor through the chest wall into the heart to stop heart fibrillation . [ 45 ] In 1972, Lown stated in the journal Circulation – "The very rare patient who has frequent bouts of ventricular fibrillation is best treated in a coronary care unit and is better served by an effective antiarrhythmic program or surgical correction of inadequate coronary blood flow or ventricular malfunction. In fact, the implanted defibrillator system represents an imperfect solution in search of a plausible and practical application." [ 46 ]
The problems to be overcome were the design of a system which would allow detection of ventricular fibrillation or ventricular tachycardia. Despite the lack of financial backing and grants, they persisted and the first device was implanted in February 1980 at Johns Hopkins Hospital by Dr. Levi Watkins Jr. assisted by Vivien Thomas . Modern ICDs do not require a thoracotomy and possess pacing , cardioversion, and defibrillation capabilities.
The invention of implantable units is invaluable to some people with regular heart problems, although they are generally only given to those people who have already had a cardiac episode.
People can live long normal lives with the devices. Many patients have multiple implants. A patient in Houston, Texas had an implant at the age of 18 in 1994 by the recent Dr. Antonio Pacifico. He was awarded "Youngest Patient with Defibrillator" in 1996. Today these devices are implanted into small babies shortly after birth.
As devices that can quickly produce dramatic improvements in patient health, defibrillators are often depicted in movies, television, video games and other fictional media. Their function, however, is often exaggerated with the defibrillator inducing a sudden, violent jerk or convulsion by the patient. The pad placement is also shown wrong, along with sudden rising of patient to large height when shock is given. In reality, while the muscles may contract, such dramatic patient presentation is rare. Similarly, medical providers are often depicted defibrillating patients with a "flat-line" ECG rhythm (also known as asystole ). This is not normal medical practice, as the heart cannot be restarted by the defibrillator itself. Only the cardiac arrest rhythms ventricular fibrillation and pulseless ventricular tachycardia are normally defibrillated. The purpose of defibrillation is to depolarize the entire heart all at once so that it is synchronized, effectively inducing temporary asystole, in the hope that in the absence of the previous abnormal electrical activity, the heart will spontaneously resume beating normally. Someone who is already in asystole cannot be helped by electrical means, and usually needs urgent CPR and intravenous medication (and even these are rarely successful in cases of asystole). A useful analogy to remember is to think of defibrillators as power-cycling, rather than jump-starting, the heart. There are also several heart rhythms that can be "shocked" when the patient is not in cardiac arrest, such as supraventricular tachycardia and ventricular tachycardia that produces a pulse ; this more-complicated procedure is known as cardioversion , not defibrillation.
In Australia up until the 1990s it was relatively rare for ambulances to carry defibrillators. This changed in 1990 after Australian media mogul Kerry Packer had a cardiac arrest due to a heart attack and, purely by chance, the ambulance that responded to the call carried a defibrillator. After recovering, Kerry Packer donated a large sum to the Ambulance Service of New South Wales in order that all ambulances in New South Wales should be fitted with a personal defibrillator, which is why defibrillators in Australia are sometimes colloquially called "Packer Whackers". [ 47 ]
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Defibrillation threshold indicates the minimum amount of energy needed to return normal rhythm to a heart that is beating in a cardiac dysrhythmia . Typical examples are the minimum amount of energy, expressed in joules , delivered by external defibrillator paddles or pads, required to break atrial fibrillation and restore normal sinus rhythm . Other common scenarios are restoring normal rhythm from atrial flutter , ventricular tachycardia or ventricular fibrillation . The defibrillation threshold ranking in these settings, from lowest to highest, would be, in order, ventricular tachycardia, atrial flutter, atrial fibrillation, ventricular fibrillation. The highest amount of energy that an external defibrillator can deliver at the present time is 360 joules biphasic. In clinical practice, the real threshold can be approximated but not exactly established, since the defibrillating shock can be delivered only once. Aside from that, energy isn't directly related to stimulus strength and efficiency, which is primarily determined by the delivered charge over time in mC and not power over time or energy, which are still used due to historical reasons. Charge based thresholds are more realistic parameters for shock efficacy. Usual values delivered by biphasic defibrillators lay between 50 and 300 mC. The amount of charge needed is influenced by certain medications, in particular sotalol , tend to lower such threshold, while others, such as amiodarone , may increase it. [ 1 ]
Defibrillation threshold is a concept also applicable to internal or implantable cardiac defibrillators . [ 2 ] The test needed to establish the defibrillation threshold is often referred to as DFT.
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In medicine , a deficiency is a lack or shortage of a functional entity, by less than normal or necessary supply or function. A person can have chromosomal deficiencies, mental deficiencies, nutritional deficiencies, complement deficiencies, or enzyme deficiencies. [ 1 ]
Protein-energy malnutrition (PEM) is a condition where people consume very little in the way of energy, proteins, or both in their diets; as a result, it is common in developing nations. The two main illnesses associated with this condition are kwashiorkor , which is characterized by severe protein deficiency, and marasmus , which is total food deprivation with abnormally low amounts of protein and energy. [ 2 ]
Certain human body cells, such as neurons, require high glucose concentrations. When there are insufficient carbohydrates in the diet, the breakdown of body proteins, dietary proteins, and glycerol from fats is what drives gluconeogenesis . Most gluconeogenesis occurs in the liver. A condition known as ketosis (increased ketones production), which is characterized by a strangely sweet-smelling patient, may result from a prolonged shortage of carbohydrates. [ 2 ]
The essential fatty acids (EFA) omega-3 and omega-6 are polyunsaturated. Clinical signs of an EFA deficiency include stunted growth in kids and babies, a scaly, dry rash, slowed wound healing and heightened susceptibility to infections. [ 2 ]
Enzymes are unique protein subtypes that are needed during metabolism , the process by which the body obtains energy for regular growth and development, to break down food molecules into fuel. A variety of conditions that can change or even endanger life are caused by inherited defects known as enzyme deficiencies, or the lack of these enzymes. Enzyme deficiencies include Niemann-Pick disease , Lysosomal storage diseases , and Mucopolysaccharidoses . [ 3 ]
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Degeneration is deterioration in the medical sense . Generally, it is the change from a higher to a lower form. More specifically, it is the change of tissue to a lower or less functionally active form.
This medical article is a stub . You can help Wikipedia by expanding it .
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Dejerine–Sottas disease , also known as, Dejerine–Sottas syndrome , [ 3 ] hereditary motor and sensory polyneuropathy type III, and Charcot–Marie–Tooth disease type 3 , is a hereditary neurological disorder characterized by damage to the peripheral nerves , demyelination , and resulting progressive muscle wasting and somatosensory loss. The condition is caused by mutations in various genes and currently has no known cure. [ 2 ]
The disorder is named for Joseph Jules Dejerine and Jules Sottas , French neurologists who first described it. [ 4 ] [ 5 ]
Onset occurs in infancy or early childhood, usually before three years of age. Progression is slow until the teenage years at which point it may accelerate, resulting in severe disability. [ 1 ]
Symptoms are more severe and rapidly progressive than in the other more common Charcot–Marie–Tooth diseases . Some patients may never walk and will be reliant on wheelchair use by the end of their first decade, while others may need only a cane, crutches, or similar support through most of their lives, but this is rare. [ 1 ]
Dejerine–Sottas disease is characterized by moderate to severe lower and upper extremity weakness and loss of sensation, mainly in the lower legs, forearms, feet, and hands. Loss of muscle mass and reduced muscle tone usually occur as the disease progresses. Other symptoms may include pain in the extremities, curvature of the spine, clawed hands, foot deformities, ataxia , peripheral areflexia , and slow acquisition of motor skills in childhood. Symptoms that are less common can include limitation of eye movements, other eye problems such as nystagmus or anisocoria , or moderate to severe hearing loss . [ 2 ]
Dejerine–Sottas neuropathy is caused by a genetic defect either in the proteins found in axons or the proteins found in myelin . [ 2 ] Specifically, it has been associated with mutations in MPZ , [ 6 ] PMP22 , [ 7 ] PRX , [ 8 ] and EGR2 [ 9 ] genes . The disorder is inherited in an autosomal dominant or autosomal recessive manner. [ 2 ]
On medical imaging, the peripheral and cranial nerves are enlarged by redundant connective tissue . On histology , this enlargement gives the nerves the appearance of an onion-bulb. Nerve excitability and conduction speed are reduced. [ 1 ]
Management is symptomatic for this condition. [ 10 ]
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This page is currently under construction.
Transfusion-related acute lung injury
Febrile non-hemolytic transfusion reaction
Transfusion-associated graft versus host disease
A delayed hemolytic transfusion reaction (DHTR) is a type of adverse reaction to a blood transfusion . [ 1 ] [ 2 ] [ 3 ] [ 4 ] DHTR is the later-onset manifestation of hemolytic transfusion reaction, which may also present as acute hemolytic transfusion reaction (AHTR) in a shorter timeframe from transfusion administration. The prevalence of AHTR has been estimated at 1 in 70,000 blood transfusions, whereas the prevalence of DHTR is thought to be underreported, although various studies estimate the prevalence of DHTR as between 1 in 800, to 1 in 11,000 transfusions. [ 1 ]
Hemolytic transfusion reactions are a possible complication from red blood cell transfusions . Hemolysis refers to the lysis (rupture) of red blood cells , and the resulting leakage of their contents. Hemolytic reactions may be immune or non-immune mediated. Immune-mediated hemolytic reactions, such as DHTR, represent a type of alloimmunity . Non-immune hemolysis may result from thermal , osmotic , or mechanical damage to red blood cells in transfusion products.
In immune-mediated DHTR, the transfusion recipient has antibodies that react with antigens on incompatible donor red blood cells, [ 5 ] prompting lysis of the red blood cells by the recipient's immune cells , such as macrophages . The severity of immune-mediated hemolytic reactions may vary based on the type and quantity of both the transfused red blood cell antigens and the recipient's antibodies against them, as well as the ability of the antibodies to activate complement or opsonization . Some recipients do not have significant pre-existing antibodies against transfused red blood cells, but then develop higher levels of such antibodies following immune stimulation by the transfused red blood cells.
While AHTR usually presents within the first 24 hours after transfusion, DHTR has the possibility to present up to 30 days later. Even though DHTR may have a lower chance of severe outcomes than AHTR, it can still be fatal or result in serious complications, and must be treated as an urgent medical issue .
If a person without a Kidd blood antigen (for example a Jka-Jkb+ patient) receives a Kidd antigen (Jka-antigen for example) in a red blood cell transfusion and forms an alloantibody (anti-Jka); upon subsequent transfusion with Jka-antigen positive red blood cells, the patient may have a delayed hemolytic transfusion reaction as their anti-Jka antibody hemolyzes the transfused Jka-antigen positive red blood cells. Other common blood groups with this reaction are Duffy , Rhesus and Kell . [ 6 ]
Immune-mediated hemolytic reactions may be classified as either intravascular or extravascular hemolysis. Intravascular hemolysis takes place while the red blood cells are still when the recipient's antibodies bind to the donor's red blood cells and cause complement activation. Extravascular hemolysis is produced when the recipient's antibodies opsonize the donor's red blood cells, leading to their sequestration and phagocytosis by phagocyte immune cells such as macrophages. Macrophage activation, in response to antibody-mediated targeting of red blood cells, can also increase production of cytokines that induce a systemic response that results in clinical symptoms, such as fever , chills , abdominal pain , and back pain .
Some hemolytic reactions are the product of incompatibility between different blood types of the ABO blood group system . Hemolytic reactions may also be caused by incompatibilities with Rh factors , Duffy antigens , Kell antigens , Kidd antigens , [ 6 ] and Lewis antigens .
Many people have antibodies to red blood cell antigens not found on the surface of their own red blood cells. Therefore, to use the ABO types as an example, those with type O blood are likely to have antibodies to type A and type B blood. Those with type A blood are likely to have antibodies to type B blood, and vice versa.
Antibodies against Kidd antigens may be difficult to detect because of significant variability in their molecular features, and weak in vitro expression. They have been reported to cause severe immediate or delayed hemolytic transfusion reactions, [ 6 ] with anti-Jk antibodies responsible for 13 of 44 cases of DHTR reported in the UK during 2021. [ 7 ]
Symptoms may include a drop in hemoglobin level, fever, jaundice, or hemoglobinuria. [ 6 ] It is also "associated with a fall in Hb or failure to increment, rise in bilirubin and LDH and an incompatible crossmatch not detectable pre transfusion." [ 10 ]
DHTR may be diagnosed by the presence of antibodies that react to red blood cells. An antiglobulin test , also known as a Coombs test, is a type of blood test used in immunohematology . An antiglobulin test may either be direct (e.g., "direct antiglobulin test" or "direct Coombs test"), or indirect. The direct test is designed to detect antibodies already bound to the surface of red blood cells in a clinical blood sample. By contrast, the indirect test is designed to detect antibodies that are freely floating in the blood, and that display in vitro reactivity against red blood cells. Both direct and indirect Coombs tests may be useful for investigating suspected blood transfusion reactions. The indirect test may also be used to determine a patient's reactivity to foreign red blood cell antigens prior to transfusion.
Hyperhemolysis differs from DHTR in that it involves the lysis of the recipient's own red blood cells in addition to those introduced from the donor. [ 11 ]
Delayed blood transfusion reactions occur at an incidence of about 1/500 to 1/10,000 transfusions in the United States. The subacute presentation, milder symptoms and paucity of reporting data make determination of the true incidence difficult. [ 12 ]
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Delirium tremens ( DTs ; lit. ' mental disturbance with shaking ' ) is a rapid onset of confusion usually caused by withdrawal from alcohol . [ 2 ] When it occurs, it is often three days into the withdrawal symptoms and lasts for two to three days. [ 2 ] Physical effects may include shaking , shivering , irregular heart rate , and sweating . [ 1 ] People may also hallucinate . [ 2 ] Occasionally, a very high body temperature or seizures (colloquially known as "rum fits") [ 5 ] [ 6 ] may result in death. [ 2 ]
Delirium tremens typically occurs only in people with a high intake of alcohol for more than a month, followed by sharply reduced intake. [ 7 ] A similar syndrome may occur with benzodiazepine and barbiturate withdrawal . In a person with delirium tremens, it is important to rule out other associated problems such as electrolyte abnormalities , pancreatitis , and alcoholic hepatitis . [ 2 ]
Prevention is by treating withdrawal symptoms using similarly acting compounds to taper off the use of the precipitating substance in a controlled fashion. [ 2 ] If delirium tremens occurs, aggressive treatment improves outcomes. [ 2 ] Treatment in a quiet intensive care unit with sufficient light is often recommended. [ 2 ] Benzodiazepines are the medication of choice with diazepam , lorazepam , chlordiazepoxide , and oxazepam all commonly used. [ 7 ] They should be given until a person is lightly sleeping. [ 2 ] Nonbenzodiazepines are often used as adjuncts to manage the sleep disturbance associated with condition. The antipsychotic haloperidol may also be used [ 2 ] in order to combat the overactivity and possible excitotoxicity caused by the withdrawal from a GABA-ergic substance. Thiamine (vitamin B 1 ) is recommended to be given intramuscularly , [ 2 ] because long-term high alcohol intake and the often attendant nutritional deficit damages the small intestine, leading to a thiamine deficiency , which sometimes cannot be rectified by supplement pills alone.
Mortality without treatment is between 15% and 40%. [ 4 ] Currently death occurs in about 1% to 4% of cases. [ 2 ]
About half of people with alcoholism will develop withdrawal symptoms upon reducing their use. [ 2 ] Of these, 3% to 5% develop DTs or have seizures. [ 2 ]
The name delirium tremens was first used in 1813; however, the symptoms were well described since the 1700s. [ 7 ] The word "delirium" is Latin for "going off the furrow", a plowing metaphor for disordered thinking. [ 4 ] It is also called the shaking frenzy and Saunders-Sutton syndrome. [ 4 ] There are numerous nicknames for the condition, including "the DTs" and " seeing pink elephants ".
The main symptoms of delirium tremens are nightmares, agitation, global confusion, disorientation, visual and auditory hallucinations, [ 8 ] tactile hallucinations , fever, high heart rate , high blood pressure , heavy sweating , and other signs of autonomic hyperactivity . These symptoms may appear suddenly but typically develop two to three days after the stopping of heavy drinking, being worst on the fourth or fifth day. [ 9 ]
These symptoms are characteristically worse at night. [ 10 ] For example, in Finnish, this nightlike condition is called liskojen yö , lit. ' the night of the lizards ' , for its sweatiness, general unease, and hallucinations tending towards the unseemly and frightening.
In general, DT is considered the most severe manifestation of withdrawal from alcohol or other GABAergic drugs, and can occur between the second and tenth days after the last drink. [ 8 ] It often overcomes the patient by surprise, because a brief period of uneventful sobriety of 1–2 days tends to precede it, it can fully manifest itself within a single hour, and unlike most other alcohol withdrawal symptoms, it is generally not relieved by more alcohol.
Other common symptoms include intense perceptual disturbance such as visions or feelings of insects, snakes, or rats. These may be hallucinations or illusions related to the environment, e.g., patterns on the wallpaper or in the peripheral vision that the patient falsely perceives as a resemblance to the morphology of an insect, and are also associated with tactile hallucinations such as sensations of something crawling on the subject—a phenomenon known as formication . Delirium tremens usually includes feelings of "impending doom". Anxiety and expecting imminent death are common DT symptoms. [ 11 ]
DT can sometimes be associated with severe, uncontrollable tremors of the extremities, and secondary symptoms such as anxiety, panic attacks, and paranoia . Confusion is often noticeable to onlookers as those with DT will have trouble forming simple sentences or making basic logical calculations. [ citation needed ]
DT should be distinguished from alcoholic hallucinosis , the latter of which occurs in approximately 20% of hospitalized alcoholics and does not carry a significant risk of mortality. In contrast, DT occurs in 5–10% of alcoholics and carries up to 15% mortality with treatment and up to 35% mortality without treatment. The most common conditions leading to death in patients with DTs are respiratory failure and cardiac arrhythmias . [ 12 ]
Delirium tremens is mainly caused by a long period of drinking being stopped abruptly. Withdrawal leads to a biochemical regulation cascade . [ citation needed ]
Delirium tremens is most common in people who are in alcohol withdrawal , especially in those who drink 10–11 standard drinks (equivalent of 7 to 8 US pints (3 to 4 L) of beer, 4 to 5 US pints (1.9 to 2.4 L) of wine or 1 US pint (0.5 L) of distilled beverage ) daily. Delirium tremens commonly affects those with a history of habitual alcohol use or alcoholism that has existed for more than 10 years. [ 13 ]
Delirium tremens is a component of alcohol withdrawal hypothesized to be the result of compensatory changes in response to chronic heavy alcohol use. Alcohol positively allosterically modulates the binding of GABA , enhancing its effect and resulting in inhibition of neurons projecting into the nucleus accumbens , as well as inhibiting NMDA receptors . This combined with desensitization of alpha-2 adrenergic receptors , results in a homeostatic upregulation of these systems in chronic alcohol use. [ 14 ]
When alcohol use ceases, the unregulated mechanisms result in hyperexcitability of neurons as natural GABAergic systems are down-regulated and excitatory glutamatergic systems are upregulated. This combined with increased noradrenergic activity results in the symptoms of delirium tremens. [ 14 ]
Diagnosis is mainly based on symptoms. In a person with delirium tremens, it is important to rule out other associated problems, such as electrolyte abnormalities , pancreatitis , and alcoholic hepatitis . [ 2 ]
Delirium tremens due to alcohol withdrawal can be treated with benzodiazepines. High doses may be necessary to prevent death. [ 15 ] Amounts given are based on the symptoms. Typically the person is kept sedated with benzodiazepines , such as diazepam , lorazepam , chlordiazepoxide , or oxazepam .
In some cases antipsychotics , such as haloperidol may also be used. Older drugs such as paraldehyde and clomethiazole were formerly the traditional treatment but have now largely been superseded by the benzodiazepines. [ 16 ]
Acamprosate is occasionally used in addition to other treatments, and is then carried on into long-term use to reduce the risk of relapse. If status epilepticus occurs it is treated in the usual way. [ citation needed ]
It can also be helpful to provide a well lit room as people often have hallucinations. [ 17 ]
Alcoholic beverages can also be prescribed as a treatment for delirium tremens, [ 18 ] but this practice is not universally supported. [ 19 ]
High doses of thiamine often by the intravenous route is also recommended. [ 2 ]
In the 1945 film The Lost Weekend , Ray Milland won the Academy Award for Best Actor for his depiction of a character who experiences delirium tremens after being hospitalized, hallucinating that he saw a bat fly in and eat a mouse poking through a wall. [ 20 ] [ 21 ] [ 22 ]
The M*A*S*H TV series episode "Bottoms Up" (season 9, episode 15, aired on March 2, 1981) featured a side story about a nurse (Capt. Helen Whitfield) who was found to be drinking heavily off-duty. By the culmination of the episode, after a confrontation by Maj. Margaret Houlihan, the character swears off alcohol and presumably quits immediately. At mealtime, roughly 48 hours later, Whitfield becomes hysterical upon being served food in the mess tent , claiming that things are crawling onto her from it. Margaret and Col. Sherman Potter subdue her. Potter, having recognized the symptoms of delirium tremens orders 5 ml of paraldehyde from a witnessing nurse.
During the filming of the 1975 film Monty Python and the Holy Grail , Graham Chapman developed delirium tremens due to the lack of alcohol on the set. It was particularly bad during the filming of the bridge of death scene where Chapman was visibly shaking, sweating and could not cross the bridge. His fellow Pythons were astonished as Chapman was an accomplished mountaineer. [ 23 ]
In the 1995 film Leaving Las Vegas , Nicolas Cage plays a suicidal alcoholic who rids himself of all his possessions and travels to Las Vegas to drink himself to death. During his travels, he experiences delirium tremens on a couch after waking up from a binge and crawls in pain to the refrigerator for more vodka . Cage's performance as Ben Sanderson in the film won the Academy Award for Best Actor in 1996.
French writer Émile Zola 's novel The Drinking Den ( L'Assommoir ) includes a character – Coupeau, the main character Gervaise's husband – who has delirium tremens by the end of the book.
In English Writer Mona Caird 's feminist novel The Daughters of Danaus (1894), "[a]s for taking enfeeblement as a natural dispensation", the character Hadria "would as soon regard delirium tremens in that light."
American writer Mark Twain describes an episode of delirium tremens in his book The Adventures of Huckleberry Finn (1884). In chapter 6, Huck states about his father, "After supper pap took the jug, and said he had enough whisky there for two drunks and one delirium tremens. That was always his word." Subsequently, Pap Finn runs around with hallucinations of snakes and chases Huck around their cabin with a knife in an attempt to kill him, thinking Huck is the "Angel of Death".
One of the characters in Joseph Conrad 's novel Lord Jim experiences "DTs of the worst kind" with symptoms that include seeing millions of pink frogs.
English author M. R. James mentions delirium tremens in his 1904 ghost story " 'Oh, Whistle, and I'll Come to You, My Lad' " . Professor Parkins while staying at the Globe Inn when in coastal Burnstow to "improve his game" of golf, despite being "a convinced disbeliever in what is called the 'supernatural ' ", when face to face with an entity in his "double-bed room" during the story's climax, is heard "uttering cry upon cry at the utmost pitch of his voice" though later "was somehow cleared of the ready suspicion of delirium tremens".
American writer Jack Kerouac details his experiences with delirium tremens in his book Big Sur . [ 24 ]
English author George Eliot provides a case involving delirium tremens in her novel Middlemarch (1871–72). Alcoholic scoundrel John Raffles, both an abusive stepfather of Joshua Riggs and blackmailing nemesis of financier Nicholas Bulstrode, dies, whose "death was due to delirium tremens" while at Peter Featherstone's Stone Court property. Housekeeper Mrs. Abel provides Raffles' final night of care per Bulstrode's instruction whose directions given to Abel stand adverse to Tertius Lydgate's orders.
Irish singer-songwriter Christy Moore has a song on his 1985 album, Ordinary Man , called "Delirium Tremens" which is a satirical song, directed towards the leaders in Irish politics and culture. Some of the people mentioned in the song include Charles Haughey (former Fianna Fáil leader), Ruairi Quinn (at the time a Labour TD, later the party leader), Dick Spring (former Labour Party leader) and Roger Casement (who was captured bringing German guns to Ireland for the 1916 Easter Rising ). English band Brotherly has a song called "DTs" on their album One Sweet Life . Fito Páez and Joaquín Sabina have a song called "Delirium Tremens " on their 1998 collaborative album, ''Enemigos Íntimos''.
Russian composer Modest Mussorgsky (1839-1881) died of delirium tremens . [ 25 ]
Nicknames for delirium tremens include "the DTs", "the shakes", "the oopizootics", "barrel-fever", "the blue horrors", "the rat's", "bottleache", "bats", "the drunken horrors", " seeing pink elephants ", "gallon distemper", "quart mania", "janky jerks", "heebie jeebies", "pink spiders", and "riding the ghost train", [ 26 ] as well as "ork orks", "the zoots", "the 750 itch", and "pint paralysis". Another nickname is "the Brooklyn Boys", found in Eugene O'Neill 's one-act play Hughie set in Times Square in the 1920s. [ 27 ] Delirium tremens was also given an alternate medical definition since at least the 1840s, being known as mania a potu , which translates to 'mania from drink'. [ 28 ]
The Belgian beer Delirium Tremens, introduced in 1988, is a direct reference and also uses a pink elephant as its logo to highlight one of the symptoms of delirium tremens. [ 29 ] [ 30 ]
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Demineralized freeze dried bone allograft , referred to as DFDBA , is a bone graft material known for its de novo bone formation properties. [ 1 ] It is used extensively in bone grafting of alveolar bone in oral and periodontal surgery.
This human musculoskeletal system article is a stub . You can help Wikipedia by expanding it .
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A demyelinating disease refers to any disease affecting the nervous system where the myelin sheath surrounding neurons is damaged. [ 1 ] This damage disrupts the transmission of signals through the affected nerves, resulting in a decrease in their conduction ability. Consequently, this reduction in conduction can lead to deficiencies in sensation, movement, cognition, or other functions depending on the nerves affected.
Various factors can contribute to the development of demyelinating diseases, including genetic predisposition , infectious agents, autoimmune reactions , and other unknown factors. Proposed causes of demyelination include genetic predisposition, environmental factors such as viral infections or exposure to certain chemicals. Additionally, exposure to commercial insecticides like sheep dip , weed killers , and flea treatment preparations for pets, which contain organophosphates , can also lead to nerve demyelination. [ 2 ] Chronic exposure to neuroleptic medications may also cause demyelination. [ 3 ] Furthermore, deficiencies in vitamin B12 can result in dysmyelination. [ 4 ] [ 5 ]
Demyelinating diseases are traditionally classified into two types: demyelinating myelinoclastic diseases and demyelinating leukodystrophic diseases . In the first group, a healthy and normal myelin is destroyed by toxic substances, chemicals, or autoimmune reactions. In the second group, the myelin is inherently abnormal and undergoes degeneration. [ 6 ] The Poser criteria named this second group dysmyelinating diseases . [ 7 ]
In the most well-known demyelinating disease, multiple sclerosis , evidence suggests that the body's immune system plays a significant role. Acquired immune system cells, specifically T-cells , are found at the site of lesions. Other immune system cells, such as macrophages (and possibly mast cells ), also contribute to the damage. [ 8 ]
Symptoms and signs that present in demyelinating diseases are different for each condition. These symptoms and signs can present in a person with a demyelinating disease: [ 9 ]
The role of prolonged cortical myelination in human evolution has been implicated as a contributing factor in some cases of demyelinating disease. Unlike other primates, humans exhibit a unique pattern of postpubertal myelination, which may contribute to the development of psychiatric disorders and neurodegenerative diseases that present in early adulthood and beyond. The extended period of cortical myelination in humans may allow greater opportunities for disruption in myelination, resulting in the onset of demyelinating disease. [ 10 ] Furthermore, humans have significantly greater prefrontal white matter volume than other primate species, which implies greater myelin density. [ 11 ] Increased myelin density in humans as a result of a prolonged myelination may, therefore, structure risk for myelin degeneration and dysfunction. Evolutionary considerations for the role of prolonged cortical myelination as a risk factor for demyelinating disease are particularly pertinent given that genetics and autoimmune deficiency hypotheses fail to explain many cases of demyelinating disease. As has been argued, diseases such as multiple sclerosis cannot be accounted for by autoimmune deficiency alone, but strongly imply the influence of flawed developmental processes in disease pathogenesis. [ 12 ] Therefore, the role of the human-specific prolonged period of cortical myelination is an important evolutionary consideration in the pathogenesis of demyelinating disease. [ citation needed ]
Various methods/techniques are used to diagnose demyelinating diseases:
Demyelinating diseases can be divided in those affecting the central nervous system (CNS) and those affecting the peripheral nervous system (PNS). They can also be classified by the presence or absence of inflammation . Finally, a division may be made based on the underlying cause of demyelination: the disease process can be demyelinating myelinoclastic , wherein myelin is destroyed; or dysmyelinating leukodystrophic , wherein myelin is abnormal and degenerative.
The demyelinating disorders of the central nervous system include: [ citation needed ]
The myelinoclastic disorders are typically associated with symptoms such as optic neuritis and transverse myelitis , because the demyelinating inflammation can affect the optic nerve or spinal cord . Many are idiopathic . Both myelinoclastic and leukodystrophic modes of disease may result in lesional demyelinations of the central nervous system .
The demyelinating diseases of the peripheral nervous system include: [ citation needed ]
Treatments are patient-specific and depend on the symptoms that present with the disorder, as well as the progression of the condition. Improvements to the patient's life may be accomplished through the management of symptoms or slowing of the rate of demyelination. Treatment can include medication, lifestyle changes (i.e. smoking cessation, increased rest, and dietary changes), counselling, relaxation, physical exercise, patient education, and in some cases, deep brain thalamic stimulation (to ameliorate tremors ). [ 13 ] : 227–248
Prognosis depends on the condition itself. Some conditions such as MS depend on the subtype of the disease and various attributes of the patient such as age, sex, initial symptoms, and the degree of disability the patient experiences. [ 14 ] Life expectancy in MS patients is 5 to 10 years lower than unaffected people. [ 15 ] MS is an inflammatory demyelinating disease of the central nervous system (CNS) that develops in genetically susceptible individuals after exposure to unknown environmental trigger(s). The bases for MS are unknown but are strongly suspected to involve immune reactions against autoantigens, particularly myelin proteins. The most accepted hypothesis is that dialogue between T-cell receptors and myelin antigens leads to an immune attack on the myelin-oligodendrocyte complex. These interactions between active T cells and myelin antigens provoke a massive destructive inflammatory response and promote continuing proliferation of T and B cells and macrophage activation, which sustains secretion of inflammatory mediators. [ 16 ] Other conditions such as central pontine myelinolysis have about a third of patients recover and the other two-thirds experience varying degrees of disability. [ 17 ] In some cases, such as transverse myelitis , the patient can begin recovery as early as 2 to 12 weeks after the onset of the condition. [ citation needed ]
Incidence of demyelinating diseases varies by disorder. Some conditions, such as tabes dorsalis appear predominantly in males and begin in midlife. Optic neuritis , though, occurs preferentially in females typically between the ages of 30 and 35. [ 18 ] Other conditions such as multiple sclerosis vary in prevalence depending on the country and population. [ 19 ] This condition can appear in children and adults. [ 15 ]
Much of the research conducted on demyelinating diseases is targeted towards discovering the mechanisms by which these disorders function in an attempt to develop therapies and treatments for individuals affected by these conditions. For example, proteomics has revealed several proteins which contribute to the pathophysiology of demyelinating diseases. [ 20 ] For example, COX-2 has been implicated in oligodendrocyte death in animal models of demyelination. [ 21 ] The presence of myelin debris has been correlated with damaging inflammation as well as poor regeneration, due to the presence of inhibitory myelin components. [ 22 ] [ 23 ]
N-cadherin is expressed in regions of active remyelination and may play an important role in generating a local environment conducive to remyelination. [ 24 ] N-cadherin agonists have been identified and observed to stimulate neurite growth and cell migration, key aspects of promoting axon growth and remyelination after injury or disease. [ 25 ]
Immunomodulatory drugs such as fingolimod have been shown to reduce immune-mediated damage to the CNS, preventing further damage in patients with MS. The drug targets the role of macrophages in disease progression. [ 26 ] [ 27 ]
Manipulating thyroid hormone levels may become a viable strategy to promote remyelination and prevent irreversible damage in MS patients. [ 28 ] It has also been shown that intranasal administration of apotransferrin (aTf) can protect myelin and induce remyelination. [ 29 ] Finally, electrical stimulation which activates neural stem cells may provide a method by which regions of demyelination can be repaired. [ 30 ]
Demyelinating diseases/disorders have been found worldwide in various animals. Some of these animals include mice, pigs, cattle, hamsters, rats, sheep, Siamese kittens, and a number of dog breeds (including Chow Chow, Springer Spaniel, Dalmatian, Samoyed, Golden Retriever, Lurcher, Bernese Mountain Dog, Vizsla, Weimaraner, Australian Silky Terrier, and mixed breeds). [ 31 ] [ 32 ]
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Denis Browne Gold Medal is a medal that was first struck in 1968, one year after the death of the paediatric surgeon Denis Browne and is awarded for outstanding contributions to paediatric surgery worldwide and is an honour bestowed by The British Association of Paediatric Surgeons . [ 1 ]
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Denise Louis-Bar was a Belgian neuropsychiatrist . Louis-Bar syndrome , an autosomal recessive neurodegenerative disorder is named after her.
Denise Bar was born on April 3, 1914, in Liège , Belgium. [ 1 ] She lived in Spain with her family until the age of 10. [ 2 ]
In 1939 Denise completed her master's degree, with a joint degree in éducation physique (physical education) from the Free University of Brussels . [ 3 ] [ 4 ]
Within a month of her marriage to Louise, they moved to the Ardennes after her husband had to join a Belgian army unit there. [ 4 ] Denise had intended to practice general medicine immediately after graduating from medical school, but the difficulties of starting a private medical practice while her husband was in the army and the outbreak of World War II forced her to change her mind and decided to specialise in neurology, enrolling at the Bung Institute in Antwerp , Belgium. [ 4 ] In 1940 Denise completed her residency at the Bunge Institute of Neurology, Antwerp . [ 1 ] There she trained under neuropathologist Ludo van Bogaert . [ 5 ] Later she worked as a lecturer in pharmacology , and later as neuropsychiatrist in the department of internal medicine at the University of Liège . [ 1 ] [ 6 ]
She did not remain in the field of neuro research for long. When her husband moved to Belgium in 1957 to join director of the Belgian Office of Study of Nuclear Energy, the family moved to Brussels, she stopped her career in research and moved into private practice, particularly, she worked as a neuropsychiatrist treating individuals with intellectual disabilities. [ 1 ] [ 7 ] [ 4 ] During the time of private practice in Brussels, Denise initiated to start twelve centers for patients with mental disabilities, including two model centers: Entraide des Travailleuses , a day-care center for pediatric rehabilitation and Centre de Réadaptation de l'Enfance à Bruxelles affiliated with the UCLouvain Medical School. [ 2 ]
Denise Louis-Bar died on November 2, 1999, at Brussels . [ 1 ]
Her spouse F. Louis was a civil engineer trained at the Faculté polytechnique de Mons of the Catholic University of Louvain , Belgium. [ 4 ]
Louis-Bar syndrome , an autosomal recessive neurodegenerative disorder is named after her. [ 1 ] She first described the condition in 1941. [ 8 ] Elizabeth A. Coon, who published a paper on Denise Louis-Bar's life in the journal Neurology in 2018, received the AAN McHenry Award in History for this article. [ 7 ]
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Dennie–Marfan syndrome is a syndrome in which there is association of spastic paraplegia of the lower limbs and mental retardation in children with congenital syphilis . [ 1 ] Both sexes are affected, and the onset of the disease can be acute or insidious, with slow progression from weakness to quadriplegia . Epilepsy , cataract , and nystagmus may also be found. [ citation needed ]
The syndrome was described by Charles Clayton Dennie in 1929, [ 2 ] and Antoine Marfan in 1936. [ 3 ]
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https://en.wikipedia.org/wiki/Dennie–Marfan_syndrome
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Dense breast tissue , also known as dense breasts , is a condition of the breasts where a higher proportion of the breasts are made up of glandular tissue and fibrous tissue than fatty tissue . Around 40–50% of women have dense breast tissue and one of the main medical components of the condition is that mammograms are unable to differentiate tumorous tissue from the surrounding dense tissue. [ 1 ] This increases the risk of late diagnosis of breast cancer in women with dense breast tissue. Additionally, women with such tissue have a higher likelihood of developing breast cancer in general, though the reasons for this are poorly understood. [ 2 ]
Dense breast tissue is defined based on the amount of glandular and fibrous tissue as compared to the percentage of fatty tissue. The current mammography classifications split up the density of breasts into four categories. Approximately 10% of women have almost entirely fatty breasts, 40% with small pockets of dense tissue, 40% with even distribution of dense tissue throughout, and 10% with extremely dense tissue. The latter two groups are those included under the definition of dense breasts. [ 2 ] [ 3 ] These categories were officially determined as a part of the American College of Radiology 's Breast Imaging Reporting and Data System ( BI-RADS ). [ 4 ]
Dense breast tissue, which is affected by hormone levels including estrogen , is more common among younger, pre-menopausal women and decreases with age. Other factors include genetics and body mass index (BMI), with those with higher BMIs tending to have less dense tissue. [ 3 ]
When undergoing a mammogram, tissue density is differentiated with bright and dark spots, with the radiolucent dark areas representing fatty tissue and the radioopaque bright spots representing combined fibroglandular tissue. Assessing the new growth of a tumor as a bright spot is the primary method radiologists use to identify early-stage cancer . However, women with dense breasts have an overall white coloration referred to as the "masking effect" that prevents the identification of new bright spots in the tissue. [ 4 ]
The problem of dense breasts and mammography screenings was first identified by John Wolfe in 1976 where Wolfe laid out a new classification system based on the density of female breasts and the prominence of fibral duct tissue. He also noted that the higher the density of a woman's breasts and how the pattern of the parenchymal tissue of the breasts formed, the higher the correlative risk there was for developing breast cancer, with the densest examples seeing a 37-fold increased risk. His findings, however, were not replicable by other researchers and so his claims about the connection between dense breasts and a higher risk of cancer were dismissed by the radiology community. [ 4 ]
While it was agreed that the "masking effect" impact of dense breasts on conducting mammograms made it difficult to identify developing breast cancer, it was not until a 2007 publication by Norman Boyd that a replication of Wolfe's work was shown. Boyd compared a wide variety of case controls and the risk of the women developing cancer over time based on the density of their breasts. He found on the extreme ends that women with a high breast density developed cancer at a rate five times higher than those with almost entirely fatty breast tissue. [ 4 ] It has also been suggested by some researchers, such as in Byrne et al. (1995), that breast density is the greatest risk factor to the development of breast cancer . [ 5 ]
Boyd suggested a new classification system that went beyond Wolfe's and titled his the Six Class Categories (SCC) that split up breasts based on the percentage density of fibroglandular versus fatty tissue. A third classification system was suggested by Tabar et al. (2005) that took into account the percentage of all three types of tissue and the linear density and defined six groups based on all four percentages at once. [ 6 ]
The creation of legislation related to dense breasts has focused on requiring the notification of women by their medical provider that they have dense breasts after this is diagnosed during mammograms, along with improving general awareness of the condition among the public.
Arguments against such legislation by some medical providers and physicians have been concerns that notification of such risks would result in women avoiding mammograms in fear of receiving a breast cancer diagnosis. [ 7 ] Yeh et al. (2015) found that notifying women resulted in an overall increase in intention of the informed individuals to have future ultrasounds and other testing to account for the higher potential risk of developing breast cancer. However, the authors noted that women with a high level of ambiguity aversion were less likely to desire future mammograms; this was especially true for women where ultrasounds were not covered by their health insurance . [ 8 ] A 2023 review of guidelines found that in general, patients wanted to receive their density information. [ 9 ]
A 2024 review of guidelines on dense breasts found that most sets of guidelines recommend annual or biannual screening mammograms for those over the age of 40 who have dense breasts, or potentially tomosynthesis imaging or breast MRI . Though some guidelines do not recommend additional screening, most updated or published in 2023–2024 recommend supplemental screening, such as ultrasound. Most place an emphasis on shared decision-making between patient and doctor; several also include providing information on modifiable cancer risk factors such as alcohol consumption and smoking, obesity, and hormonal factors. [ 10 ]
The issues of diagnosing breast cancer for such affected women are required to be a part of the information given and the suggestion of additional testing using alternative methods. Most legislation also has any mammograms taken be given to the patient's physician and made a part of their medical record. [ 7 ] The first state legislation on dense breast notifications was passed in 2009 in Connecticut after advocacy by breast cancer survivor Nancy Cappello , who had been diagnosed with stage 3 cancer owing to the failure of mammograms to detect the growing tumor. [ 11 ] Other states have passed their own legislation, with Texas, for example, passing Henda's Law in 2011. [ 12 ] By 2015, 19 states had legal notification statutes for dense breast tissue. [ 13 ]
A federal law titled the Mammography Quality Standards Act (MQSA) already covers and regulates how mammography reports are handled and requires sending dense breast identification to physicians. But the law did not include notifying the patient; state-level laws have sought to account for this gap in regulation since 2009. A federal bill to expand the MQSA was presented to Congress in October of 2011, but was not passed. [ 7 ] Subsequent federal bills were signed into law in February of 2019 and resulted in the FDA updating the MQSA to require reporting of mammograms to patients by all mammography facilities. [ 14 ] The MQSA was amended again in 2023, requiring all patients to be notified of their breast density ("dense" or "not dense") in their mammogram reports as of September 10, 2024. [ 15 ] [ 16 ]
Research in 2021 by Kressin et al. on the impact of the state and federal laws regarding dense breasts found that notification laws increased the likelihood of women being informed about dense breasts by 1.5 times, but women who were people of color (POC) and particularly those with lower incomes were less likely to be informed by their physicians than non-POC who were in wealthier income brackets. This included being informed of the higher risk of developing breast cancer. [ 17 ] Another 2021 review found that breast density notifications led to higher supplemental screening. [ 18 ]
As of 2023 [update] , most provinces require notification of breast density level; some regions such as Quebec, the Northwest Territories, and Yukon record the data but do not automatically inform patients. [ 19 ]
In 2022, the European Society of Breast Imaging, part of the European Society of Radiology , published a recommendation that women be informed at screenings of their breast density, as well as recommending MRI screening every two to four years for those between the ages of 50 and 70 with extremely dense breast tissue. [ 20 ] A 2025 review published in the European Journal of Radiology found that MRI screening on extremely dense breasts may be limited due to inaccessibility and high cost. [ 3 ]
The 2020 position statement from BreastScreen Australia states that the "Standing Committee on Screening recommends that, until more evidence is available on how breast density is best assessed and managed (including evidence to support clinical pathways), BreastScreen Australia should not routinely record breast density or provide supplemental testing for women with dense breasts." [ 21 ] As of 2023 [update] , women in South Australia will be informed of their breast density after a study showed they strongly preferred to be informed of this information. [ 22 ]
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https://en.wikipedia.org/wiki/Dense_breast_tissue
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The Dental Admission Test (abbreviated DAT ) is a multiple-choice standardized exam taken by potential dental school students in the United States and Canada (although there is a separate Canadian version with differing sections, both American and Canadian versions are usually interchangeably accepted in both countries' dental schools. This article will specifically describe the American DAT). The DAT is a computer based test that can be administered almost any day of the year. Tests are taken at Prometric testing centers throughout the United States after the preliminary application through the American Dental Association is completed. Each applicant may only take the test a total of three times before having to ask special permission to take the exam again. After taking the exam, applicants must wait 90 days before repeating it. Each exam costs $525, all of which is non-refundable.
The DAT comprises four sections: survey of the natural sciences (90 minutes), perceptual ability (often called the PAT, 60 minutes), reading comprehension (60 minutes), and quantitative reasoning (45 minutes). The mathematics of the quantitative exam is similar to that of the SAT . The first section is divided into questions about biology (40 questions), general chemistry (30 questions), and organic chemistry (30 questions). The second section is divided into six different problem sets designed to test perceptual ability, specifically in the areas of three-dimensional manipulation and spatial reasoning. The third section of the DAT is divided into three academic essays, each of which is followed by questions about the passage's content. The final section tests basic mathematics skills, with emphasis placed on algebra, critical thinking, fractions, roots, and trigonometric identities. [ citation needed ]
The test specifications for the Biology section changed in 2014. These changes reflected a shift on the way that Biology is taught in survey courses. This means that the questions now focus on "complex interactions within biological systems, rather than viewing biology in a reductionist manner". [ 3 ] There are also changes to the Quantitative Reasoning section. It has been "revised to eliminate the sections for numerical calculations, conversions, geometry, and trigonometry. Items have been added in the following areas: data analysis, interpretation, and sufficiency; quantitative comparison; and probability and statistics." During 2014 and 2015, examinees may have seen some questions that reflect such changes, however, they were not scored. Actual changes to the sections did not take place sooner than 2015. [ 3 ]
Immediately after completion of the test, eight standard scores on a scale of 1–30 are calculated and passed on to the test taker. The first six scores come directly from the test: perceptual ability, reading comprehension, quantitative reasoning, biology, general chemistry, and organic chemistry. The remaining two scores reported are summaries of the previous six: the Academic Average is the average of five scores rounded to the nearest whole number: quantitative reasoning, reading comprehension, biology, general chemistry, and organic chemistry. The Total Science score is a standard score based on all 100 questions in the biology, general chemistry, and organic chemistry tests. Dental schools frequently summarize their applicant's scores by listing the academic, science, and perceptual ability (PAT) scores they typically see in their matriculating classes. [ citation needed ]
The mean (average) score for any scored section is set at 17, with the exception of the reading comprehension section, in which the 50th percentile score is a 19. Scores above and below this represent fractions of standard deviations from the mean. This probabilistic scoring system results in the maximum not occurring for the compiled section scores (natural sciences and academic average) in a given year. For example, in 2003 a 25 academic average was labeled as 100.0th percentile, such that less than eight people received this score, and none higher (approximately 13,000 people take the DAT per year). [ citation needed ]
The mean academic average score for admissions is commonly 19. [ 4 ] There are varying perspectives on the relative importance of sections, wherein the PAT or reading comprehension can be viewed as the most important or conversely, ignored. The PAT in particular is most often viewed as a threshold score, and therefore is the only score not included in the academic average; the threshold varies between 16 and 18. [ citation needed ]
As of the 2011 dental application cycle, applicants no longer self-report their American DAT scores on their applications. Using the applicant's DENTPIN , the application service ADEA AADSAS Archived 2010-06-26 at the Wayback Machine will officially download all scores to the applicant's dental application. All test scores will be downloaded if the test is taken multiple times. During registration for the DAT, the applicant can indicate potential dental schools to send the scores to. As long as the applicant indicates at least one ADEA AADSAS-participating dental school in the DAT registration, the official DAT scores will be imported into the dental school application that is sent to every school designated in the ADEA AADSAS application. The only exception is if the school an applicant is applying to does not participate in the ADEA AADSAS application process. [ 5 ]
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https://en.wikipedia.org/wiki/Dental_Admission_Test
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The Dental Laboratories Association (DLA) is the professional body for dental laboratory owners in the United Kingdom . It is estimated that members of the DLA are responsible for over 80 per cent of the dental laboratory services in the UK.
The DLA began as a division of the Surgical Instrument Manufacturers Association, later becoming a separate entity. The first meeting of the DLA Council took place in London in 1961. The first Secretary was John Wrench and administration was provided by a firm of accountants called Hughes Allan.
In 1977 Trevor Roadley, a Nottingham dental laboratory owner was appointed as Secretary. Operating initially at his laboratory and then in the DLA's first premises, Roadley gradually built up the range of member services and heightened the standing of the association. The DLA moved to larger premises in Nottingham in 1986, a converted chapel that was being used as a dental laboratory. At this stage the DLA had approximately 400 members. In 1987 Bill Courtney took over as Secretary. Like Trevor before him, Bill was a dental laboratory owner and member of the DLA Council.
By now the DLA was a recognised and respected member of the dental world and regularly met with organisations such as the General Dental Council , Orthodontic Technicians Association , British Dental Association and the Department of Health . These close relationships continue to this day and the DLA has presented evidence to the Health Select Committee at the House of Commons on the challenges faced by the profession.
The DLA was instrumental in setting up the Dental Technicians Education and Training Advisory Board (DTETAB), which is now known as the Dental Technologists Association (DTA). The late 1980s and early 1990s saw the emergence of the Medical Devices Directive and the introduction of Quality Systems to the industry. The DLA worked to establish an industry-led standard and the first example of this was a system based on BS 5750 called the Certification Authority for Dental Laboratories and Suppliers (CADLAS), which is still operating as AMTAC MEDICA and is now audited to ISO9002. With the lessons learned in setting up CADLAS, a new system called the Dental Appliance Manufacturers Audit Scheme (DAMAS) was launched in 1998. This is based around ISO 9000 and also addresses the Medical Devices Regulations (MDR).
By now the Association membership had risen to over 900 and the association moved into new offices at Arboretum Gate in February 1997.
There have been many changes since 2000, including the retirement of Bill Courtney and appointment of Richard Daniels as Chief Executive. Membership has passed the 1,000 mark, and the DLA is building a profile as a campaigning organisation with appearances across the media.
In May 2001 the Association moved to their current offices on Wollaton Road , Beeston in Nottingham .
The DLA logo is circular in shape with the initials "DLA" in the middle.
The DLA is a member of the British Dental Health Foundation (BDHF), the Royal Society for the Prevention of Accidents (RoSPA) and the Federation of European Dental Laboratory Owners (FEPPD).
As the flagship event of the Dental Laboratories Association (DLA), the Dental Technology Showcase (DTS) is a highly respected platform for dental technicians, clinical dental technicians and lab owners to update and refresh their knowledge and skills.
Held alongside The Dentistry Show since 2014, the event offers vast networking opportunities as well as outstanding education, verifiable CPD and access to the very latest innovations in the UK industry.
DTS 2015 will take place on Friday 17th and Saturday 18 April at the NEC in Birmingham UK, ensuring a convenient and central location for thousands of dental professionals to attend. An extensive trade exhibition will host over 100 leading dental suppliers and manufacturers including 3Shape, Bracon, Cendres + Metaux, Nobel Biocare , Straumann , Metrodent, Ivoclar Vivadent and Schottlander to name but a few, each demonstrating the latest products, materials and technologies available. Experts will be on hand to provide any information, advice or guidance you may need, helping you to choose the most suitable equipment for optimal clinical results, streamlined workflows and maximum return on investment.
The DLA Council is the governing body of the association and is elected by the members. Its Chairman is Gordon Watters. The DLA is run by the Nationally Elected Council. All member laboratories may send an observer to Council meetings.
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https://en.wikipedia.org/wiki/Dental_Laboratories_Association
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The Dental Procedure Education System ( DPES ), is a web-based resource containing a collection of procedures from the dental disciplines. The procedures presented in DPES were developed [ when? ] by individual faculty members at the Faculty of Dentistry , University of Toronto , in collaboration with a group of educational media and technology experts. Consequently, DPES reflects the philosophy that guides the teaching methods and the clinical practice of these procedures at the Faculty of Dentistry. [ 1 ]
DPES was designed and built to serve primarily the instructional needs of the students at the Faculty of Dentistry, University of Toronto. However, due to the public ramifications of the act of providing dental health care, a public extension to DPES was also developed. DPES has multiple purposes, which can be summarized as follows:
Given the purposes outlined above, DPES is divided in two distinct parts:
The following two sections of this article describe in more detail the features of and differences between the two versions of DPES.
The public version, going by the same title as the parent program (DPES) is provided by the Faculty of Dentistry as an open source of information and dental care education. It is targeted in equal measure to the Faculty's patients and to the rest of the public. As such, DPES uses simple language to explain the steps involved in the performance of a specific dental procedure.
Patients are provided with a visual presentation of the procedure, which employs a combination of 3D animations, actual video footage and still images to illustrate those steps. In addition, a written article describing the procedure is placed under the visual presentation. Where applicable, the article details some of the concepts presented visually or provides the patient with further relevant information, such as post-operative care or follow-up visits.
Because the patients can be instructed by their dentists to view the procedures in advance, the patients may gain a better understanding of the various aspects involved in a particular procedure. Thus, DPES may contribute to reducing the patients' pre-operative anxiety levels and to expediting the informed consent process.
Finally, depending on the procedure involved, a patient may review online the dentist's post-operative recommendations included in the visual presentation or in the written article.
DPES Professional, or DPES Pro, is intended primarily for the education of the Faculty of Dentistry's students in the undergraduate Doctor of Dental Surgery program (DDS) and it is not open to the public. As is the case with the patient version, DPES Pro uses the same combination of high-end visuals to demonstrate the techniques and methods of conducting a procedure. However, the language used in DPES Pro differs from the patient version in that the terminology is geared toward dental practitioners. The visual demonstration is normally longer than that in the patient version and, thus, it is divided into chapters for easy access to specific parts of the presentation.
The written article that accompanies the visual presentation provides an extended scholarly explanation of the procedure, by including sections such as preliminary background or historical information about the procedure, recent research findings and their clinical implications, competing views about procedural techniques or methods, contentious or controversial issues regarding the procedure, etc. True to academic form, the article contains a list of references used in the body of the text. Thus, the student has access to the most recent literature that the author of the article considers relevant for a specific procedure.
DPES procedures follow a well-defined production cycle before they are published. The first step involves the drafting of an article for the procedure in DPES Pro by a faculty member or several faculty members of the Faculty of Dentistry. In normal circumstances, the same faculty member(s) will also be the one(s) teaching the procedure. The article is posted internally to the online repository. Once the article is drafted, it is submitted to two other faculty members for review.
Upon the completion of the review process, the author extracts the procedural section of the article and writes two separate scripts that will serve as the narrations for the visual parts of the procedures in DPES Pro and DPES, respectively. The visual presentation for DPES Pro is then assembled by the media team according to the script and with the input of the author. As soon as the visual elements are created and assembled, the author performs a final review of the visual presentation. Once the visual presentation is approved by the author, it is placed at the top of the written article in DPES Pro.
The visual presentation for DPES (public version) is created from the visual material already developed for DPES Pro. However, the public version is generally shorter and its script uses plain terms to explain the procedure. In the case of DPES, the script may also serve as the written article for the procedure, but the author may choose to extend it, annotate it or to create an entirely new article to be placed under the visuals.
When the two versions of the procedures are completed and approved, they are published and released to their particular audiences.
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https://en.wikipedia.org/wiki/Dental_Procedure_Education_System
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The Dental Professionals Association , previously known as the Dental Practitioners Association and the General Dental Practitioners Association , is a trade union for professionals involved in primary dental care in the United Kingdom. It is based in Harley Street in London.
In 1952 and also on 9 November 1953 a group of dentists comprising Mr N L Newman BDS, Dr Malik, Mr Herbert Murray, Mr Peter Glazebrook, Mr Jonas and others [ 1 ] met in East London. [ 2 ] In 1954 they formed the General Dental Practitioners Association in response to a perceived failure of the British Dental Association to lobby aggressively on behalf of general dental practitioners who had joined the National Health Service at its inception in 1948 only to see the first NHS patient charges imposed on dentures and successive cuts in dental fees.
The associate met in London in those early days, often at dental supply houses. Members included Mr Combiere, qualified in law, Herbert Murray the first treasurer, Frank Barlow, Hans Orlay (a pioneer of implants with titanium), Sidney Smith and Ian Simpson (the first GDPA member of the General Dental Council ).
Alan d'Arcy Fearn became President of both the GDPA and the BDA and the longest ever serving member of the GDC (35 years).
Until 2009 membership of the DPA was restricted to dentists in high-street practice. On 19 November 2009 it announced that membership would be opened to all dental care professionals registered with the General Dental Council or having an interest in primary dental care. Membership of the Association was expanded to include dental nurses, hygienists, therapists, technicians and the dental trade.
As a trade union the DPA is subject to the full provisions of the Trade Union and Labour Relations (Consolidation) Act 1992 as amended, and must hold elections for the chairman and secretary and for membership of its principal executive committee, the council.
The DPA's aims, contained in the Rules, are to represent members in the UK, to maintain the status of the profession, to improve its members' terms and conditions and to assist and provide services for members. It provides a podcast relevant to dentistry in the UK. Benefits include contracts and the industry-standard Private Fees and Wages Guide which is compiled from a survey of private fees charged by members.
The DPA maintains contacts with government and others that enable it to provide a briefing service to help members reduce their business risk in the UK dental market. It also actively considers alternative dental treatment provision systems with the objective of promoting oral health in the UK. It gives evidence annually to the Review Body on Doctors and Dentists Remuneration on dentists' terms and conditions.
Members receive a bimonthly magazine the GDP (formerly the General Dental Practitioner, formerly The Probe) (Identifier: ISSN 0954-4186 ; BNB:GB8958084). This began as a newsletter in 1954 and was turned by Sol Chandler, an experienced Fleet Street journalist into a magazine, The Probe, in 1958. Ken Brown took over as Editor in 1964. In 1968 a contract was signed with Bouverie Press which saw the magazine expand to 56 pages in 1973. The magazine was purchased by Ken Brown in 1982. When the Probe name was sold to an independent publisher the GDPA magazine was relaunched as the General Dental Practitioner. The title was later abbreviated to the GDP with effect from vol. 8, no. 6 (July/Aug. 1996).
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https://en.wikipedia.org/wiki/Dental_Professionals_Association
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Abrasion is the non-carious, mechanical wear of tooth from interaction with objects other than tooth-tooth contact. [ 1 ] It most commonly affects the premolars and canines , usually along the cervical margins . [ 2 ] Based on clinical surveys, studies have shown that abrasion is the most common but not the sole aetiological factor for development of non-carious cervical lesions (NCCL) and is most frequently caused by incorrect toothbrushing technique. [ 3 ]
Abrasion frequently presents at the cemento-enamel junction and can be caused by many contributing factors, all with the ability to affect the tooth surface in varying degrees. [ 4 ]
The appearance may vary depending on the cause of abrasion, however most commonly presents in a V-shaped caused by excessive lateral pressure whilst tooth-brushing. The surface is shiny rather than carious, and sometimes the ridge is deep enough to see the pulp chamber within the tooth itself.
Non-carious cervical loss due to abrasion may lead to consequences and symptoms such as increased tooth sensitivity to hot and cold, increased plaque trapping which will result in caries and periodontal disease, and difficulty of dental appliances such as retainers or dentures engaging the tooth. It may also be aesthetically unpleasant to some people. [ 3 ]
For successful treatment of abrasion, the cause first needs to be identified and ceased (e.g. overzealous brushing). Once this has occurred, subsequent treatment may involve the changes in oral hygiene, application of fluoride to reduce sensitivity, or the placement of a restoration to help prevent further loss of tooth structure and aid plaque control. [ 4 ]
Cause of abrasion may arise from interaction of teeth with other objects such as toothbrushes , toothpicks , floss , and ill-fitting dental appliance like retainers and dentures. Apart from that, people with habits such as nail biting, chewing tobacco, lip or tongue piercing, [ 5 ] and having occupation such as joiner, are subjected to higher risks of abrasion.
The aetiology of dental abrasion can be due to a single stimulus or, as in most cases, multi-factorial. [ 6 ] The most common cause of dental abrasion is the combination of mechanical and chemical wear.
Tooth brushing is the most common cause of dental abrasion, which is found to develop along the gingival margin , due to vigorous brushing in this area. [ 7 ] [ 8 ] The type of toothbrush, the technique used and the force applied when brushing can influence the occurrence and severity of resulting abrasion. [ 9 ] Further, brushing for extended periods of time (exceeding 2-3 min) in some cases, when combined with medium/hard bristled toothbrushes can cause abrasive lesions. [ 10 ] Abrasion may also be exacerbated by overzealous use of certain types of dentifrice; some have more abrasive qualities to remove stains such as whitening toothpastes.
The bristles combined with forceful brushing techniques applied can roughen the tooth surface and cause abrasion as well as aggravating the gums. [ 11 ] Repetitive irritation to the gingival margin can eventually cause recession of the gums. When the gums recede, the root surface is exposed which is more susceptible to abrasion. [ 12 ] Comparatively, electric toothbrushes have less abrasive tendencies. [ 13 ]
When combined with incorrect brushing technique, toothpastes can also damage enamel and dentine due to the abrasive properties. [ 14 ] Specific ingredients are used in toothpaste to target removal of the bio-film and extrinsic staining however in some cases can contribute to the pastes being abrasive. [ 15 ] [ 11 ] In-home and clinical whitening have been proven to increase the likelihood of an individual experiencing dental abrasion. It is believed that dental abrasion due to the whitening process is caused by a combination of both mechanical and chemical irritants, for example, using whitening toothpaste and at home bleaching kits together. [ 16 ] However, if an individual is regimented in their after-whitening care then they can avoid loss of tooth structure and in turn abrasion can be avoided. [ 17 ]
Another factor that can contribute to abrasive loss of tooth structure is the alteration of pH levels at the tooth surface. This can associated with the consumption of acidic foods and liquids or regurgitation of stomach acid, a process known as dental erosion . An increase in acidity at the tooth surface can induce demineralization and softening, therefore leaving the tooth structure susceptible to abrasive factors such as tooth brushing. [ 18 ] When the surface of the tooth structure is softened by acid, mechanical forces such as brushing can cause irreparable damage on tooth surface. [ 16 ] [ 19 ] [ 20 ] Remineralization of the softened surface can help prevent this damage from occurring.
Relative dentin abrasivity ( RDA ) is a standardised measurement of the abrasive effect that the components of a toothpaste. [ 10 ]
The RDA scale was developed by the American Dental Association (ADA), government bodies and other stakeholders to quantify the abrasivity of a toothpaste. [ 21 ] It was not designed to rank safety of toothpastes, [ 21 ] and all toothpastes with an RDA of 250 or less are considered to be equally safe for regular use in terms of abrasivity. [ 22 ] The RDA scale compares toothpaste abrasivity to standard abrasive materials and measures the depth of cut at an average of 1 millimetre per 100,000 brush strokes onto dentine. [ 23 ] This comparison generates abrasive values for the dentifrices that would be safe for daily use. [ 12 ]
Since 1998, the RDA value is set by the standards DIN EN ISO 11609. [ 24 ] Currently, the claim on products such as toothpaste are not regulated by law, however a dentifrice is required to have a level lower than 250 to be considered safe and before being given the ADA seal of approval. [ 25 ] The vast majority of toothpastes commercially available have RDA values of 250 or less and are unlikely to have a significant impact on abrasion of tooth structure over a lifetime of use. [ 12 ] [ 26 ] On average, data suggests less than 400 μm of tooth wear occurs over a lifetime using toothpastes of RDA 250 or less. [ 23 ]
The RDA score of a toothpaste is not the primary factor to consider when managing and preventing dental abrasion. [ 23 ] [ 12 ] [ 27 ] Other factors such as the amount of pressure used whilst brushing, the type, thickness and dispersion of bristle in the toothbrush and the time spent brushing are significant factors that contribute to the risk of dental abrasion. [ 27 ] [ 28 ]
There are several reasons to treat abrasion lesion(s) (also known as ‘Class V cavity’) such as:
In order for successful treatment of abrasion to occur, the aetiology first needs to be identified. The most accurate way of doing so is completing a thorough medical, dental, social and diet history. All aspects need to be investigated as in many cases the cause of abrasion can be multi-factorial. Once a definitive diagnosis is completed the appropriate treatment can commence.
Treatment for abrasion can present in varying difficulties depending on the current degree or progress caused by the abrasion. Abrasion often presents in conjunction with other dental conditions such as attrition, decay and erosion. Evidence suggest there is a decrease in the effect of dental abrasion with dental erosion when fluoride varnish is applied onto teeth. [ 29 ] Successful treatment focuses on the prevention and progression on the condition and modifies the current habit/s instigating the condition.
If the cause of abrasion is due to habitual behaviours, the discontinuation and change of habit is critical in the prevention of further tooth loss. [ 30 ] The correct brushing technique is pivotal and involves a gentle scrub technique with small horizontal movements with an extra-soft/soft bristle brush. [ 27 ] Excessive lateral force can be corrected by holding the toothbrush in a pen grasp or by using the non-dominant hand to brush. [ 27 ] If abrasion is the result of an ill-fitting dental appliance, this should be corrected or replaced by a dental practitioner and should not be attempted in a home setting.
The current selection of dentifrice should also be critically analysed and changed to include a less abrasive and gentler paste such as sensitive toothpaste as evidence suggests that a very abrasive toothpaste would lead to loss of tooth structure. [ 31 ] A toothpaste containing increased fluoride will also help combat the increased sensitivity and risk to dental decay. [ 32 ] Toothpastes containing stannous fluoride have been shown to inhibit acid erosion of tooth structure, thereby reducing its susceptibility to abrasive wear. [ 33 ] Fluoride varnish can also be used as a preventive measure for patients at high risk of dental erosion, as the fluoride varnish increases resistance to erosion and subsequent tooth wear. [ 29 ]
Treatment in the dental chair may include a fluoride application or the placement of a restoration in more severe cases. If the lesion is small and confined to enamel or cementum, a restoration is not warranted, instead the eradication of rough edges should occur to reduce plaque retentive properties. [ 34 ] However, in the case of dental decay, aesthetic concerns or defects close to the pulp a restoration may be completed. [ 35 ] Further restorative work may be required when the lesion compromises the overall strength of the tooth or when the defect contributes to a periodontal problem the lesion may be restored. [ 36 ]
Once abrasive lesions have been diagnosed and treated they should be closely monitored to identify further progression or potential relief of symptoms.
Ideal properties of restoration materials particularly for these lesions include: [ 37 ]
There are other properties of restoration materials which could be considered appropriate, although not specific to Class V restorations, which includes:
Dental materials such as amalgam, glass ionomer (GI), resin-modified glass ionomer (a variant of GI) and resin composite are the types of restoration materials available when active treatment by means of restoration is appropriate.
Taking into consideration these factors and their respective dental materials' properties, evidence and studies has shown that resin-modified glass ionomer (RMGI) restoration material is the recommended restoration material in clinical situations as it performs optimally - provided aesthetics is not the top priority when restoring these lesions. [ 37 ] The surface of such lesions should be roughened prior to its restoration [ 38 ] [ 39 ] [ 40 ] [ 41 ] [ 42 ] - whether material is GI-based or resin-based [ 37 ] - with no need for bevelling of the coronal aspect of the cavity. [ 39 ] [ 43 ] [ 44 ]
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https://en.wikipedia.org/wiki/Dental_abrasion
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A dental aerosol is an aerosol that is produced from dental instrument , dental handpieces , three-way syringes, and other high-speed instruments. These aerosols may remain suspended in the clinical environment. [ 1 ] Dental aerosols can pose risks to the clinician , staff, and other patients. The heavier particles (e.g., >50 μm) contained within the aerosols are likely to remain suspended in the air for relatively short period and settle quickly onto surfaces, however, the lighter particles may remain suspended for longer periods and may travel some distance from the source. [ 2 ] These smaller particles are capable of becoming deposited in the lungs when inhaled and provide a route of diseases transmission. [ 3 ] Different dental instruments produce varying quantities of aerosol, and therefore are likely to pose differing risks of dispersing microbes from the mouth. Air turbine dental handpieces generally produce more aerosol, with electric micromotor handpieces producing less, although this depends on the configuration of water coolant used by the handpiece. [ 4 ] [ 5 ]
These dental aerosols are bioaerosols which may be contaminated with bacteria , fungi , and viruses from the oral cavity, skin , and the water used in dental units. [ 6 ] Dental aerosols also have micro-particles from dental burs, and silica particles which are one of the components of dental filling materials like dental composite . [ 7 ] Depending upon the procedure and site, the aerosol composition may change from patient to patient. Apart from microorganisms , these aerosols may consist of particles from saliva , gingival crevicular fluid, blood , dental plaque , calculus , tooth debris, oronasal secretions, oil from dental handpieces, and micro-particles from grinding of the teeth and dental materials. [ 8 ] They may also consist of abrasive particles that are expelled during air abrasion and polishing methods. [ 3 ]
Dental aerosols contain a wide range of particles with the majority being less than 50 μm. The smaller particles with size between 0.5 and 10 μm are more likely to be inhaled and have the potential to transmit infection . [ 3 ] Smaller particles are likely to remain suspended for longer periods of time, and may travel further from the source. Settling time of particles is described by Stokes' law in part as a function of their aerodynamic diameter.
The water used in the dental units may be contaminated with Legionella , and the aerosols produced by dental handpieces may contribute to the spread of the Legionella in the environment; there is therefore a risk of inhalation by the dentist , staff and patients. [ 9 ] The dental unit water lines (DUWLs) may also be contaminated with other bacteria like Mycobacterium spp and Pseudomonas aeruginosa . [ 10 ] Infection from Legionella species causes infections like Legionellosis and several pneumonia like diseases. [ 11 ] However, still there is no strong evidence that suggests the dentists are at greater occupational risk from Legionella . [ 9 ] Transmission of tuberculosis also occurs from the cough producing procedures on the patients with tuberculosis that involve production of aerosols. [ 12 ] Mycobacterium tuberculosis is transmitted in the form of droplet nuclei which are smaller than 5 μm which stay suspended in the environment for longer duration. The development of active tuberculosis in Dental Health Care Workers (DHCWs) is less likely than the rest of the other Health Care Workers (HCWs). There are lacking evidences to prove the active tuberculosis development resulting from this transmission in Dental health care Workers (DHCWs). [ 13 ]
The virus that caused the COVID-19 pandemic is named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by the International Committee on Taxonomy of Viruses (ICTV) on 11 February 2020. [ 14 ] SARS-CoV-2 remains stable in aerosols for several hours. [ 15 ] The virus is viable for hours in aerosols and for few days on surfaces, hence the transmission of SARS-CoV-2 is feasible through aerosols and also shows fomite transmission. [ 16 ]
Dentists have previously been described as one of the top of the working groups with high risk of exposure to SARS-CoV-2. Due to the close proximity of the dental health care workers to the patients, dental procedures involving aerosol production is not advisable in patients who tested positive for COVID-19 except for emergency dental treatment. [ 17 ] On 16 March 2020, the American Dental Association ( ADA ) has advised dentists to postpone all elective procedures. [ 18 ] ADA also developed guidance specific to address dental services during the COVID-19 pandemic . [ 19 ]
Elements like calcium, aluminium, silica and phosphorus can also be found in the dental aerosols produced during the procedures like debonding of orthodontic appliances. [ 20 ] These particles may range from 2 to 30 μm in diameter and there are chances of inhaling them. [ 21 ]
A number of methods have been proposed, and are widely used, to control dental aerosols and reduce risk of disease transmission. For example, dental aerosols can be controlled or reduced using dental suction, [ 22 ] rubber dam, [ 5 ] alternative handpieces, [ 2 ] and local exhaust ventilation (extra-oral suction). [ 23 ]
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https://en.wikipedia.org/wiki/Dental_aerosol
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This discussion of the dental amalgam controversy outlines the debate over whether dental amalgam (the mercury alloy in dental fillings ) should be used. Supporters claim that it is safe, effective and long-lasting, while critics argue that amalgam is unsafe because it may cause mercury poisoning and other toxicity . [ 1 ] [ 2 ] [ 3 ]
Supporters of amalgam fillings point out that it is safe, durable, [ 4 ] relatively inexpensive, and easy to use. [ 5 ] On average, amalgam lasts twice as long as resin composites , takes less time to place, is tolerant of saliva or blood contamination during placement (unlike composites), and is often about 20–30% less expensive. [ 6 ] Consumer Reports has suggested that many who claim dental amalgam is not safe are "prospecting for disease" and using pseudoscience to scare patients into more lucrative treatment options. [ 7 ]
Those opposed to amalgam use suggest that modern composites are improving in strength. [ 8 ] In addition to their claims of possible health and ethical issues, opponents of dental amalgam fillings claim amalgam fillings contribute to mercury contamination of the environment. The World Health Organization (WHO) reports that health care facilities, including dental offices, account for as much as 5% of total wastewater mercury emissions. [ 9 ] The WHO also points out that amalgam separators, installed in the waste water lines of many dental offices, dramatically decrease the release of mercury into the public sewer system. [ 9 ] In the United States, most dental practices are prohibited from disposing amalgam waste down the drain. [ 10 ] Critics also point to cremation of dental fillings as an additional source of air pollution, contributing about 1% of global emissions. [ 11 ]
The World Health Organization recommends a global phase out of dental mercury in their 2009 report on "Future Use of Materials For Dental Restorations, based on aiming for a general reduction of the use of mercury in all sectors, and based on the environmental impacts of mercury product production." [ 12 ]
It is the position of the FDI World Dental Federation [ 13 ] as well as numerous dental associations and dental public health agencies worldwide [ 14 ] [ 15 ] [ 16 ] [ 17 ] [ 18 ] [ 19 ] [ 20 ] that amalgam restorations are safe and effective. Numerous other organizations have also publicly declared the safety and effectiveness of amalgam. These include the Mayo Clinic , [ 21 ] Health Canada , [ 22 ] Alzheimer's Association , [ 23 ] American Academy of Pediatrics, [ 24 ] Autism Society of America , [ 25 ] U.S. Environmental Protection Agency (EPA), [ 26 ] National Multiple Sclerosis Society, [ 27 ] New England Journal of Medicine , [ 28 ] International Journal of Dentistry , [ 29 ] National Council Against Health Fraud , [ 30 ] The National Institute of Dental and Craniofacial Research NIDCR, [ 31 ] American Cancer Society , [ 32 ] Lupus Foundation of America , [ 33 ] the American College of Medical Toxicology , [ 34 ] the American Academy of Clinical Toxicology , [ 34 ] Consumer Reports [ 7 ] Prevention , [ 35 ] WebMD [ 36 ] and the International Association for Dental Research . [ 37 ]
The U.S. Food and Drug Administration (FDA) formerly stated that amalgam is "safe for adults and children ages 6 and above" [ 38 ] but now recommends against amalgam for children, pregnant/nursing women, and other high-risk groups. [ 39 ]
Dental amalgam has had a long history and global impact. [ 3 ] It was first introduced in the Chinese materia medica of Su Kung in 659 A.D. during the Tang dynasty. [ 3 ] In Europe, Johannes Stockerus, a municipal physician in Ulm, Germany, recommended amalgam as a filling material as early as 1528. [ 3 ] In 1818, Parisian physician Louis Nicolas Regnart added one-tenth by weight of mercury to the fusable metals used as fillings at the time to create a temporarily soft metal alloy at room temperature. Thus, amalgam (an alloy of mercury with another metal or metals, from the French word amalgame) was invented. This was further perfected in 1826, when Auguste Taveau of Paris used a silver paste made from mixing French silver-tin coins with mercury, which offered more plasticity and a quicker setting time. [ 3 ] In Europe, before 1818, carious teeth were either filled with a melted metal, usually gold or silver (which would often lead to death of the nerve of the tooth from thermal trauma), or the tooth would be extracted. [ 3 ]
In 1855, Dr. J. Foster Flagg, a professor of dental pathology in Philadelphia, experimented with new mixtures of amalgam. In 1861, he presented his findings to the Pennsylvania Association of Dental Surgeons and, in 1881, he published his book, Plastic and Plastic Fillings . (Amalgam fillings were often called "plastic fillings" at the time.) The inevitable result of this affair was that silver amalgam was proven to be "an excellent filling material", and expanded dentistry's "ability to save teeth". Around the same time, John and Charles Tomes in England conducted research on the expansion and contraction of the various amalgam products. During the American Civil War, the debate on the merits of amalgam continued. In dental meetings, with now decades of use and dental research came the recognition of the importance of good technique and proper mixture on long-term success. It was argued, "the fault was not in the material but in the manipulation.... Some men's amalgam is good universally, and some men's gold is bad universally; the difference lies in the preparation of the tooth and in the plug (filling)." [ 40 ]
More controversy came in 1872, when an amalgam filling was reported as the cause of death of a Nebraska middle-aged man, resulting in a public outcry against the use of amalgam. [ 41 ] His physicians reported that the filling caused swelling of his mouth, throat, and windpipe, completely hindering respiration. Given that the involved tooth was a lower second molar, it was later considered very likely that the patient died from Ludwig's angina , which is a type of cellulitis , rather than mercury poisoning . Another alleged case of " pytalism " causing headache, fever, rapid pulse, metallic taste, loss of appetite, and generalized malaise was reported in 1872 in a female patient following the insertion of eight amalgam fillings. [ 42 ] Later, however, another dentist examined the fillings and noted they had, in a short period, washed away, and that upon gentle pressure the metal crumbled away. He removed all the fillings with an explorer in three minutes and concluded poor workmanship alone could have explained the patient's symptoms.
Alfred Stock was a German chemist who reported becoming very ill in the 1920s and traced his illness to his amalgam fillings and resulting mercury intoxication. He described his recovery after the fillings were removed and believed that amalgam fillings would come to be seen as a "sin against humanity". [ 43 ] Stock had also previously been exposed to toxic levels of mercury vapor during his work, due to his use of liquid mercury in some novel laboratory apparatus he invented. [ 44 ]
Oral galvanism , amalgam disease , or Galvanic shock was a term for the association of oral or systemic symptoms to either: electric currents between metal in dental restorations and electrolytes in saliva or dental pulp . [ 45 ] [ 46 ] [ 47 ] Any existence of galvanic pain or association of either currents or mercury to presence of symptoms has been disproven. [ 46 ] [ 45 ] Beyond acute allergic reaction amalgam has not been found to be associated with any adverse effects . [ 48 ]
Very weak currents have been measured in the mouth of those with multiple dental fillings consisting of different alloys, but there was no association between presence of current and symptoms, [ 45 ] and any symptoms associated with currents between oral fillings are likely to be psychosomatic in nature. [ 46 ] No association between presence of mercury and symptoms have been found, with symptoms likely to be psychosomatic in nature and do not improve with chelation therapy . [ 45 ] [ 47 ] [ 49 ] Claims of causing a variety of symptoms such as oral discomfort, skin irritation , headaches and a metallic taste in the mouth have been discredited. [ 45 ]
The condition was originally proposed in 1878, [ 50 ] and became well known in Sweden during the 1970s and 80s, because of a campaign to educate about and replace oral amalgam fillings with mercury with other compounds such as ceramic or polymer restorations. [ 45 ]
In the 1990s, several governments evaluated the effects of dental amalgam and concluded that the most likely health effects would be due to hypersensitivity or allergy. Germany, Austria, and Canada recommended against placing amalgam in certain individuals, such as pregnant women, children, those with renal dysfunction, and those with an allergy to metals. In 2004, the Life Sciences Research Office analyzed studies related to dental amalgam published after 1996 and concluded that mean urinary mercury concentration (μg of Hg/L in urine, HgU) was the most reliable estimate of mercury exposure. [ 51 ] It found that those with dental amalgam were unlikely to reach the levels where adverse effects are seen from occupational exposure (35 μg HgU). Some 95% of study participants had μg HgU below 4–5. Chewing gum, particularly for nicotine, along with more amalgam, seemed to pose the greatest risk of increasing exposure. One gum-chewer had 24.8 μg HgU. Studies have shown that the amount of mercury released during normal chewing is extremely low. It concluded that there was not enough evidence to support or refute many of the other claims such as increased risk of autoimmune disorders , but stated that the broad and nonspecific illness attributed to dental amalgam is not supported by the data. [ 51 ] Mutter in Germany, however, concludes, "removal of dental amalgam leads to permanent improvement of various chronic complaints in a relevant number of patients in various trials." [ 52 ]
Hal Huggins , a Colorado dentist (previous to having his license revoked), was a notable critic of dental amalgams and other dental therapies he believed to be harmful. [ 53 ] His views on amalgam toxicity were featured on 60 Minutes [ 54 ] and he was later criticized as a dentist, "prospecting for disease" and having only an "aura of science" by Consumer Reports . [ 7 ] In 1996, a Colorado state judge recommended that Huggins's dental license be revoked, for tricking chronically ill patients into thinking that the true cause of their illness was mercury. Time reported the judge's conclusion that Huggins, "diagnosed 'mercury toxicity' in all his patients, including some without amalgam fillings." [ 55 ] Huggins's license was subsequently revoked by the Colorado State Board of Dental Examiners for gross negligence and the use of unnecessary and unproven procedures. [ 56 ] [ 57 ] [ 58 ]
According to the WHO , all humans are exposed to some level of mercury. [ 59 ] Factors that determine whether health effects occur and their severity include the type of mercury concerned ( methylmercury and ethylmercury , commonly found in fish, being more serious than elemental mercury); the dose; the age or developmental stage of the person exposed (the foetus is most susceptible); the duration of exposure; and the route of exposure (inhalation, ingestion or dermal contact). [ 59 ] The universal standard for examining mercury toxicity is usually discussed in terms of the amount of mercury in the bloodstream for short-term exposure or the amount of mercury excreted in the urine relative to creatine for long-term mercury exposure. [ 7 ] Elemental mercury (which is a component of amalgam) is absorbed very differently than methylmercury (which is found in fish). [ 2 ] The exposure to mercury from amalgam restorations depends on the number and size of restorations, composition, chewing habits, food texture, grinding, brushing of teeth, and many other physiological factors. [ 2 ]
The greatest degree of mercury exposure occurs during filling placement and removal. However, this is not the only time mercury vapors are released. When chewing for extended periods (more than 30 minutes) an increased level of mercury vapor is released. Vapor levels will return to normal approximately 90 minutes following chewing cessation. This contributes to a daily mercury exposure for those with amalgam fillings. [ 60 ]
According to one dental textbook, eating seafood once a week raises urine mercury levels to 5 to 20 μg/L, which is equivalent to two to eight times the level of exposure that comes from numerous amalgam fillings. Neither exposure has any known health effect. [ 61 ] Scientists agree that dental amalgam fillings release elemental mercury vapor, but studies report different amounts. Estimates range from 1 to 3 micrograms (μg) per day according to the FDA. [ 62 ] The effects of that amount of exposure are also disputed. [ 51 ] [ 52 ]
Newer studies sometimes use mercury vapor analysis instead of the standard exposure test. Because this test was designed for factories and large enclosures, Consumer Reports has reported that this is not an accurate method of analysis for the mouth. It is less reliable, less consistent, and tends to greatly exaggerate the amount of mercury inhaled. [ 7 ] Moreover, it is argued that this test additionally exaggerates the amount of mercury inhaled by assuming that all the mercury vapor released is inhaled. This assumption was reviewed by the U.S. Department of Health and Human Services and not found to be valid. Their research review found that most of the mercury vapor released from amalgam fillings is mixed with saliva and swallowed, some part is exhaled, and the remaining fraction is inhaled. [ 63 ] Of these amounts, it is important to note that the lungs absorb about 80% of inhaled mercury. [ 63 ]
A study conducted by measuring the intraoral vapour levels over 24 hours in patients with at least nine amalgam restorations showed that the average daily dose of inhaled mercury vapour was 1.7 μg (range from 0.4 to 4.4 μg), which is approximately 1% of the threshold limit value of 300 to 500 μg/day established by the WHO, based on a maximum allowable environmental level of 50 μg/day in the workplace. [ 2 ] Critics point out that: (1) the workplace safety standards are based on allowable maxima in the workplace, not mercury body burden ; (2) the workplace safety numbers do not apply to continuous 24-hour exposure, but are limited to a normal work day and a 40-hour workweek; [ 64 ] and (3) the uptake/absorption numbers are averages and not worst-case patients (those most at risk). [ 65 ]
A test that was done throughout the 1980s by some opposition groups and holistic dentists was the skin patch test for mercury allergies. As part of "prospecting for disease", Consumer Reports wrote that these groups had placed high doses of mercuric chloride on a skin patch, which was guaranteed to produce irritation on the patient's skin and subsequent revenue for the person administering the test. [ 7 ]
The current recommendations for residential exposure (not including amalgam fillings already accounted for) are as follows: The ATSDR Action Level for indoor mercury vapor in residential settings is 1 μg/m 3 and the ATSDR MRL (Minimal Risk Level) for chronic exposure is 0.2 μg/m 3 [ 66 ] According to the ATSDR, the MRL(Minimal Risk Level) is an estimate of the level of daily exposure to a substance that is unlikely to cause adverse non-cancerous health effects. The Action Level is defined as an indoor air concentration of mercury that would prompt officials to consider implementing response actions. It is a recommendation and does not necessarily imply toxicity or health risks. [ 66 ] Breathing air with a concentration of 0.2 μg mercury/m 3 would lead to an inhaled amount of approximately 4 μg/day (respiratory volume of 20m 3 /day). About 80% of inhaled mercury vapor would be absorbed. [ 67 ]
A 2003 monograph on mercury toxicity from the WHO concluded that dental amalgam contributes significantly to mercury body burden in humans with amalgam fillings and that dental amalgam is the most common form of exposure to elemental mercury in the general population, constituting a potentially significant source of exposure to elemental mercury. Estimates of daily intake from amalgam restorations range from 1 to 12.5 μg/day, with the majority of dental amalgam holders being exposed to less than 5 μg mercury/day. [ 67 ] They also note that this will continue to decline as the number of amalgam restorations is declining.
As public pressure demands more research on amalgam safety, an increasing number of studies with larger sample sizes are being conducted. Those who are not opposed to amalgam claim that, aside from rare and localized tissue irritation, recent evidence-based research has continued to demonstrate no ill effects from the minute amounts of mercury exposure from amalgam fillings. [ 14 ] [ 68 ] [ 69 ] A 2004 systematic review conducted by the Life Sciences Research Office , whose clients include the FDA and NIH, concluded, "the current data are insufficient to support an association between mercury release from dental amalgam and the various complaints that have been attributed to this restoration material." [ 51 ] A systematic review in 2009 demonstrated that mercury released from amalgam restorations does not give rise to toxic effects on the nervous system of children. [ 70 ] In 2014, a Cochrane Systematic review found "insufficient evidence to support or refute any adverse effects associated with amalgam or composite restorations." [ 71 ]
Those opposed to dental amalgam suggest that mercury from dental amalgam may lead to nephrotoxicity , neurobehavioural changes, autoimmunity , oxidative stress, autism , skin and mucosa alterations, non-specific symptoms and complaints, Alzheimer's disease , calcium-building in the kidneys, kidney stones, thyroid issues, and multiple sclerosis . [ 52 ]
Both those opposed and those not opposed to dental amalgam recognize that amalgam has been found to be a rare contributor to localized and temporary tissue irritation known as oral lichenoid lesions . [ 14 ] [ 68 ] [ 69 ] [ 72 ] These mild, lichenoid reactions have also been reported in composite resin fillings. [ 73 ] Those opposed to amalgam believe that amalgam fillings are also associated with increased risk of other autoimmune conditions such as multiple sclerosis (MS), lupus, thyroiditis, and eczema. [ 74 ]
Consumer Reports considered these alleged associations between amalgam and chronic disease made by some health practitioners as "prospecting for diseases". [ 7 ] The National Multiple Sclerosis Society (USA) similarly has stated, "There is no scientific evidence to connect the development or worsening of MS with dental fillings containing mercury, and therefore no reason to have those fillings removed. Although poisoning with heavy metals-such as mercury, lead, or manganese can damage the nervous system and produce symptoms such as tremor and weakness, the damage is inflicted in a different way than occurs in MS and the process is also different." [ 27 ] The Lupus Foundation of America also states on their website, "At the present time, we do not have any scientific data that indicates that dental fillings may act as a trigger of lupus. In fact, it is highly unlikely that dental fillings aggravate or cause SLE." [ 33 ]
In 2006, a literature review was undertaken to evaluate the research on amalgam and its potential health effects on dentists and dental staff. [ 75 ] It was reported that there is currently no conclusive epidemiological evidence regarding risks for adverse reproductive outcomes associated with mercury and dental professionals. It is mentioned that evidence to date fails to account for all confounding variables (such as alcohol consumption) and recommends more comprehensive and rigorous studies to adequately assess the hazards faced by dental personnel. [ 75 ]
The American College of Medical Toxicology and the American Academy of Clinical Toxicology still claim that mercury from amalgams does not cause illness because "the amount of mercury that they release is not enough to cause a health problem". [ 34 ] In response to some people wanting their existing amalgam removed for fear of mercury poisoning, these societies advise that the removal of fillings is likely to cause a greater exposure to mercury than leaving the fillings in place. [ 34 ] These societies also claim that removal of amalgam fillings, in addition to being unnecessary health care and likely to cause more mercury exposure than leaving them in place, is also expensive. [ 34 ]
Dentists who advocate the removal of amalgam fillings often recommend wearing breathing apparatus, using high-volume aspiration, and performing the procedure as quickly as possible. Sources of mercury from the diet, and the potential harm of the composite resins to replace the purportedly harmful amalgam fillings, may also need to be considered. [ 76 ]
Alternative materials which may be suitable in some situations include composite resins, glass ionomer cements, porcelain, and gold alloys. [ 77 ] Most of these materials, with the notable exception of gold, have not been used as long as amalgam, and some are known to contain other potentially hazardous compounds. Teaching of amalgam techniques to dental students is declining in some schools in favor of composite resin, [ 78 ] and at least one school, the University of Nijmegen in the Netherlands, eliminated dental amalgam from the curriculum entirely in 2001. [ 79 ] This is largely a response to consumer pressure for white fillings for cosmetic reasons, and also because of the increasing longevity of modern resin composites. These alternative dental restorative materials are not free of potential health risks, such as allergenicity, inhalation of resin dust, cytotoxicity, and retinal damage from blue curing light. [ 80 ]
Anti-amalgam sources typically promote the removal of amalgam fillings and the substitution with other materials. Detoxification may also be advised, including fasting, restricted dieting to avoid mercury-containing foods, and quasi- chelation therapies , allegedly to remove accumulated mercury from the body. [ 81 ] The American College of Medical Toxicology and the American Academy of Clinical Toxicology recommend against chelation therapy and say that chelation therapy can artificially and temporarily elevate the levels of heavy metals in the urine (a practice referred to as "provoked" urine testing). [ 34 ] They also mention that the chelating drugs may have significant side effects, including dehydration, hypocalcemia, kidney injury, liver enzyme elevations, hypotension, allergic reactions, and mineral deficiencies. [ 34 ]
Better dental health overall coupled with increased demand for more modern alternatives such as resin composite fillings (which match the tooth color), as well as public concern about the mercury content of dental amalgam, have resulted in a steady decline in dental amalgam use [ 82 ] in developed countries, though overall amalgam use continues to rise worldwide. Given its superior strength, durability, and long life relative to the more expensive composite fillings, it will likely be used for many years to come. [ 83 ] [ 84 ] Over a lifetime, dietary sources of mercury are far higher than would ever be received from the presence of amalgam fillings in the mouth. For example, due to pollution of the world's oceans with heavy metals, products such as cod liver oil may contain significant levels of mercury.
There is little evidence to suggest that amalgam fillings have any negative direct effects on pregnancy outcomes or on an infant post-pregnancy. A study, consisting of 72 pregnant women, was conducted to determine the effects of dental amalgam on fetuses in utero. Results indicated that although the amount of amalgam the mother had was directly related to the amount of mercury in the amniotic fluid, no negative effects on the fetus were found. A larger study, consisting of 5,585 women who had recently given birth, was used to determine if amalgam restorations during pregnancy had any effects on infant birthweight. Among the study group, 1,117 women had infants with low birth weights and 4,468 women had infants with normal birth weights. Approximately five percent of the women had one or more amalgam filling restorations during their pregnancy. These women had little to no difference in infant birth weight compared to the women who did not undergo amalgam restoration during pregnancy. [ 2 ]
A 2006 Zogby International poll of 2,590 US adults found that 72% of respondents were not aware that mercury was a main component of dental amalgam and 92% of respondents would prefer to be told about mercury in dental amalgam before receiving it as a filling. [ 85 ] A 1993 study published in FDA Consumer found that 50% of Americans believed fillings containing mercury caused health problems. [ 86 ] Some dentists (including a member of the FDA's Dental Products Panel) suggest that there is an obligation to inform patients that amalgam contains mercury. [ 87 ] [ 88 ]
A prominent debate occurred in the late 20th century, with consumer and regulatory pressure to eliminate amalgam being "at an all-time high". [ 88 ] In a 2006 nationwide poll, 76% of Americans were unaware that mercury is the primary component in amalgam fillings, [ 85 ] and this lack of informed consent was the most consistent issue raised in a recent U.S. Food and Drug Administration (FDA) panel on the issue by panel members. [ 88 ]
The broad lack of knowledge among the public was also displayed when a December 1990 episode of the CBS news program 60 Minutes covered mercury in amalgam. This resulted in a nationwide amalgam scare and additional research into mercury release from amalgam. The following month Consumer Reports published an article criticizing the content of the broadcast, stating that it contained a great deal of false information and that the ADA spokesperson on the program was ill-prepared to defend the claims. [ 7 ] For example, 60 Minutes reported that Germany was planning to pass legislation within the year to ban amalgam, but the Institute of German Dentists said one month later that there was no such law pending. Also, one physiologist interviewed by Consumer Reports noted that the testimonials are mostly anecdotal, and both the reported symptoms and the rapid recovery time after the fillings are removed are physiologically inconsistent with that of mercury poisoning. Consumer Reports goes on to criticize how 60 Minutes failed to interview the many patients who had fillings or teeth removed, only to have the symptoms stay the same or get worse. [ 7 ]
In 1991, the United States Food and Drug Administration concluded, "none of the data presented show a direct hazard to humans from dental amalgams." [ 89 ] In 2002, a class action lawsuit was initiated by patients who felt their amalgam fillings caused them harm. The lawsuit named the ADA, the New York Dental Association, and the Fifth District Dental Society for deceiving "[the] public about health risks allegedly associated with dental amalgam." On 18 February 2003, the New York Supreme Court dismissed the two amalgam-related lawsuits against organized dentistry, stating the plaintiffs had "failed to show a 'cognizable cause of action'". [ 90 ]
The proper interpretation of the data is considered controversial only by those opposed to amalgam. The vast majority of past studies have concluded that amalgams are safe. However, although the vast majority of patients with amalgam fillings are exposed to levels too low to pose a health risk, many patients (i.e. those in top 0.1%) exhibit urine test results which are comparable to the maximum allowable legal limits for long-term work place (occupational) safety. [ 64 ] [ 65 ] Two recent randomized clinical trials in children [ 91 ] discovered no statistically significant differences in adverse neuropsychological or renal effects observed over five years in children whose caries were restored using dental amalgam or composite materials. In contrast, one study showed a trend of higher dental treatment need later in children with composite dental fillings, and thus claimed that amalgam fillings are more durable. However, the other study (published in JAMA ) cites increased mercury blood levels in children with amalgam fillings. The study states, "during follow-up [blood mercury levels were] 1.0 to 1.5 μg higher in the amalgam group than in the composite group." EPA considers high blood mercury levels to be harmful to the fetus and also states, "exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages." Currently, the EPA has set the "safe" mercury exposure level to be at 5.8 μg of mercury per one liter of blood. [ 92 ] While mercury fillings themselves do not increase mercury levels above "safe" levels, they have been shown to contribute to such an increase. However, such studies were unable to find any negative neurobehavioral effects. [ 93 ] [ 92 ] [ 94 ]
Environmental concerns over external costs exist as well. [ 95 ] In the United States, dental amalgam is the largest source of mercury received by sewage treatment plants. The mercury contaminates the treatment plant sludge , which is typically disposed of by land application , landfilling or incineration . [ 10 ] In the United States, several states, including New Jersey , [ 96 ] New York , [ 97 ] and Michigan , [ 98 ] required the installation of dental amalgam separators before 2017. [ 99 ] EPA promulgated an effluent guidelines regulation in 2017 which prohibits most dental practices from disposing amalgam waste down the drain. Most dental offices nationwide are now required to use amalgam separators. [ 10 ] [ 100 ]
The WHO reported in 2005 that in the United Kingdom, mercury from amalgam accounted for 5% of total mercury emissions. [ 9 ] In Canada, dental amalgam was estimated to contribute one-third of the mercury in sewer system waste, but it is believed amalgam separators in dental offices may dramatically decrease this burden on the public sewer system. [ 9 ]
The 2005 WHO report stated that mercury from amalgam was approximately 1% of total global mercury emissions, and that one-third of the total mercury in most sewage systems was discharged from dental offices. [ 9 ] Other studies have shown this to be a gross exaggeration or not reflective of developed countries. Concerning pollution in the United States , a study done in 1992 showed that batteries "accounted for 86 percent of discarded mercury and dental amalgam a mere 0.56 percent". [ 101 ] Mercury is an environmental contaminant and the WHO, OSHA , and NIOSH have established specific occupational exposure limits. Mercury imposes health risks upon the surrounding population. In economics, this pollution is considered an external cost not factored into the private costs of using mercury-based products. Environmental risks from amalgam can be mitigated by amalgam separators, and the ISO has issued standards regarding the proper handling and disposal of amalgam waste. [ 102 ] Mercury is a naturally occurring element that is present throughout the environment [ 103 ] [ 104 ] and the vast majority of the pollution (about 99%) comes from large-scale human industrial activity (such as coal-fired electricity generation, hydroelectric dams, and mining, which increase both airborne and waterborne mercury levels). [ 104 ] [ 105 ] Eventually, the airborne mercury finds its way into lakes, rivers, and oceans, where it is consumed by aquatic life. [ 104 ] Amalgam separators may dramatically decrease the release of mercury into the public sewer system, but they are not mandatory in some jurisdictions. [ 106 ] When mercury from these sources enters bodies of water, especially acidic bodies of water, it can be converted into the more toxic methylmercury. [ 107 ]
Cremation of bodies containing amalgam restorations results in near-complete emission of the mercury into the atmosphere, as the temperature in cremation is far greater than the boiling point of mercury. In countries with high cremation rates (such as the UK), mercury has become a great concern. Proposals to remedy the situation have ranged from removing amalgam-containing teeth before cremation to installing activated carbon adsorption or other post-combustion mercury capture technology in the flue gas stream. According to the United Nations Environment Programme, it is estimated that globally about 3.6 tonnes of mercury vapor was emitted into the air through cremation in 2010, or about 1% of total global emissions. [ 11 ] Mercury emissions from cremation are growing in the US, both because cremation rates are increasing and because the number of teeth in the deceased is increasing due to better dental care. [ citation needed ] Since amalgam restorations are very durable and relatively inexpensive, many of the older deceased have amalgam restorations. [ citation needed ] According to work done in Great Britain, [ citation needed ] mercury emissions from cremation are expected to increase until at least 2020.
The American Dental Association (ADA) has asserted that dental amalgam is safe and has held, "the removal of amalgam restorations from the non-allergic patient for the alleged purpose of removing toxic substances from the body, when such treatment is performed solely at the recommendation or suggestion of the dentist, is improper and unethical". [ 108 ] Under the comments of the American Dental Association before the FDA's Dental Products Panel [ 109 ] of the Medical Devices Advisory Committee, [ 110 ] the ADA supports the 2009 FDA ruling on dental amalgam. [ 14 ] [ 111 ] ADA states, "dental amalgam has an established record of safety and effectiveness, which the scientific community has extensively reviewed and affirmed." [ 112 ] [ 113 ] [ 114 ] The ADA also supports the 2017 EPA wastewater regulation and is providing information and assistance to its members in the implementation of amalgam separators. [ 115 ] The ADA asserts the best scientific evidence supports the safety of dental amalgam. [ 116 ] Clinical studies have not established an occasional connection between dental amalgam and adverse health effects in the general population. [ 117 ]
In 2002, Dr. Maths Berlin of the Dental Material Commission published an overview and assessment of the scientific literature published between November 1997 and 2002 for the Swedish Government on amalgam and its possible environmental and health risks. [ 118 ] A final report was submitted to the Swedish Government in 2003 and included his report as an annex to the full report. In the final report from 2003, Berlin states that the 1997 summary had found "... no known epidemiological population study has demonstrated any adverse health effects in amalgam". He reports that researchers have been able to show effects of mercury at lower concentrations than before and states, "... the safety margin that it was thought existed concerning mercury exposure from amalgam has been erased." He recommends eliminating amalgam in dentistry for medical and environmental reasons as soon as possible. [ 118 ]
After the FDA's deliberations and review of hundreds of scientific studies relating to the safety of dental amalgam, the FDA concluded, "clinical studies have not established a causal link between dental amalgam and adverse health effects in adults and children age six and older." [ 119 ] The FDA concluded that individuals age six and older are not at risk of mercury-associated health effects from mercury vapor exposure that come from dental amalgam. [ 111 ]
In 2009, the FDA issued a final rule that classified dental amalgam as a "Class II" (moderate risk) device, placing it in the same category as composite resins and gold fillings. [ 14 ] In a press release announcing the reclassification, the agency again stated, "the levels [of mercury] released by dental amalgam fillings are not high enough to cause harm in patients." [ 120 ]
Also, in the FDA final regulation on dental amalgam in 2009, the FDA recommended the product labeling of dental amalgam. The suggested labeling included: a warning against the use of dental amalgam in patients with mercury allergy, a warning that dental professionals use appropriate ventilation when handling dental amalgam, and a statement discussing scientific evidence on dental amalgam's risks and benefits to make informed decisions among patients and professional dentists. [ 111 ] [ 121 ]
In 2020, the FDA updated its guidelines to recommend against amalgam for certain high-risk groups, including children, pregnant and nursing women, people with neurological disease, impaired kidney function, and known sensitivity to mercury, due to the potential harmful health effects of mercury vapor. [ 39 ] They acknowledge that breathing in mercury vapor may harm certain populations, but recommend against removal of amalgam fillings unless medically necessary. [ 122 ]
Mercury in dental fillings is considered safe and effective in all countries practicing modern dentistry (see below). There are currently two countries, Norway and Sweden, that have introduced legislation to prohibit or restrict use of amalgam fillings; however, in both cases amalgam is part of a larger program of reducing mercury in the environment and includes the banning of mercury-based batteries, thermometers, light bulbs, sphygmomanometers, consumer electronics, vehicle components, etc. In many countries, unused dental amalgam after a treatment is subject to disposal protocols for environmental reasons. Over 100 countries are signatories to the United Nations " Minamata Convention on Mercury ". [ 123 ] Unlike mercury-based batteries, cosmetics, and medical devices, which were banned as of the year 2020, the treaty has not banned the use of dental amalgam, but allows phasing down amalgam use over some time appropriate to domestic needs, an approach advocated by the World Health Organization (WHO). [ 124 ] [ 125 ]
FDI World Dental Federation recognizes the safety and effectiveness of amalgam restorations. FDI is a federation of approximately 200 national dental associations and specialist groups representing over 1.5 million dentists. In collaboration with the WHO, they have produced an FDI position statement and WHO consensus statement on dental amalgam. [ 13 ] Their position regarding the safety of dental amalgam is that, aside from rare allergic reactions and local side effects, "the small amount of mercury released from amalgam restorations, especially during placement and removal, has not been shown to cause any other adverse health effects." The paper goes on to say that there have been "no controlled studies published that show adverse systemic effects" from amalgam restorations, and there is no evidence that removing amalgam restorations relieves any general symptoms. More recently, FDI has published a resolution confirming that their position on the safety and effectiveness of amalgam has not changed despite the phasing out in some countries. [ 126 ]
In the United States, numerous respected professional and non-profit organizations consider amalgam use safe and effective and have publicly declared such. [ 5 ] In addition to the American Dental Association , [ 14 ] [ 127 ] other American organizations, including the Mayo Clinic , [ 21 ] the U.S. Food and Drug Administration (FDA), [ 38 ] Alzheimer's Association , [ 23 ] American Academy of Pediatrics, [ 24 ] Autism Society of America , [ 25 ] U.S. Environmental Protection Agency , [ 26 ] National Multiple Sclerosis Society, [ 27 ] New England Journal of Medicine, [ 28 ] International Journal of Dentistry, [ 29 ] National Council Against Health Fraud , [ 30 ] The National Institute of Dental and Craniofacial Research NIDCR, [ 31 ] American Cancer Society , [ 32 ] Lupus Foundation of America , [ 33 ] Consumer Reports [ 7 ] and WebMD [ 36 ] have all given formal, public statements declaring that amalgam fillings are safe based on the best scientific evidence.
On 28 July 2009, the U.S. Food and Drug Administration (FDA) recategorized amalgam as a class II medical device, which critics claim indicates a change in their perception of safety. The ADA has indicated that this new regulation places encapsulated amalgam in the same class of devices as most other restorative materials, including composite and gold fillings. [ 14 ]
Despite the research regarding the safety of amalgam fillings, the state of California requires warning information given to patients for legal reasons (informed consent) as part of Proposition 65 . This warning also applied to resin fillings for a time, since they contain bisphenol A (BPA), a chemical known to cause reproductive toxicity at high doses. [ 128 ]
In Canada, amalgam use is considered safe and effective by some groups. A 2005 position statement from the Canadian Dental Association (CDA) states, "current scientific evidence on the use of dental amalgam supports that amalgam is an effective and safe filling material that provides a long-lasting solution for a broad range of clinical situations. The CDA has established its position based on the current consensus of scientific and clinical experts and on recent extensive reviews of strong evidence by major North American and international organizations, which have satisfactorily countered any safety concerns." [ 15 ] Amalgam use is regulated by Health Canada as are all medical treatments [ 129 ] and Health Canada has also stated that dental amalgam is not causing illness in the general population. [ 22 ]
Australia recognizes the safety and effectiveness of amalgam restorations. In 2012, the Australian Dental Association published a position paper on the safety of dental amalgam. [ 16 ] Their position is "Dental Amalgam has been used as a dental restorative material for more than 150 years. It has proved to be a durable, safe, and effective material which has been the subject of extensive research over this time" and "amalgam should continue to be available as a dental restorative material". [ 130 ]
Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) is a scientific committee within the European Commission. In a 2008 document of 74 pages, its research on the subject of amalgam safety concluded "there is no scientific evidence for risks of adverse systemic effects exist [ sic ] and the current use of dental amalgam does not pose a risk of systemic disease." [ 131 ]
England and Scotland recognize the safety and effectiveness of amalgam restorations. A policy statement from the British Dental Health Foundation states that they do not consider amalgams containing mercury a significant health risk. [ 132 ]
Ireland recognizes the safety and effectiveness of amalgam restorations. The Irish Dental Association has published on their website: "Dental amalgam has been used on patients for over 150 years. All available worldwide research indicates that amalgam is not harmful to health.... No Government or reputable scientific, medical or dental body anywhere in the world accepts, on any published evidence, that dental amalgam is a health hazard." [ 18 ] The Irish Dental Association provides additional detail in a published patient information letter. [ 19 ]
France has publicly recognized the safety and effectiveness of amalgam restorations. A position paper on the Association Dentaire Française website states that amalgam restorations have proven to have no biological or toxic effect. [ 20 ] They also mention that no serious pathological fact has ever been observed and no general toxic action has been scientifically proven to date. [ 20 ] The most exposed subjects remain dentists, in whom it did not identify occupational diseases related to mercury and other rare that any allergies. These amalgam allergies are about 40 times less than that of resin fillings [ 20 ]
During the 1980s and 1990s in Norway, there was considerable and intense public debate on the use of dental amalgam. [ 133 ] The Norwegian Dental Patients Association (Forbundet Tenner og Helse), made up of people who believe they suffered health effects from amalgam fillings, was a driving force in this debate. [ 133 ] During this time, the media often featured interviews with people claiming that their health problems were caused by amalgam fillings, and who have regained their health after replacing their amalgam fillings with a different material. Some scientific studies also reported that patients have been restored to health after having had their amalgam fillings replaced. However, these studies were heavily disputed at the time and the Norwegian Board of Health still maintains there is no scientifically proven connection between dental amalgam and health problems. [ 133 ]
In 1991, organized through the ministry of the environment, Norway began phasing out the use of most mercury-containing products (not limited to amalgam fillings but also including mercury-based batteries, thermometers, sphygmomanometers, consumer electronics, vehicle components, etc.). [ 134 ] The ban on the import, export, and use of most mercury-based products began on 1 January 2008. [ 134 ] The Norwegian officials stressed that this is not a decision based on using an unsafe health product, but rather that the "overall, long term goal is to eliminate the use and release of mercury to the environment". [ 133 ] Despite the mercury ban, dental offices in Norway may apply for exemptions to use amalgam on a case-by-case basis. [ 133 ]
Similar to Norway, from 1995 to 2009 the Environment Ministry of the Government of Sweden gradually banned the import and use of all mercury-based products (not limited to amalgam fillings alone, but also including mercury-based batteries, thermometers, sphygmomanometers, consumer electronics, vehicle components, lightbulbs, analytical chemicals, cosmetics, etc.). [ 135 ] [ 136 ] These mercury-based products were phased out for environmental reasons and precautionary health reasons. [ 137 ] Like Norway, there was considerable public pressure in the years leading up to the ban. [ 133 ] Since the ban, the Government of Sweden continued to investigate ways of reducing mercury pollution. [ 138 ] The Swedish Chemicals Agency states that they may grant exemptions on the use of amalgam on a case-by-case basis. [ 138 ]
Following the Minamata Convention on Mercury, from July 2018 onwards, the EU Mercury Regulation prohibits the use of dental amalgam in children under 15 years old and pregnant or breastfeeding women. Additional requirements include the use of pre-encapsulated mercury and the ethical disposal of waste amalgam. [ 139 ] On 1 January 2025, dental amalgam was prohibited for use in the EU, except when deemed strictly necessary by the dentist based on the specific needs of the patient. [ 140 ] The British Dental Association has worked with the Council of European Dentists to prevent an immediate ban of amalgam until further research into practicalities has been undertaken, [ 141 ] which is currently ongoing. [ 142 ] [ 143 ] The European Commission will report to European Parliament by June 2020, and to the European Council by 2030 regarding the viability of ending dental amalgam use by 2030. [ 139 ]
In Japan , the use of amalgam began to decline around the 1990s; since 2016, fillings with amalgam alloys have been excluded from insurance coverage . Amalgam is still allowed as of 2023, but is rarely used because it is very expensive. Dental composite and palladium alloys are used instead. [ 144 ]
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https://en.wikipedia.org/wiki/Dental_amalgam_controversy
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Dental anesthesia (or dental anaesthesia ) is the application of anesthesia to dentistry . It includes local anesthetics , sedation , and general anesthesia.
In dentistry, local anesthetic medications (LA) are often used to control any potential pain that may occur with procedures. [ 1 ] Local anesthetic injections are given in specific areas of the mouth, rather than the whole body. Although several different medications are available, the most commonly used local anesthetic to prevent pain in the area around a tooth is lidocaine (also called xylocaine or lignocaine ). Lidocaine's half-life in the body is about 1.5–2 hours. [ 2 ] The time it takes for the anesthetic medication to prevent pain in the area (speed of onset) and length of time that the area does not have painful sensations are considerations when choosing an appropriate approach to dental treatment. Other considerations include procedural considerations, the presence of inflammation, techniques used to administer the anesthetic medication, and adverse effects. [ 1 ] In root canal treatment, for example, more Lidocaine is required than for a simple filling. [ 2 ]
Other local anesthetic agents in current use include articaine (also called septocaine or Ubistesin), bupivacaine (a long-acting anesthetic), prilocaine (also called Citanest), and mepivacaine (also called Carbocaine or Polocaine). Different types of local anaesthetic drugs vary in their potency and duration of action. A combination of these may be used depending on the situation. Some agents come in two forms: with and without epinephrine (adrenaline) or other vasoconstrictor that allow the agent to last longer. This controls bleeding in the tissue during procedures. Usually the case is classified using the ASA Physical Status Classification System before any anesthesia is given. [ citation needed ]
Drugs with a short duration of action (approximately 30 minutes of pulpal anaesthesia) include Mepivacaine HCl 3%, and Prilocaine HCl 4% without vasoconstrictor. [ 3 ]
Drugs with an intermediate duration of action (enabling pulpal anaesthesia for roughly 60 minutes) include Articaine HCl 4% + epinephrin 1:100,000, Articaine HCl 4% + epinephrin 1:200,000, Lidocaine HCl 2% + epinephrine 1:50,000, Lidocaine HCl 2% + epinephrine 1:80,000; Lidocaine HCl 2% + epinephrine 1:100,000 and Prilocaine HCl 4% + epinephrine 1:200,000. [ 3 ]
Bupivicaine HCl 0.5% + epinephrine 1:200,000 gives a long duration of action of pulpal anaesthesia at more than 90 minutes. [ 3 ]
Multiple factors affect the depth and duration of local anaesthetics' action. Examples of these factors include the patients individual response to the drug, vascularity and pH of tissues at the site of drug administration, the type of injection administered etc. [ 3 ] Hence figures citing the duration of action of local anaesthetics is an approximation, as extreme variations may occur among patients.
Commercially used LA in dental practice has a low pH of 3–4, this is advantageous as it will extend the shelf life of the product and prevent early oxidation. However, low pH LA's may produce a burning sensation, have a slower onset and decrease clinical efficacy. The pH of Local anaesthetic can be increased to increase alkalinity using sodium bicarbonate which reduces pain at the injection site and produces a faster onset. Buffered local anaesthetics have a 2.29 times increased success rate compared with non buffered solutions. [ 4 ]
Local anaesthesia is deposited at the buccal (cheek) side of the maxillary alveolus which can diffuse through the thin cortical plate of the maxilla , then further into the pulp of the tooth in order to achieve dental anaesthesia effect.
Both regional block and infiltration techniques are considered the first choice injections for anaesthetising the mandibular teeth.
Different techniques are chosen based on different factors:
The inferior alveolar nerve block is probably one of the most common methods used by dentist to anaesthetise the mandibular teeth in adults. This technique aims to inject the needle and deposit local anaesthetic close to the nerve before it enters the mandibular foramen , which locates on the medial aspect of the mandibular ramus. This is to block the nerve transmission in the inferior alveolar nerve before entering into the bone through the mandibular foramen. [ 6 ]
[ 5 ] [ 7 ] [ 8 ]
Intraosseous anaesthesia is an alternative anaesthetic injection technique that was first published in 1910. [ 9 ] Intraosseous anaesthetic injection involves the deposition of anaesthetic solution directly into the cancellous alveolar bone adjacent to the apex of the root of the tooth to be anaesthetised through a small hole. Additionally, more complex dental procedures like surgery or endodontic therapy (like root canals ) might make use of it.
Intraligamentary or periodontal ligament anaesthesia is a technique used primarily for endodontic treatment and to supplement inferior dental blocks where they may have failed. This technique involves 'the deposition of at least 0.2ml of local anaesthetic solution for each root of the tooth' [ 10 ] diffusing into the marrow spaces surrounding the teeth. Clinicians may adopt this technique due to some benefits such as: no soft tissue anaesthesia, use of a smaller amount of anaesthetic and single tooth anaesthesia however use may be contraindicated due to claims that patients report sharp pain upon administration of interligamentary aesthetic. However the use of a high-pressure syringe and ultra fine needle provide both chemical anaesthesia (by action of anaesthetic agent) and mechanical anaesthesia (by pressure from deposition). Interligamentary anaesthetic may be complicated by poor operator technique where rapid injection and excessive volume is used; this could lead to sensitivity to biting and percussion. [ 11 ]
Research has shown that the rate of onset of anaesthesia in the patients was between 15 and 20 second; this provides an advantage compared to that of inferior alveolar dental block. [ 12 ] Other advantages include a decrease in overall trauma in comparison to conventional blocks therefore being an ideal procedure for extractions and endodontic treatment in children.
Intrapulpal anaesthesia involves the direct placement of anaesthetic agent using a small needle (of 25 or 27 gauge) into the pulp chamber ; it is injected under pressure leading to brief yet intense discomfort. This particular technique provides effective pulpal anaesthesia as the pulpal tissue is subject to chemical action by the anaesthetic agent and mechanical stimulus due to the pressure applied. [ 11 ] This method is usually adopted when all other techniques have been unsuccessful and must include pre-operative warnings of sharp pain. However it may prove useful for pulpal extirpation or endodontic treatment on any tooth where anaesthesia is difficult to achieve. Nevertheless, due to the patient discomfort associated with this technique it should not be the primary anaesthetic technique used.
Intra-papillary anaesthesia is used as a supplementary technique to infiltrations in order to increase comfort for the patient and is primarily used to replace palatal or lingual infiltrations. This is exceptionally successful in paediatric patients and works to replace or increase comfort for particularly uncomfortable infiltrations such as palatal or lingual infiltrations. The technique involves direct deposition of anaesthetic agent into the papilla with associated tissue blanching at site of injection. The point of penetration should lie in attached gingiva 2mm apical of the papilla [ 13 ]
Pressure with a cotton swab in the area to distract the nerve sensation of pain when the needle enters certain areas such as palatal tissue. [ 14 ]
Technology that involves using electric current to block the reception or generation of pain signals; the pain control can be transient.
A jet injection aims to create a release of pressure strong enough to push a liquid medication dose through a small orifice. This is usually done with the help of an energy source which is mechanical. With this, a thin column of fluid is created which has the force to penetrate soft tissues, thus a needle is not required. [ 15 ]
Advantages:
However, in dentistry, the effectiveness of this technique has been reported to be limited. [ 15 ]
Examples of jet injections include: Syrijet, MED-JET H III and iCT injection SE by Dentium. [ 16 ]
References: [ 17 ] [ 18 ] [ 19 ] [ 20 ]
Septanest
Lignospan Special
Xylocaine
When considering the use of a local anaesthesia there are many factors which should be considered. In terms of contraindications associated with LA there are "absolute" and "relative" contraindications . When something is said to have an "absolute" contraindication this underlines that under no circumstance would that LA be selected to administer to that specific patient as it poses a potential life-threatening risk e.g. allergy. When the LA has a "relative" contraindication the administration of the LA is not preferable and should be avoided, but does not pose a life-threatening risk.
As stated previously, local anaesthesia used in dentistry can vary significantly as there are various preparations with a multitude of qualities. Each preparation has slight differences in how the anaesthetic affects the body. This is due to the use of different constituents. Local Anaesthetics which contain adrenaline such as Lidocaine (using 1:80,000 of adrenaline) or Articaine (using 1:100,000 of adrenaline) have a direct effect on the cardiac output by increasing the rate and contraction of the heart itself. Due to these effects, if a patient has unstable angina or severe cardiac dysrhythmia, these preparations are often discouraged as they may predispose to unfavourable side effects. [ 21 ] Studies found that both articaine given by infiltration and lidocaine given by inferior block were equally efficient when used for routine dental treatments in pediatric patients, however, articaine injections caused less post-operative pain. [ 22 ]
As an alternative, other preparations such as Mepivicaine Hydrochloride or Prilocaine (containing Felypressin) can be used. Prilocaine is especially suitable for a patient who wishes to avoid adrenaline or may have a latex/preservative allergy. The main contraindication of Prilocaine is that it has a short half life and it possesses a mild cytotoxic effect, therefore should be avoided in pregnancy. This cytotoxic effect can influence the uterine tone and interfere with circulation, which can pose detrimental effects on the pregnancy. Mepivicaine Hydrochloride is then considered if Prilocaine is contraindicated. Mepivicaine is the least vasodilatory anesthetic as it has no vasoconstrictors and no preservatives added. [ 23 ]
The dose of local anesthesia is often reduced when a patient has any systemic health implications or habits which may cause an interference. From time to time the local anaesthetic itself should be reduced (therefore reducing the maximum dose). This is particularly done when alcoholism , anaemia (if using Prilocaine), anorexia , bradycardia , or GORD (Gastroesophageal reflux disease) is concerned. On other occasions the vasoconstrictor used (often adrenaline) must be reduced when an individual has angina , bradycardia , chronic bronchitis , cardiac arrhythmia , COPD (Chronic Obstructive Pulmonary Disease), or glaucoma . Other issues include drug abuse , calcium channel blocker containing medications, beta blocker medications, or liver disease as these impair metabolism of the anaesthetic.
The variety of techniques associated when giving a local anaesthetic can affect the success and if done incorrectly lead to a possible fracture of the needle tip. It is extremely rare for the needle to fracture whilst giving an injection intra-orally unless an inadequate technique is adopted. To prevent such an occurrence, especially when performing an inferior alveolar nerve block, it is recommended to not bend the needle, to use the correct needle length and to not insert the needle up to the hub.
The Inferior alveolar nerve anaesthesia or block or IANB (sometimes termed "inferior dental block", or wrongly referred to as the "mandibular block") probably is anesthetized more often than any other nerve in the body. An injection blocks sensation in the inferior alveolar nerve , which runs from the angle of the mandible down the medial aspect of the mandible, innervating the mandibular teeth, lower lip, chin, and parts of the tongue, which is effective for dental work in the mandibular arch. To anesthetize this nerve, the needle is inserted somewhat posterior to the most distal mandibular molar on one side of the mouth. The lingual nerve is also anesthetized through diffusion of the agent to produce a numb tongue as well as anesthetizing the floor of the mouth tissue, including that around the tongue side or lingual of the teeth. [ 24 ]
Several nondental nerves are usually anesthetized during an inferior alveolar block. The mental nerve , which supplies cutaneous innervation to the anterior lip and chin , is a distal branch of the inferior alveolar nerve. When the inferior alveolar nerve is blocked, the mental nerve is blocked also, resulting in a numb lip and chin. Nerves lying near the point where the inferior alveolar nerve enters the mandible often are also anesthetized during inferior alveolar anesthesia, such as affecting hearing (auriculotemporal nerve). [ 24 ]
The facial nerve lies some distance from the inferior alveolar nerve within the parotid salivary gland, but in rare cases anesthetic can be injected far enough posteriorly to anesthetize that nerve. The result is a transient facial paralysis, with the injected side of the face having temporary loss of the use of the muscles of facial expression that include the inability to close the eyelid and the drooping of the labial commissure on the affected side for a few hours, which disappears when the anesthesia wears off. [ 14 ]
In contrast, the superior alveolar nerves are not usually anesthetized directly because they are difficult to approach with a needle . For this reason, the maxillary arch is usually anesthetized locally for dental work by inserting the needle beneath the oral mucosa surrounding the teeth so as to anesthetize the smaller branches. [ 24 ]
A dental syringe is a syringe for the injection of a local anesthetic . [ 25 ] It consists of a breech-loading syringe fitted with a sealed cartridge containing an anesthetic solution.
In 1928, Bayer Dental developed, coined and produced a sealed cartridge system under the registered trademark Carpule ® . The current trademark owner is Kulzer Dental GmbH .
The carpules have long been reserved for anesthetic products for dental use. It is practically a bottomless flask. The latter is replaced by an elastomer plug that can slide in the body of the cartridge. This plug will be pushed by the plunger of the syringe. The neck is closed with a rubber cap. The dentist places the cartridge directly into a stainless steel syringe, with a double-pointed (single-use) needle. The tip placed on the cartridge side punctures the capsule and the piston will push the product. There is therefore no contact between the product and the ambient air during use.
In the UK and Ireland, manually operated hand syringes are used to inject lidocaine in to a patient's gums. [ 26 ] [ 27 ] [ 25 ]
Topical anaesthesia can also be used to reduce dental phobia, especially in children, by reducing discomfort and pain.
Provided a dentist performs proper aspiration to avoid intravenous injections, local anesthetics containing epinephrine (adrenaline) are safe to use during pregnancy. lignocaine and prilocaine are assigned a category B ranking by the FDA and are therefore safe for use during pregnancy. Lignocaine and prilocaine are sold as 2% and 4% formulations, respectively. It is therefore safer to use the lignocaine so as to administer a lower concentration of the drug to the pregnant patient. [ 28 ]
Mepivicaine, articaine, bupivicaine are given an FDA category C ranking and so should be avoided. Benzocaine, the ingredient of most topical anesthetic formulations, is also ranked as category C and should be avoided. Lignocaine should be used as topical anesthetic instead. [ 28 ]
Epinephrine in high doses is harmful to a pregnant woman in that it affects uterine blood flow. However its use in low dose with local anesthetic administration is warranted. The epinephrine causes vasoconstriction which in turn reduces systemic distribution of the anesthetic as well as prolongs its action in addition to decreasing bleeding at the operating site. Lidocaine 2% with 1:100,000 adrenaline is the local anesthetic of choice in the treatment of pregnant women. [ 28 ]
Allergic reactions from local anaesthesia have been reported in some patients. However, this occurrence is rare even in patients who had a history of adverse reactions to LA.
There are mainly 2 classes of local anaesthetic agents: Amide or Ester linkages, based on their chemical structure. [ 29 ]
Genuine allergic reactions of an amide LA is very uncommon. An ester LA is more possible to result in an allergic reaction because the compound will be broken down to para-aminobenzoic acid (PABA) which is a trigger for allergic reactions. [ 30 ] In general dentistry, only topical applications of LA contains esters (benzocaine) when applied onto area before LA is administered.
If one is allergic to an ester LA, then the use of other types of ester LA should be avoided as the breakdown of all esters will produce PABA. However, patients allergic to ester LA will usually not be affected by amide LA because PABA is not produced upon breakdown of amide LA. Unlike ester LA, allergy to an amide LA will not eliminate the use of other types of amide LA. [ 30 ]
Some reactions are caused by administration of too much drug, usually because of the route of entry of drug (intravenously) or the quick uptake of drug into the system, or the aftereffect of the vasoconstrictor. [ 31 ] Unfavourable reactions to LA can be classified into 3 different groups: psychogenic, allergic, toxic.
Unfavourable reactions to LA are commonly due to a hyperemotional response to a perceived danger within someone's mind, and it could be demonstrated in several ways. Examples are temporal loss of consciousness, sweating, flush, change in heart rate or blood pressure, panic attack, hyperventilation, of which may be mistaken as allergic reactions. When treating such patients, treat them with care and take into consideration their anxiety. During treatment if the patients feel faint or experiences a drop in blood pressure, lay them flat and keep their legs elevated in an attempt to restore their blood pressure. Loosen any tight clothing and keep the patients sugary food/drink after they regain consciousness. Reassure the patient. [ 30 ]
It is important to ensure that children and adolescents experience less anxiety and fear to aid acceptance of future dental treatment. A study compared different methods to increase the acceptance of delivery of local anaesthetics to patients aged between 2–16 years old. These methods included the use of; audiovisual distraction (using 3D video glasses), a "wand" (computerised injection device), practising hypnosis , electrical counter-stimulation (a form of distraction) and video modelling. However, the evidence was insufficient to support their use. [ 32 ]
This may occur when there are large amounts of anaesthetic within their vascular system, which may owe to their receiving repeated LA, intravenous entry of drug or have underlying systemic conditions that do not metabolize or utilize the drug efficiently. [ 30 ] Signs and symptoms mainly involve the nervous system e.g. aggressive behaviour, drowsiness, speech alteration, disorientation etc.
Symptoms should usually resolve in a few hours, up to 12 hours, as the body will gradually rid the bloodstream of the drug. Assure the patient that their symptoms will improve after a few hours and that such a reaction should not recur and that there is no need to abstain from that drug hereafter.
Such reactions can be minimized via practising safe injection methods using an aspirating syringe to prevent injecting in blood vessels, slow administration of drug, and avoid overprescribing LA, keeping in mind the patient's weight, age and medical history.
Genuine allergy to LA will manifest either as Type 1 or Type 4 hypersensitivity. Signs and symptoms will vary depending on the type of allergy. Type 1 reactions have a rapid onset of symptoms which include swelling, redness, rashes, itchiness, chest tightness, breathing problems. A Type 4 reaction has a delayed onset of symptoms and is usually localized to the site of injection.
If a genuine allergic reaction to LA should occur, the patient should be treated as an emergency for anaphylaxis, according to the guidelines in the respective areas. For the UK, the section on medical emergencies in dental practice in the "Prescribing in Dental Practice" part in the BNF should be referred to. The patient should be sent immediately to the hospital if their condition worsens. [ 30 ]
The individual should undergo further tests to certify their allergy to the LA or for other possible causes of the adverse reaction.
The gate control theory explains that pain can be reduced if the touch nerve fibres are stimulated due to non-harmful stimuli.
Advancements in techniques used to deliver local anaesthesia are very important. There are types of local anaesthesia that apply vibrations to the skin while the injection is being placed into the skin. This uses the gate control theory to minimise pain to the patient. The high frequency vibrations coming from the device which is attached to the syringe inhibit the pain sensations coming from the needle insertion. The nerve fibres that are stimulated are the Aβ fibres which respond to pressure or vibration. Meissner's corpuscles , located in deeper tissues and bone are also affected. This closes a 'neural gate' which decreases the patient's feeling of pain.
Methods used by dentist to reduce pain during anaesthesia by using the gate control theory are: Warming of the local anaesthetic cartridge, Stretching the oral mucosa, Gentle rubbing of the extra-oral skin. [ 33 ]
Although complications of myotoxicity in dental anaesthesia are rare, myotoxic injuries are primarily mediated by disturbances in calcium homeostasis. The onset of a myotoxic episode can occur within a few hours to a few days after local anaesthetic (LA) administration. A greater concentration and longer exposure to LA have been found to have a positive correlation with myotoxic effects. It can take human muscles from 4 days to a year to recover from a myotoxic insult. Local anaesthetics used clinically can be ranked in increasing order of their risk of myotoxicity, this includes Lidocaine, Ropivacaine and Bupivacaine. [ 34 ]
Dental anaesthesia can present with many complications such as occlusal complications. There are many forms of dental anaesthesia that can cause these issues for example an Inferior Dental Block (IDB). Most commonly, ocular complications will present on the same side of the face where the injection was given. Symptoms include double vision followed by partial or full weakness in the eye muscle . Many pathophysiological processes have been discussed as a cause of these complications, including intra-arterial injection and autonomic dysregulation. Furthermore, following an incident, the patient should be reassured, and the eye should be covered with gauze to protect the eye until the corneal (blinking) reflex has returned. These symptoms usually resolve on their own but in the occurrence of persistence or deterioration, appropriate referral to an ophthalmologist should be made. [ 35 ]
Issues can also arise with use of nitrous oxide in patients who have had pneumatic retinopexy (alone or in conjunction with a vitrectomy ), commonly used to treat retinal detachments . In these procedures, a gas is injected into the vitreous cavity as a tamponade and to promote re-adhesion of the detached retina. The gas bubble causes diffusion of nitrogen out of the bloodstream and into the bubble causing it to expand. Nitrous oxide is 34 times more soluble than nitrogen and will cause an extreme expansion, raising the intraocular pressure to dangerous levels. Such high intraocular pressures cause ischemia of the central retinal artery , leading to irreversible vision loss. [ 36 ] [ 37 ]
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Dental anesthesiology is the specialty of dentistry that deals with the advanced use of general anesthesia , sedation and pain management to facilitate dental procedures.
In the United States, a dentist anesthesiologist is a dentist who has successfully completed an accredited postdoctoral anesthesiology residency program of three or more years duration, in accordance with the Commission on Dental Accreditation's standards or meets the eligibility requirements for examination by the American Dental Board of Anesthesiology. [ 1 ]
An anesthesiologist not only has a wide arsenal of anesthesia techniques, but is also a specialist in monitoring the patient's condition during procedures. [ 2 ] It monitors the indicators of functional systems of the patient's body, maintains its stable condition and prevents possible complications. [ 3 ] [ 4 ] Аn anesthesiologist in dentistry works closely with the rest of the specialists, such as implant surgeons, pediatric dentists, and adult therapists. [ 5 ] [ 6 ] Acting as a guarantor of patient safety and comfort, the participation in the treatment process allows for high quality dental care.
The anesthesiologist chooses the drug for general anesthesia in advance. [ 7 ] [ 8 ] The method of administration depends on this: inhalation through a mask or intravenous injection. [ 9 ] At the beginning of treatment, the anesthesiologist puts the patient into a state of sleep or comfortable half-sleep. [ 10 ] [ 11 ] The patient's vital signs are then monitored with a heart monitor throughout the procedure. Surveillance is conducted in accordance with the expanded Harvard protocol.
General anesthesia is performed only by a qualified anesthesia team consisting of a physician anesthesiologist and a nurse anesthetist, who accompany the patient from the moment of falling asleep to full awakening.
The drugs used in anesthesiology today have a high safety profile.
Dental Anesthesiology is a recognized specialty of dentistry in both the United States and Canada. The American Dental Board of Anesthesiology (ADBA) examines and certifies dentists who complete an accredited program of anesthesiology training in the United States or Canada. Dentists may then apply for board certification through the ADBA which requires ongoing and continual post-graduate education for maintenance. [ 12 ]
The American Society of Dentist Anesthesiologists is the only organization that represents dentists with three or more years of anesthesiology training. [ 13 ]
Dental Anesthesiology was the first specialty of dentistry to be recognized by both the American Board of Dental Specialties [ 14 ] and the National Commission on Recognition of Dental Specialties and Certifying Boards. [ 15 ]
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Dental antibiotic prophylaxis is the administration of antibiotics to a dental patient for prevention of harmful consequences of bacteremia , that may be caused by invasion of the oral flora into an injured gingival or peri-apical vessel during dental treatment.
This issue remains a subject under constant revision, with the intention of providing recommendations based on sound scientific evidence.
In the past, bacteremia caused by dental procedures (in most cases due to viridans streptococci , which reside in oral cavity), such as a cleaning or extraction of a tooth was thought to be more clinically significant than it actually was. However, it is important that a dentist or a dental hygienist be told of any heart problems before commencing treatment. Antibiotics are administered to patients with certain heart conditions as a precaution, although this practice has changed in the US, with new American Heart Association guidelines released in 2007, [ 1 ] and in the UK as of August 2018 due to new SDCEP advice in line with the NICE guidelines. Everyday tooth brushing and flossing will similarly cause bacteremia. Although there is little evidence to support antibiotic prophylaxis for dental treatment, the current AHA guidelines are highly accepted by clinicians [ 2 ] and patients. [ 3 ]
Currently, there are official guidelines for dental antibiotic prophylaxis for the prevention of infective endocarditis and of infection of prosthetic joint. These guidelines are in constant controversy and revisions by various professional committees. In addition, there are various medical conditions for which clinicians recommended antibiotic prophylaxis, although there is no evidence to support this practice. These conditions include renal dialysis shunt , cerebrospinal fluid shunt, vascular graft , immunosuppression secondary to cancer and cancer chemotherapy , systemic lupus erythematosus , and type 1 diabetes mellitus . [ 4 ]
It is of importance to dental patients and practitioners to remain current with regards to the latest recommendations rendered by professional governing bodies such as the Scottish Dental Clinical Effectiveness Programme (SDCEP), American Dental Association (ADA), American Heart Association (AHA) and the American Association of Orthopaedic surgeons (AAOS). Antibiotic prophylaxis is intended to avoid adverse outcomes in certain patients at "highest risk of postoperative complications." Standard antibiotic regimens are routinely prescribed and taken before dental procedures to avoid systemic complications secondary to the transient bacteremia caused by manipulation of the oral tissues. Although the ADA, in collaboration with AHA and AAOS have published guidelines specifying those patients who should receive antibiotic prophylaxis, research continues to further define the role dental treatment may play in causing adverse outcomes in these patients.
The Scottish Dental Clinical Effectiveness Programme (SDCEP) had published recommendations in this scope (August 2018) for the dental team on how best to adhere to the guidelines by NICE . These recommendations have been recognised and acknowledged by NICE in July 2018. The recommendations aim to clarify circumstances and management when patients are not within the scope of NICE's guideline on antibiotic prophylaxis.
Infective Endocarditis (IE) is the infection of heart valves. [ 6 ]
Previous beliefs were held that IE can be induced from dental procedures due to the invasive nature of treatment, therefore antibiotics were widely prescribed before dental treatment to prevent this. This belief has changed with evidence to show that the risk of IE occurrence from everyday routine such as toothbrushing and eating is the same as that of undergoing invasive dental procedure. [ 7 ] [ 8 ] [ 9 ] Increasing concerns regarding rise in antibiotic resistance have also pushed for change in advice on antibiotic prophylaxis, where the British National Formulary (BNF) has now opposed the use of antibiotic prophylaxis in dentistry. [ 10 ] [ 11 ]
It is now established that ‘Antibiotic prophylaxis against IE is not recommended routinely for people undergoing dental procedures’ according to NICE 2016, recommendation 1.1.3.
Only a selected body of patients are categorized with a more significant risk of IE who might require antibiotic prophylaxis. These patients undergo non-routine management. [ 13 ] [ 1 ]
[Table adapted from SDCEP AB Prophylaxis against IE [ 5 ] ]
Check patient's cardiac condition and determine whether they belong in the selected body of patients who are at a more significant risk of IE. If they do, the dentist should consult with the patient's cardiologist regarding antibiotic cover before dental treatment. Antibiotic cover is only considered when undergoing invasive dental procedures. [ 5 ]
Educate patient about the importance and relevance of good oral hygiene and infective endocarditis
Review any patients with significant risk of IE if they develop a dental infection, and manage without delay to minimize risk of IE development.
Dental treatment commenced without antibiotic cover. Patients need to be informed regarding their cardiac condition and infective endocarditis, and how this may affect dental treatment. [ 5 ]
If patients are insistent on antibiotic prophylaxis, consult the patient's cardiologist before proceeding.
Children with cardiac conditions have the same risks of IE as an adult patient. Difference in management lies with gaining consent where Gillick competence comes into play. [ 5 ]
A child may lack cooperation for dental procedures in which case, they may be considered to be referred for dental treatment under sedation or general anaesthetic. [ 14 ]
Check patient's cardiac condition and determine whether they belong in the selected body of patients who are at a more significant risk of IE. Consulting with a local cardiology centre or the patient's cardiologist may be appropriate. Manage infections without delay to minimise risk of IE development.
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The dental arches are the two arches (crescent arrangements) of teeth , one on each jaw , that together constitute the dentition . In humans and many other species, the superior ( maxillary or upper) dental arch is a little larger than the inferior ( mandibular or lower) arch, so that in the normal condition the teeth in the maxilla (upper jaw) slightly overlap those of the mandible (lower jaw) both in front and at the sides. The way that the jaws, and thus the dental arches, approach each other when the mouth closes, which is called the occlusion , determines the occlusal relationship of opposing teeth, and it is subject to malocclusion (such as crossbite ) if facial or dental development was imperfect.
Because the upper central incisors are wider than the lower ones , the other teeth in the upper arch are arrayed somewhat distally , and the two sets do not quite correspond to each other when the mouth is closed: thus the upper canine tooth rests partly on the lower canine and partly on the lower first premolar , and the cusps of the upper molar teeth lie behind the corresponding cusps of the lower molar teeth.
The two series, however, end at nearly the same point behind; this is mainly because the molars in the upper arch are the smaller.
Since there are a standard number of teeth in humans, the size of the dental arch is of vital importance in determining how the teeth are positioned when they appear. While the arch can expand as a child grows, a small arch will force the teeth to grow close together. This can result in overlapping and improperly positioned teeth. Teeth may tilt at an awkward angle, putting pressure on gums when food is being chewed. This can ultimately lead to compromised gums or infections.
Dentists replace missing, damaged, and severely decayed teeth by fixed or removable prostheses to restore or improve mastication function. There is a fundamental question in any treatment plan, namely, the desirable/mandatory length of an occlusal table.
There have been various references in the literature to the concept of the short dental arch (SDA) as a defined treatment option for the partially dentate patient. While many dentists may accept that restoring the complete dental arch is not always necessary, there still is the need to provide the patient with an affordable and functional treatment, a need satisfied by the short dental arch. [ 1 ]
A hemiarch ( hemi- + arch ) is the right or left half of an arch. It corresponds to 1 of the 4 quadrants .
This article incorporates text in the public domain from page 1114 of the 20th edition of Gray's Anatomy (1918)
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Dental assistants are members of the dental team. [ 1 ] They support a dental operator (such as a dentist or other treating dental auxiliary ) in providing more efficient dental treatment . Dental assistants are distinguished from other groups of dental auxiliaries (such as dental therapists , dental hygienists and dental technicians ) by differing training, roles and patient scopes. [ 2 ] [ 1 ]
C. Edmund Kells , a pioneering dentist operating from New Orleans, enlisted the first dental assistant. [ 3 ] [ 4 ] The dental field was initially dominated by males, but after this first addition of a female, it was then acceptable for women to seek dental treatment without their husbands. This led to dental assistants of that era also being known as "Ladies in Attendance". [ 5 ] Thanks to the addition of women to dentistry , the profession flourished with more and more women seeking treatment and more patients overall receiving care. [ 4 ]
It was not until almost four decades later that in 1923 the first dental assistant association was founded by Juliette Southard , named the American Dental Assistant Association and it is still in practise now. [ 6 ] It began with just five members, now reaching more than 10,000. [ 6 ]
The dental assistant's role is often thought to be to support the dental operator by typically passing instruments during clinical procedures. However, in fact, their role extends much further to include: providing patients help with their oral hygiene skills, preparing the patient for treatment, sterilising instruments, assisting during general anaesthetic dental procedures, positioning suction devices, exposing dental radiographs , taking dental impressions , recording patient notes and administration roles such as scheduling appointments, ensuring compliance with OSHA and CDC standards, maintaining sterilization logs, and conducting regular operatory disinfection. [ 2 ] [ 7 ]
It was customary for oral health care workers and dental assistants in the 1980s to practice oral health care without wearing gloves, masks or eye protection. [ 8 ] This was at a crucial time due to the human immunodeficiency virus (HIV) spreading rapidly at a global rate. [ 8 ] At the time, the transmission risks associated with bloodborne pathogens like HIV and hepatitis B were not fully understood, and personal protective equipment (PPE) was not yet standard in most clinical settings. However, the increased awareness and understanding of these infectious diseases by the late 1980s and early 1990s led to significant changes in infection control protocols across health care fields, including dentistry. [ 9 ] However, in 2018 gloves, masks and eye protection have become part of the standard infection control guidelines which has been implemented in all oral health care settings as a means of preventing the spread of infectious disease . [ 10 ] Infection control in oral health care not only protects the patient but it also protects the oral health care workers. [ 8 ] This includes: dentists , dental specialists, oral health therapists, dental hygienists and dental assistants. [ 8 ]
Dental assistants play a crucial role in maintaining high levels of infection control in the oral health care setting. [ 8 ] The dental assistant is the major link between oral health care workers and the patient. [ citation needed ] To perform infection control responsibilities well, the dental assistant must have the appropriate education, training and work experience. Examples of infection control protocols that the dental assistant needs to follow in an oral health setting include:
Hand hygiene aims to reduce the number of microorganisms on hands. Antimicrobial agents such as alcohol-based hand rub or antimicrobial soap and water are effective agents to remove most antimicrobial bacteria on hands in dental settings. [ 10 ]
Gloves, gown, hair net and eye protection are essential barrier protection items that enable the dental assistant to reduce the transmission of infectious diseases to themselves, other dental co-workers and patients. [ 10 ] Gloves and masks need to be disposed after each patient, eyewear can be disposable or reusable and gowns need to be replaced if visibly soiled. [ 10 ] Lastly, footwear must include leather closed toe shoes; this minimises the risk of sharps injury. [ 10 ]
It is crucial to wear sterile gloves when the dental assistant is assisting in surgery with the oral health care clinician. [ 10 ] Hand hygiene using antimicrobial soap and water is imperial to maintaining adequate infection control in this setting, as this minimises the risk of infection . [ 10 ]
It is crucial that sharp instruments which include: needles, scalers, scalpels, burs, orthodontics bands and endodontic files need to be handled with care and appropriate techniques to minimise any potential sharps injury. [ 10 ] Sharps also need to be disposed accordingly into the sharps containers, separate from other disposable bins. [ 10 ] The dental assistant needs to be aware of what is required to go into the sharps containers and what is not. [ 10 ] This minimises the chance of spreading infectious diseases . [ 10 ]
It is imperative that when performing change over, that the dental assistant is able to distinguish the difference between medical related waste compared to contaminated waste. [ 10 ] Contaminated waste needs to be placed in a leak proof thick yellow bag with a biohazard symbol label. [ 10 ]
The dental assistant should put on utility gloves when cleaning working surfaces during the changeover between patients. Each person in the dental office needs to have his or her own pair/s of utility gloves. [ 11 ] [ 12 ] They must also be able to distinguish between clean and dirty zones as this minimises the spread of infectious diseases between co-workers and patients. [ 10 ] Additionally, plastic barriers are placed on: instruments such as; hand pieces connected to the chair, overhead lights, amalgamators, x-ray machines , mixing materials and other miscellaneous dental instruments , materials or appliances. [ 13 ] One of the roles that the dental assistant participates in is changing these plastic barriers after each patient has left that surgery. [ 13 ] This ensures that the surgery is set up ready for the next patient. [ 13 ]
Dental assistants play a large role in ensuring that the reusable dental instruments used daily in dental practices are sterilized adequately after each use. [ 14 ] Sterilisation is an essential part of the infection control protocol. This can be defined as free of all life forms where the elimination of considerable number of the most heat resistant spores (bacterial and mycotic) is the basic criteria sterilisation. Sterilisation process consists of [ 15 ]
Disinfectant is also one of the major roles of dental assistant where chemicals applied to inanimate surfaces such as lab tops, counter tops, headrests, light handles, etc. This is to make sure that germicide and/or microbiostatic are achieved. [ 16 ] Antiseptic chemical agents similar to disinfectants but they may be applied safely to living tissue, is another task for dental assistant where Alcohol is the most commonly used. [ 16 ]
Dental assistants make a difference in the community by participating in health promotion activities and programs. These programs may take place at schools, preschools, immunisation events or at maternal health clinics. Dental operators may also be supported by dental assistants during pre-school or school screenings. [ 17 ]
Dental assistants can extend their scope to provide oral health promotion to patients in Australia by completing the Certificate IV in Dental Assisting (Oral Health Promotion). [ 18 ] The dental assistant will have the ability to implement an individualised oral health promotion program and oral hygiene program. After the appropriate training the dental assistant may;
Dental assistants help other dental and allied health professionals in health promotion. These dental assistants implement oral health programs by providing resources and presentation promoting oral health messages to several target groups and community settings. [ 19 ] These settings include:
Dental assistant can educate the community and schools by advising on:
Currently in Australia , dental assistants are not required to be registered under the Dental Board of Australia. [ 20 ] However, dental assistants who have attained their certificate IV in dental assisting – Dental Radiography must hold a current license with the relative state or territory radiation authority. [ 20 ] Dental assistants that decide to take on further study into their certificate IV in dental assisting - dental radiography, have an advantage of exposing patients to radiation also known as an x-ray, with regards to oral health care. [ 20 ] The dental assistant will take training to further their practical and theoretical skills relevant to the role of the dental radiographer. [ 20 ]
Upon successful completion of the training program dependent on the course structure, the dental assistant may:
Expose intra-oral radiographs that ensures an optimum radiographic image. [ 21 ]
Looking to the future of dentistry and oral health, the roles for dental assistants are ever-changing and expanding. With the increase in an ageing population, it will become more and more commonplace for dental assistants to be employed to support dental operators with providing oral health promotion and treatment within residential care facilities. [ 22 ]
The number of newly graduated dentists and dental auxiliaries is increasing and with that the need for dental assistants. [ 1 ] According to the Bureau of Labor Statistics of America the rate of employed dental assistants will likely increase by 18% in the ten years between 2014 and 2024. [ 1 ] With an increase in dental assistants comes the possibility of extension in the dental assistant roles and scope. As seen in some states of the United States of America, dental assistants are able to perform some simple fillings with the supervision of a practising dentist. [ 1 ] By allowing dental assistants to extend their scope alongside the appropriate training, the workload of the other members of the dental team is lessened and increases efficiency of the dental clinic management. This may have the potential to reach other countries in the future as the need for dental and oral health treatments increase. [ 1 ]
Dental assistant roles can vary depending on different country qualifications and regulations. Below are examples of dental assisting roles which the dental assistant is able to perform, respective to that country.
According to the Australian Government, Department of Health, in 2006 there were 15,381 registered dental assistants supporting dental operators. Of those, 171 were Indigenous.
In Australia Dental Assistants should have the following skills: [ 23 ] [ 24 ]
Dental Assistants work as part of a wider dental team, primarily with Dentists, but also with Dental Specialists, Oral Health Therapists, Dental Therapists, Dental Technitions, Dental Hygienists and Dental Prosthetists. [ 26 ] [ 27 ]
Tasks include: [ 28 ] [ 29 ]
VICTORIA
1day/week
2day/week
Goulburn Ovens Institute of TAFE
2-3day/month
Technology (Private)
months work experience
Technology (Private)
months work experience
Technology (Private)
NEW SOUTH WALES
(months)
(Radiography)
(Oral Health Promotion)
TAFE NSW
TAFE NSW
TAFE NSW
TAFE NSW
QUEENSLAND
(Queensland)
NORTHERN TERRITORY
WESTERN AUSTRALIA
of Further Studies
of Further Studies
SOUTH AUSTRALIA
TASMANIA
Australian Dental assistants perform limited and restricted duties and are not permitted to perform any of the following: [ 20 ] [ 31 ]
Dental Assisting is not a registered profession in Australia and as such training courses are not mandatory, although those with nationally recognised qualifications will enjoy the benefits of higher wages and better employment opportunities. [ 20 ]
There is no formal training required of entry level dental assistants in order to commence or undertake work in private practice in Australia. [ 32 ] Most dental assistants gain practical experience at a place of employment although there are vocational qualifications which are nationally recognised and highly recommended for increasing a person's job prospects, remuneration, and professional development. [ 20 ]
The National Vocational Qualification HLT35015 Certificate III in Dental Assisting is the entry level of vocational training for dental assisting while HLT45015 Certificate IV in Dental Assisting are suitable for those who seek to further their skills and duties and elect units from particular streams such as dental radiography, oral health promotion, practice administration, general anaesthesia and conscious sedation. [ 20 ] [ 32 ] These formal qualifications can be offered only by registered training organisations such as TAFE and professional associations while Certificate III in Dental Assisting may also be offered as a traineeship in most States of Australia and as a School-based Traineeship for years 11 and 12 in some States. [ 20 ] [ 32 ]
Currently dental assistants are not required to be registered under the Dental Board of Australia or with any State and Territory Boards since dental assisting is not a registered profession. Dental Assistants who have attained a Certificate IV in Dental Assisting – Dental Radiography and are required to operate dental radiography apparatus as part of their job role, must hold a current license with the relevant state or territory Radiation Authority. [ 20 ]
Dental assistants are strongly encouraged to have current vaccinations for Hepatitis B, and Tetanus along with the normal childhood vaccination recommendations (Measles, mumps, varicella, polio) and influenza. Many state and territory public health care facilities and training providers will require students and workers to present evidence of Hepatitis B immunity and the results of a criminal history check prior to commencing clinical placement. Most private dental clinics will also require employees to have current vaccination records and may also require workers to undertake annual influenza vaccinations. [ 33 ] [ 34 ]
According to Occupational Employment Statistics, in the USA in 2017 there are a total of 337,160 Dental Assistants: [ 35 ] they all should have the following personal qualities: [ 36 ] [ 37 ] [ 38 ]
Unlike Australia, in the USA dental assisting is a registered profession represented by the American Dental Assistants Association (ADAA) [ 39 ] [ 40 ] and members should possess both front desk and chairside skills. [ 41 ]
Routine duties include: [ 42 ] [ 37 ] [ 36 ]
Extended duties may include: [ 43 ] [ 44 ]
In some U.S. states, dental assistants can work in the field without a college degree, while in other states, dental assistants must be licensed or registered. [ 36 ]
Dental assistants can receive formal education through academic programs at community colleges, vocational schools, career colleges, technical institutes, universities and dental schools with most programs needing only 8 to 11 months to complete. [ 36 ]
The Commission on Dental Accreditation of the American Dental Association accredits dental assisting school programs, of which there are over 200 in the United States. [ 45 ]
To become a Certified Dental Assistant, or CDA, dental assistants must take the DANB (Dental Assisting National Board) CDA examination after they have completed an accredited dental assisting program, [ 46 ] while those who have been trained on the job or have graduated from non-accredited programs are eligible to take the national certification examination after they have completed two years of full-time work experience as dental assistants. [ 47 ] [ 48 ] Some dentists are willing to pay a dental assistant-in-training that has a good attitude and work ethic. [ 47 ] [ 49 ]
In the USA the Dental Assisting National Board offers three nationally recognised certifications, namely: [ 36 ]
Expanded duties dental assistants or expanded functions dental assistants, [ 50 ] as they are known in some states, may work one on one with the patient performing restorations after the doctor has removed decay [ 43 ] [ 44 ] Ideally, a dental assistant should have both administrative and clinical skills although it's still acceptable to have one or the other.
Duties may also include seating and preparing the patient, charting, mixing dental materials, providing patient education and post-operative instructions. They also keep track with inventory control and ordering supplies.
In the UK, Registered Dental Nurses are prohibited from carrying out any form of direct dental treatment on the patient, including teeth whitening procedures, under the GDC scope of practice. [ 51 ] Dental nurses found to be carrying out dental procedures are liable to be removed from the statutory GDC register. [ 52 ]
Duties include: [ 52 ] [ 53 ]
Those with additional training or skills developed during their careers can undertake expanded duties that may include: [ 51 ] [ 54 ] [ 55 ]
Entry level working as a trainee dental nurse does not require any qualification, but progression to qualified dental nurse requires completion of a formal course of study, either part or full-time, approved by the General Dental Council. A minimum 2 GCSEs (C grade or above) in English language and maths or a science subject are usually required for part-time courses while full-time courses may require evidence of A-level or AS-level study. A level 3 apprenticeship in dental nursing is an alternative pathway to gaining the required qualifications in dental nursing. [ 52 ]
In Ireland dental assistants have the following tasks: [ 56 ] [ 57 ]
Skills Required [ 56 ] [ 57 ]
In the Republic of Ireland, it is often dental nurses (and teeth whitening technicians) who carry out teeth whitening procedures rather than dentists. [ 58 ]
This practice mainly occurs in clinics focusing solely on laser teeth whitening. In Ireland, registration as a dental nurse with The Irish Dental Council is voluntary; however, nurses who are registered and who carry out teeth whitening may face disciplinary action if caught. [ 56 ] [ 58 ]
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A dental auxiliary is any oral health practitioner other than a dentist & dental hygienist, including the supporting team assisting in dental treatment. [ 1 ] [ 2 ] They include dental assistants (known as dental nurses in the United Kingdom and Ireland), dental therapists and oral health therapists, dental technologists , and orthodontic auxiliaries. The role of dental auxiliaries is usually set out in regional dental regulations, defining the treatment that can be performed.
Dental assistant help make dental treatment more efficient by assisting the clinician. They hold and pass instruments, retract tissues and apply suction to assist better vision of the operating field . They also mix materials, help maintain dental records, and sterilize instruments and equipment. Some also engage in professional teeth whitening procedures, particularly in The Republic of Ireland where laser teeth whitening is classified as a cosmetic procedure and not dental treatment. This practice usually occurs in clinics solely devoted to laser teeth whitening and not routine dental treatment.
Dental therapists are licensed dental auxiliaries in some countries. Therapists were created in New Zealand in 1921, with the formation of the School Dental Service , and spread mainly to other Commonwealth countries. Local regulations determine the duties therapists are allowed to perform, including either working under the prescription of a dentist or independently, and either exclusively treating children, or patients of any age. Therapists may work in government or private clinics, and are typically licensed to examine teeth, take radiographs , administer local anesthesia , restore teeth, administer vital pulp treatments such as pulpotomies , extraction of deciduous (primary) teeth, provide sealants , scaling and polishing, and apply topical fluoride .
Training for dental hygienists and dental therapists was combined in Queensland , Australia in 1998 to create oral health therapists or OHTs . They are now also trained in New Zealand, Singapore, and Indonesia. Depending on local regulations, oral health therapists may work in consultation with dentists, or independently. And depending on regulations and training, may treat only children, or patients of any age. Duties usually include examining teeth and/or gingiva (gums), taking and interpreting intra and extra-oral radiographs, diagnosing dental caries (decay) and periodontal (gum) disease, restoring teeth (either deciduous (primary) or both deciduous and permanent), extraction of deciduous teeth, scaling or debridement to remove calculus, polishing to remove stain, applying fissure sealants and topical fluoride, patient education, and oral hygiene instruction.
Although dental hygienists and dental therapists can be jointly-trained in the UK, the oral health therapy scope does not exist there.
Dental technologists or dental technicians are dental professionals who fabricate dental appliances: removable protheses including dentures and orthodontic retainers , and fixed restorative work such as crown and bridges for the dental operator to insert. Denturists or clinical dental technologists or technicians are dental technicians with postgraduate training who see patients to fabric and fit dentures. [ 3 ]
Orthodontic auxiliaries are oral health professionals who work exclusively under the direction of an orthodontist or dentist providing orthodontic treatment. Under supervision they place and remove orthodontic brackets, wires , bands , and appliances on patients, as treatment-planned by the orthodontist or dentist, in order to improve efficiency.
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Dental avulsion is the complete displacement of a tooth from its socket in alveolar bone owing to trauma , such as can be caused by a fall, road traffic accident, assault, sports, or occupational injury. [ 1 ] [ 2 ] Typically, a tooth is held in place by the periodontal ligament , which becomes torn when the tooth is knocked out. [ 3 ]
Avulsions of primary teeth are more common in young children as they learn to move independently (walk and run) and also from child abuse. Avulsed deciduous (primary) teeth should not be replanted. Deciduous teeth are not replanted because of the risk of damaging the developing permanent tooth germ. Pulp necrosis with draining fistula, crown discoloration and external root resorption are reported consequences of primary tooth replantation. Tooth dilaceration, impaction and deviation from proper eruption path have been reported to have occurred in permanent teeth as a result of reimplantation of primary teeth. [ 4 ]
Avulsed permanent teeth however may be replanted, i.e., returned to the socket. Immediate replantation is considered ideal, but this may not be possible if the patient suffered other serious injuries. If properly preserved, teeth may be replanted up to one hour after avulsion. The success of delayed replantation depends on the survival of the cells remaining on the root surface. Storage in an environment similar to the tooth socket can protect these cells until replantation can be attempted. [ 5 ]
Contact sports carry a significant risk of dental injury, [ 6 ] which can be reduced by wearing a mouthguard or helmet . [ 7 ] Mouthguards are often less effective if not fitted properly to the teeth. [ 6 ]
Despite their wide availability, the use of mouthguards is relatively uncommon. [ 8 ] [ 9 ] Many people do not use them even in situations that carry a high risk of dental injury, or when their use is mandated. [ 10 ] In addition, mouthguards may be dislodged from the wearer's mouth, leaving the teeth unprotected.
Certain occlusal characteristics, such as class II malocclusions with increased overjet , are associated with a higher risk of dental trauma. [ 11 ] [ 12 ] These conditions can be corrected by an orthodontist reducing risk of injury due to sports related activities.
Dental avulsion is a true dental emergency in which prompt management affects the prognosis of the tooth. [ 14 ] Replantation of the tooth within 15 minutes is associated with the best prognosis as periodontal ligament (PDL) cells are still viable. Total extra-oral dry time of more than 60 minutes, regardless of storage media, has poor prognosis. The avulsed permanent tooth should be gently but well rinsed with saline, with care taken not to damage the surface of the root which may have living periodontal fiber and cells. Once the tooth and mouth are clean an attempt can be made to re-plant the tooth in its original socket within the alveolar bone and be splinted (stabilized) by a dentist for several weeks. [ 15 ] Failure to re-plant the avulsed tooth within the first 40 minutes after the injury may result in a less favorable prognosis for the tooth. [ 15 ] If the tooth cannot be immediately replaced in its socket, follow the directions for any knocked-out (avulsed) teeth kit, or place it in cold milk or saliva and take it to an emergency room or a dentist. If the mouth is sore or injured, cleansing of the wound may be necessary, along with stitches, local anesthesia, and an update of tetanus immunization if the mouth was contaminated with soil. Management of injured primary teeth differs from management of permanent teeth; avulsed primary tooth should not be re-planted (to avoid damage to the permanent dental crypt ). [ 16 ]
Although dentists advise that the best treatment for an avulsed tooth is immediate replantation, [ 17 ] [ 18 ] for a variety of reasons this can be difficult for the layperson. The teeth are often covered with debris. This debris must be washed off with a physiological solution and not scrubbed. Often multiple teeth are knocked-out and the person will not know to which tooth socket an individual tooth belongs to. The injured victim may have other more serious injuries that require more immediate attention or injuries such as a severely lacerated bleeding lip or gum that prevent easy visualization of the socket. Pain may be severe, and the person may resist replantation of the teeth. People may, in light of infectious diseases (e.g., HIV ), fear handling the teeth or touching the blood associated with them. If immediate replantation is not possible, the teeth should be placed in an appropriate storage solution and brought to a dentist who can then replant them. The dentist will clean the socket, wash the teeth if necessary, and replant them into their sockets. S/he will splint them to other unaffected teeth for a maximum of two weeks for teeth. Properly handled, even replantation of periodontally compromised permanent teeth in older patients under good maintenance have been reported, with splinting extending for over 4 weeks due to the reduced support structure for the root due to periodontal disease . [ 19 ] Dental pulp of the avulsed teeth should be removed within 2 weeks of replantation and the teeth should receive root canal therapy. [ 5 ]
In addition, as recommended in all cases of dental traumas , good oral hygiene with 0.12% chlorhexidine gluconate mouthwash , a soft and cold diet, and avoidance of smoking for several days may provide a favorable condition for periodontal ligaments regeneration. [ 14 ]
When a patient arrives at the dentist they should be seen immediately. If the tooth has not been placed in a suitable storage medium, the dentist will do this first. A thorough extra-oral and intra-oral examination should be performed. The clinician should consider the age of the patient, the history of the injury, status of tooth root apex and whether it is in line with clinical findings. It is advisable to check the patient's tetanus status. If there is concern about non-accidental injury, then child protection procedures should be followed. [ 20 ] [5]
Prior to the beginning of the procedure, a local anesthetic should be administered to both the palatal/lingual tissues to minimize discomfort. Gentle irrigation with a saline solution, should be performed as this removes any clots within the socket, which could prevent the proper re-positioning of the tooth into its original position. The tooth should always be handled via the enamel on the crown, not the root. Wash the root surface with saline, be careful not to scrub the root surface, as this may crush the delicate cells. Any stubborn debris can be removed by agitating it in the storage medium or by rinsing under a stream of saline. [ 21 ] [5]
Stabilize the tooth for 2 weeks using a passive and flexible wire (0.016” or 0.4 mm. Alternatively composite, nylon fishing line can be used to create a flexible splint. If associated with alveolar fracture a more rigid splint may be placed for up to 4 weeks. Systemic antibiotic therapy may be recommended. The patient should be asked to avoid contact sports, eat a soft diet, brush their teeth with a soft toothbrush after each meal, and use Chlorhexidine (0.12%) mouth rinse twice a day for 2 weeks. [5]
Every tooth is connected to its surrounding bone by the periodontal ligament. The tooth receives its nourishment through this ligament. When a tooth is knocked out, this ligament is stretched and torn. If the torn periodontal ligament can be kept alive, the tooth can be replanted, and the ligament will reattach, and the tooth can be maintained in its socket. The torn ligament that stays on the socket wall, since it remains connected to the bone and blood supply, is naturally kept alive. However, the ligament cells that remain on the tooth root lose their blood and nutrition supply and must be artificially maintained. They must be protected from two potentially destructive processes: cell crushing and loss of normal cell metabolism . [ 3 ] All treatment between the time of the accident and the ultimate replantation must be focused on preventing these two possibilities.
When teeth are knocked out, they end up on an artificial surface: the floor, the ground or material such as carpeting. If the surface is hard, the tooth root cells will be traumatized. Since the cells remaining on the tooth root are very delicate, additional trauma to the PDL cells must be avoided so as to avoid more cell crushing. This damage can occur while picking the tooth up and/or during transportation to the dentist.
When a tooth is picked up, it should always be grasped by the enamel on the crown. [ 17 ] [ 18 ] [ 22 ] Finger pressure on the tooth root cells will cause cell crushing. Any attempt to clean off any debris should be avoided. Debris should always be washed off gently with, at the very least, a physiologic saline. Even with the use of a physiologic saline, the "scrubbing" of the tooth root to remove debris must be avoided. [ 3 ] When placed in a physiologic solution, the tooth should be gently agitated to permit the cleansing of the tooth root. At the same time that this agitation occurs, the bumping of the tooth root against a hard surface such as glass, plastic or even cardboard must also be avoided. [ 3 ] For the same reasons, the method in which the knocked-out teeth are transported must be carefully selected. [ 3 ] Placing the knocked-out teeth by transporting in tissues and handkerchiefs can be damaging and transporting them in glass or cardboard containers can also be potentially damaging to the cells. In addition to the potential damage that the hard surface can cause, glass containers have the added possibility of breakage or leakage of the physiologic storage fluid. If the glass container does not have a tightly fitting top, then during the transportation, the physiologic storage solution can spill out and the teeth can fall, once again, on the floor and, at the same time, be out of a physiologic environment.
Normally metabolizing tooth root cells have an internal cell pressure (osmolality) of 280–300 mOs and a pH of 7.2. [ 23 ] When there is an uninterrupted blood supply, all of the metabolites (calcium, phosphate, potassium) and glucose that the cells require are provided. When the tooth is knocked out, this normal blood supply is cut off and within 15 minutes [ 22 ] most of the stored metabolites have been depleted and the cells will begin to die. Within one to two hours, enough cells will die that rejection of the tooth by the body at a later time is the usual outcome. [ 24 ] [ 25 ] [ 26 ] [ 27 ] The method by which the body rejects the replanted tooth is a process called "replacement root resorption". [ 7 ] During this process, the tooth root cells become necrotic (dead) and will activate the immunologic mechanism of the body to attempt to remove this necrotic layer and literally eats away the tooth root. This is called "root resorption". It is a slow, but non-painful, process that is sometimes not observed by x-rays for years. Once this process starts, it is irreversible, and the tooth will eventually fall out. In growing children, this can cause bone development problems because the replacement resorption (also termed ankylosis ) attaches the tooth firmly to the jawbone and stops normal tooth eruption and impedes normal jaw growth. [ citation needed ]
Research has shown that the critical factor for reduction of the death of the tooth root cells and the subsequent root replacement resorption following reimplantation of knocked-out teeth is maintenance of normal cell physiology and metabolism of the cells left on the tooth root while the tooth is out of the socket. [ 3 ] In order to maintain this normalcy, the environment in which the teeth are stored must supply the optimum internal cell pressure, cell nutrients and pH. [ 23 ]
Immediate replantation, where the tooth is quickly reinserted into its socket, is the best course of action to preserve the tooth's viability and function. However, due to various factors such as the condition of the avulsed tooth, patient circumstances, or delay in accessing dental care, immediate replantation might not always be possible. [ 1 ] [ 28 ] [ 5 ]
In cases where immediate replantation is not feasible, selecting an appropriate storage medium to preserve the viability of the periodontal ligament (PDL) cells becomes paramount. These cells are essential for the successful reintegration of the tooth into its socket, aiding the healing process and preventing resorption. Storage media serve the critical role of maintaining cell viability by providing an environment with suitable pH, osmolality, and nutrient content, thereby sustaining cell health until the tooth can be properly replanted. The International Association of Dental Traumatology (IADT) guidelines stress the importance of minimizing the tooth's dry time and choosing an effective storage medium to enhance replantation success. [ 1 ] [ 28 ] [ 5 ]
Universally considered the most preferred storage medium for avulsed teeth, milk's effectiveness is attributed to its pH level and osmolality, which closely resemble the natural conditions necessary for sustaining PDL cell viability. Milk's widespread availability, combined with its nutritional content, provides an optimal environment that supports the survival of PDL cells during the critical period before replantation. Research indicates that the type of milk (e.g., whole, skimmed, or low-fat) can play a role in the preservation efficacy, with whole milk often recommended for its balanced nutrient composition. However, any readily available milk can serve as an effective temporary storage medium, making it a practical choice in emergency situations. [ 1 ] [ 28 ] [ 5 ]
Hank's Balanced Salt Solution (HBSS) is a medically formulated solution containing essential nutrients designed to preserve avulsed teeth until they can be replanted. HBSS is distinguished by its balanced pH and osmolality, closely simulating the natural conditions necessary for the survival of periodontal ligament (PDL) cells. [ 28 ] [ 5 ] The solution has demonstrated effectiveness in maintaining PDL cell viability for up to 48 hours. [ 1 ]
Despite its effectiveness, HBSS is not as commonly available for immediate use as household items like milk, which poses a challenge in emergency dental care situations. However, it remains highly recommended in dental trauma care, especially in commercial preparations tailored for dental emergencies. [ 5 ] These preparations are specifically designed to replenish lost metabolites, providing an optimal environment for the temporary storage of avulsed teeth and significantly enhancing the prospect of successful replantation.
Recent evidence suggests oral rehydration solutions, propolis, rice water, and even cling film might also be beneficial for preserving cell viability, though further validation is needed. [ 28 ]
Saline solution and pure water are discouraged due to their lack of essential nutrients and hypotonic nature, respectively, which can lead to decreased viability of PDL cells. Other alternatives like coconut water, egg white, and various probiotic solutions have shown mixed effectiveness. [ 1 ] [ 28 ] However, ongoing research continues to explore the viability of other natural and synthetic substances as potential storage media. The exploration into these alternatives aims to identify solutions that might offer practical benefits similar to or better than those provided by milk, especially in scenarios where milk may not be immediately available.
Despite the treatment provided, dental avulsion carries one of the poorest outcomes with 73–96% of the replanted teeth eventually being lost. [ 29 ] There are three main factors which significantly influence the prognosis of the tooth. These include:
Additionally, the choice of treatment is closely related to the maturity of the root (open or closed apex) and the condition of the PDL cells, which is dependent on the time out of the mouth and the storage medium used. Minimizing the dry time is crucial for the survival of the PDL cells, with viability sharply declining after an extra-alveolar dry time of 30 minutes. [ 5 ]
From a clinical perspective, assessing the condition of the PDL cells is vital, classifying the avulsed tooth into one of three groups before treatment. These include:
This classification guides dentists in prognosis and treatment decisions, though exceptions occur. [ 5 ]
PDL healing is the primary outcome measure when assessing interventions for tooth avulsion. [ 33 ] When the healing of the PDL is unfavorable it means that there is no longer protection for the root from the surrounding alveolar bone. The bone that surrounds the tooth is continually undergoing physiological remodeling. Over time, the root is gradually replaced by bone, [ 34 ] which leads to tooth loss. [ 33 ]
The results of replanting permanent incisor teeth can be divided into short, medium and long-term survival of the tooth. [ 33 ] If the tooth is replanted it acts in the short term to maintain space, maintain bone and provide good to excellent aesthetics. [ 33 ] If unfavorable healing has occurred, the tooth can last into the medium term for 2-10+ years [ 30 ] depending on the speed of bone turnover. [ 34 ] [ 31 ] Long-term survival of the tooth only happens when favorable healing of the periodontal ligament has occurred. If this happens the tooth can be estimated to survive as long as any other tooth [ 33 ]
Research has shown that more than five million teeth are knocked-out each year in the United States . [ 35 ] Dental avulsion is a type of dental trauma, and the prevalence of dental trauma is estimated at 17.5% and varies with geographical area. [ 36 ] Although dental trauma is relatively low, dental avulsion is the fourth most prevalent type of dental trauma. [ 37 ]
Dental avulsion is more prevalent in males than females. Males are three times more likely to suffer from dental avulsion than females. [ 37 ]
Up to 25% of school-aged children and military trainees experience some kind of dental trauma each year. [ 2 ] [ 3 ] The occurrence of dental avulsion in school aged children ranges from 0.5 to 16% of all dental trauma. Many of these teeth are knocked-out during school activities or sporting events such as contact sports , football , basketball , and hockey . It is important for laypersons who are related to children, working, or witnessing sports that they be educated on this subject matter. Being educated could aid in minimizing injuries that could do further harm to the victim. Being informed and spreading awareness of dental avulsion, its treatment, and prevention could make an impact. [ 38 ]
The first reported cases of knocked-out teeth being replanted was by Pare in 1593. In 1706, Pierre Fauchard also reported replanting knocked out teeth. Wigoper in 1933 used a cast gold splint to hold reimplanted teeth in place. In 1959, Lenstrup and Skieller [ 39 ] declared that the success rate of replanted knocked out teeth should be considered a temporary procedure because the success rate of less than 10% was so poor. In 1966 [ 40 ] [ 41 ] in a retrospective study, Andreasen theorized that 90% of avulsed teeth could be successfully retained if they were replanted within the first 30 minutes of the accident. In 1974, Cvek [ 42 ] showed that removal of the dental pulp following reimplantation was necessary to prevent resorption of the tooth root. In 1974, Cvek [ 42 ] showed that storage of knocked out teeth in saline could improve the success of replanted teeth. In 1977, Lindskog et al. [ 43 ] showed that the key to retention of the knocked-out teeth was to maintain the vitality of the periodontal ligament. In 1980, Blomlof [ 23 ] showed that storing the periodontal ligament cells in a biocompatible medium could extend the extra oral time to four hours or more. He found that the best storage medium was a medical research fluid called Hank's Balanced Solution. In this study, it was serendipitously discovered that milk could also maintain cell viability for two hours. In 1981, Andreasen [ 24 ] [ 25 ] [ 26 ] showed that crushing of cells on the tooth root could cause death of the cells and lead to resorption and reduction in prognosis. In 1983, Matsson et al. [ 44 ] showed that soaking in Hank's Balanced Solution for thirty minutes prior to reimplantation could revitalize extracted dog's teeth that were dry for 60 minutes. In 1989, [ 45 ] a systematic storage device was developed to optimally store and preserve knocked out teeth. In 1992, Trope et al. [ 46 ] showed that extracted dog's teeth could be stored in Hank's Balanced Solution for up to 96 hours and still maintain significant vitality. In this study, milk was only able to maintain vitality for two hours.
In ancient times, ritual dental avulsion was widespread among different cultures around the world. For example, it was common during the Early Holocene (from around 11,500 BP up to 5,000 BP) in North Africa and was occasionally observed in the Natufian culture (14,000 to 11,500 BP). [ 47 ]
Such tooth avulsion was the intentional removal of one or more teeth, which was done for ritual or aesthetic reasons. It was also used to denote group affiliation. Typically, the maxillary incisors were the teeth most often selected for removal. This practice is still common in parts of Africa. [ 48 ]
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A dental board is a group of elected or appointed officials from a given state, province or country that meet to ensure public safety in the application of dental care . The scope of function may include review of current rules and regulations, adopting new regulations with the advent of new services, disciplinary action to the dental professionals, and public education .
In America, dental boards are sometimes named different things in different states, such as Board of Dental Examiners, Dental Bureau, State Dental Commission, Board of Dentistry, Board of Dental Health Care, and so forth. [ 1 ]
A dental board may also be referred to as a professional order (in Quebec), a health college (in Ontario), or a self-regulatory body.
Group may consist of dentists, specialist, auxiliary personnel as well as a “lay” member.
This article about a medical organization or association is a stub . You can help Wikipedia by expanding it .
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Adhesive dentistry is a branch of dentistry which deals with adhesion or bonding to the natural substance of teeth, enamel and dentin . It studies the nature and strength of adhesion to dental hard tissues, properties of adhesive materials, causes and mechanisms of failure of the bonds, clinical techniques for bonding and newer applications for bonding such as bonding to the soft tissue. [ 1 ] There is also direct composite bonding which uses tooth-colored direct dental composites to repair various tooth damages such as cracks or gaps.
Dental bonding is a dental procedure in which a dentist applies a tooth-colored resin material (a durable plastic material) and cures it with visible, blue light. This ultimately "bonds" the material to the tooth and improves the overall appearance of teeth. [ 2 ] Tooth bonding techniques have various clinical applications including operative dentistry and preventive dentistry as well as cosmetic and pediatric dentistry , prosthodontics , and orthodontics .
Adhesive dentistry began in 1955 with a paper by Dr. Michael Buonocore on the benefits of acid etching. [ citation needed ] Technologies have changed multiple times since then, with generally recognized generations established in the literature. [ citation needed ] Dental bonding agents have evolved from no-etch to total-etch (4th- and 5th-generation) to self-etch (6th- and 7th-generation) systems. [ 3 ] improved convenience and reduced sensitivity to operator errors. However, the best bonding and longevity was achieved with 4th generation agents (having separate etch, prime, and bond steps). [ 4 ]
Irwin Smigel founder and current president of the American Society for Dental Aesthetics and diplomate of the American Board of Aesthetic Dentistry, was one of the first to broaden the usage of bonding by using it to close gaps between teeth, lengthen teeth as well as to re-contour the entire mouth rather than using crowns. Having done more extensive work on the process than any other dentist, Dr. Smigel lectures worldwide on aesthetic dentistry. In 1979 he published a guide to aesthetic dentistry entitled “Dental Health/Dental Beauty.” [ 5 ]
In 2012, new dental universal adhesives are commercialized. The universal adhesives bond to all dental substrates, which include enamel, dentin, metal, porcelain, ceramic and zirconia, with a single application. The term “universal” adhesive is not new. In fact, many early bonding agents were named or described as “universal” adhesives, such as XP Bond-Universal Total-etch Adhesive (Dentsply), One-Step-Universal Dental Adhesive (Bisco). However, there is still not a definition of dental “universal adhesive”. It is highly confusing what the term “universal” means. In 2012, the term “universal adhesive” has several definitions which may include: [ 6 ]
Bonding of orthodontic brackets to teeth is crucial to enable effective treatment with fixed appliances. There is no clear evidence on which to make a clinical decision of the type of orthodontic adhesive to use. [ 7 ] [ 8 ]
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A number of professional degrees in dentistry are offered by dental schools in various countries around the world.
Dental degrees may include:
In some universities, especially in the United States, some postgraduate programs award certificates only.
In commonwealth countries, the Royal Colleges of Dentistry (or Faculty of Dentistry of the college) awards post-nominals upon completion of a series of examinations.
In the U.S., most dental specialists attain Board Certification (Diplomate Status) by completing a series of written and oral examinations with the appropriate Boards. e.g. Diplomate, American Board of Periodontics.
Each fully qualifies the holder to practice dentistry in at least the jurisdiction in which the degree was presented, assuming local and federal government licensure requirements are met.
Australia has nine dental schools:
(*) indicates new university dental programs that have opened up to aim at increasing the number of rural dental students entering and to return to rural practice. Traditional "sandstone" universities have been Sydney, Melbourne, Queensland, Adelaide and Western Australia.
Sydney (as of 2001), Melbourne (as of 2010) and Western Australia (as of 2013) have switched to 4-year graduate program that require a previous bachelor's degree for admission.
Postgraduate training is available in all dental specialties. Degrees awarded used to be Master of Dental Surgery/Science (MDS/MDSc), but lately have changed to Doctorate in Clinical Dentistry (DClinDent).
New Zealand has only one dental school:
The Faculty of Dentistry awards Bachelor of Dental Surgery (BDS) and Master of Community Dentistry (MComDent) for public health & community dentistry, and Doctorate in Clinical Dentistry (DClinDent) for the other dental specialties.
The body responsible for registering dental practitioners is the Dental Council of New Zealand (DCNZ).
Both Australia and New Zealand recognize the educational and professional qualifications and grant professional licenses via reciprocity identical to the United States and Canada.
The United Kingdom General Dental Council had been recognizing the Australian and New Zealand dental qualification as registrable degree until 2000. Graduates who have applied for dental license registration in the United Kingdom now have to sit the Overseas Registration Exam (ORE), a three-part examination.
Australia and Canada have a reciprocal accreditation agreement, which allows graduates of Canadian or Australian dental schools to register in either country. However, this only applies to the graduates of 2011 class and does not apply to the previous years' graduates.
Royal Australasian College of Dental Surgeons (RACDS) is a postgraduate body that focuses on postgraduate training of general practitioners and specialist dentists. Additional postgraduate qualifications can be obtained through the college after the candidate has completed the Primary Examination (basic science examination in anatomy, histology, physiology, biochemistry, pathology and microbiology) and the Final Examination (clinical subjects in dentistry). After the successful completion of the examinations and meeting the college requirements, the candidate is awarded the title of Fellow of Royal Australasian College of Dental Surgeons (FRACDS). For the dental specialists, the exam pathway is similar (Primary Examinations) and then clinical/oral examinations just prior to completing the specialist training leads to the award of the title Member of Royal Australasian College of Dental Surgeons in Special Field Stream (MRACDS (SFS)). For the busy GP dentists, MRACDS in general stream is also available.
The graduation in Dentistry is named here as Bachelor of Dental Surgery (BDS) also have diploma in Dentistry. At present there are three universities that have medical faculty that offer dental degrees: The University of Dhaka, the University of Chittagong, the University of Rajshahi, and diplomas also by the state medical faculty. These public universities have dental colleges and hospitals that may be publicly or privately funded, that offer education for the degree.
At present, postgraduate degrees in specialized dentistry exist in main four clinical specialities:
There are ten approved dental schools in Canada:
Several universities in Canada offer the DDS degree, including the University of Toronto , the University of Western Ontario , the University of Alberta , and Dalhousie University , while the remaining Canadian dental schools offer the Doctor of Dental Medicine degree to their graduates.
Additional qualifications can be obtained through the Royal College of Dentists of Canada (RCDC) , which administers examinations for qualified dental specialists as part of the dentistry profession in Canada . The current examinations are known as the National Dental Specialty Examination (NDSE). Successful completion may lead to Fellowship in the college (FRCD(C)) and may be used for provincial registration purposes.
Canada has a reciprocal accreditation agreement with Australia, Ireland, and the United States, which recognize the dental training of graduates of Canadian dental schools. Obtaining licensure to work in any of the three other countries often requires additional steps, such as successfully completing national board examinations and fulfilling requirements of local governing bodies.
China has many universities teaching dental degrees both at undergraduate and postgraduate level. Chinese universities have adapted the programmes of American and European degrees. The undergraduate degree is Bachelor of Medicine with a major in stomatology or dental surgery, and the postgraduate degree is Master of Medicine in stomatology ( 口腔医学硕士 ). Recently, [ when? ] China has a new name for its master's degree as Master of Stomatological Medicine (MSM). The MSM has been offered by top class Chinese universities. This program includes a comprehensive syllabus to produce graduates with extensive knowledge in respective specialties, skills in clinical practice, and research potential. The other branches of dentistry remain the same as American universities.
In Finland, education in dentistry is through a 5.5-year Licenciate of Dental Medicine (DMD or DDS) course, which is offered after high school graduation. Application is by a national combined dental and medical school entry examination. As of 2011, dentistry is provided by Faculties of Medicine in four universities:
The first phase of training begins with a unified two-year preclinical training for dentists and physicians. Problem-based learning (PBL) is employed depending on university. The third year-autumn consists of clinico, theoretical phase in pathology, genetics, radiology and public health, and is partially combined with physicians' second phase. Third-phase clinical training lasts for the remaining three years and includes periods of being on call at University Central Hospital Trauma Centre, Clinic of Oral and Maxillofacial Diseases, and the Children's clinic. Candidates who successfully complete the fourth year of training qualify for a paid summer rotation in a Community health center of their choice. Annual intake of dentists into Faculties of Medicine is a national total 160 students.
Doctor of Philosophy (PhD) research is strongly encouraged alongside postgraduate training, which is available in all four universities and lasts an additional 3–6 years. Starting in 2014, the University of Helsinki introduced a new doctoral training system. In this new system, all doctoral candidates belong to a doctoral programme within a doctoral school. FINDOS Helsinki – Doctoral Programme in Oral Sciences – is a programme in the Doctoral School in Health Sciences. [ 4 ]
The 11 postgraduate programs are:
In India, training in dentistry is through a five-year Bachelor of Dental Surgery (BDS) course, which includes four years of study followed by one year of internship. As of 2019, 310 colleges (40 run by the government and 292 in the private sector) were offering dental education. This amounts to an annual intake of 33,500 graduates. [ 6 ]
The three-year, full-time postgraduate Master of Dental Surgery (MDS) is the highest degree in dentistry awarded in India, and its holders are bestowed as consultants in one of these specialties:
Israel has two dental schools , the Hebrew University - Hadassah School of Dental Medicine in Jerusalem , founded by the Alpha Omega fraternity and the Tel Aviv University School of Dental Medicine in Tel Aviv . The two schools have six-year program and grant the Doctor of Dental Medicine (DMD) degrees. In recent decades, [ when? ] students are eligible for the Bachelor of Medical Sciences (BMedSc) degree after the first three years of training.
Training in South Africa generally comprises the five-year Bachelor of Dental Surgery, followed by one year's compulsory medical service/internship. The country has five universities with dental faculties: [ 7 ]
Until 2003, Stellenbosch University offered the BChD degree. In 2004, the dental faculties of the University of the Western Cape and Stellenbosch University merged and moved to the University of the Western Cape, which is currently the largest dental school in Africa.
Specialisation is through one of the universities as a Master of Dentistry , or through the College of Dentistry within the Colleges of Medicine of South Africa , with certifications offered in oral medicine and periodontics , orthodontics , and prosthodontics . Research degrees are the MSc (Dent) / MDS and PhD (Dent).
Many universities award BDS degrees, including the University of Sheffield, the University of Bristol, Barts and the London School of Medicine and Dentistry, the University of Birmingham, the University of Liverpool, the University of Manchester, the University of Glasgow, the University of Dundee, the University of Aberdeen, King's College London, Cardiff University, Newcastle University, Queen's University Belfast, the University of Central Lancashire, and Peninsula College of Medicine and Dentistry.
In the Republic of Ireland, the University College Cork awards BDS degrees and Trinity College Dublin awards BDentSc degrees.
The University of Leeds awards BChD and MChD (Bachelor/Master of Dental Surgery) degrees. [ 8 ]
The Royal College of Surgeons of England , Edinburgh , Glasgow , and Ireland award LDS (Licence/Licentiate in Dental Surgery) degrees.
Many universities award BDS and a few BChD (Baccalaureus Chirurgiae Dental) degrees. In Nigeria, training in dentistry is through a six-year course, typically, three years of preclinical training followed by three years of clinical training after passing part I exams comprising anatomy, biochemistry, and physiology. This is followed by one year of internship or housemanship, after which graduates can go into clinical practice as general dentists. Some go on to specialty training by completing a residency program, to become hospital consultants.
As of 2022, 11 dental schools, were active, including two with partial accreditations. Fully accredited programs are at the University of Lagos, University of Ibadan, University of Benin, University of Port-Harcourt, University of Nigeria (Enugu), University of Maiduguri, Bayero University (Kano), Lagos State University, and Obafemi Awolowo University (Ile-Ife). [ 9 ]
In the United States, at least three years of undergraduate education are required to be admitted to a dental school; however, most dental schools require at least a bachelor's degree . No particular course of study is required as an undergraduate other than completing the requisite "predental" courses, which generally includes one year of general biology , chemistry , organic chemistry , physics , English , and higher-level mathematics such as statistics and calculus . Some dental schools have requirements that go beyond the basic requirements such as psychology , sociology , biochemistry , anatomy , physiology , etc. The majority of predental students major in a science, but this is not required as some students elect to major in a nonscience-related field.
In addition to core prerequisites, the Dental Admission Test , a multiple-choice standardized examination , is also required for potential dental students. The DAT is usually taken during the spring semester of one's junior year. The vast majority of dental schools require an interview before admissions can be granted. The interview is designed to evaluate the motivation, character, and personality of the applicant. [ 10 ]
For the 2009–2010 application cycle, 11,632 applicants applied for admission to dental schools in the United States. Just 4,067 were eventually accepted. The average dental school applicant entering the school year in 2009 had an overall GPA of 3.54 and a science GPA of 3.46. Additionally, their mean DAT Academic Average (AA) was 19.00, while their DAT Perceptual Ability Test (PAT) score was 19.40. [ 11 ]
Dental school is four academic years in duration and is similar in format to medical school: two years of basic medical and dental sciences, followed by two years of clinical training (with continued didactic coursework). Before graduating, every dental student must successfully complete the National Board Dental Examination Part I and II (commonly referred to as NBDE I & II). The NBDE Part I is usually taken at the end of the second year after the majority of the didactic courses have been completed. The NBDE Part I covers gross anatomy , biochemistry , physiology , microbiology , pathology , and dental anatomy and occlusion . The NBDE Part II is usually taken during winter of the last year of dental school and consists of operative dentistry, pharmacology , endodontics , periodontics , oral surgery , pain control , prosthodontics , orthodontics , pedodontics , oral pathology , and radiology . NBDE Part I scores are Pass/Fail since 2012.
Since the COVID-19 pandemic, nearly all jurisdictions now utilize the INBDE system.
After graduating, the vast majority of new dentists go directly into practice, while others enter a residency program. Some residency programs train dentists in advanced general dentistry such as General Practice Residencies and Advanced Education in General Dentistry Residencies, commonly referred to as GPR and AEGD. Most GPR and AEGD programs are one year in duration, but several are two years long or provide an optional second year. [ 12 ] GPR programs are usually affiliated with a hospital and thus require the dentist to treat a wide variety of patients including trauma, critically ill, and medically compromised patients. Additionally, GPR programs require residents to rotate through various departments within the hospital, such as anesthesia, internal medicine, and emergency medicine, to name a few. AEGD programs are usually in a dental-school setting where the focus is treating complex cases in a comprehensive manner.
In the United States, the Doctor of Dental Surgery and Doctor of Dental Medicine are terminal professional doctorates, which qualify a professional for licensure. The DDS and DMD degrees are considered equivalent. The American Dental Association specifies:
The DDS (Doctor of Dental Surgery) and DMD (Doctor of Dental Medicine) are the same degrees. They are awarded upon graduation from dental school to become a General Dentist. The majority of dental schools award the DDS degree; however, some award a DMD degree. The education and degrees are, in substance, the same. [ 13 ]
Harvard University was the first dental school to award the DMD degree. [ 14 ] Harvard only grants degrees in Latin, and the Latin translation of Doctor of Dental Surgery, "Chirurgiae Dentium Doctoris", did not share the "DDS" initials of the English term. [ 15 ] "The degree 'Scientiae Dentium Doctoris', which would leave the initials of DDS unchanged, was then considered, but was rejected on the ground that dentistry was not a science." [ 15 ] (The word order in Latin is not fixed, only the inflections ; "Scientiae Dentium Doctoris" = "Doctoris Dentium Scientiae".) A Latin scholar was consulted. It was finally decided that "Medicinae Doctoris" be modified with "Dentariae". [ 15 ] This is how the DMD, or "Doctor Medicinae Dentariae" degree, was started. [ 15 ] (The genitive inflection -is on "Doctoris" instead of the nominative "Doctor" simply reflects that the syntax on the diploma was "the degree of Doctor of Dental Medicine"; they are both correct.) The assertion that "dentistry was not a science" [ 15 ] reflected the view that dental surgery was an art informed by science, not a science per se —notwithstanding that the scientific component of dentistry is today recognized in the Doctor of Dental Science (DDSc) degree.
Other dental schools made the switch to this notation, and in 1989, 23 of the 66 North American dental schools awarded the DMD. No meaningful difference exists between the DMD and DDS degrees, and all dentists must meet the same national and regional certification standards to practice. [ 16 ]
Some other prominent dental schools that award the DMD degree are the University of Florida, Midwestern University-IL, Midwestern University-AZ, Medical University of South Carolina, Augusta University (formerly Medical College of Georgia), University of Connecticut, University of Alabama at Birmingham, University of Louisville, University of Puerto Rico, Rutgers University, Tufts University, Oregon Health and Sciences University, University of Pennsylvania, Case Western Reserve University, University of Illinois at Chicago, Boston University, Temple University, Western University of Health Sciences, University of Pittsburgh, University of Nevada, Las Vegas, and East Carolina University.
The United States Department of Education and the National Science Foundation do not include the DDS and DMD among the degrees that are equivalent to research doctorates. [ 17 ]
To practice, a dentist must pass a licensing examination administered by an individual state or more commonly a region. A handful of states maintain independent dental licensing examinations, while the majority accept a regional board examination. The Northeast Regional Board (NERB), Western Regional Board (WREB), Central Regional Dental Testing Service (CRDTS), and Southern Regional Testing Agency (SRTA), Council of Interstate Testing Agencies (CITA) [ 18 ] are the five regional testing agencies that administer licensing examinations. Once the examination is passed, the dentist may then apply to individual states that accept the regional board test passed. Each state requires prospective practitioners to pass an ethics/jurisprudence examination, as well, before a license is granted. To maintain one's dental license, the doctor must complete Continuing Dental Education (CDE) courses periodically (usually annually). This promotes the continued exploration of knowledge. The amount of CE required varies from state to state, but is generally 10-25 CE hours a year.
The completion of a dental degree can be followed by either an entrance into private practice, further postgraduate study and training, or research and academics.
Twelve dental specialties are recognized in the United States. Becoming a specialist requires one to train in a residency or advanced graduate training program. Once residency is completed, the doctor is granted a certificate of specialty training. Many specialty programs have optional or required advanced degrees such as a master's degree: (MS, MSc, MDS, MSD, MDSc, MMSc, MPhil, or MDent), doctoral degree: (DClinDent, DChDent, DMSc, PhD), or medical degree : (MD/MBBS specific to maxillofacial surgery ).
The following are currently recognized as dental specialties in the US under the American Board of Dental Specialties (ABDS) :
The following are not currently recognized as dental specialties in the US.
Dentists who have completed accredited specialty training programs in these fields are designated registrable (U.S. "Board Eligible") and warrant exclusive titles such as anesthesiologist, orthodontist, oral and maxillofacial surgeon, endodontist, pedodontist, periodontist, or prosthodontist upon satisfying certain local (U.S. "Board Certified"), (Australia/NZ: "FRACDS"), or (Canada: "FRCD(C)") registry requirements.
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Dentistry throughout the world is practiced differently, and training in dentistry varies as well.
Dentistry in Egypt has a long history, with the dentist occupation first appearing as early as 3000 BC. [ citation needed ]
There is a syndicate for all dentists which regulate the work in dental clinics in association with the Ministry of Health.
For dental clinicians to practise, they should be enrolled in the dental syndicate.
Dentists complete a 5-year-study course plus 1 year of practice in their dental school or general hospitals in the country.
Most governmental dental schools give degrees of Bachelor, Master's degree & PhD in all dental fields. However, obtaining a chance for postgraduate studies in the field of orthodontics is somehow difficult according to many of Egypt general dental practitioners. [ citation needed ]
In Iran dentists require six years of post-secondary education. The whole program is one single degree of D.D.S. (Doctor of Dental Surgery). After this, those wishing to specialize in a particular field may pursue higher education. Upon graduation, a dentist may need to fulfill two years of military service (as a dentist in uniform for males) or governmental service (both males and females) in order to collect enough scores to start in private practice. [ citation needed ] The current universities offering Dentistry are:
In Israel there are two dental schools , The Hebrew University - Hadassah School of Dental Medicine in Jerusalem , founded by the Alpha Omega dental fraternity, and The Tel Aviv University School of Dental Medicine in Tel Aviv . The two schools provide Doctor of Dental Medicine (DMD) degrees. In addition, there are several post-graduation training centers such as Rambam Health Care Campus in Haifa and Barzilai Medical Center in Ashkelon . The post-graduation programs in the Sheba Medical Center in Tel Hashomer are held by the Medical Corps of the Israel Defense Forces .
The first step to becoming a dentist in Brazil is to take a 10-subject examination (Biology, Physics, Chemistry, Mathematics, Literature, Foreign Language, Portuguese, History, Geography and an Essay) which might be compared to the SAT exam in the US. These examinations vary from institution to institution; however, dentistry is one of the hardest courses to get in and most students come from upper classes due to the level of difficulty and steep tuition prices. Students must complete the 4 or 5-year Bachelor of Dental Surgery (B.D.S.). Skills capacitation courses after graduation are required in different dental areas, which take between 2 and 3 years (D.D.S). Universities of dental care are provided by both the private and public sector. The course's conclusion must be registered and licensed by the nationalized Dental Board of Brazil so that the students obtain the Dentistry Diploma. However, private clinics are the most common place a person would go if a dentist is needed. Today, the private market is dominated by large companies that hire mostly recently graduated dentists. Nevertheless, there are thousands of small clinics spread throughout the country. The practice of dentistry in Brazil is overseen by CFO Conselho Federal de Odontologia , a federal entity that coordinates the 26 state bodies plus Federal District. This institution has 340,000 registered dentists and 191 dental schools in Brazil. Brazil has become a leading country at the international level in areas such as Dentistry International Research, Implantology, Periodontics, Endodontics, Phrosthodontics, Aesthetics Dentistry, Pedodontics, Orthodontics, and Oral & Maxillofacial Surgery. Brazilian Dentistry Department develops, all over the country, many innovative techniques and conducts dentistry research related to different aspects. Dentists in the Mercosur are eligible to work in Argentina, Chile, Paraguay, Uruguay and Peru.
The practice of dentistry in Canada is overseen by the National Dental Association Examination Board of Canada (NDAEB) , while specialization is overseen by the Royal College of Dentists . Today, Canada has about 16,000 dentists. Canadian dentistry is not publicly run (see Medicare (Canada) ); however, some provinces [ 1 ] provide for free dental care for children and the elderly. Other Canadians are mostly covered by workplace dental plans, but many have to pay out-of-pocket .
For most of the early colonial period dentistry was a rare and unusual practice in Canada. In severe situations, barbers or blacksmiths would pull a tooth, but for many years Canada lagged behind European advances. The first dentists in Canada were United Empire Loyalists who fled the American Revolution . The first recorded dentist in Canada was a Mr. Hume who advertised in a Halifax newspaper in 1814.
During the first half of the 19th century, dentistry expanded rapidly. In 1867 the Ontario Dental Association was formed and in 1868 they founded Canada's first dental school in Toronto , the Royal College of Dental Surgeons of Ontario . The University of Toronto agreed to be affiliated with the dental school. As time passed, other Canadian universities also created dentistry programmes. However, the University of Toronto still has the largest dental school in Canada that features the most postgraduate research opportunities as well as certifications for all the dental specialties. The UBC Faculty of Dentistry supports five specialty programs being Prosthodontics , Endodontics , Orthodontics , Pedodontics and Periodontics .
Dental care is not covered by the Canadian health care system , as it is in many other countries with public health care, although public dental services have long been provided to certain categories of the population. [ 2 ] Nevertheless, studies have estimated that at least 6 million Canadians avoid going to a dentist because of the cost. [ 3 ]
Dental schools in the USA, Ireland, Australia and New Zealand are also recognized as accredited in Canada.
In Chile, dentists require six years of post secondary education which, after 2 years dedicated to fundamental scientific and medical knowledge (chemistry, physics, biology, morphology, anatomy, histology, etc.) puts a particular emphasis on practice and the accountability to patients in the last 4 years. Specialization programs of 3–4 years (admission by competition) are possible after a minimum of 3 years' working experience has been completed. The first dental school was established at the Universidad de Chile in the year 1888. Other institutions providing professional dental education in Chile are Universidad Austral de Chile since 2004, Universidad de Concepción since 1919, Pontificia Universidad Católica de Chile (since 2009), Universidad de Valparaíso since 1952, Universidad de la Frontera (since 1992), Universidad de Talca , which are public universities, and the following private universities: Universidad Finis Terrae , Universidad Nacional Andrés Bello , Universidad Mayor , Universidad de los Andes , Universidad Diego Portales , Universidad del Desarrollo , Universidad San Sebastián and Universidad de Antofagasta .
After having been influenced for decades by both the European (especially from German-speaking countries) and North American dentistry, Chilean education and practice in dentistry have now reached a self-sufficient level and benefits from a range of top-level institutes, professors and practitioners. Research has developed at a fast pace and many articles find their path to international publications.
Dentistry is overseen by the Colegio de Cirujanos Dentistas de Costa Rica. Dentists complete 6-year courses from the University of Costa Rica in D.D.S. ( Doctor of Dental Surgery ), or similar courses from various private universities. Costa Rica is often cited as being one of the top ten countries in the world for medical tourism , including dentistry.
In Peru , dentists require five years of post secondary education in a university. There are several universities that provides dental education. The three first study years are similar education to the Human Medicine schools, then fourth and fifth years are dental studies and practices in the school clinic. In the last year, students have to complete evaluated and paid services in a public hospital and in a rural medical post (where there are no hospitals or doctors nearby, they will frequently have to deal with general medicine cases). The students obtain their degree in Dentistry (Bachelor's in Dentistry), if they want to practice in Peru the students have to prepare and defend a thesis to obtain the Cirujano Dentista (C.D.) degree (Dental Surgeon). Dentistry is overseen by the Colegio Odontológico del Perú (COP).
Lima
Chimbote
Tacna
Trujillo
Iquitos
Puno
In the United States dentistry is generally practiced by dentists who have completed a post-graduate course of professional education. This has resulted in a high quality of care. Government-sponsored health care programs Medicare does not cover routine dental treatment [ citation needed ] . Medicaid does provide extensive dental coverage and benefits for beneficiaries under the age of 21 under the early periodic screening diagnosis and treatment (EPSDT) and a growing number of states also offer comprehensive dental services for adult Medicaid members as well.
In the United States, dentists earn either a D.D.S. ( Doctor of Dental Surgery ) or D.M.D. ( Doctor of Dental Medicine ) degree. There is no difference in the training for either degree. The degrees are equivalent, and recognized equally by all state boards of dentistry. There are 56 accredited dental schools in the United States requiring 4 years of post graduate study (except for one unique 3-year program at the University of the Pacific ). [ 5 ] Most applicants to dental school have attained at least a B.S. or B.A. degree, but a small percentage are admitted after only fulfilling specific prerequisite courses. So unlike many other countries (other than US, Canada, and Australia), it usually takes more than 8 years to become a dentist. The difference relates to the history involved in the division of medicine and surgery in medical practice.
There are limited opportunities for dental education in the United States with little growth in graduation rate from approximately 6700 ADA 2022 Number of Graduates , up from 5,750 in 1982. Due to the hands-on training required, dental education is expensive and is limited on subsidized funding towards dental education by the federal and most state governments. According to the American Dental Education Association, "average educational debt for all indebted dental school graduates in the Class of 2019 was $292,169." [ 6 ]
Licensure is organized on three levels in most areas. Many dentists must pass National Boards, Regional Boards, and then take a jurisprudence exam accepted by their state to fulfill their requirements to get a state license. Not all states require or even accept regional boards. Although a state license is only valid in the issuing state, because of the regional boards a dentist may be able to apply for licensure in any other state within the jurisdiction of their regional board. There are many cooperative agreements between states that allow recognition of another state's license so as to procure a license either via "licensure by credentials" or "licensure by reciprocity." Although a national licensure exam has yet to be made, the American Dental Association (ADA) has worked with education and examining groups to form such an exam. [ 7 ]
A dentist may go on for further training in a dental specialty which requires an additional 1 to 7 years of post-doctoral training. There are 9 recognized dental specialties. These include Endodontics (root canal treatment), Oral and Maxillofacial Pathology, Oral and Maxillofacial Radiology, Pediatric Dentistry, Periodontics (gums), Prosthodontics (complicated dental reconstruction), Orthodontics (moving teeth), Oral and Maxillofacial Surgery (surgery of the mouth and face), and Dental Public Health. There is no specialty in esthetic dentistry or implantology, and no additional training is required for a dentist to make the claim of being an esthetic or cosmetic dentist. Dentists are forbidden to claim that they are specialists in areas of practice in which there is no recognized specialty. [ clarification needed ] They may limit their practices to a single area of dentistry, and claim that their practice is limited to that area.
Any general dentist may perform those procedures designated within the enumerated specialties if they deem themselves competent. Many general dentists train in certain aspects of the above specialties such as the placement and restoration of dental implants, advanced prosthodontics and endodontics, and have limited or heavily focused their practices to these areas. When a general dentist performs any procedure that falls within the realm of a specialty, they are expected to perform with the same level of expertise as a certified specialist and are legally held to such standards with respect to any issues of malpractice.
Australian dentistry is overseen by the Australian Dental Council and the Dental Board of Australia The professional body for dentists is the Australian Dental Association .
Dentists trained in Australia must meet the entry requirements of one of the Australian institutions offering dental courses, and then complete the required full-time academic training leading to a dental degree . If dentists wish to specialize, they must complete extra study after having had clinical experience.
As of July 2010 [update] , in order to practice dentistry in Australia you must obtain registration and licensing from the nationalized Dental Board of Australia. Generally, the only persons immediately entitled to apply to be registered as dentists are persons holding the qualifications of DDS, BDS, BDSc, BDent, BDentSc, DMD, MDent, or GradDipDent from an accredited Australian and New Zealand university. Usually registration will not be granted to a foreign graduate until he or she has passed the ADC examinations and/or completed a 2-year advance standing program in order to obtain a locally accredited dental qualification
The Universities of Queensland , Adelaide , Western Australia , Griffith, James Cook, Charles Sturt and Latrobe all offer undergraduate dental degree courses of 5 years in length. Sydney University offers a graduate entry program which is 4 years duration and requires a previous bachelor's degree for admission. Melbourne University also has a 4-year graduate entry dental program starting in 2011. The qualifications awarded by these schools satisfy the formal academic requirements for registration.
Australian dental schools include but are not limited to:
To become a dentist in Hong Kong, one must complete the 6-year Bachelor of Dental Surgery (B.D.S.) course in The University of Hong Kong . Students learn basic health sciences, dental sciences under a problem-based learning curriculum. Besides, formal training and supervised practice are prescribed. It is accepted that only after 5 years of such training would the trainees achieve a superior level of professional competence.
Graduates can enter general practice or pursue a specialist M.D.S. degree after gaining one to two years of working experience.
Before the dental school was established in the University of Hong Kong (in 1980), most of the practicing dentists obtained their dental degree from the Philippines.
In India, dentistry is through the BDS (Bachelor of Dental Surgery) degree, which includes 4 years of study and 1-year compulsory internship. As of 2010, there were a total of 291 colleges (39 run by the government and 252 in the private sector) offering dental education. This amounts to an annual intake of 23,690 graduates. [ 8 ] Dental education in India is regulated by the Dental Council of India .
In most states, 15% of seats in state run Dental Colleges are filled through a national examination conducted by the CBSE (Central Board for Secondary Education). The remaining seats are filled up by the respective state's designated authority. Some autonomous universities conduct their own selection tests. Selection to privately run Dental Colleges vary and usually require payment of higher fees.
Post graduate training is for three years in the concerned specialty. Master of Dental Surgery (MDS) is offered in the following subjects -
Since 2016, NEET (National Eligibility cum Entrance Test) has started for all aspirants – Indian & Foreign. No Autonomous University can conduct its own exam anymore.
Selection to postgraduate courses are through national / state entrance examinations (NEET) and are very competitive. In addition, certificate courses of 2 years duration are offered in Dental Mechanics and Dental Hygiene .
List of dental colleges in India – (lisi of dental colleges)
The first dental degree program in Malaysia was offered by University of Malaya. [ 9 ] The qualification was moderated and recognised by the Malaysian Dental Council and one of the leading associations representing dental surgeons of Malaysia is the Malaysian Dental Association .
Dental surgeries (or better known as dental clinics) in Malaysia are required to be registered and approved by the Ministry of Health Malaysia under the Healthcare Facilities And Services Act 1998. [ 10 ] It is a requirement that all dental surgeons hold a valid Annual Practising Certificate. Foreign dentists, that is, qualified dentists from other countries are not allowed to hold an annual practising certificate unless they are studying or lecturing at a higher-learning institute.
New Zealand dentistry is overseen by the Dental Council, [ 11 ] while specialization is also overseen by the Royal Australasian College of Dental Surgeons .
University of Otago is New Zealand's only dental school that offers the required academic training.
Entry into New Zealand's only dental school requires the student to compete into the second year dentistry course via the Health Sciences First Year course. [ 12 ] Once in the course, students will start their dental education in their second year of university study. The total time to complete the course, including the first-year competitive course, is 5 years of full-time academic study.
The history of dentistry in Pakistan started before the country's independence. Pakistan's premier and oldest dental institution De'Montmorency College of Dentistry was established in 1934 at Lahore by then Governor of Punjab Sir Jeff Fitz Harway de' Montmorency. Later in 1974, Nishtar Institute of Dentistry joined the list. De'Montmorency College of Dentistry has a very rich heritage of academic and clinical excellence both before and after independence. The history of dentistry in Pakistan is in fact the story of progress of de'Montmorency College of Dentistry. At present there are 32 dental schools (public & private) throughout Pakistan, according to the Pakistan Medical and Dental Council the state regulatory body has upwards of 11500 registered dentists. The four-year training culminates in achieving a Bachelor of Dental Surgery (BDS) degree, which requires a further one year compulsory internship to be a registered dentist in Pakistan. [ 13 ] As per recent stats, According to the Pakistan Medical Commission , there are almost 28,561 registered BDS doctors in January 2021. [ 14 ]
Most Filipino Dentists must earn a total of 6 years of dental school (2 years preparatory; 4 years proper) to obtain the degree Doctor of Dental Medicine (D.M.D.). Presently, the country has a total of 25 dental schools, in which the board licensing is administered and regulated by the Board of Dentistry of the Professional Regulation Commission .
All the dental schools are undergraduate entry in Taiwan. After graduating from high school, students are required to take a 6-year dental program to complete their DDS/DMD degree. Dental school admissions are competitive in Taiwan. Only students obtain top 3% of academic results in the Taiwan Joint College Entrance Exam for admission in Taiwan will be admitted. The tuition for dental schools are around TWD 70,000-75,000 (~USD 2,200-2,400) per semester. Students are also required to pay additional fees for tools and other materials most of time. Students should complete 5 years of medical basic and dental professional courses at their own universities, followed by a year of internships before graduation. During summer vacation, clerkship is recommended for students to acquire experience for the future. The first dental school in Taiwan belonged to the School of Dentistry at National Taiwan University which was founded in 1953. [ citation needed ] Dental schools in Taiwan include: [ citation needed ]
The Thai Dental Council, established in 1994, is the premier governing body of dental practice, and now on formulating uniform competency requirements for dental practitioners, thus directly influencing the teaching programs at the dental schools. [ 15 ] The Ministry of Public Health plays an important role in dental manpower planning for the dental public health services. The Thai Dental Council, the Ministry of Public Health and the Consortium of the Dental Schools work together to promote scientifically based dental education. In addition, the Thai government is placing more importance on the dental public health of its citizens.
In 2007 the number of Thai Dentists in the workforce was 7175,2093,1400 and 76 for dentists, dental nurses, chairside assistants, and laboratory technicians. In 2009, the number of dentists in public sector was 3,892 and in private practice 4,551. [ 16 ] There were 849 and 218 dentists in the university and military.
In all European countries, there exist public dental services and/or subsidies [ 17 ] that ensure that most (if not all) citizens have access to the dental services they require, regardless of their ability to pay. Information regarding the various levels of dental care provision throughout Europe can be found in the Manual of Dental Practice, published by the Council of European Dentists. [ 18 ]
In Finland, education in dentistry is through a 5.5 year Licenciate of Dental Medicine (DMD or DDS) course, which is offered after high school graduation. Application is by a national combined dental and medical school entry examination. As of 2011, dentistry is provided by Faculties of Medicine in 4 universities:
1st phase of training begins with a unified 2-year pre-clinical training for dentists and physicians. Problem-based learning (PBL) is employed depending on the university. 3rd year autumn consists of clinico-theoretical phase in pathology, genetics, radiology and public health and is partially combined with physicians' 2nd phase. 3rd phase clinical training lasts for the remaining 3 years and includes periods of being on call at University Central Hospital Trauma Centre, Clinic of Oral and Maxillofacial Diseases and at the Children's clinic. Candidates who successfully complete the 4th year of training qualify for a paid summer rotation in a Community health center of their choice. Annual intake of dentists into Faculties of Medicine is a national total 160 students.
Ph.D. research is strongly encouraged and is mandatory alongside post graduate training. Post graduate training is available in all 4 universities and lasts an additional 4–6 years. [ 19 ]
In Italy dentists complete 6 years of undergraduate study to earn a degree. Nevertheless, it is possible to agree on certain basic clinical competences common to all member states of the European Union .
Admission to Dentistry school is regulated by an entrance test, also used for Medical schools, composed of 80 questions about five subjects: biology, chemistry, mathematics, physics and general knowledge.
The first course leading to a degree in Dental Surgery, at the University of Malta, commenced in 1933. The qualification was recognized by the Medical Council of the United Kingdom in 1936.
Dental Surgery was established as a separate Faculty in 1954, previous to which the course was under the direction of a Board of Studies within the Faculty of Medicine and Surgery. The faculty caters for an undergraduate intake of 8 students annually. A B.Ch.D Degree is awarded at the completion of the 5-year course.
All practicing dentists must be subscribed in the national medical register called the BIG-register .
The registry can be freely consulted through the internet, if one wants to check if his or her dentist has got the right credentials.
The dental curriculum was just [ when? ] changed from 5 years study to 6 years. There are three dental schools in the Netherlands:
The oldest dental education in the Netherlands used to be taught at the University of Utrecht. The faculty of dentistry in Utrecht was closed because of governmental economizing.
The 5-year dental education is offered at three universities:
All dentists in Norway are organized through "Tannlegeforeningen". Dental services are free for children. Some complicated procedures such as the fitting of new prosthesis and some oral surgeries are partially covered by the national health service, usually at the rate of 50%.
NFZ (National Health Fund) in Poland provides 100% cover only for basic dental health services. [ 20 ] [ 21 ]
All the dental schools are undergraduate entry in Portugal. After graduating from high school, students are required to take a 5-year dental program to complete their DDS/DMD degree. There are 7 dental schools with 3 being public. [ citation needed ]
In Slovakia , dentists complete 6 years of undergraduate study to earn a MDDr. (lat. Medicinae Dentalis Doctor ) degree. A MDDr. graduate can perform the therapeutic interventions in area of restorative dentistry , prosthodontics and endodontics . For performing orthodontics a post graduate course is required in length of 3 years and for dentoalveolar surgery the post graduate course in length of at least 6 months is required. For oral and maxillofacial surgery the length of 4 years of post graduate course is required. Also the absolvent of general medicine (titled as MUDr. ) can run course for oral and maxillofacial surgery , but the attestation course takes five years. Dental education is offered at three universities: Comenius University in Bratislava , Slovak Medical University in Bratislava and University of Pavol Jozef Safarik in Košice . Part of dental service is paid from health insurance but mostly treatment (fillings, prosthodontics) is paid cash by patients.
The 5-year dental education is offered at four universities:
Most dentists in Sweden are organized through "Tandläkarförbundet" which also issues the scientific 'Swedish Dental Journal'. [ 22 ]
Dental care is provided at public and private dental offices. Dental services are free for everyone up to 20 years of age. From the age of 20 and upwards there is a fixed state refund which usually is, depending on the dentist's fee and what type of dentistry performed, around 10% – 15% of the total cost. [ citation needed ] For more expensive dental work above the age of 65 the patients only pay 7800 SEK (~ $1,000) plus the cost of the dental material that was used.
The English title given to dental graduates in Sweden is D.D.S (University D egree in D ental S urgery [ 23 ] [ 24 ] ) until 2013. Due to the implementation of Bologna the dental high schools changed the title D.D.S to Degree of Master of Science in Dental Surgery and also awarding a purely academic title of Master of Science (120 credits) in Dental Science. [ 25 ] [ 26 ] [ 27 ]
All dentists in the European Union/EES are eligible to work in Sweden. Dentists with an exam outside EES are required to take a one-year course at Karolinska in Stockholm.
From April 15, 2016, fluent Swedish language is required also for Dentists with exam from EES.
In the United Kingdom, dentists complete 5 years of undergraduate study to earn a B.D.S. or BChD degree. After graduating most dentists will enter a V.T. (vocational training) scheme, of either 1 or 2 years length, to receive their full National Health Service registration. Dentists must register with the G.D.C. ( General Dental Council ), and meet their requirements as the governing body of the profession, before being allowed to practice. The Dentists Act 1957 defines dentistry with the intention of confining the practice of dentistry to those on the Dental Register. It provided the following definition: "For the purposes of this Act, the practice of dentistry shall be deemed to include the performance of any such operation and the giving of any such treatment, advice or attendance as is usually performed or given by dentists." [ 28 ]
There are sixteen dental schools in the UK, five of which are graduate entry programmes, only admitting applicants with at least an upper 2.1 in a classified undergraduate degree with a significant component of biomedical sciences. Thus the competition for places is fierce (approximately 1 successful candidate admitted in every 41 applicants in 2018). [ 29 ] [ 30 ] Because of the low numbers of dental schools, funding for building and service developments in the schools can be very high. Well known UK universities providing dental courses are the universities of Leeds , Liverpool , Glasgow , Cardiff , Queen's Belfast , Birmingham , Bristol , Dundee , Manchester , Plymouth , Sheffield , Queen Mary, London and King's College London . [ 31 ] [ 32 ] As of 2013, the only UK universities offering a 4-year graduate-entry BDS programme are Liverpool , King's College London , BLSMD , UCLan and Aberdeen .
Dentists may undertake work under the National Health Service or privately. The may opt for either of these alternatives, or both.
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A dental emergency is an issue involving the teeth and supporting tissues that are of high importance to be treated by the relevant professional. Dental emergencies do not always involve pain, although this is a common signal that something needs to be looked at. Pain can originate from the tooth, surrounding tissues or can have the sensation of originating in the teeth but be caused by an independent source ( orofacial pain and toothache ). Depending on the type of pain experienced an experienced clinician can determine the likely cause and can treat the issue as each tissue type gives different messages in a dental emergency.
Many emergencies exist and can range from bacterial, fungal, or viral infections to a fractured tooth or dental restoration , each requiring an individual response and treatment that is unique to the situation. Fractures ( dental trauma ) can occur anywhere on the tooth or to the surrounding bone, depending on the site and extent of the fracture the treatment options will vary. Dental restoration falling out or fracturing can also be considered a dental emergency as these can impact function in regards to aesthetics, eating and pronunciation and as such should be tended to with the same haste as loss of tooth tissue. All dental emergencies should be treated under the supervision or guidance of a dental health professional in order to preserve the teeth for as long as possible.
By contrast, a medical emergency is often more precisely defined as an acute condition that presents an immediate threat to life, limb, vision, or long-term health. Consequently, dental emergencies can rarely be described as medical emergencies in these terms. Some define a dental emergency in terms of the individual's willingness to attend for emergency dental treatment at any time at short notice, stating that persons who are fussy about when they are available for treatment are not true emergency cases. [ 1 ] : 702 There are often divergent opinions between clinicians and patients as to what constitutes a dental emergency. E.g. a person may suddenly lose a filling, crown, bridge, etc. and although they are completely pain-free, still have great cosmetic concerns about the appearance of their teeth and demand emergency treatment on the basis of perceived social disability.
Pain is described as 'an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. [ 2 ] It is one of the most common reasons patients seek dental treatment and many diseases or conditions may be responsible for the cause. [ 3 ]
Odontogenic pain is pain associated with the teeth, originating in the dental pulp and/or the peri-radicular tissues. [ 4 ] The following table shows the different classifications of pulp status. [ 4 ]
Peri- radicular pain can be of pulpal origin, most commonly due to disease in the pulp extending into the peri-radicular tissues but can also be of periodontal origin due to periodontal disease . [ 4 ] Apical periodontitis is acute inflammation of the periodontal ligament surrounding the tooth. This can be caused by inflammatory mediators from irreversibly inflamed pulp, bacterial toxins from necrotic pulp, restorations that have not been property contoured and in some cases, from treatments such as endodontic treatment . [ 4 ] There is both an acute and chronic form of this condition. [ 4 ] Acute apical periodontitis features include moderate to severe pain, usually stimulated by touch and pressure and may also include spontaneous pain. [ 4 ] The chronic form of the condition can be asymptomatic but may also include pain from surrounding tissues when stimulated. [ 4 ] Apical abscess is an extension of apical periodontitis where the bacteria have infiltrated the peri radicular tissues and are causing a severe inflammatory response; there is also an acute and chronic form of this condition. [ 4 ] An acute apical abscess can cause facial swelling and can cause other systemic consequences such as a high temperature and feelings of malaise. [ 4 ] In some cases this condition can be life-threatening when the inflammation compromises the airway; this is termed Ludwig's Angina. [ 4 ] A chronic apical abscess can be asymptomatic as the pressure from the inflammation is being drained through a sinus tract; a draining sinus can usually be seen clinically. [ 4 ] A periodontal abscess is a localised inflammation affecting the periodontal tissues. [ 4 ] It is caused by bacteria pre-existing in a periodontal pockets, traumatic insertion of bacteria or foreign body or can occur after periodontal treatment. [ 4 ] This condition has a rapid onset, is stimulated by touch and involves spontaneous pain. [ 4 ] It is important to note that an apical abscess may drain through the periodontal pocket giving a false interpretation of periodontal abscess or a periodontal abscess may appear at the apex of the tooth giving a false interpretation of apical abscess; a tooth may also have both lesions at one point in time. [ 4 ]
Dental trauma refers to an injury on hard and soft tissues of the oral cavity and face. This includes the teeth and surrounding tissues, the periodontium, tongue, lips and cheeks. It is more prevalent with children between 8– 12 years of age but can still happen to anyone. The prognosis of the tooth is worse the longer it is out of the mouth. [ 5 ]
The following is a list of dental trauma affecting different surfaces of the teeth and periodontium.
Dental barotrauma and barodontalgia . [ 6 ] A sudden incapacitation of diver or aviator due to barometric -induced tooth fracture or toothache , respectively, may be life-threatening to the individual and the airplane passengers.
A fractured, ditched or dislodged filling that is broken or lost may cause discomfort or sharp pain due to jagged edges. There can be aesthetical concerns if the filling is in a visible area. Patients need to be aware of the sharp edges and ensure their tongue does not constantly apply pressure around that area, as it can cause cuts to the tongue. However, in some cases the result of the loss of a filling can cause irritation to the side of the cheek and potentially lead to an ulcer . Sharp edges can easily be dealt with by levelling the filling or tooth edges from your local dentist during the emergency appointment. Hypersensitivity issues may also arise, short sharp pain caused by exposed underlying dentine, after the deterioration of the filling material. [ 2 ]
Reasons for the deterioration of a restoration vary in different cases, the cause may be underlying caries or it could be occlusal trauma, caused from natural dentition during mastication. The longevity of restorative materials could also be a factor; the survival rates of amalgam are usually 10–15 years, composite 7 years, while gold and ceramic fillings have over a 20-year longevity. [ 2 ]
During the emergency appointment the dentist will need to take a set of radiographs to assess for any underlying caries , bone loss or possible abscess . The clinical examination will detect the reasons behind the failure of the restoration. Upon treatment the dentist will provide options on the tooth's prognosis, these may include a new restoration, extraction, root canal or placement of a crown. The tooth prognosis includes the tooth's vitality and restorability. [ 7 ]
A crack, fracture and the mobility of a tooth are all interrelated as the pain and symptoms experienced from a tooth that has been cracked are very similar to that of a tooth that has been fractured. [ 2 ] A tooth crack is defined as an incomplete fracture of enamel or dentine and therefore is not usually associated with noticeable mobility. [ 8 ] The cause of a tooth crack can be by excessive force applied to a healthy tooth or physiologic forces applied to a weakened tooth. The teeth most commonly involved are usually the lower molars, followed by the upper premolars and molars. The condition is extremely common in the age range of 30–60 years. [ 2 ]
A diagnosis of a cracked tooth is extremely difficult. Careful history and assessment of the symptoms presented needs to be taken into account; radiographs and certain tests will be conducted in the dental office. Most common symptoms are cold sensitivity, sharp pain when using force to chew, these pain results from the release of pressure and are very important indicators of a cracked tooth. However, the symptoms may differ from various patients, subject to the depth and orientation of the crack.
Crowns can become broken by a fracture, non-retentive preparation, secondary caries, weak cement, excessive occlusal forces, decementation or loosening of the crown. [ 8 ] The consequences of a crown becoming loose include the risk of ingestion and less likely, inhalation. The management of the loose crown includes immediate recementation or a replacement crown, depending on the assessment conducted by the dentist. [ citation needed ]
The factors that are taken into consideration in making this decision include the strength of the temporary crown to be placed and occlusal forces. Thus, a thorough occlusal examination is of paramount importance, strength of the cement, a strong alternative of cement should be considered. The occlusion assessment should also include the static and functional occlusion as well as the possible presence of Para functional habits, such as clenching or bruxism. [ citation needed ]
Management includes cleaning all the cement and residues, to carefully inspect for any underlying caries or fractures. Details that need to be assessed include margins, gingivae and contact points; occlusion needs to be checked in both ICP and in lateral and protrusive excursions, before the crown can be re-cemented. Stronger cement should be used than the original such as resin cements, especially in cases of heavy occlusal forces. [ citation needed ]
In some cases, immediate reconstruction of the abutment may be deemed inappropriate, if the underlying structure is deemed deficient due to caries or a fracture then this issue needs to be addressed. The treatment plan may vary with the addition of a root canal treatment or a temporary crown for the reconstruction of a new crown.
Immediate management includes a chair side repair of the fractured veneer with composite material. Bonding composite to the exposed metal will involve achieving macro mechanical retention by making grooves and notches or abrading the surface.
Bonding material back onto exposed porcelain involves abrading, hydrofluoric acid etching and silanating then followed by a conventional bonding procedure. Composite patch will remain a temporary solution as the longevity of composite restorations is not predictable as well as the colour of composite is not as stable as porcelain for aesthetical reasons. [ 2 ]
A fracture can involve any damage to the denture. Any type of repair to the denture is much less ideal then making a new one. The ratio of fracture to a denture is a 1:3 ratio of the upper to lower. [ 8 ]
The most common reason for fracture in a denture; is accidental dropping of the denture in the case of the lower denture, and improper fitting and stability of the denture in the upper denture.
Individuals should not continue to wear a broken denture and seek the help of their dentist as soon as possible.
Implant success is relatively high, the rate of implant survival is between 85 and 95%, [ 9 ] although it is not uncommon for emergency management of a failing implant or one of its components. The failure is most likely due to infection of the implant. It is highly recommended to visit or refer patient to the specialist who provided the implant. [ citation needed ]
Late failures that occur with implants are usually due to moderate to severe bone loss, mostly located in the posterior areas of teeth and involve a multi-unit prosthesis. A fracture or decementation of a post or loosening of the abutment screw of an implant could be the result of dissolved cement, secondary caries, use of a weak post, or excessive occlusal forces. [ 8 ] Oral home care needs to remain at a high standard, brushing twice a day for the duration of two minutes with the use of fluoridated tooth paste. Interdental cleaning once a day using either floss, interdental brushes, wood sticks. Regular dental appointments every 6 months to maintain gingival health, professional cleans, radiographs to examine the bone loss and the implant status. All the following is needed to prolong the longevity of the implant and reduce the risk of peri-implantitis .
An acute condition may be defined as a suddenly presenting disorder, usually with only a short history of symptoms, but with a degree of severity that causes significant disruption to the patient. [ 2 ]
Types of acute conditions
A swelling is a transient abnormal enlargement of a body part or area not caused by proliferation of cells but by accumulation of fluid in tissues. It can occur throughout the body (generalized), or a specific part or organ can be affected (localized). A swelling may arise intra-orally or externally around the face, jaws and neck and can be caused by trauma (hematoma, swelling due to fracture, TMJ dislocation), infection or inflammation. Swelling can occur in the gums, palate, lips, buccal space, etc. It can happen due to periodontal problems, infection, abscess, cysts, allergic reaction (anaphylactic shock), salivary gland tumour, inflammation or obstruction of salivary gland. [ citation needed ]
Bacterial infection in the oro-facial region can lead to abscess and swelling. The rapid spread of this infection through connective tissue spaces, is often referred to as cellulitis. The clinical features of cellulitis are a painful, diffuse, brawny swelling. The overlying skin is red, tense and shiny. There is usually an associated trismus, cervical lymphadenopathy, malaise and pyrexia. Cellulitis usually develops
quickly, over the course of hours, and may follow an inadequately managed or ignored local dental infection. If the infection spreads to involve the floor of mouth and pharyngeal spaces, then the airway can be compromised. Initially, the floor of the mouth will be raised and the patient will have difficulty in swallowing saliva; this
pools and may be observed running from the patient's mouth. This sign indicates the need for urgent management. Cellulitis involving the tissue spaces on both sides of the floor of mouth is described as Ludwig's angina [ 10 ] Such presentations require immediate attention.
Localised dental abscesses may be appropriately treated by intra-oral drainage via tooth extraction, opening of root canals and/or intra-oral incision and drainage. Wherever there are signs of spreading cervico-facial infection or significant systemic disturbance, however, patients should be referred urgently further management. [ citation needed ]
Pericoronitis is defined as inflammation in the soft tissues surrounding the crown of a partially erupted tooth. The acute form is characterised by severe pain, often referred to adjacent areas, causing loss of sleep, swelling of the pericoronal tissues, discharge of pus, trismus, regional lymphadenopathy, pain on swallowing, pyrexia, and in some cases spread of the infection to adjacent tissue
spaces. [ 11 ]
Trismus may be defined as inability to open the mouth due to muscle spasm, but the term is frequently used for limited movement of the jaw from any cause and usually refers to temporary limitation of movement. [ 8 ] Trismus can occur as a result of temporomandibular joint disorder, infection, cancer therapy, complicated extraction, arthritis, complication from a mandibular block and fractures. [ 12 ]
Whilst haemorrhage from the oro-facial region may present spontaneously, particularly from gingival tissue as a result of a bleeding diathesis or a haematological abnormality such as leukaemia, the most common cause is in response to trauma or a post-operative haemorrhage following dental extraction. [ 2 ]
Cysts can be common lesions found in the jaw. They are defined as cavities filled with fluid or semi-fluid content, created from the resorption of bone. They can wholly or partly be lined by epithelium and connective tissue. [ 13 ] They are not to be confused with abscesses , which are cavities filled with pus. Cysts can cause root resorption of adjacent teeth, tooth mobility and can be associated with mandibular fracture. [ 14 ] [ 15 ] [ 16 ] Cyst would usually require surgical management if indicated. [ 17 ]
Following a tooth extraction, if a blood clot forms inadequately in the socket or it is broken down, a painful infection may develop which is often referred to as a ‘ dry socket ’. It is clinically characterized by a putrid odor and intense pain that radiates to the ear and neck. Pain is considered the most important symptom of dry socket. It can vary in frequency and intensity, and other symptoms, such as headache, insomnia, and dizziness, can be present. [ 18 ] Pre-disposing factors to dry socket include smoking, traumatic extraction, history of radiotherapy and bisphosphonate medication.
A dry socket can be managed by irrigating the socket with chlorhexidine or warmed saline to remove debris followed by dressing of the socket with bismuth iodoform paraffin paste and lidocaine gel on ribbon gauze to protect the socket from painful stimuli. [ 2 ] If pus is seen in the socket and there is localised swelling and possibly lymphadenopathy, it has become infected and can often be managed as in dry
socket, but usually antibiotics should be prescribed. A radiograph is useful to see if there is a retained root or bony sequestrum, which could be the cause of the infection. Clearly, if one or both is present, further treatment is indicated. [ 2 ]
Mild inflammatory swelling may follow dental extractions but is unusual unless the procedure was difficult and significant surgical trauma occurred. More significant swelling usually indicates postoperative infection or presence of a haematoma . Management of infection may require systemic antibiotics or drainage. A large haematoma may need to be drained. [ citation needed ]
Orthodontic emergencies can be classified as urgent problems relating to the maintenance of orthodontic appliances, or excessive pain caused by orthodontic appliances. General dental practitioners should be able to manage orthodontic emergencies, including referral to an orthodontist when necessary. [ 19 ]
Removable active appliance are used by dentist to tip teeth using screws, springs and bows of various types to correct malocclusion. The appliance can be taken out for cleaning and for adjustments made by orthodontists. [ 20 ] If the appliance is loose in an emergency situation, the dentist can adjust the retentive component of the appliance to increase the retention of the appliance by using Adams pliers.
Suppose the appliance breaks, the orthodontist should be alerted as soon as possible. The wearer should not use the appliance as it could cause trauma and could pose a significant risk of airway obstruction if the wearer accidentally inhales. [ 21 ]
There are many components to the fixed appliance which have a potential to break off if the patient chews on hard or crunchy food. Wearers should wear a mouth guard over the appliance if when playing contact sports. If one of the components is loose or comes off, the user must call the orthodontist right away. [ 21 ] If the component is loose the dentist as an emergency treatment can cover the component with orthodontic relief wax. If the component breaks off, then the dentist can use a pair of tweezers to remove it making sure to protect the airway at all times. [ citation needed ]
Ligatures are small elastics or wires which aim to secure the archwire firmly within the brackets on the teeth. If a ligature becomes loose or lost, this can render the appliance less effective as the forces on that particular tooth are reduced. In this case, a loose elastic can be re-positioned with tweezers, ideally by an orthodontist however general dental practitioners are also able to do so. If a wire ligature becomes loose, it should be secured or replaced only by a trained orthodontist and in the meantime, if causing irritation, orthodontic relief wax should be used over any sharp ends. The patient should avoid replacing the wire ligature themselves if it is lost and should seek an appointment with their orthodontist. [ 22 ]
Separators , also known as orthodontic spacers, are usually placed between posterior teeth to open up contact point prior to placing metal orthodontic bands. The separators should ideally be kept in place until the patient's next appointment in order for the orthodontic band to fit. If the separator is lost, the orthodontist should be informed and he/she can advise for a next appointment for the patient. [ citation needed ]
The archwire in fixed orthodontic appliances should be flat against the tooth, however if the wire is protruding it can cause irritation to the surrounding soft tissues. Wire benders or a dental flat plastic can be used to bend the wire into place, or if this is not possible, the protruding wire can be covered with wax. [ 23 ] If there are significant problems, the wire can be clipped using distal end cutters, being careful to avoid inhaling or ingesting wire fragments. As a last resort measure, the whole wire and ligatures can be removed. [ 24 ]
De-bonded brackets, if left untreated, can result in irritation of lip and cheek in short term. If a bracket de-bonds from the tooth, the de-bonded bracket can be removed from the archwire by initially removing the ligature holding it in place. Alternatively, orthodontic wax relief can be used to secure the de-bonded bracket to the adjacent bracket as a temporary measure to prevent irritation of lip and cheek. However, it is essential to inform the orthodontist as soon as possible so that appropriate actions are taken to address the de-bonded brackets immediately.
The most common allergy in orthodontics is to nickel. Nickel is found in multiple orthodontic components, such as nickel-titanium (NiTi) archwires and stainless steel brackets. If patients are previously exposed to nickel, for example with nickel-containing jewellery, the re-exposure with orthodontic components are more likely to lead to a Type IV delayed hypersensitivity immune response. [ 25 ] This response is usually delayed for a few days or weeks. In this case, the orthodontist must be informed immediately to make arrangements for patient to receive nickel-free components. [ 26 ] However, such immune response to nickel is rare, as it is believed that the oral mucosa requires a much higher concentration to illicit a response compared to the skin.
When a small removable appliance or a loose component obstructs a patient's airway a true medical emergency arises. If the object is visible, recline the patient and attempt to remove it while otherwise encouraging the patient to cough the object out. If this is not immediately successful call for help and an ambulance. [ 22 ] Follow the guidelines for 'choking/aspiration' in the 'Medical Emergencies and Resuscitation' document provided by the Resuscitation Council UK. [ citation needed ]
It is not unheard of to ingest an orthodontic component or appliance, usually being asymptomatic causing no harm to the patient. No treatment is required except for monitoring stools to ensure the component has passed safely. If however the patient is having symptoms of pain or vomiting, the component may be lodged in the oesophagus or oropharynx. In such situations the patient must be sent to hospital.
If the component is more than 5 cm long the patient should always be sent to A&E as there is a higher risk of obstruction or perforation of the gastrointestinal tract so removal may be advised instead of allowing the component to pass naturally. [ 22 ] When sending a patient to hospital the referral letter must contain details regarding the components size, shape, flexibility, radio-opacity as well as information about the incident for example when it was swallowed. [ 22 ]
Aspiration of an orthodontic component which was unable to be removed must be referred to A&E for chest radiographs and subsequent removal of the component. The referral letter again must include details as described above. [ 22 ]
The treatment is cause-related. For example, oil of cloves , which contains eugenol , can be used to treat dental pain; a drop can be applied with a cotton swab as a palliative . [ citation needed ] After wisdom tooth extraction, for example, a condition known as dry socket can develop where nerve endings are exposed to air. A piece of sterile gauze or cotton soaked in oil of cloves may be placed in the socket after careful cleaning with saline to relieve this form of pain . [ citation needed ]
Over-the-counter topical anesthetics containing active ingredients such as benzocaine or choline salicylate may be applied directly to the gum in order to deaden sensation. [ citation needed ]
Analgesics such as aspirin , paracetamol (acetaminophen) and ibuprofen are also commonly used; aspirin and ibuprofen have the additional benefits of being anti-inflammatories . Ice and/or heat are also frequently applied . [ citation needed ] A dentist may prescribe an anti-inflammatory corticosteroid such as Dexameth for pain relief prior to treatment. [ citation needed ]
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https://en.wikipedia.org/wiki/Dental_emergency
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A dental extraction (also referred to as tooth extraction , exodontia , exodontics , or informally, tooth pulling ) is the removal of teeth from the dental alveolus (socket) in the alveolar bone . Extractions are performed for a wide variety of reasons, but most commonly to remove teeth which have become unrestorable through tooth decay , periodontal disease , or dental trauma , especially when they are associated with toothache . Sometimes impacted wisdom teeth (wisdom teeth that are stuck and unable to grow normally into the mouth) cause recurrent infections of the gum ( pericoronitis ), and may be removed when other conservative treatments have failed (cleaning, antibiotics and operculectomy ). In orthodontics , if the teeth are crowded , healthy teeth may be extracted (often bicuspids ) to create space so the rest of the teeth can be straightened.
Extractions could be categorized into non-surgical (simple) and surgical, depending on the type of tooth to be removed and other factors.
A comprehensive history taking should be performed to find out the pain history of the tooth, the patient's medical history and the history of previous difficult extractions. [ 2 ] The tooth should be assessed clinically i.e. checked visually by the dentist. [ 2 ] Pre-extraction radiographs are not always necessary but are often taken to confirm the diagnosis and hence appropriate treatment plan. [ 2 ] Radiographs also help in visualising the shape and size of roots which are beneficial in planning the extraction. [ 2 ] All this information will aid the dentist in foreseeing any difficulties and hence preparing appropriately. [ 2 ]
In order to obtain permission from patient for extraction of tooth, the dentist should explain that other treatment options are available, what is involved in the dental extraction procedure, the potential risks of the procedure and the benefits of the procedure. [ 2 ] The process of gaining consent should be documented in clinical notes. [ 2 ]
Before extracting a tooth, the dentist would deliver local anaesthetic to ensure the tooth and surrounding tissues are numb before they start the extraction. [ 2 ] There are several techniques to achieve numbness of the tooth including
The two most commonly used local anaesthetics in the UK are lidocaine and articaine . [ 3 ] Prior to injection, topical anaesthetic gel or cream, such as lidocaine or benzocaine , can be applied to the gum to numb the site of the injection up to a few millimetres deep. [ 2 ] This should reduce the discomfort felt during the injection and thus help to reduce patient anxiety. [ 2 ]
During extraction, multiple instruments are used to aid and ease the removal of the tooth whilst trying to minimally traumatise the tissues to allow for quicker healing.
Extraction forceps are commonly used to remove teeth. Different shaped forceps are available depending on the type of tooth requiring removal, what side of the mouth (left or right) it is on and if it is an upper or lower tooth. The beaks of the forceps must grip onto the root of the tooth securely before pressure is applied along the long axis of the tooth towards the root.
Different movements of the forceps can be employed to remove teeth. Generally, while keeping downwards pressure attempts to move the tooth towards the cheek side (buccal) and then the opposite direction (palatal or lingual) are made to loosen the tooth from its socket. [ 2 ] For single, conical-rooted teeth such as the incisors , rotatory movements are also used. [ 2 ] A 'figure of eight' movement can be used to extract lower molars . [ 2 ]
Instruments used are summarised below:
In terms of operator positioning when removing a tooth, the patient is placed more supine when extracting an upper and more upright when extracting a lower. This is to allow direct vision for the operator during the procedure. A right handed operator will stand to the front of the patient and to their right when removing any upper teeth or lower left teeth. However, they will stand behind the patient and to the right when extracting a lower right tooth. [ 4 ]
Dental elevators can be used to aid removal of teeth. Various types are available that have different shapes. Their working ends are designed to engage into the space between the tooth and bone of the socket. [ 2 ] Rotatory movements are then made to dislodge the tooth from the socket. [ 2 ] Another similar looking but sharper instrument that can be used is a luxator; this instrument can be used gently and with great care to cut the ligament between the tooth and its boney socket (periodontal ligament). [ 2 ]
Biting down on a piece of sterile gauze over the socket will provide firm pressure to the wound. Normally this is sufficient to stop any bleeding and will promote blood clot formation at the base of the socket. [ 5 ]
Moreover, the patient must be inhibited from eating and drinking hot food in the first 24 hours. Using straw for drinking is also prohibited due to the negative pressure it can produce which will lead to removal of a newly formed clot from the socket.
The source of any bleeding can either be from soft tissues ( gingiva and mucosa ) or hard tissue (the bony socket). [ 5 ] Bleeding of soft tissues can be controlled by several means including suturing the wound (stitches) and/ or using chemical agents such as tranexamic acid , ferric sulphate and silver nitrate . [ 5 ] Bony bleeding can be arrested by using haemostatic gauze and bone wax. [ 5 ] Other means of achieving haemostasis include electrocautery . [ 5 ]
Medical/Dental
Orthodontic
Aesthetics
Extractions are often categorized as "simple" or "surgical".
Simple extractions are performed on teeth that are visible in the mouth, usually with the patient under local anaesthetic , and require only the use of instruments to elevate and/or grasp the visible portion of the tooth. Typically the tooth is lifted using an elevator , and using dental forceps , specific tooth movements are performed (e.g. rocking the tooth back and forth) expanding the tooth socket. Once the periodontal ligament is broken and the supporting alveolar bone has been adequately widened the tooth can be removed. Typically, when teeth are removed with forceps, slow, steady pressure is applied with controlled force.
Surgical extractions involve the removal of teeth that cannot be easily accessed or removed via simple extraction, for example because they have broken under the gum or because they have not erupted fully, such as an impacted wisdom tooth. [ 2 ] Surgical extractions almost always require an incision. In a surgical extraction the dentist may elevate the soft tissues covering the tooth and bone, and may also remove some of the overlying and/or surrounding jaw bone with a drill or, less commonly, an instrument called an osteotome . Frequently, the tooth may be split into multiple pieces to facilitate its removal.
Common risks after any extraction include pain, swelling, bleeding, bruising, infection, trismus (not being able to open as wide as normal) and dry socket . There are additional risks associated with the surgical extraction of wisdom teeth in particular: permanent or temporary damage to the inferior alveolar nerve +/- lingual nerve, causing permanent or temporary numbness, tingling or altered sensation to the lip, chin +/- tongue. [ 16 ] [ 17 ]
Anticoagulants are drugs that interfere with the clotting cascade. Antiplatelets are drugs that interfere with platelet aggregation. These drugs are prescribed in certain medical conditions/situations to reduce the risk of a thromboembolic event. With this comes an increased risk of bleeding. Historically, the anticoagulant warfarin (belonging to the group of drugs called coumarins) and antiplatelets such as aspirin or clopidogrel, were prescribed commonly in these circumstances. However, whilst these drugs are still used, newer antiplatelet (e.g. ticagrelor) and anticoagulant (e.g. rivaroxaban , apixaban and dabigatran) drugs are being used more commonly. When considering dental treatment (including dental extractions) different guidance/precautions need to be followed depending on the drug prescribed and the individual patient circumstances. The Scottish Dental Clinical Effectiveness Programme (SDCEP) provides excellent guidance on this topic. [ 18 ]
Individual patient circumstances should be evaluated prior to the use of antibiotics to reduce the risks of certain post-extraction complications. There is evidence that use of antibiotics before and/or after impacted wisdom tooth extraction reduces the risk of infections by 66%, and lowers incidence of dry socket by one third. For every 19 people who are treated with an antibiotic following impacted wisdom tooth removal, one infection is prevented. [ 19 ] Use of antibiotics does not seem to have a direct effect on manifestation of fever, swelling, or trismus seven days post-extraction. In the 2021 Cochrane review, 23 randomized control double-blinded experiments were reviewed and, after considering the biased risk associated with these studies, it was concluded that there is moderate overall evidence supporting the routine use of antibiotics in practice in order to reduce risk of infection following a third molar extraction. There are still reasonable concerns remaining regarding the possible adverse effects of indiscriminate antibiotic use in patients. There are also concerns about development of antibiotic resistance which advises against the use of prophylactic antibiotics in practice. [ 19 ]
The inferior alveolar nerve (IAN), a branch of the trigeminal nerve (cranial nerve V), is a nerve that runs through the mandible (lower jaw) and supplies sensation to all the lower teeth, the lip and the chin. The lower teeth, and in particular the lower wisdom teeth, can therefore be in close proximity to this nerve. Damage to the inferior alveolar nerve is a risk of lower wisdom tooth removal (and other surgical procedures in the mandible). [ 20 ] This means there is a risk of temporary or permanent numbness or altered sensation to the lip +/- chin on the side the surgery is taking place. Therefore, in order to assess this risk and inform the patient, the position of the inferior alveolar nerve in relation to a lower wisdom tooth needs to be assessed radiographically prior to extraction. [ 20 ]
The proximity of the root to the canal can be assessed radiographically and there are several factors which can indicate high risk of nerve damage: [ 21 ]
The lingual nerve can also be damaged (temporary or permanent) during surgical procedures in the mandible, in particular lower wisdom tooth removal. This would present as temporary or permanent numbness/altered sensation/altered taste to the side of tongue (side corresponding to side of surgery). [ 22 ]
Immediately following the removal of a tooth, bleeding or oozing very commonly occurs. Pressure is applied by the patient biting on a gauze swab, and a thrombus (blood clot) forms in the socket ( hemostatic response). Common hemostatic measures include local pressure application with gauze, and the use of oxidized cellulose (gelfoam) and fibrin sealant . Dental practitioners usually have absorbent gauze, hemostatic packing material ( oxidized cellulose , collagen sponge), and suture kit available. [ 23 ] Sometimes 30 minutes of continuous pressure is required to fully arrest bleeding.
Talking, which moves the mandible and hence removes the pressure applied on the socket, instead of keeping constant pressure, is a very common reason that bleeding might not stop. This is likened to someone with a bleeding wound on their arm, when being instructed to apply pressure, instead holds the wound intermittently every few moments.
Coagulopathies (clotting disorders, e.g. hemophilia ) are sometimes discovered for the first time if a person has had no other surgical procedure in their life, but this is rare. Sometimes the blood clot can be dislodged, triggering more bleeding and formation of a new blood clot, or leading to a dry socket ( see complications). Some oral surgeons routinely scrape the walls of a socket to encourage bleeding in the belief that this will reduce the chance of dry socket, but there is no evidence that this practice works. [ citation needed ]
The most serious post extraction healing complication is that slow or halted healing caused by the adverse effects of use of bisphosphonates which can cause osteochemonecrosis of the bone.
The chance of further bleeding reduces as healing progresses, and is unlikely after 24 hours. The blood clot is covered by epithelial cells which proliferate from the gingival mucosa of socket margins, taking about 10 days to fully cover the defect. [ 24 ] In the clot, neutrophils and macrophages are involved as an inflammatory response takes place. The proliferative and synthesizing phase next occurs, characterized by proliferation of osteogenic cells from the adjacent bone marrow in the alveolar bone. Bone formation starts after about 10 days from when the tooth was extracted. After 10–12 weeks, the outline of the socket is no longer apparent on an X-ray image. Bone remodeling as the alveolus adapts to the edentulous state occurs in the longer term as the alveolar process slowly resorbs. In maxillary posterior teeth, the degree of pneumatization of the maxillary sinus may also increase as the antral floor remodels. [ citation needed ] [ clarification needed ]
Post-operative instructions following tooth extractions can be provided to encourage healing of the socket and prevent post-operative complications from arising. The advice listed below is usually given verbally, and can be supplemented with instructions in the written form. The combination of both methods of delivery has been found to reduce the severity of pain experienced by patients post-extraction and results in higher levels of patient satisfaction compared to verbal post-operative instructions alone. [ 25 ]
The following can be recommended to encourage healing after a tooth extraction.
Many drug therapies are available for pain management after third molar extractions including NSAIDS ( non-steroidal anti-inflammatory ), APAP ( acetaminophen ), and opioid formulations. [ 30 ] Although each has its own pain-relieving efficacy, they also pose adverse effects. According to two doctors, Ibuprofen-APAP combinations have the greatest efficacy in pain relief and reducing inflammation along with the fewest adverse effects. Taking either of these agents alone or in combination may be contraindicated in those who have certain medical conditions. For example, taking ibuprofen or any NSAID in conjunction with warfarin (a blood thinner) may not be appropriate. Also, prolonged use of ibuprofen or APAP has gastrointestinal and cardiovascular risks. [ 31 ] There is high quality evidence that ibuprofen is superior to paracetamol in managing postoperative pain. [ 32 ]
Socket preservation or alveolar ridge preservation (ARP) [ 33 ] is a procedure to reduce bone loss after tooth extraction to preserve the dental alveolus (tooth socket) in the alveolar bone . At the time of extraction a platelet rich fibrin (PRF) [ 34 ] membrane containing bone growth enhancing elements is placed in the wound or a graft material or scaffold is placed in the socket of the extracted tooth. [ 35 ] [ 36 ]
Post-extraction bleeding is bleeding that occurs 8–12 hours after tooth extraction. [ 37 ] It is normal for bleeding to occur for up to 30 minutes following the extraction. It is not uncommon for the extraction site to discharge a small amount of blood or to see saliva blood-stained for up to 8 hours. [ 38 ]
Should post-extraction bleeding occur, UK guidance recommends biting onto a piece of damp gauze for at least 20 minutes whilst sitting in an upright position. [ 28 ] It is important that the gauze is damp, but not soaking, to avoid disrupting clot formation and consequently inducing a rebound bleed. If the socket continues to bleed, it is recommended to repeat the process with a fresh piece of damp gauze for 20 minutes again. Should both attempts fail to stem the bleed, it is advised to seek professional advice.
Various factors contribute to post-extraction bleeding. [ 39 ] [ 40 ] [ 41 ]
Local factors
Systemic factors
1. Primary prolonged bleeding
This type of bleeding occurs during/immediately after extraction, because true haemostasis has not been achieved. It is usually controlled by conventional techniques, such as applying pressure packs or haemostatic agents onto the wound.
2. Reactionary bleeding
This type of bleeding starts 2 to 3 hours after tooth extraction, as a result of cessation of vasoconstriction . Systemic intervention might be required.
3. Secondary bleeding
This type of bleeding usually begins 7 to 10 days post extraction, and is most likely due to infection destroying the blood clot or ulcerating local vessels.
There is no clear evidence from clinical trials comparing the effects of different interventions for the treatment of post-extraction bleeding. [ 42 ] In view of the lack of reliable evidence, clinicians must use their clinical experience to determine the most appropriate means of treating this condition, depending on patient-related factors. [ 42 ]
Atraumatic extraction is a novel technique for extracting teeth with minimal trauma to the bone and surrounding tissues. It is especially useful in patients who are highly susceptible to complications such as bleeding, necrosis , or jaw fracture. It can also preserve bone for subsequent implant placement. [ 57 ] Techniques involve minimal use of forceps, which damage socket walls, relying instead on luxators, elevators and syndesmotomy. [ citation needed ] [ 58 ]
Following dental extraction, a gap is left. The options to fill this gap are commonly recorded as Bind , and the choice is made by dentist and patient based on several factors.
Historically, dental extractions have been used to treat a variety of illnesses. Before the discovery of antibiotics , chronic tooth infections were often linked to a variety of health problems, and therefore removal of a diseased tooth was a common treatment for various medical conditions. Instruments used for dental extractions date back several centuries. In the 14th century, Guy de Chauliac invented the dental pelican, [ 59 ] which was used through the late 18th century. The pelican was replaced by the dental key [ 60 ] which, in turn, was replaced by modern forceps in the 19th century. [ 61 ] As dental extractions can vary tremendously in difficulty, depending on the patient and the tooth, a wide variety of instruments exist to address specific situations. Rarely, tooth extraction was used as a method of torture, e.g. , to obtain forced confessions. [ 62 ]
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Dental fear , or dentophobia, is a normal emotional reaction to one or more specific threatening stimuli in the dental situation. [ 1 ] [ 2 ] However, dental anxiety is indicative of a state of apprehension that something dreadful is going to happen in relation to dental treatment , and it is usually coupled with a sense of losing control. [ 1 ] Similarly, dental phobia denotes a severe type of dental anxiety, and is characterized by marked and persistent anxiety in relation to either clearly discernible situations or objects (e.g. drilling, local anesthetic injections) or to the dental setting in general. [ 1 ] The term ‘dental fear and anxiety’ (DFA) is often used to refer to strong negative feelings associated with dental treatment among children , adolescents and adults , whether or not the criteria for a diagnosis of dental phobia are met. Dental phobia can include fear of dental procedures, dental environment or setting, fear of dental instruments or fear of the dentist as a person. [ 3 ] People with dental phobia often avoid the dentist and neglect oral health, which may lead to painful dental problems and ultimately force a visit to the dentist. The emergency nature of this appointment may serve to worsen the phobia. This phenomenon may also be called the cycle of dental fear. [ 3 ] Dental anxiety typically starts in childhood. [ 1 ] There is the potential for this to place strains on relationships and negatively impact on employment. [ 4 ]
Dental fear, anxiety, and phobia seem to be interchangeably used, however, there is a fundamental difference between each.
Dental anxiety is fear of the unknown. It's the worry that people commonly experience because they are about to do something that they have never done, possibly going to dental clinic for the first time or getting a new procedure.
Dental fear is a response to past negative experiences that triggers apprehension.
Dental phobia is a severe, irrational fear of dental situations leading to complete avoidance of dental care, often impacting daily functioning and health. [ 5 ]
As with all types of fear and phobias, dental fear can manifest as single or combination of emotional, physiological, cognitive and behavioural symptoms. [ 6 ]
Dental Phobia can be classified into 3 broad classes:
Emotional response
Physiological response
Cognitive response
Behavioural response
Research suggests that there is a complex set of factors that lead to the development and maintenance of significant dental anxiety or dental phobia, which can be grouped as genetic, behavioral and cognitive factors. [ 8 ] In comparison to other phobias, literature on odontophobia is relatively limited.
In order to better address the patients with dental fear, it is very important to understand the causes and factors associated with them.
Several theories have been proposed; however, a 2014 review describes five pathways which relate specifically to development dental fear and anxiety: Cognitive Conditioning, Vicarious, Verbal Threat, Informative, and Parental. However, there may be a variety of background factors common to all general fear and anxiety conditions that may be at play and affect these more specific pathways. [ 8 ]
Conditioning
Conditioning is defined as the process by which a person learns through personal experience that an event or stimulus will result in a detrimental outcome, e.g. "if I visit the dentist, it is going to be sore". As, expected dental fear is associated with previous traumatic experiences, especially their first one. [ 1 ] It is believed to be the most commonly used pathway for patients to develop dental fear and anxiety. [ 8 ]
Informative
This indirect pathway relates to fear acquisition through gaining information and becoming bias to the dental environment from dental phobic elders, negative connotations advertised by media ( e.g . television, movies), and friends with personal negative experiences. [ 8 ]
Vicarious
The vicarious pathway suggests that fear is acquired through imagination of the feelings, experience or actions of another person. Whether this pathway occurs on its own or in combination with others is still unknown. It has been suggested that dental fear in the very young is passed through this pathway through observation of expressions of fear by elders/parents at the dentist. [ 8 ]
Verbal threat
This pathway can be seen as similar to the informative pathway, however it is more reliant on the emotion of fear elicited by "word of mouth" and is heavily modulated by the messenger. In essence the verbal threat pathway is the fear induced when an authority figure threatens an individual with a painful experience. In the case of dental fear, the painful and/or negative experiences linked to dental visits. Although at a glance, the verbal threat and informative pathway are similar, in odontophobia the two pathways differ in that the verbal threat pathway occurs when a “visit to the dentist” is literally used as a form of punishment for bad behaviour. This does not occur in the informative pathway. [ 8 ]
Parental modelling
There is a significant relationship between child and parental dental fear, [ 10 ] especially that of the mothers. [ 8 ] it has been suggested that this relationship is strongest in children 8 years or younger. [ 8 ] However, it is important to note the parental modelling pathway may overlap with the informative or vicarious pathways are all linked in some way.
Several methods have been developed to diagnose dental fear and anxiety. In addition to identifying the patients with dental fear, different categories of dental fear have been established. [ 3 ] [ 11 ] These include:
The presence of dental phobia can have major impacts on overall health, wellbeing, and quality of one's life, in addition to directly impacting their dental health.
Dental fear varies across a continuum, from very mild fear to severe. Therefore, in a dental setting, it is also the case where the technique and management that works for one patient might not work for another. Some individuals may require a tailored management and treatment approach. [ 6 ]
The management of people with dental fear can be done using shorter term methods such as hypnosis and general anesthetic, or longer term methods such as cognitive behavioral therapy and the development of coping skills. Short term methods have been proven to be ineffective for long-term treatment of the phobia, since many return to a pattern of treatment avoidance afterwards. Psychological approaches are more effective at maintaining regular dental care, but demand more knowledge from the dentist and motivation from the patient [ 3 ]
Similarly, distraction techniques can also be utilized to divert the patient's attention to allow them to avoid supposed negativity and be more comfortable. This can be achieved through television or movies, or a physical distraction such as focusing on another body part such as wiggling the toes or fingers. [ 6 ]
More recent research indicates that the use of conscious sedation combined appropriate communication techniques may relieve the anxiety in the long-term. [ 15 ]
Modelling is a form of psycho-behavioural therapy used to alleviate dental fear. Commonly used in paediatric dentistry , it involves the showing of a procedure under a simulated environment. It allows the patient to observe the behaviour of a friend, family member, or other patient when put in a similar situation, therefore, accommodating for the learning of new coping mechanisms . [ 6 ] Modelling can be presented live using a parent or actor as well as virtually through pre-recorded films. [ 4 ]
Tell-show-do is a common non-pharmacological practice used to manage behaviour such as dental fear, especially in paediatric dentistry . [ 6 ] The purpose of this intervention is to promote a positive attitude towards dentistry and to build a relationship with the patient to improve compliance. The patient is gradually introduced to the treatment. Firstly, the dentist "tells" the patient what the dental procedure will be using words. In 'show' phase, the patient is familiarized with dental treatment using demonstrations. Lastly, in 'do' phase, the dentist proceeds with the treatment following the same procedure and demonstrations illustrated to the patient. [ 16 ]
A technique known as behavioral control involves the person giving a signal to the clinician when to stop the procedure. This could be simply raising a hand to let the clinician know, however, the signal that is chosen will be discussed prior. This technique provides the people with a sense of control over the appointment and as so, instills trust in the dentist. [ 4 ]
Cognitive behavioral therapy (CBT) appears to decrease dental fear and improve the frequency people go to the dentist. [ 17 ] CBT for dental anxiety is often performed by psychologists, but the effect has proven to be good also when administered by trained dentists. [ 18 ] [ 15 ] Other measures that may be useful include distraction, guided imagery, relaxation techniques, and music therapy. [ 4 ] [ 19 ] Behavior techniques are believed to be sufficient for the majority of people with mild anxiety. [ 20 ] The quality of the evidence to support this, however, is low. [ 21 ]
It has been suggested that the ambience created by the dental practice can play a significant role in initiating dental fear and anxiety by triggering sensory stimuli. It has been suggested that the front of house staff, e.g. receptionist and dental nurses contribute to elicit a better cognitive and emotional experience for anxious patients by showing a positive and caring attitude and by adopting good communication techniques. [ 6 ] For patients whose dental avoidance is related to their experiences of assault and trauma, being guided by the patients' preferences, for aspects like chair positioning, may help to avoid retriggering them. [ 22 ] Anxious patients should not be made to wait too long in waiting rooms, so that they have less time to recall and absorb negative feelings. There is some small evidence that the waiting areas with soft music playing and dimmer lights and cooler in temperature produces a more calming effect. It has also been stipulated that masking strong clinical smells like eugenol with more pleasant smells can help to reduce anxiety, however this is more likely to be effective in moderate rather than severe anxiety. [ 6 ]
Hypnosis may be useful in certain people. [ 4 ] Hypnosis may improve a person's level of cooperation and decrease gagging. [ 23 ]
Music therapy has shown promising results as a non-invasive method for reducing dental anxiety. By using music as a therapeutic tool, patients can experience decreased stress levels and improved relaxation during dental procedures. Music can help lower cortisol levels, modulate autonomic responses, and provide a distraction from the sounds and sensations of dental work however review of RCT's show minimal to no effect of music therapy on dental phobia. [ 24 ]
VRET has shown to be very effective in managing different type of phobias and in recent times few studies have been done to determine its implications in Dental phobia. Gujjar et al.'s RCT showed VRET condition patients showed a significant reduction in anxiety scores. [ 25 ]
Ideally done in a sitting position, this relaxation technique for certain muscle groups can be implemented in the waiting room.
The major muscles groups include
The steps according to Edmund Jacobson are as follows:
Desensitisation in dentistry refers to the gradual exposure of a new procedure to the patient in order to calm their anxiety . It is based on the principle that a patient can overcome their anxiety if they are gradually exposed to the feared stimuli, whether imagined or real, in a controlled and systematic way. Exposure to the feared stimuli or situation is recognised as a central treatment component for specific phobias. [ 26 ] [ 27 ]
Pharmacological techniques to manage dental fear range from conscious sedation to general anaesthesia ; these are often used and work best in conjunction with behavioural (non-pharmacological) techniques. [ 28 ]
Premedication refers to medication given prior to initiation of dental treatment. [ 29 ] Benzodiazepines, a class of sedative drugs, are commonly used as premedication, in the form of a tablet, to aid anxiety management before dental treatment. [ 30 ] Benzodiazepines are however addictive and subject to abuse, therefore only the minimum number of tablets required should be prescribed. Patients may also be required to be accompanied to their dental appointment by an escort. [ 31 ] In the UK, temazepam used to be the drug of choice however, lately, midazolam has become much more popular. In children, a recent meta-analysis comparing oral midazolam against placebo showed some improvement in co-operation in children using midazolam. [ 30 ] One of the disadvantages of oral premedication is that it is not titratable (i.e. it is difficult to adjust the dose to control the level of sedation desired) and therefore this technique should be only be used when other titratable sedation techniques are inappropriate. [ 19 ]
Conscious sedation refers to the use of a single or combination of drugs to help relax and reduce pain during a medical or dental procedure. There are a range of techniques and drugs that can be used; these need to be tailored to the individual need of the patient taking into account the medical history, the skill and training of the dentist/sedationist and the facilities and equipment available. Conscious sedation is traditionally considered a short-term solution for patients with dental anxiety, but recent research indicate that provided good communication techniques and the use of other adaptations throughout the treatment, the dental anxiety reduction achieved may be lasting. [ 15 ]
General anaesthesia is rarely used in the general dental practice, but can be provided. This is usually performed in practices specifically set up to provide this level of sedation. Most often this type of sedation is reserved for the developmentally disabled and is provided by an anesthesiologist working in conjunction with a general dentist. This service, though rare, can often be found in larger cities such as Portland, Oregon. [ 32 ]
The use of general anaesthesia to reduce the pain and anxiety associated with dental treatment should be discouraged and general anaesthesia should be undertaken only when absolutely necessary. [ 6 ]
Individuals who are highly anxious about undergoing dental treatment comprise approximately one in six of the population. [ 4 ] Middle-aged women appear to have higher rates of dental anxiety compared to men. [ 4 ]
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A dental hygienist or oral hygienist is a licensed dental professional, registered with a dental association or regulatory body within their country of practice. Prior to completing clinical and written board examinations, registered dental hygienists must have either an associate's or bachelor's degree in dental hygiene from an accredited college or university. Once registered, hygienists are primary healthcare professionals who work independently of or alongside dentists and other dental professionals to provide full oral health care. They have the training and education that focus on and specialize in the prevention and treatment of many oral diseases.
Dental hygienists have a specific scope of clinical procedures they provide to their patients. They assess a patient's condition in order to offer patient-specific preventive and educational services to promote and maintain good oral health. A major role of a dental hygienist is to perform periodontal therapy which includes things such periodontal charting , periodontal debridement ( scaling and root planing ), prophylaxis (preventing disease) or periodontal maintenance procedures for patients with periodontal disease . The use of therapeutic methods assists their patients in controlling oral disease, while providing tailored treatment plans that emphasize the importance of behavioral changes. [ 1 ] Some dental hygienists are licensed to administer local anesthesia and perform dental radiography . [ 2 ] Dental hygienists are also the primary resource for oral cancer screening and prevention. [ 3 ] In addition to these procedures, hygienists may take intraoral radiographs , apply dental sealants , administer topical fluoride , and provide patient-specific oral hygiene instruction. [ 4 ]
Dental hygienists work in a range of dental settings, from independent, private, or specialist practices to the public sector. [ 5 ] [ 6 ] Dental hygienists work together with dentists , dental therapists , oral health therapists, as well as other dental professionals. Dental hygienists aim to work inter-professionally to provide holistic oral health care in the best interest of their patient. Dental hygienists also offer expertise in their field and can provide a dental hygiene diagnosis, which is an integral component of the comprehensive dental diagnosis. [ 7 ]
In the dental office, the dentist and the dental hygienist work together to meet the oral health needs of patients. Since each country has its own specific regulations regarding their responsibilities, the range of services performed by hygienists varies. Some of the services provided by dental hygienists may include:
Jobs for dental are well paid almost on all states of the United States. The median annual wage for dental hygienists was $77,810 in May 2021. [ 9 ] The median annual wages for dental hygienists in the top industries in which they worked were as follows:
[ 10 ] States with the highest employment level in Dental Hygienists:
[ 11 ] Top paying states for Dental Hygienists:
[ 11 ] Metropolitan areas with the highest employment level in Dental Hygienists:
[ 11 ] Top paying metropolitan areas for Dental Hygienists:
[ 11 ]
Gum disease is caused by a sticky film of bacteria called plaque. Plaque is always forming on teeth, but if it is not cleaned well, the bacteria in plaque can cause gums to become inflamed. When this happens, the gums pull away from the teeth and form spaces called pockets. Plaque then gets trapped in these pockets and cannot be removed with regular brushing. Untreated gum disease can lead to bone and tooth loss. If the periodontal pockets are too deep a deep cleaning (scaling and root planing) is necessary to remove the plaque in these pockets. [ 12 ]
Scaling and root planing is a careful cleaning of the root surfaces to remove plaque and calculus from deep periodontal pockets and to smooth the tooth root to remove bacterial toxins. Scaling and root planing is sometimes followed by adjunctive therapy such as local delivery antimicrobials, systemic antibiotics, and host modulation, as needed on a case-by-case basis.
Most periodontists agree that after scaling and root planing, many patients do not require any further active treatment. However, the majority of patients will require ongoing maintenance therapy to sustain health. The maintenance phase involves continuous care, at patient specific levels. [ 13 ]
Dental hygienists in Australia must be graduates from a dental hygiene program, with either an advanced diploma (TAFE), associate degree, or more commonly a bachelor's degree from a dental hygiene school that is accredited by the Australian Dental Council (ADC) under the Australian Health Practitioner Regulation Agency . [ 26 ]
In Australia it is a legal requirement for dental hygienist and oral health therapist graduates to be registered with the Dental Board of Australia before practising their scope in periodontology in any state or territory in Australia. [ 27 ]
The Dental Hygienists' Association of Australia (DHAA) Inc., established in 1975, is the peak body representing registered dental hygiene service providers in Australia.
A dental hygienist does not need to be employed by a dentist but can independently assess patients and make treatment plans within their scope of practice whilst working in the community. Practising as an autonomous decision maker, and working within the scope of only what they are "formally" trained in.
The National Law requires the same level of professional responsibility from dental hygienists, oral health therapists and dental therapists as it does from dentists, dental specialists and dental prosthetists in that all practitioners must have their own professional indemnity insurance and radiation licences. They are also required to complete 60 hours of mandatory continuing professional development in a three-year cycle. [ 28 ] [ 29 ]
A Bachelor of Oral Health is the most common degree program. Students entering a bachelor's degree program are required to have a high school diploma or equivalent. Most Bachelor of Oral Health programs now qualify students as both dental hygienists and dental therapists, collectively known as oral health therapists. [ 30 ]
Dental hygienists in Canada must have completed a diploma program, which can take from 19 months to 3 years to complete. All dental hygiene students must pass a NDHCB examination after graduation. [ 31 ] This examination is offered three times per year, January, May and September. Three universities in Canada offer Bachelor of Science degrees in Dental Hygiene: Dalhousie University, [ 32 ] University of Alberta, [ 33 ] University of British Columbia. [ 34 ]
Dental Hygiene across Canada is a well-respected regulated health care profession with many opportunities. These possibilities include working in clinical, administration, education, research and public health positions. The wages vary throughout the country; from approximately $40 per hour in some areas to as high as $65 per hour in others. A surplus of new dental hygiene graduates in recent years has resulted in a decrease in wages in some regions. [ citation needed ]
Some of the downfalls to practicing in different provinces are the different regulations. For instance, in BC, the hygienist cannot provide treatment without the patient receiving a dental exam in the previous 365 days unless the practicing hygienist has an extended duty module (resident-care module). In AB, BC, MB,NS and SK, hygienists also administer local anesthesia if qualified to do so. Home College of Dental Hygienists of British Columbia / Saskatchewan Dental Hygienists Association HOME In Ontario, dental hygienists may take further training to become a restorative dental hygienist. University based programs incorporate restorative dentistry in the clinical portion of their programs; graduates of these programs are immediately prepared for a broader scope of practice when they graduate. Registered dental hygienists must register every year by December 31. All Canadian dental hygienists must also prove continuing competence by maintaining a professional portfolio yearly.
In all provinces, dental hygienists are registered with their provincial College of Dental Hygienists. [ 35 ] [ 36 ]
Dental hygienists in BC, ON, NS and AB are able to open their own private clinics and practice without a dentist on staff.
Dental hygienists are no longer trained in New Zealand . Instead, training has been combined with that of dental therapists to train oral health therapists. Dental hygienists were first domestically trained in 1974 for use in the New Zealand Defence Force . The 1-year course was taught by the Royal New Zealand Dental Corp at the Burnham army base outside Christchurch . [ 22 ] Hygiene training was briefly offered at the Wellington School for Dental Nurses in 1990 as 2-week a supplement to Dental Therapy students training. [ 22 ] However, this was quickly discontinued. [ 22 ]
The first independent non-military training began in 1994. [ 22 ] Otago Polytechnic began offering a 15-month Certificate in Dental Hygiene in Dunedin. [ 22 ] In 1998, the programme was modified to be a 2-year Diploma. [ 22 ] Otago Polytech stopped offering the course in 2000. [ 22 ] The following year, University of Otago began offering a 2-year Diploma in Dental Hygiene qualification. [ 22 ] In 2002, the university added a 3-year Bachelor of Health Sciences (endorsed in Dental Hygiene) degree alongside the Diploma. [ 22 ]
From 2006, [ 22 ] New Zealand dental hygienists and now oral health therapists have been trained at either University of Otago in Dunedin (at the country's only Dental School ) or at Auckland University of Technology . [ 37 ] Until official establishment of the oral health therapy scope in late 2017, the qualifications (Bachelor of Oral Health at Otago, Bachelor of Health Science (Oral Health) at AUT) enabled graduates to register and practise as both a dental hygienist and a dental therapist. [ 22 ]
In order to practise, dental hygienists and oral health therapists must register and annually recertify with the Dental Council of New Zealand. [ 38 ] One dental hygienist is represented on Council for a 3-year term. [ 39 ]
The representing body for dental hygienists was the New Zealand Dental Hygienists' Association. [ 25 ] The association was founded in 1993, [ 24 ] and is affiliated with the International Federation of Dental Hygienists. [ 40 ] In 2021 the association merged with the New Zealand Dental and Oral Health Therapists Association to become the New Zealand Oral Health Association.
Dental hygienists in the United States must be graduates from a dental hygiene program, with either an associate degree (most common), a certificate, a bachelor's degree or a master's degree from a dental hygienist school that is accredited by the American Dental Association (ADA). [ 41 ]
All dental hygienists in the United States must be licensed by the state in which they practice, after completing a minimum of two years of school and passing a written board known as the National Board Dental Hygiene Examination as well as a clinical board exam. After completing these exams and licenses, dental hygienists may use "R.D.H" after their names to signify that they are a registered dental hygienist. [ 42 ] [ 43 ] Dental hygienists also have to become licensed in the state in which they intend to practice. State licensure requirements vary, however most states require an associate degree in Dental Hygiene, successful completion of a state licensure examination, as well as a clinical examination also typically administered by the state.
Dental hygienists school programs usually require both general education courses and courses specific to the field of dental hygiene. General education courses important to dental hygiene degrees include college level algebra, biology, and chemistry. Courses specific to dental hygiene may include anatomy, oral anatomy, materials science , pharmacology , radiography , periodontology , nutrition , and clinical skills. [ citation needed ]
A Bachelor of Science in Dental Hygiene is typically a four-year program. Students entering a bachelor's degree program are required to have a high school diploma or equivalent, but many dental hygienists with an associate degree or certification enter the bachelor's degree programs to expand their clinical expertise and help advance their careers. [ citation needed ]
Graduate degrees in the field of dental hygiene are typically two-year programs and are completed after the bachelor's degree. Common graduate courses in dental hygiene include Healthcare Management, Lab Instruction, and Clinical Instruction. [ citation needed ]
In addition, the American Dental Hygienists' Association has defined a more advanced level of dental hygiene, the Advanced Dental Hygiene Practitioner otherwise known as a dental therapist.
Dental hygienist students perform practical oral examinations free of charge at some institutions which have expressed a shortage in recent years. [ 44 ]
The dental hygienists in some parts of North America can provide oral hygiene treatment based on the assessment of a patient's needs without the authorization of a dentist, treat the patient in absence of a dentist, and also maintain a provider-patient relationship.
The Dental Hygienist Course in India is a full-time 2-year diploma course. The Dental Hygienist course is regulated and controlled by the Dental Council of India. After completing the course, a dental hygienist should register with a state dental council. Any registered dental hygienist in one state may practice as in any other. The Federation of Indian Dental Hygienists Association is the primary national body representing the dental hygienist profession in India, however, some state dental hygienist associations also work at the state level. In India, dental hygienists do not need to be employed by a dentist but can have their own clinic.
1995 - A client must have seen a dentist within the previous 365 days in order for the hygienist to provide dental hygiene treatment.
2012 - New bylaws offers an exemption from the 365-day rule if hygienists are registered in the Full Registration (365 Day Rule Exempt) class. [ 45 ]
2006 - Dental hygienists are able to offer their services in many practice settings including independent practice. [ 46 ]
2008 - If the dental hygienist has practiced for more than 3000 hours, and the client does not have a complex medical condition then the hygienists do not require the supervision of a dentist. [ 47 ]
2007 - Registered dental hygienists in Ontario who have been approved by the College of Dental Hygienists of Ontario can practice independently. [ 48 ]
1998 - Registered dental hygienist in alternative practice (RDHAP): RDHAPs may provide services for homebound persons or at residential facilities, schools, institutions and in dental health professional shortage areas without the supervision of a dentist. RDHAPs can provide patient care for up to 18 months and longer if the patient obtains a prescription for additional oral treatment from a dentist or physician . [ 49 ]
1987 - Unsupervised practice: Hygienists may have their own dental hygiene practice; there are no requirement for the authorization or supervision of a dentist for most services. Colorado is currently the only state where this is approved. Case was won by JoAnn Grant, a dental hygienist from Fort Collins , CO . [ 50 ]
1999 - Public health dental hygienist: dental hygienists may practice without supervision in institutions, public health facilities, group homes, and schools as long as they have two years of work experience. [ 51 ]
2008 - Independent practice dental hygienist: A dental hygienist licensed with an independent practice may work without the supervision of a dentist, providing that the dental hygienist has to complete 2,000 work hours of clinical practice during the two years prior to applying for an independent license, as well as a bachelor's degree from a CODA accredited dental hygiene program or complete 6,000 work hours of clinical practice during the six years prior to applying for an independent license, as well as an associate degree from a CODA accredited dental hygiene program. [ 52 ]
2005 - PA 161 Dental hygienist: hygienists with grantee status can work in a public or nonprofit environment, a school or nursing home that administers dental care to a low-income population. Dentists collaborating with dental hygienists do not need to be present to authorize or administer treatment. However, dental hygienists must have the availability to communicate with a dentist in order to review patient records and establish emergency protocols. Hygienists need to apply to the state department of community health for grantee status. [ 53 ]
1984 - Unsupervised practice: dental hygienist practice without the supervision of a dentist is allowed in hospitals, group homes, nursing homes, home health agencies, Health and Human Service state institutions, jails, and public health facilities as long as the hygienist refers their patients to a dentist for treatment. Hygienists must have at least two years of work experience within the last 5 years. [ 54 ]
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A dental impression is a negative imprint of hard and soft tissues in the mouth from which a positive reproduction, such as a cast or model, can be formed. It is made by placing an appropriate material in a dental impression tray which is designed to roughly fit over the dental arches. The impression material is liquid or semi-solid when first mixed and placed in the mouth. It then sets to become an elastic solid, which usually takes a few minutes depending upon the material. This leaves an imprint of a person's dentition and surrounding structures of the oral cavity.
Digital impressions using computerized scanning are now available.
Impressions, and the study models, are used in several areas of dentistry including:
The required type of material for taking an impression and the area that it covers will depend on the clinical indication. Common materials used for dental impressions are: [ 1 ]
Impressions can also be described as mucostatic or mucocompressive , being defined both by the impression material used and the type of impression tray used (i.e. spaced or closely adapted). Mucostatic means that the impression is taken with the mucosa in its normal resting position. These impressions will generally lead to a denture which has a good fit during rest, but during chewing, the denture will tend to pivot around incompressible areas (e.g. torus palatinus ) and dig into compressible areas. Mucocompressive means that the impression is taken when the mucosa is subject to compression. These impressions will generally lead to a denture that is most stable during function but not at rest. Dentures are at rest most of the time, so it could be argued that mucostatic impressions make better dentures, however in reality it is likely that tissue adaption to the presence of either a denture made with a mucostatic or a mucocompressive technique make little difference between the two in the long term.
Another type of impression technique is selective pressure technique in which stress bearing areas are compressed and stress relief areas are relieved such that both the advantages of muco static and muco compressive techniques are achieved.
The preparation border must be accurately captured by the light bodied impression material when taking impressions for crown and bridge work. As a result, the gingival tissues must be pushed away from the preparation margin in order for the impression material to be accessible. Inserting a retraction cord into the gingival crevice is one method of retracting gingival tissues away from the tooth. [ 2 ]
Impression materials can be considered as follows:
Plaster of Paris is traditionally used as a casting material once the impression has been taken, however its use as an impression material is occasionally useful in edentate patients. [ 2 ] The tissues are not displaced during impression taking, hence the material is termed mucostatic. Mainly composed of β-calcium sulphate hemihydrate, impression plaster has a similar composition and setting reaction to the casting material with an increase in certain components to control the initial expansion that is observed with Plaster of Paris. Additionally, more water is added to the powder than with the casting material to aid in good flow during impression taking. As the impression material is very similar to the casting material to be used, it requires the incorporation of a separating medium (e.g. sodium alginate) to aid in separating the cast from the impression. If a special tray is to be used, impression plaster requires 1–1.5mm spacing for adequate thickness.
Advantages: [ 2 ]
Disadvantages: [ 2 ]
Impression compound has been used for many years as an impression material for removable prostheses. Although its use has recently declined with the advent of better materials. Due to its poor flow characteristics, it is unable to reproduce fine detail and so its use is somewhat limited to the following scenarios:
Impression compound is a thermoplastic material; it is presented as a sheet of material, which is warmed in hot water (> 55–60 °C) for one minute, and loaded on a tray prior to impression taking. Once in the mouth, the material will harden and record the detail of the soft tissues. The impression can further be hardened by placing it in cold water after use. Impressions with compound should be poured within an hour as the material exhibits poor dimensional stability. There are two main presentations of impression compound: red compound and greenstick. The latter is mainly used for border moulding and recording the post-dam area.
vinyl polysiloxane dental impression materials used for making accurate dental impressions with excellent reproducibility. It is available in Putty and light body consistencies to aid dentists make perfect impressions for fabrication of crowns, bridges, inlays, onlays and veneers.
Example Flexceed
Advantages:
Impression paste is traditionally used to take the working (secondary) impressions for a complete denture. When used with a special tray it requires 1 mm of spacing to allow for enough thickness of the material; this is also termed a close fitting special tray. [ 2 ] It is available as a two-paste system:
The two pastes should be used in equal amounts and blended together with a stainless steel spatula (Clarident spatula) on a paper pad. Zinc-oxide Eugenol plaster will produce a mucostatic impression.
Advantages: [ 2 ]
Disadvantages: [ 2 ]
Agar is a material which provides high accuracy. Therefore, it is used in fixed prosthodontics (crowns, bridges) or when a dental model has to be duplicated by a dental technician. Agar is a true hydrophilic material, hence the teeth do not need to be dried before placing it into the mouth. [ 1 ] It is a reversible hydrocolloid which means that its physical state can be changed by altering its temperature which allows to reuse the material multiple times. The material comes in form of tubes or cartridges. A special hardware is required in the process of taking agar impressions, namely a water bath and rim lock trays with coiled edges allowing passage of cold water for cooling the material to set while in the mouth. The bath consists of three containers filled with water at different temperatures: the first is set at 100 °C to liquefy the agar, the second is used to lower down the temperature of the material for safe intra-oral use (usually set at 43–46 °C) and the third one is used for storage and is set at 63–66 °C. The storage container can maintain agar tubes and cartridges at temperature 63–66 °C for several days for convenient immediate use. The tray is connected to a hose, material is loaded onto the tray and placed in the mouth over the preparation – an adequate thickness of the material is required, otherwise distortion may occur upon removal from the mouth. The other end of the hose is connected to a cold water source. The hydrocolloid is then cooled down through the tray wall which results in setting of the material. The models should be poured as soon as possible to avoid changes in dimensional stability. [ 1 ]
Modern dentistry offers other materials (e.g. elastomerics) which provide high accuracy impressions and are easier to use hence agar is used less frequently.
Advantages: [ 1 ]
Disadvantages: [ 1 ]
Alginate , on the other hand, is an irreversible hydrocolloid. It exists in two phases: either as a viscous liquid, or a solid gel, the transition generated by a chemical reaction. [ 3 ] The impression material is created through adding water to the powdered alginate which contains a mixture of sodium and potassium salts of alginic acid. The overall setting double composition reaction is as follows:
Potassium (sodium) alginate + calcium sulphate dihydrate + water → calcium alginate + potassium (sodium) sulphate
Sodium phosphate is added as a retarder which preferentially reacts with calcium ions to delay the set of the material.
Alginate has a mixing time of 45–60 secs, a working time of 45 secs (fast set) and 75 secs (regular set). The setting time can be between 1 – 4.5 mins which can be varied by the temperature of water used: the cooler the water, the slower the set and vice versa. You want to ensure that the material is fully set before removal from the mouth.
The water content that the completed impression is exposed to must be controlled. Improper storage can either result in syneresis (the material contracts upon standing and exudes liquid) or imbibition (water uptake which is uncontrolled in extent and direction). Therefore, the impression must be stored correctly, which involves wrapping the set material in a damp tissue and storing it in a sealed polythene bag until the impression can be cast. Alginate is used in dental circumstances when less accuracy is required. For example, this includes the creation of study casts to plan dental cases and design prosthesis , and also to create the primary and working impressions for denture construction.
Several faults can be encountered when using an alginate impression material, but these can generally be avoided through adequate mixing, correct spatulation, correct storage of the set material, and timely pouring of the impression.
Due to the increased accuracy of elastomers, they are recommended for taking secondary impressions over alginate. Patients both preferred the overall experience of having an impression taken with an elastomer than with alginate, and also favoured the resultant dentures produced. [ 4 ]
Advantages:
Disadvantages:
As stated above, there are times clinically where the accuracy of an alginate impression is not acceptable, particularly for the construction of fixed prosthodontics . Agar may be used but as discussed has a number of technical difficulties in its use. As such elastomers were developed to capture the fine detail and accuracy required.
Polysulphides have become increasingly unpopular due to their unpleasant taste/smell. The material is presented as a paste to paste system mixed by a dental nurse prior to use. The material sets by a condensation polymerisation reaction. Initially the polymer chains increase in length causing a slight increase in temperature, of 3–4 °C. This is then followed by cross linking of the polymer chains and finally the release of water as a by product. This later reaction slightly contracts the material making it stiffer and more resistant to permanent deformation. When poured and cast this slight contraction means the resulting model is slightly larger and as such creates space for the luting cement.
Advantages: [ 2 ]
Disadvantages: [ 2 ]
Polyethers are the most hydrophilic impression material of the hydrophobic elastomers. This property makes it a commonly used material in general practice as it more likely to capture preparation margins when moisture control is not perfect.
Presented as a paste to paste system the material is often used with a monophase impression technique, meaning both the material syringed round the preparation and the bulk within the tray are the same material. Note when mixing polyether the base to accelerator ratio is not 1:1 like with most elastomers, but 1:4.
Advantages: [ 2 ]
Disadvantages: [ 2 ]
Indications:
There are two types of silicone resin impression material, addition and condensation (reflecting each of their setting reactions). Silicones are inherently hydrophobic and as such require excellent moisture control for optimal use.
Addition silicones have become the most used impression material in advanced restorative dentistry. There are many forms available, based on their differing amounts of filler content. This dictates the flow properties of each type with more filler resulting in a thicker, less flowable material. The most common forms are: extra light-bodied (low filler content), light-bodied, universal or medium-bodied, heavy-bodied and putty (high filler content). However each type follows the same addition polymerisation reaction and is presented as a paste to paste system. The reaction does not produce any by-product making it dimensionally stable and very accurate.
Advantages: [ 2 ]
Disadvantages: [ 2 ]
Indications:
Contraindications
Condensation silicones are commonly used as a putty, paste or light bodied material. The systems are usually presented as a paste or putty and a liquid/paste catalyst; meaning accurate proportioning is difficult to achieve resulting in varied outcomes. For example, the setting reaction of putty is started by kneading a low viscosity paste accelerator into a bulk of silicone with high filler content.
As stated the material sets by a condensation reaction forming a three-dimensional silicone matrix whilst releasing ethyl alcohol as a by-product. This in turn results in a minimally exothermic set with marked shrinkage on setting (shrinkage being relative to filler content, where high filler content has reduced shrinkage).
Advantages: [ 2 ]
Disadvantages: [ 2 ]
Indications:
An impression tray is a container which holds the impression material as it sets, and supports the set impression until after casting. Impression trays can be separated into two main categories- stock trays and special trays.
Stock trays are used to take primary impressions and come in a range of sizes and shapes, and can be plastic or metal. Stock trays can be rounded (designed to fit the mouths of people with no remaining teeth) or squared (designed to fit people with some remaining teeth). They can be full arch, covering all the teeth in either the upper or lower jaw in one impression, or a partial coverage tray, designed to fit over about three teeth (used when making crowns). The stock tray with the closest size and shape to the patient's own arch dimensions is selected for impressions.
Stock trays must meet various requirements in order to obtain a satisfactory impression. A good stock tray will:
Stock trays can be dentate or edentulous, and perforated (used with alginate) or non-perforated (allows the impression material to run through the holes and increase the bond of the impression material to the tray when set).
Plastic stock trays are generally injection moulded from a high-impact styrene such as polystyrene. The Triple Tray is a type of plastic tray used for taking impressions for a crown using the double arch or dual bite impression technique. It is used for taking impressions of the tooth preparation and the opposing teeth, by the use of a special impression material, usually elastomer. The accuracy of the results is however subject to the ability of the patient to close their teeth when the tray is present in the mouth. It cannot produce results of the complete arch, therefore its usefulness is limited.
Metal stock trays are often preferred over plastic stock trays, due to the lack of rigidity in plastic stock trays. Although expensive to purchase, they have the benefit of being reusable, so can be more cost-efficient in the long-term.
A special tray is an impression tray custom made for an individual patient by a denturist (dental technician), usually made from acrylic, such as polymethyl methacrylate , or shellac. A stock tray is used to make a preliminary impression, from which a model can be cast. This is then used for wax to make the tray to be laid down. The thickness corresponds to specific spacing, and can be classed as spaced, where about 3mm of space is left between the tray and the mucosa for the impression material to occupy, or closely adapted, where less space is left for the impression material. This is determined by the impression material to be used.
Specific features can be given to the special tray to improve the accuracy of the impression such as a window which can help to record displaceable tissues such as flabby ridges when used with a less viscous impression material. Special trays can be given perforations if required by drilling holes in tray.
Customised trays have been less frequently used since the advent of putties. This is due to the putty providing good support for light bodied material, and showing very little dimensional change which provides a fine detailed dental impression. There is now a large increase in the variety of stock trays available.
Tray adhesives are used to ensure the retention of the impression material in the impression tray, with or without the presence of perforations, and are based on contact adhesive technology. Maximum retention can be achieved with the presence of both a tray adhesive and perforations in the impression tray. The adhesive is applied to the internal surface of the tray, as well as over the margins to ensure the binding of the outer edge of the impression material to the tray. A suitable amount of adhesive (usually two thin coats) should be applied to the tray to prevent pooling of the adhesive which can weaken the bond between the tray and impression material. The adhesive should be completely dried prior to impression-taking.
Tray adhesives usually come in a screw-top bottle with a brush attached to the lid that can be used for applying the adhesive. Overtime, the adhesive can accumulate around the cap, causing the evaporation of the solvent, and consequently the thickening of the adhesive. This can reduce the efficacy of the adhesive to bind to the tray.
Various tray adhesives are available, corresponding to the impression material used.
Digital impressions using extra-oral or intra-oral scanner systems are being adopted in dentistry. A model can be produced from the digital scan by milling or stereolithography . [ 6 ] [ 7 ]
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Dental insurance is a form of health insurance designed to pay a portion of the costs associated with dental care .
The American Dental Association has lobbied against the US government providing dental insurance coverage for all Medicare recipients. [ 1 ]
In the US, two-thirds of dentists do not accept dental insurance through Medicaid. [ 2 ] [ 3 ] Medicaid covers both basic and emergency dental care for children while it only covers emergency care for adult Medicaid recipients. [ 4 ]
With indemnity dental plans, the insurance company generally pays the dentist a percentage of the cost of services. Restrictions may include the co-payment requirements, waiting period , stated deductible , annual limitations, graduated percentage scales based on the type of procedure, and the length of time that the policy has been owned.
Dental Health Maintenance Organization plans entail dentists contracting with a dental insurance company that dentists agree to accept an insurance fee schedule and give their customers a reduced cost for services as an In-Network Provider. Many DHMO insurance plans have little or no waiting periods and no annual maximum benefit limitations, while covering major dental work near the start of the policy period. This plan is sometimes purchased to help defray the high cost of the dental procedures. Some dental insurance plans offer free semi-annual preventive treatment. Fillings, crowns, implants, and dentures may have various limitations.
In the United States, Participating Provider Network or PPO, also referred to as Preferred Provider Organization, is an organization governed by medical doctors, hospitals, other health centers, and medical care providers. This organization has an agreement with an insurer or the third party administrator to provide health insurance to the people associated with their client at reduced or low rates. Participating Provider Network plan may work similar to a DHMO while using an In-Network facility. However, a PPO allows Out-of-Network or Non-Participating Providers to be used for service. Any difference of fees will become the financial responsibility of the patient, unless otherwise specified.
Dental insurance companies divide benefits, services, or procedures into categories and refer to them with American Dental Association (ADA) 3-4 digit code. As an example, Preventive and Diagnostic procedures often include exams (ADA code 0120), x-rays (ADA code 0210), and basic cleanings or prophylaxis (ADA code 1110). Basic procedures often include fillings , periodontics , endodontics , and oral surgery . Major procedures often are crowns , dentures , and implants . Procedures such as periodontics , endodontics , and oral surgery may be considered major, depending on the policy.
Some dental insurance plans may have an annual maximum benefit limit. Once the annual maximum benefit is exhausted any additional treatments may become the patient's responsibility. Each year, the annual maximum is reissued. The reissue date may vary as a calendar year, company fiscal year, or date of enrollment based on the specific plan.
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Dental intrusion is an apical displacement of the tooth into the alveolar bone . This injury is accompanied by extensive damage to periodontal ligament , cementum , disruption of the neurovascular supply to the pulp, and communication or fracture of the alveolar socket. [ 1 ]
Intrusive traumas have been found to comprise 0.3-1.9% of the traumas affecting permanent dentition.
In most cases of intrusion with fully erupted permanent dentition, diagnosis can be made by comparing incisal height of teeth next to the injured one. In cases with mixed dentition, a percussion test must be performed as an intruded tooth can mimic an erupting tooth.
Clinical findings show shortened crown length to various degree and up to no visible crown in severe cases. Tooth is immobile, and percussion gives high, metallic sound. Bleeding around crown margins can be observed. [ 2 ]
Radiographical findings shows dislocation of root in an apical direction, and periodontal ligament space is not continuous or can disappear completely. [ 2 ]
Management of intrusion depends on several factors such as whether the tooth has a closed or open apex, type of teeth (primary or permanent dentition) and how much the tooth is intruded in mm. This type of dental trauma is complex and is commonly associated with pulpal necrosis and inflammatory ankylosis. Management is focused on reducing this effect and is commonly achieved by root canal treatment.
[ 4 ]
Intruded teeth with closed apex will likely become necrotic. Recommended root canal therapy within 2–3 weeks after repositioning. Where surgical or orthodontic reposition required, after repositioning tooth must be stabilize with a flexible splint for 4 weeks.
Frequent follow up appointments are required to monitor healing process clinically and radiographically:
Dental trauma
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The dental key is an instrument that was used in dentistry to extract diseased teeth . Before the era of antibiotics , dental extraction was often the method of choice to treat dental infections , and extraction instruments date back several centuries.
The dental key, (also known as Clef de Garengeot , Fothergill -Key, English-Key, Dimppel Extractor or Tooth Key) was first mentioned in Alexander Monro 's Medical Essays and Observations in 1742, but had probably been in use since around 1730. It remained popular into the 20th century when it was replaced by the more modern forceps.
Modeled after a door key, the dental key was used by first inserting the instrument horizontally into the mouth, then its "claw" would be tightened over a tooth. The instrument was rotated to loosen the tooth. This often resulted in the tooth breaking, causing jaw fractures and soft tissue damage.
The design of the dental key evolved over the years. The original design featured a straight shaft, which caused it to exert pressure on the tooth next to the one being extracted. This led to a newer design in 1765 by F. J. Leber where the shaft was slightly bent. In 1796 the claw was fixed via a swivel enabling it to be set in various positions by a spring-catch. Newer designs, such as those manufactured by medical instrument maker Charriere featured interchangeable claws. By the end of the 19th century, the introduction of forceps made popular notably by Sir John Tomes , rendered the tooth key mostly obsolete. However, a modern version of the dental key, the Dimppel Extractor, briefly revitalized its use later in the 20th century.
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Dental laboratories manufacture or customize a variety of products to assist in the provision of oral health care by a licensed dentist. These products include crowns, bridges, dentures and other dental products. Dental lab technicians follow a prescription from a licensed dentist when manufacturing these items, which include prosthetic devices (such as denture teeth and implants) and therapeutic devices (such as orthodontic devices). The FDA regulates these products as medical devices [ 1 ] and they are therefore subject to FDA's good manufacturing practice ("GMP") and quality system ("QS") requirements. In most cases, however, they are exempt from manufacturer registration requirements. [ 2 ] Some of the most common restorations manufactured include crowns , bridges , dentures , and dental implants . Dental implants [ 3 ] is one of the most advanced dental technologies in the field of dentistry.
Certification in the dental laboratory profession is strictly voluntary. Laboratories who have taken the extra steps to become certified represent the top of their field. The most easily obtainable certification is the CDL (Certified Dental Laboratory). A Certified Dental Laboratory has met standards in personnel skill, training, infection control, tracking mechanisms and good business and manufacturing practices. The certification is based on a third party review of photos of the facility. [ 4 ] [ 5 ] The next tier for certification is DAMAS (Dental Appliance Manufacturers Audit Scheme). DAMAS requires a third party on-site inspection. Based on international standards for the manufacturing of medical devices, the DAMAS certification ensures the lab environment operates in such a way as to ensure product and patient safety. It provides a formula for improved documentation of many aspects of dental lab activity (from dental prescriptions to material traceability). [ 6 ] DAMAS standards mirror the FDA's quality system and good manufacturing practice standards, which all domestic dental laboratories must comply with. [ 7 ]
The highest level of manufacturing certifications available to dental laboratories are through the ISO "International Organization for Standardization". The ISO develops standards through the consensus of standards organizations from 161 countries. Members represent both the public and private sectors of countries around the world. ISO standards are thought to represent the best interests and needs of the broader global society. [ 8 ] ISO 9001 is a set of standards for quality management systems. [ 9 ] ISO 13485 is a set of standards, published in 2003, that represents the requirements for a comprehensive management system for the design and manufacture of medical devices. [ 10 ] It emphasizes meeting regulatory requirements and managing risk in order to ensure the production of safe design and distribution of medical devices. Product documentation is thorough and covers the entire life cycle of product design, manufacture and post-delivery. Although not considered a substitute, ISO 13485 will align a dental lab's management system not only with the FDA QS-GMP regulation, but various other regulatory requirements found throughout the world. [ 11 ]
The National Association of Dental Laboratories (NADL) was formed in the United States in 1951 after the merger of Dental Laboratory Institute of America and the American Dental Laboratory Association. It became a federation of state commercial dental laboratory associations. This merger took place in Chicago and then, in 1952, NADL established its headquarters offices in Washington, D.C. , which were moved to Tallahassee , Florida later in 2001.
The association was known as the National Association of Certified Dental Laboratories from 1968 to 1971 when it changed back to its original name. Its mission is to be the recognized advocate for the dental laboratory technology industry by promoting professionalism, setting technical standards and providing valued services to its membership. [ 12 ] The stated purpose of NADL is to uphold and advance the dignity, honor and efficiency of those engaged as operators of dental laboratories, to advance their standards of service to the dental profession and to establish cooperation among its members. [ 13 ]
NADL offers several benefits to its members and one of such benefits is that it promotes high standards and aims to work as a unified voice for the dental laboratory trade. [ 14 ] NADL establishes alliances with professional businesses to benefit its members with either discounts or services. Members also benefit from NADL's educational programs ranging from seminars, conferences, materials, the NADL University which offers a Certificate in Dental Laboratory Management, to the Wealth of Knowledge Videotape Library. These programs inform and educate NADL members on topics such as production, marketing, and promotion, and also serve as continuing education credits. Furthermore, this association offers the NADL Pillar Scholarship aimed to provide qualified dental technicians the opportunity to take the necessary examinations to complete the Certified Dental Technician examination process.
NADL also has its set of communications tools to keep its members informed about the industry trends. Two examples are the Journal of Dental Technology (JDT), a journal published 9 times a year, and JDT Unbound, a mail newsletter that includes regular updates.
Its Board of Directors comprises 14 members and its current President is Robert Savage. NADL also has an independent board, the National Board for Certification in Dental Laboratory Technology, founded in 1955 as an independent certification organization. [ 15 ] It administered the first Certified Dental Technician (CDT) tests in October 1958 and awarded the first CDT certificates in March of the following year.
CDTs can retain certification if they apply to the NBC every year for renewal and prove they have complied with the local laws governing their work and undergone continuing technical education. They are also required to pay a renewal fee .
It is in NADL best interests to protect the patients' health and assure their restorations are safe for use. To fulfill this objective, NADL has supported federal and state regulations since 2003 and has worked close with the U.S. Food and Drug Administration (FDA), state health officials and the dental industry as well. It has also developed regulatory guidelines aimed to be a basic standard of regulation. Although its main objective is to benefit the general public it is also intended to be effective for the dental technicians and the dental industry. One of the requests from NADL to the FDA has been to protect patient's safety. In this sense, the Association intends that the source of dental devices be disclosed to the patient.
NADL has expressed its support to establish mandatory certification and continuing education for dental technicians dedicated to restoration manufacture; mandatory registration of all dental laboratories with the competent authority; mandatory documentation of those materials used in any restoration and their point of origin; as well as mandatory documentation of the mentioned items in the patient's dental records. [ 16 ]
In their Guidelines for Establishing Statutory Regulation, NADL has noted that certification is a way to recognize individuals who have met established qualifications, therefore, they should be the only ones legally acknowledged to use the designated title.
All Dental Technicians and Clinical Dental Technicians in the UK are required by law to be registered with the General Dental Council (GDC). The GDC is an organisation which regulates all dentists and dental care professionals, they set and maintain standards in UK dentistry. [ 17 ]
Many of those who work for Dental Laboratories are also registered with the Dental Technologists Association (DTA). The DTA is a professional association representing the interests of dental technicians in the UK. [ 18 ]
The GDC ensures that dental professionals have the necessary qualifications and are trained to the necessary levels. Dental technicians must prove their knowledge is up-to-date by taking part in Continuing Professional Development (CPD).
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The dental midline is the midsagittal line of maxillary and mandibular dental arches possessing teeth of ideal size, shape, and position, when situated in maximum intercuspation. Each arch also possesses its own midline, which can be used to refer to the location of contact between the mesial surfaces of the central incisors . Thus, if an individual's mandibular teeth are shifted over to the left in a mesial-distal dimension, by 2 mm, for example, that individual's midline would be said to be deviated 2 mm to the left.
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Dental professionals, in writing or speech, use several different dental notation systems for associating information with a specific tooth. The three most common systems are the FDI World Dental Federation notation (ISO 3950), the Universal Numbering System , and the Palmer notation . The FDI notation is used worldwide, and the Universal is used widely in the United States. The FDI notation can be easily adapted to computerized charting.
Another system is used by paleoanthropologists .
A committee of the American Dental Association (ADA) recommended the use of the Palmer notation method in 1947.
Since Palmer notation method required the use of symbols, its use was difficult on keyboards. As a result, the association officially supported the Universal system in 1968. The World Health Organization and the Fédération Dentaire Internationale officially uses the two-digit numbering system of the FDI system.
However, in 1996, the ADA adopted the ISO System as an alternative to the Universal System.
The FDI World Dental Federation notation ("FDI notation" or "ISO 3950" [ 1 ] ) is widely used by dental professionals internationally to identify and describe a specific tooth.
The FDI notation uses a two-digit numbering system in which the first digit represents a tooth's quadrant and the second digit represents the number of the tooth from the midline of the face. For permanent teeth , the patient's upper right teeth begin with the number "1", the upper left teeth begin with the number "2", the lower left with "3", and the lower right with "4". For primary teeth, the sequence of numbers similarly is 5, 6, 7, and 8 for the teeth in the upper right, upper left, lower left, and lower right respectively. When speaking about a certain tooth such as the permanent maxillary central incisor , the notation is pronounced “one, one”. [ citation needed ]
Beware of mixing up the teeth in written form such as 11, 12, 13, 14, 15, 16, 17, 18 between the Universal and ISO systems. [ citation needed ]
For example: retention of a primary molar tooth in the otherwise regular intact lower right jaw, position 5, would be noted as: 41, 42, 43, 44, 85, 46, 47, 48.
Palmer notation is a system used by dentists to associate information with a specific tooth. It was originally termed the "Zsigmondy system" after the Hungarian dentist Adolf Zsigmondy who developed the idea in 1861, using a Zsigmondy cross to record quadrants of tooth positions. [ 2 ]
Permanent teeth (adult) were numbered 1 to 8, and the child primary dentition (also called deciduous, milk or baby teeth) were depicted with a quadrant grid using Roman numerals I, II, III, IV, V to number the teeth from the midline distally. Palmer changed this to A, B, C, D, E. [ citation needed ]
The Palmer notation consists of a symbol (┘└ ┐┌) designating the quadrant of the tooth and a number indicating the position from the midline. Adult teeth are numbered 1 to 8, with primary teeth indicated by a letter A to E. Hence the left and right maxillary central incisor would have the same number, "1", but the right one would have the symbol, "┘", underneath it, while the left one would have, "└". [ citation needed ]
Although supposedly superseded by the FDI World Dental Federation notation , it overwhelmingly continues to be the preferred method used by dental students and practitioners in the United Kingdom. [ 3 ]
Despite its name, the Universal Numbering System is commonly used only in the United States. It is also called the "American system". [ 4 ]
The uppercase letters A through T are used for primary teeth and the numbers 1 – 32 are used for permanent teeth. The tooth designated "1" is the maxillary right third molar (" wisdom tooth ") and the count continues along the upper teeth to the left side. Then the count begins at the mandibular left third molar, designated number 17, and continues along the bottom teeth to the right side. Each tooth has a unique number or letter , allowing for easier use on keyboards.
In alphanumeric notation (or "Letters and numbers system"), the four quadrants are designated as:
Within each quadrant, the teeth are numbered as in the Palmer notation: 1–8 for permanent and A-E for deciduous, both starting at the midline. For example, the permanent left maxillary first molar is designated UL6 .
To prevent uncertainty or ambiguity, teeth may be indicated using more than one notation, particularly when referring for an extraction; this makes it less likely for the incorrect tooth to be needlessly extracted. For instance, a dentist may give an instruction to "extract the 24 (UL4)" for the upper left first premolar tooth.
Paleoanthropologists use a system suitable to other primates as well. The upper teeth are denoted I 1 , I 2 , C − , Pm 3 , Pm 4 , M 1 , M 2 , and M 3 . Left or right has to be specified. The lower teeth are I 1 , I 2 , C − , Pm 3 , Pm 4 , M 1 , M 2 , and M 3 . The reason the premolars are labeled 3 and 4 is that in earlier primates there were two other premolars between them and the canines. [ 5 ]
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Dental pharmacology is the study of drugs used to treat conditions of the oral cavity . [ 1 ] [ citation needed ]
Some of these drugs include antibiotics , analgesics , anti-inflammatory drugs and anti- periodontitis agents. [ citation needed ]
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A dental prosthesis is an intraoral (inside the mouth ) prosthesis used to restore (reconstruct) intraoral defects such as missing teeth , missing parts of teeth, and missing soft or hard structures of the jaw and palate . [ 1 ] Prosthodontics is the dental specialty that focuses on dental prostheses. Such prostheses are used to rehabilitate mastication (chewing), improve aesthetics, and aid speech. A dental prosthesis may be held in place by connecting to teeth or dental implants , by suction, or by being held passively by surrounding muscles. Like other types of prostheses, they can either be fixed permanently or removable; fixed prosthodontics and removable dentures are made in many variations. Permanently fixed dental prostheses use dental adhesive or screws, to attach to teeth or dental implants. Removal prostheses may use friction against parallel hard surfaces and undercuts of adjacent teeth or dental implants, suction using the mucous retention (with or without aid from denture adhesives), and by exploiting the surrounding muscles and anatomical contours of the jaw to passively hold in place. [ 2 ]
Some examples of dental prostheses include:
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Dental Public Health is a para-clinical specialty of dentistry that deals with the prevention of oral disease and promotion of oral health. [ 1 ] [ 2 ] Dental public health is involved in the assessment of key dental health needs and coming up with effective solutions to improve the dental health of populations rather than individuals. [ 3 ]
Dental public health seeks to reduce demand on health care systems by redirection of resources to priority areas. [ 4 ] Countries around the world all face similar issues in relation to dental disease. Implementation of policies and principles varies due to availability of resources. Similar to public health , an understanding of the many factors that influence health will assist the implementation of effective strategies. [ 4 ]
Dental-related diseases are largely preventable. Public health dentistry is practiced generally through government-sponsored programs, directed for the most part to public-school children in the belief that their education in oral hygiene is the best way to reach the general public. The pattern for such programs in the past was a dental practitioner's annual visit to a school to lecture and to demonstrate proper tooth-brushing techniques.
In the 1970s a more elaborate program emerged. It included a week of one-hour sessions of instruction, demonstration, and questions and answers, conducted by a dentist and a dental assistant and aided by a teacher who had previously been given several hours of instruction. Use was also made of televised dental health education programs, which parents were encouraged to observe. [ 5 ]
Even with fluoridation and oral hygiene , tooth decay is still the most common diet–related disease affecting many people. Tooth decay has the economic impact of heart disease , obesity and diabetes . [ 6 ]
Tooth decay is, however, easily prevented by reducing acid demineralisation caused by the remaining dental plaque left on teeth after brushing. Risk factors for tooth decay include physical, biological, environmental, behavioural, and lifestyle-related factors such as high numbers of cariogenic bacteria , inadequate salivary flow, insufficient fluoride exposure, poor oral hygiene , inappropriate methods of feeding infants, and poverty. [ 7 ] Neutralising acids after eating and at least twice a day brushing with fluoridated toothpaste will assist prevention. [ 8 ]
Cavities can develop on any surface of a tooth , but are most common inside the pits and fissures in grooves on chewing surfaces. This is where the toothbrush bristles and fluoride toothpaste cannot reach effectively. [ 9 ]
Gum diseases gingivitis and periodontitis are caused by certain types of bacteria that accumulate in remaining dental plaque . The extent of gum disease depends a lot on host susceptibility. [ 10 ]
Daily brushing must include brushing of both the teeth and gums . Effective brushing itself, will prevent progression of both tooth decay and gum diseases . Neutralising acids after eating and at least twice a day brushing with fluoridated toothpaste will assist preventing dental decay . Stimulating saliva flow assists in the remineralisation process of teeth, this can be done by chewing sugar free gum. [ 7 ] Using an interdental device once daily will assist prevention of gum diseases . [ 10 ]
Fissure sealants applied over the chewing surfaces of teeth, block plaque from being trapped inside pits and fissures. The sealants make brushing more effective and prevent acid demineralisation and tooth decay. [ 11 ] A diet low in fermentable carbohydrates will reduce the buildup of plaque on teeth. [ 7 ]
The American Board of Dental Public Health devised a list of competencies for dental public health specialists to follow. [ 12 ] Dental public health specialists are a select group of certified dentists. The ten competencies allow for growth and learning of individuals and set expectations for the future. An advantage of the design is that they are implementable on a global level. The list is updated periodically. [ 12 ]
Major areas of dental public health activity include: [ 13 ] [ 14 ]
National Oral Health Surveillance system (NOHSS) is designed to monitor the effects of oral disease on the population, as well as monitor how the oral care is delivered. Additionally, the status of water fluoridation on both a state and a national level is continually supervised.
Dental health is concerned with promoting health of an entire population and focuses on an action at a community level, rather than at an individual clinical approach. Dental public health is a broad subject that seeks to expand the range of factors that influences peoples oral health and the most effective means of preventing and treating these oral health problems. [ 4 ]
To allow a health problem to be properly managed, a set of rules or criteria may determine what is defined as a public health problem and what is the best way to manage health problems in communities. [ 4 ] Once these questions have been answered, the way a public health problem is acted upon to protect a population can be determined. [ 4 ]
Water fluoridation is the implementation of artificial fluoride in public water supplies with the intentions to halt the progression of dental diseases. [ 15 ] Fluoride has the ability to interfere with the demineralisation and remineralisation process that occurs on the tooth surface and improves the mineral intake when the pH level may reduce below the neutral pH level. [ 16 ]
This achievement was implemented through the public health development in the 19th, 20th century and led into the 21st century. Research into the effects of fluoride on teeth began due to the concern about the presence of dental fluorosis . [ 17 ]
Many clinical case trials occurred in the beginning of the 20th century. However, the very first clinical trial to have occurred dates back to the 19th century when Denninger conducted a trial prescribing children and pregnant women with calcium fluoride . [ 16 ] From this trial, it was recognised fluoride's significance on tooth tissue. From this point, many clinical trials were conducted [ 15 ] Following these studies, the recognition of the positive outcome on dental tissues became clear and projects in water fluoridation became of significant importance. [ 18 ]
The development of artificial water fluoridation began in 1945 in Grand Rapids, Michigan followed by Newburgh, New York and Evanston, Illinois. [ 19 ] In 1955, three towns Watford, Kilmarnock and Anglesey trialled the water fluoridation implementation scheme. [ 15 ] In 1960, the Republic of Ireland implemented all public water supplies with artificial fluoridated water and four years later extending this into the main cities of Dublin and Cork. [ 15 ]
40 countries have fluoridated water schemes implemented. Fluoride is still yet to be completely implemented across the full population . Progress is slowly improving and access is becoming more common. [ 15 ]
Prevention methods such as oral health promotion began with the education of clinicians and the population in the health promotion strategies. Since the mid 19th century, oral health practice has revolved more around prevention and education rather than treatment of disease. [ 21 ] This education can be focused towards dental practitioners and to the wider population who may interested. [ 22 ]
There has been a change in focus in the education of developing clinicians all over the world. The first dental school was developed in 1828 [ 23 ] and was followed by an ever-growing field of practice. The dental practice began with its main focus on the treatment of oral disease and branched into a wide scope of practice with many dental occupations involved. [ 24 ]
The most common form of dental clinicians are either general dentists, oral health therapists, dental therapists and dental hygienist . When desired, some of these clinicians may seek further experience in projects that may assist the dental public system in bringing further awareness to prevention of dental diseases. [ 25 ]
Oral health prevention is the current form of practice of many clinicians. Health professionals generally prefer education in oral care to the population to the treatment of the disease. Dental university education develops clinicians to focus on the education of patients, education of the community and a wider population using different approaches. [ 21 ]
Oral health promotion outlines the strategies for improving and educating the general public about how they can better take improve and maintain their current oral health. Oral health promotion is part of both government and private incentives to create a healthier and better educated generation of individuals. [ 26 ]
Below are the nine key principles involved for oral health promotion: [ 27 ]
Three ways to achieve oral health promotion include addressing the determinants of oral health, ensuring community participation, and implementing a strategy approach that involves a range of complementary actions. [ 27 ]
Oral health promotion focuses on individual behaviour, socioeconomic status and environmental factors. Underlying determinants, including non-milk extrinsic sugars consumption, alcohol consumption and smoking, can impact oral health. [ 27 ]
The ability to remove dental plaque, exposure to fluoride and access to quality dental care can affect the ways the aforementioned underlying factors are and can be modified to the needs of the individual to obtain optimum oral health. [ 27 ] Ways in which oral health promotion can minimise the effects of these determinants include:
These factors are also influenced by sociopolitical considerations that are outside the control of most individuals. [ 27 ]
Community participation is a key factor in oral health promotion. Inter-sectoral collaboration is where relevant agencies and sectors are involved in partnership to identify key oral health issues and to implement new methods to improve oral health. [ 27 ]
The World Health Organization has agreed on a health promotion approach as the foundation for oral health improvement strategies and policies for the population. Oral health promotion is based on the principles of the framework, Ottawa Charter . There are five areas of action outlined to achieve oral health promotion; building Health public policy, creating supportive environment, strengthening community action, developing personal skills, re-orienting healthcare services. [ 26 ]
A study investigating the efficacy of staff workers' oral care education on improving the oral health of care home residents found that despite the education and training of care workers, certain ongoing barriers prevented them from conducting the necessary daily oral hygiene care for the residents. The most frequently listed obstacles to care included the residents' bad breath, inadequate time to perform oral care and uncooperative residents who do not perceive the need for oral care. [ 29 ]
Another study on the effects of oral health educational interventions for nursing home staff or residents, or both, to maintain or improve the oral health for nursing home residents shows insufficient supporting evidence. [ 30 ]
It is unclear whether or not school screening programs improve attendance at the dentist. There is low-certainty evidence that school screening initiatives with incentives attached, such as free treatment, may be helpful in improving oral health of children. [ 31 ]
One-to-one oral hygiene advice (OHA) is often given on a regular basis to motivate individuals and to improve one's oral health. However, it is still unclear if one-to-one OHA in a dental settings is effective in improving one's oral health. [ 32 ] Regardless of the increased oral hygiene education programs in schools due to the higher quality of life, there is an increased intake of processed food, especially of sweetened beverages. [ 33 ] The favorable effect of the increased level of dental health education may be counteracted by nutritional behavior, especially sweets intake and low attendance of regular dental office check-ups and insufficient oral health practices (tooth brushing) generating a still increased caries prevalence and DMFT index in adolescents. [ 34 ] Irregular dental check-up and sugary dietary habits were associated with high prevalence the occurrence of dental conditions as assessed by the decayed, missing (due to caries), and filled teeth (DMFT) index. [ 35 ]
A systematic review sought to determine the effectiveness of different interventions in preventing dental caries in children and when was the most effective time to intervene during childhood. Overall, the evidence showed low certainty that combining oral health education alongside supervised tooth-brushing or professional intervention would reduce dental caries in children (from birth to 18). The most effective time to intervene in childhood was still unclear as well. Improving the diets of children and the access to fluoride showed only a limited impact to improving the oral health of children. [ 36 ]
To find out if a child is eligible, families can contact the Department of Human Services [ 37 ]
In 1985 three dentists with the sponsorship of Colonel Joy Wheeler Dow, Jr., implemented an Oral Health Program in the Autonomous Region of Madeira with the aid of five assistants.
The four-year program reached 15,000 children around the main island and Porto Santo and it included Oral Hygiene Instruction classes, informative literature including films, fortnightly fluoride mouth-rinse and daily fluoride tables with the collaboration of the school teachers.
During this period a study was undertaken using the World Health Organization (WHO) Combined Oral Health Assessment (CPTIN) plan resulting in the final report where it was found that there had been a decrease of 44% in the need for fillings, 40% decrease in the need for extractions, whilst the caries free children population grew from the initial 1% to 5%.
National Health Service (NHS) is the name of the public health services of England, Scotland and Wales and is directly funded from taxation . The dentistry services are available to all, regardless of wealth. In order to find a NHS dentist search NHS Dentist Near You Some clinics may not have the capacity to take on new patients so waiting lists may occur. [ 38 ]
All treatment deemed necessary to maintain optimal oral health will be provided by the dentist, however not all treatments will be funded by the Dentistry NHS and will incur private fees. [ 38 ]
Dentistry performed under the Dentistry NHS will involve fees, however are heavily subsidized by the government, below is some information which explains how the fee system works, only one charge is required per treatment course of care, regardless of the amount of appointments needed. [ 38 ]
[ 38 ]
Nepalese population is at a greater disadvantage than westernized societies in terms of oral health. The benefit of implementing health insurance is to assist a large number of people with similar risks by sharing funding. [ 39 ] In Nepal, implementing health insurance is difficult due to limited supply of finances. To assist families with accessing health care “elimination of direct payments is necessary but is not sufficient alone; costs of transportation and loss of income can have more impact than direct payment of services” must be considered. [ 39 ]
For more information, you can access the Around Good People fact sheet Archived 2017-03-15 at the Wayback Machine
The earliest known person identified as a dental practitioner dates back to 2600BC, an Egyptian scribe states that he was ‘the greatest of those who deal with teeth ad of physicians’ [ citation needed ]
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Dental pulp stem cells ( DPSCs ) are stem cells present in the dental pulp , which is the soft living tissue within teeth . DPSCs can be collected from dental pulp by means of a non-invasive practice. It can be performed with an adult after simple extraction or to the young after surgical extraction of wisdom teeth. [ 1 ] They are pluripotent , as they can form embryoid body -like structures (EBs) in vitro and teratoma -like structures that contained tissues derived from all three embryonic germ layers when injected in nude mice. [ 2 ] DPSCs can differentiate in vitro into tissues that have similar characteristics to mesoderm , endoderm and ectoderm layers. [ 2 ] They can differentiate into many cell types, such as odontoblasts, neural progenitors, osteoblasts, chondrocytes, and adipocytes. DPSCs were found to be able to differentiate into adipocytes and neural-like cells. [ 3 ] DPSC differentiation into osteogenic lines is enhanced in 3D condition and hypoxia. [ 4 ] These cells can be obtained from postnatal teeth, wisdom teeth, and deciduous teeth , providing researchers with a non-invasive method of extracting stem cells. [ 5 ] The different cell populations, however, differ in certain aspects of their growth rate in culture, marker gene expression and cell differentiation, although the extent to which these differences can be attributed to tissue of origin, function or culture conditions remains unclear. [ 6 ] As a result, DPSCs have been thought of as an extremely promising source of cells used in endogenous tissue engineering. [ 7 ]
Studies have shown that the proliferation rate of DPSCs is 30% higher than in other stem cells, such as bone marrow stromal stem cells (BMSSCs). [ 8 ] These characteristics of DPSCs are mainly due to the fact that they exhibit elevated amounts of cell cycling molecules, one being cyclin-dependent kinase 6 (CDK6), present in the dental pulp tissue. [ 8 ] Additionally, DPSCs have displayed lower immunogenicity than MSCs. [ 9 ]
Atari et al., established a protocol for isolating and identifying the subpopulations of dental pulp pluripotent-like stem cells (DPPSC). These cells are SSEA4+, OCT3/4+, NANOG+, SOX2+, LIN28+, CD13+, CD105+, CD34-, CD45-, CD90+, CD29+, CD73+, STRO1+, and CD146-, and they show genetic stability in vitro based on genomic analysis with a newly described CGH technique. [ 2 ]
The human mouth is vulnerable to craniofacial defects, microbial attacks, and traumatic damages. [ 10 ] Although preclinical and clinical partial regeneration of dental tissues has shown success, the creation of an entire tooth from DPSCs is not yet possible. [ 10 ]
Distraction osteogenesis (DO) is a method of bone regeneration, commonly used in the surgical repair of large craniofacial defects. [ 7 ] The area in which the defect is present is purposely broken in surgery, allowed to heal briefly, and then the bone segments are gradually separated until the area has healed satisfactorily. A study conducted in 2018 by Song et al. found that DPSCs transfected with Sirtuin-1 (SIRT1) in rabbits were more effective in promoting bone formation during DO. [ 7 ] SIRT1 directly regulated MSCs into osteoblasts which then shows the accumulation of significantly higher levels of calcium after osteogenic differentiation in vitro, suggesting the potential role of DPSCs in enhancing the efficiency of DO. [ 7 ]
Calcine tooth powder (CTP) is obtained by burning extracted teeth, destroying the potential infection-causing material within the tooth, resulting in tooth ash [ 11 ] Tooth ash has been shown to promote bone repair. [ 12 ] Although recent studies have shown that calcine tooth powder- culture media (CTP-CM) does not affect proliferation, they have shown that CTP-CM has significantly increased levels of osteo/odontogenic markers in DPSCs. [ 11 ]
Stem cells from human exfoliated deciduous teeth (SHED) are similar to DPSCs in the sense that they are both derived from the dental pulp, but SHED are derived from baby teeth, whereas DPSCs are derived from adult teeth. SHED are a population of multipotent stem cells that are easily collected, as deciduous teeth either shed naturally or are physically removed in order to facilitate the proper growth of permanent teeth . [ 13 ] [ 14 ] These cells can differentiate into osteocytes , adipocytes , odontoblast , and chondrocytes in vitro . [ 14 ] Recent work has shown the enhanced proliferative capabilities of SHED when compared with that of dental pulp stem cells. [ 14 ]
Studies have shown that under the influence of oxidative stress , SHED (OST-SHED) displayed increased levels of neuronal protection. [ 15 ] The properties of these cells exhibited in this study suggest that OST-SHED could potentially prevent of oxidative stress-induced brain damage and could aid in the development of therapeutic tools for neurodegenerative disorders. [ 15 ] After SHED injection into Goto-Kakizaki rats, type II diabetes mellitus (T2DM) was ameliorated, suggesting the potential for SHED in T2DM therapies. [ 16 ]
Recent studies have also shown that the administration of SHED in mice ameliorated the T cell immune imbalance in allergic rhinitis (AR), suggesting the cells' potential in future AR treatments. [ 17 ] After introducing SHED, mice experienced reduced nasal symptoms and decreased inflammatory infiltration. [ 17 ] SHEDs were found to inhibit the proliferation of T lymphocytes, increase levels of an anti-inflammatory cytokine, IL-10 , and decrease the levels of a pro-inflammatory cytokine, IL-4 . [ 17 ]
Additionally, SHED can potentially treat liver cirrhosis . [ 18 ] In a study conducted by Yokoyama et al. (2019), SHED were differentiated into hepatic stellate cells . [ 18 ] They found that when hepatic cells derived from SHED were transplanted into the liver of rats, liver fibrosis was terminated, allowing for the healing of the liver structure. [ 18 ]
[ 30 ]
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Dental pulpal testing is a clinical and diagnostic aid used in dentistry to help establish the health of the dental pulp within the pulp chamber and root canals of a tooth. Such investigations are important in aiding dentists in devising a treatment plan for the tooth being tested.
There are two major types of dental pulp tests. Vitality testing assesses the blood supply to the tooth, whilst sensitivity testing tests the sensory supply.
Dental pulp tests are valuable techniques used to establish the pulpal health status of a tooth in dentistry. The diagnostic information obtained from pulpal testing is then used alongside a patient's history, clinical and radiographic findings to determine a diagnosis and prognosis of the tooth.
Pulp tests are useful for the following procedures in dentistry:
Pulpal tests may be conducted via stimulation of the sensory fibres within the pulp (sensitivity testing) or by assessing pulpal blood flow (vitality testing). All available techniques are reported to have limitations in terms of accuracy and reproducibility [ 1 ] and therefore require careful interpretation in clinical practice.
Sensitivity tests assess the sensory response of a tooth to an external stimulus, results which may be extrapolated to indirectly determine pulpal health status. Sensory stimuli, such as heat, cold or an electrical current, are applied to the tooth in question in order to stimulate the nocireceptors within the pulp. The type of sensory fibres activated and therefore the response felt by the patient depends on the stimulus used. Sensibility testing is based on Brännström's hydrodynamic theory , which postulates that the activation of nocireceptors is caused by fluid movement within the dentinal tubules in response to thermal, electrical, mechanical or osmotic stimuli. [ 2 ]
There are three primary outcomes of a pulp sensitivity test:
Thermal testing, which involves the application of either hot or cold stimuli to the tooth, is the most common form of sensibility test.
A number of products are available for cold testing, each with varying melting points. Although household ice (0 °C [32 °F]) is cheap and easy to obtain, it is not as accurate as colder products. [ 3 ] Dry ice (−78 °C [−108 °F]) can be used, however there have been concerns regarding the damaging effects of using something so cold in the oral cavity [ 4 ] despite evidence to suggest that dry ice has no negative impact on mucosal [ 5 ] or tooth structure. [ 6 ] [ 7 ] Refrigerant sprays, such as ethyl chloride (−12.3 °C [9.9 °F]), 1,1,1,2-tetrafluoroethane (−26.5 °C [−15.7 °F]) or a propane/butane/isobutane gas mixture are further commonly used cold tests. Cold testing is thought to stimulate Type Aδ fibres in the pulpal tissue, which elicit a short, sharp pain.
Heat tests include using heated instruments, such as a ball-ended probe or gutta-percha , a rubber commonly used in root canal procedures. Such tests are less commonly used as they are thought to be less accurate than cold tests, and may be more likely to cause damage to the teeth and surrounding mucosa. [ 4 ]
An electrical current can be applied to the tooth in order to generate an action potential in the Type Aδ fibres within pulp, eliciting a neurological response. Such tests are conducted by applying a conducting medium (e.g. toothpaste) on a dried tooth and placing the probe tip of an electric pulp tester on the surface of the tooth closest to the pulp horn(s). The patient is then directed to hold the end of the conducting probe to complete the circuit and asked to let go of the probe when a ‘tingling’ sensation [ 8 ] is felt.
The use of electric pulp testing has been questioned in patients with traditional cardiac pacemakers despite no evidence of interferences in humans, particularly with more modern devices. [ 4 ] Care must be taken if using an electric pulp test on a tooth adjacent to metallic restorations, as these can create electrical conduction and yield false negative results.
When pulp testing results are inconclusive and that patients cannot localise or specify the pain or symptoms, an anaesthetic would be helpful and be used. The most posterior tooth in the area where the pain resonates undergoes anaesthesia by either infiltration or intraligamentary injection until pain diminishes. If the pain is still present, the procedure is repeated on the mesial teeth, one by one until the pain diminishes and is gone. If one can still not determine the source of the pain, the procedure will be repeated on the opposite arch. In the case that the pain cannot be localised to either the maxillary or mandibular arch, an inferior alveolar nerve block would be used. If the pain stops, such would imply that it involves teeth of the mandibular arch. [ 9 ]
The test cavity technique is only used as a last resort when results produced by all other methods above are inconclusive. High-speed burs are used without anaesthetic, drilling through enamel, or restorations to dentine. Throughout the drilling process, the patient is asked whether a painful sensation is felt, which would indicate pulpal vitality. In the event of a vital pulp, a painful response is provoked when dentin is contacted by the bur and the procedure will be stopped. A restoration would be then placed. Contrarily, when compared with vital pulp, pulp with partial necrosis will not be stimulated as extensively. In the case of partial necrosis, access to and into dentine would be needed, with the dentist progressively invading and drilling deeper into dentine, checking the sensory response—which is usually without sensory response because of the partial necrosis. Due to the invasiveness and possible anxiety that it may generate in patients, the test cavity technique is generally avoided. Also, there is little literature supporting its effectiveness, and it has been relatively anecdotal within clinical practice. [ 9 ]
All tests have some limitations and test results should be interpreted by an experienced dentist under the bidirectional consideration of both clinical symptoms and radiography. Sensitivity tests only indicate the presence or absence of the nerve supply to an individual tooth. Even though a prolonged response to aforementioned tests indicate pulpal inflammation, the degree of inflammation or innervation cannot be inferred from these tests.
False positive or false negative results are possible when performing a sensitivity testing. A false positive response occurs when a patient is respondent to sensitivity testing despite a lack of sensory tissue in the tooth that is being tested. Such responses may occur due to innervation of adjacent teeth due to inadequate isolation of the tooth being tested, or in anxious patients who perceive pain despite no sensory stimulus, or in multi-rooted teeth which still have residual pulpal tissue residing in canals. [ 10 ] [ 11 ] False negative results occurs when innervated teeth do not respond to sensibility testing. Such can occur in individuals who have recently traumatised teeth, teeth with incomplete root development, teeth with heavy restorations or teeth that have significantly reduced pulp size due to production of tertiary or sclerotic dentine. [ 12 ]
Pulpal sensitivity testing may be regarded as inferior to vitality testing as they do not definitively prove that the tooth has a blood supply and is vital. Nonetheless, electric pulp testing and cold testing tests have been found to be accurate and reliable in the case of assessing pulpal health, especially when tests are used in combination. [ 13 ] [ 14 ] In addition, cold testing is also more accurate than electric pulp in the case of running tests upon immature or traumatised teeth. [ 15 ]
Despite the insights gained from sensitivity testing, a research study found that the density of nerve fibers and blood vessels in the pulp tissue, and the degree of oxygen saturation, may play a crucial role in interpreting the results. The presence of a higher density of nerve fibers may contribute to a lower threshold for electrical stimulation, suggesting the involvement of neural factors in pulp sensibility. Moreover, the positive correlation between blood vessel density and oxygen saturation, as well as the negative correlation between nerve fiber density and electrical voltage perception, provide valuable insights into the complex nature of dental pulp. Therefore, in addition to the standard sensitivity testing, more objective and accurate methods such as pulse oximetry might be necessary for a comprehensive understanding of pulp vitality. However, the findings of this study should be generalized with caution due to its small sample size and focus on healthy teeth extracted for orthodontic reasons. [ 16 ]
Vitality tests assess the vascular supply of a tooth. Vascular supply is generally accepted as the earliest indicator of pulpal health. [ 17 ] [ 18 ] However, vitality tests have limitations and require strict adherence to correct application techniques. [ 14 ] The diagnostic methods to assess the vascular response of the pulp include:
Laser Doppler flowmetry is able to assess blood flow within the dental pulp directly. A laser beam directed onto the tooth follows the path of dentinal tubules to the pulp. [ 19 ] The viability of the vascular supply of the pulp is determined by the output signal generated by the backscattered reflected light from circulating blood cells. [ 20 ] The reflected light is Doppler-shifted and has a different frequency to those reflected by the surrounding tissues which are static. An arbitrary unit of measurement, ‘perfusion unit’ (PU), is used to measure the concentration and velocity (flux) of blood cells. [ 19 ] [ 21 ] The output of laser Doppler flowmetry may be influenced by the blood flow in surrounding tissues, and therefore the test tooth must be adequately isolated to avoid inaccuracies. [ 22 ]
Pulse oximetry utilises the difference in red and infrared light absorption by oxygenated and deoxygenated red blood cells within blood circulation to determine the oxygen saturation level (SaO2). [ 23 ] [ 24 ] Pulse oximetry, as well as laser Doppler flowmetry vitality tests may not truly reflect the real state of health of the dental pulp. This mainly happens in clinical scenarios when the dental pulp is diseased, yet a viable blood supply is maintained. [ 14 ] In a study from Slovenia, correlations were found between clinical tests and histological analysis of dental pulp in 26 healthy permanent premolars extracted for orthodontic reasons. It was found that a higher density of blood vessels in the pulp tissue corresponded to increased oxygen saturation levels measured through pulse oximetry, lending support to the validity of pulse oximetry as a reliable method for assessing pulp vitality. Furthermore, teeth with closed apices had a higher density of nerve fibers in the upper part of the dental pulp compared to teeth with open apices. This further indicated individual variations in sensitivity, with teeth showing a higher density of nerve fibers having a lower threshold for electrical stimulation. [ 25 ]
The use of dual wavelength light establishes the contents within the pulp chamber. [ 26 ]
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Dental radiographs , commonly known as X-rays , are radiographs used to diagnose hidden dental structures, malignant or benign masses , bone loss , and cavities .
A radiographic image is formed by a controlled burst of X-ray radiation which penetrates oral structures at different levels, depending on varying anatomical densities, before striking the film or sensor. Teeth appear lighter because less radiation penetrates them to reach the film. Dental caries , infections and other changes in the bone density, and the periodontal ligament , appear darker because X-rays readily penetrate these less dense structures. Dental restorations (fillings, crowns) may appear lighter or darker, depending on the density of the material.
The dosage of X-ray radiation received by a dental patient is typically small (around 0.150 mSv for a full mouth series [ 1 ] ), equivalent to a few days' worth of background environmental radiation exposure, or similar to the dose received during a cross-country airplane flight (concentrated into one short burst aimed at a small area). Incidental exposure is further reduced by the use of a lead shield, lead apron, sometimes with a lead thyroid collar. Technician exposure is reduced by stepping out of the room, or behind adequate shielding material, when the X-ray source is activated.
Once photographic film has been exposed to X-ray radiation, it needs to be developed, traditionally using a process where the film is exposed to a series of chemicals in a dark room, as the films are sensitive to normal light. This can be a time-consuming process, and incorrect exposures or mistakes in the development process can necessitate retakes, exposing the patient to additional radiation. Digital X-rays, which replace the film with an electronic sensor, address some of these issues, and are becoming widely used in dentistry as the technology evolves. They may require less radiation and are processed much more quickly than conventional radiographic films, often instantly viewable on a computer. However digital sensors are extremely costly and have historically had poor resolution , though this is much improved in modern sensors.
It is possible for both tooth decay and periodontal disease to be missed during a clinical exam, and radiographic evaluation of the dental and periodontal tissues is a critical segment of the comprehensive oral examination. The photographic montage at right depicts a situation in which extensive decay had been overlooked by a number of dentists prior to radiographic evaluation.
Placing the radiographic film or sensor inside the mouth produces an intraoral radiographic view.
Periapical radiographs are taken to evaluate the periapical area of the tooth and surrounding bone [ 2 ]
For periapical radiographs, the film or digital receptor should be placed parallel vertically to the full length of the teeth being imaged. [ 3 ]
The main indications for periapical radiography are [ 4 ]
Intraoral periapical radiographs are widely used for the preoperative due to its simple technique, low cost and less radiation exposure and widely available in clinical settings. [ 7 ]
The bitewing view is taken to visualize the crowns of the posterior teeth and the height of the alveolar bone in relation to the cementoenamel junctions , which are the demarcation lines on the teeth which separate tooth crown from tooth root. Routine bitewing radiographs are commonly used to examine for interdental caries and recurrent caries under existing restorations. When there is extensive bone loss, the films may be situated with their longer dimension in the vertical axis so as to better visualize their levels in relation to the teeth. Because bitewing views are taken from a more or less perpendicular angle to the buccal surface of the teeth, they more accurately exhibit the bone levels than do periapical views. Bitewings of the anterior teeth are not routinely taken.
The name bitewing refers to a little tab of paper or plastic situated in the center of the X-ray film, which when bitten on, allows the film to hover so that it captures an even amount of maxillary and mandibular information.
The occlusal view reveals the skeletal or pathologic anatomy of either the floor of the mouth or the palate . The occlusal film, which is about three to four times the size of the film used to take a periapical or bitewing, is inserted into the mouth so as to entirely separate the maxillary and mandibular teeth, and the film is exposed either from under the chin or angled down from the top of the nose. Sometimes, it is placed in the inside of the cheek to confirm the presence of a sialolith in Stenson's duct, which carries saliva from the parotid gland . The occlusal view is not included in the standard full mouth series.
1. Anterior oblique occlusal mandible – 45°
Technique: the collimator is positioned in the midline, thru the chin aiming an angle of 45° to the image receptor which is placed centrally into the mouth, on to the occlusal surface of the lower arch.
Indications:
1) Periapical status of lower incisor teeth for patients who cannot tolerate periapical radiographs.
2) Assess the size of lesions such as cyst or tumours at anterior area of mandible
2. Lateral oblique occlusal mandible – 45°
Technique: The collimator is positioned from below and behind the angle of mandible and parallel to the lingual surface of the mandible, aiming upwards and forwards at the image receptors which is placed centrally into the mouth, on to the occlusal surface of lower arch. Patients must turn their head away from the side of investigation.
Indications:
1) Detection of any sialoliths in submandibular salivary glands
2) Used to demonstrate unerupted lower 8's
3) Assess the size of lesions such as cyst or tumours in the posterior of body and angle of mandible [ 4 ]
A full mouth series is a complete set of intraoral X-rays taken of a patients' teeth and adjacent hard tissue. [ 8 ] This is often abbreviated as either FMS or FMX (or CMRS, meaning Complete Mouth Radiographic Series). The full mouth series is composed of 18 films, taken the same day:
The Faculty of General Dental Practice of the Royal College of Surgeons of England publication Selection Criteria in Dental Radiography [ citation needed ] holds that given current evidence full mouth series are to be discouraged due to the large numbers of radiographs involved, many of which will not be necessary for the patient's treatment. An alternative approach using bitewing screening with selected periapical views is suggested as a method of minimising radiation dose to the patient while maximizing diagnostic yield. Contrary to advice that emphasises only conducting radiographs when in the patient's interest, recent evidence suggests that they are used more frequently when dentists are paid under fee-for-service [ 9 ]
Accurate positioning is of utmost importance to produce diagnostic radiographs and to avoid retakes, hence minimizing the radiation exposure of the patient. [ 10 ] The requirements for ideal positioning include: [ 4 ]
However, the anatomy of the oral cavity makes it challenging to satisfy the ideal positioning requirements. Two different techniques have hence been developed to be utilised in the undertaking of an intra-oral radiograph – Paralleling technique and Bisected angle technique. It is generally accepted that the paralleling technique offers more advantages than disadvantages, and gives a more reflective image, as compared to the bisecting angle technique. [ 11 ]
This can be used for both periapical and bitewing radiographs. The image receptor is placed in a holder and positioned parallel to the long axis of the tooth being imaged. The X-ray tube head is aimed at right angles, both vertically and horizontally, to both the tooth and the image receptor. This positioning has the potential to satisfy four out of the five above requirements – the tooth and image receptor cannot be in contact whilst they are parallel. Because of this separation, a long focus-to-skin distance is required to prevent magnification. [ 4 ]
This technique is advantageous as the teeth are viewed exactly parallel with the central ray and therefore there are minimal levels of object distortion. [ 12 ] With the use of this technique, the positioning can be duplicated with the use of film holders. This makes the recreation of the image is possible, which allows for future comparison. [ 4 ] There is some evidence that the use of the paralleling technique reduces the radiation hazard to the thyroid gland, as compared to the use of the bisecting angle technique. [ 12 ] This technique, however, may be impossible in some patients due to their anatomy, e.g. a shallow/flat palate. [ 4 ]
The bisecting angle technique is an older method for periapical radiography. It can be a useful alternative technique when the ideal receptor placement using the paralleling technique cannot be achieved, for reasons such as anatomical obstacles e.g. tori, shallow palate, shallow floor of mouth, or narrow arch width. [ 13 ]
This technique is based on the principle of aiming the central ray of the X-ray beam at 90° to an imaginary line which bisects the angle formed by the long axis of the tooth and the plane of the receptor. [ 12 ] The image receptor is placed as close as possible to the tooth under investigation, without bending the packet. Applying the geometrical principle of similar triangles, the length of the tooth on the image will be the same as that of the actual length of the tooth in the mouth. [ 4 ]
The many inherent variables can inevitably result in image distortion and reproducible views are not possible with this technique. [ 14 ] An incorrect vertical tube head angulation will result in foreshortening or elongation of the image, while an incorrect horizontal tube head angulation will cause overlapping of the crowns and roots of teeth. [ 4 ]
Many frequent errors that arise from the bisecting angle technique include: improper film positioning, incorrect vertical angulation, cone-cutting, and incorrect horizontal angulation. [ 15 ]
Placing the photographic film or sensor outside the mouth, on the opposite side of the head from the X-ray source, produces an extra-oral radiographic view.
A lateral cephalogram is used to evaluate dentofacial proportions and clarify the anatomic basis for a malocclusion, and an antero-posterior radiograph provides a face-forward view.
Lateral cephalometric radiography (LCR) is a standardized and reproducible form of skull radiography [ 4 ] taken from the side of the face with precise positioning. [ 16 ] It is used primarily in orthodontics and orthognathic surgery to assess the relationship of the teeth to the jaws, and the jaws to the rest of the facial skeleton. [ 4 ] LCR is analyzed using cephalometric tracing or digitizing to obtain maximum clinical information. [ 17 ]
Indications of LCR include: [ 4 ]
Panoramic films are extraoral films, in which the film is exposed while outside the patient's mouth, and they were developed by the United States Army as a quick way to get an overall view of a soldier's oral health. Exposing eighteen films per soldier was very time consuming, and it was felt that a single panoramic film could speed up the process of examining and assessing the dental health of the soldiers; as soldiers with toothache were incapacitated from duty. It was later discovered that while panoramic films can prove very useful in detecting and localizing mandibular fractures and other pathologic entities of the mandible, they were not very good at assessing periodontal bone loss or tooth decay. [ 18 ]
There is increasing use of CT (computed tomography ) scans in dentistry, particularly to plan dental implants; [ 19 ] there may be significant levels of radiation and potential risk. Specially designed CBCT (cone beam CT) scanners can be used instead, which produce adequate imaging with a stated tenfold reduction in radiation. [ 20 ] Although computed tomography offers high quality images and accuracy, [ 21 ] the radiation dose of the scans is higher than the other conventional radiography views, and its use should be justified. [ 22 ] [ 23 ] Controversy surrounds the degree of radiation reduction though as the highest quality cone beam scans use radiation doses not dissimilar to modern conventional CT scans. [ 24 ]
Cone beam computed tomography (CBCT), also known as digital volume tomography (DVT), is a special type of X-ray technology that generates 3D images. In the recent years, CBCT has been developed specifically for its use in the dental and maxillofacial areas [ 4 ] to overcome the limitations of 2D imaging such as buccolingual superimposition. [ 25 ] It is becoming the imaging modality of choice in certain clinical scenarios although clinical research justifies its limited use. [ 4 ]
Indications of CBCT, according to the SEDENTEXCT (Safety and Efficacy of a New and Emerging Dental X-ray Modality) guidelines include: [ 4 ] [ 26 ]
Developing dentition
Restoration of dentition (if conventional imaging is inadequate)
Surgical
Research A cross sectional diagnostic study compared and correlated bone sounding and open bone measurements with conventional radiograph and CBCT for periodontal disease. The study did not find any superior result of CBCT over the conventional techniques, except for lingual measurements. [ 27 ]
The concept of parallax was first introduced by Clark in 1909. It is defined as "the apparent displacement or difference in apparent direction of an object as seen from two different points not on a straight line with the object". [ 28 ] It is used to overcome the limitations of the 2D image in the assessment of relationships of structures in a 3D object.
It is mostly used to ascertain the position of an unerupted tooth in relation to the erupted ones (i.e. if the unerupted tooth is buccally / palatally placed / in line of the arch). [ 29 ] [ 30 ] Other indications for radiographic localization include: separating the multiple roots/canals of teeth in endodontics, assessing the displacement of fractures, or determining the expansion or destruction of bone.
With the rise in 3D radiographic techniques, the use of CBCT can be used to replace the undertaking of parallax radiographs, overcoming the limitations of the 2D radiographic technique. [ 33 ] In cases of impacted teeth, the image obtained via CBCT can determine the buccal-palatal position and angulation of the impacted tooth, as well as the proximity of it to the roots of adjacent teeth and the degree of root resorption, if any. [ 34 ]
Dental radiographs are an essential component to aid in diagnosis. Alongside an efficient clinical examination, a dental radiograph of a high quality can show essential diagnostic information crucial for the ongoing treatment planning for a patient. Of course when a dental radiograph is recorded many faults may arise. This is immensely variable due to differing use of: image receptor type, X-ray equipment, levels of training and processing materials etc.
As previously stated a major difference in dental radiography is the versatile use of film vs digital radiography. This in itself leads to a long list of faults associated with each type of image receptor. Some typical film faults are discussed below with a variety of reasons as to why that fault has occurred.
As film and digital are very different in how they work and how they are handled it is inevitable that their faults will also differ. Below is a list of some typical digital faults which may arise. It must be kept in mind that these also vary as per the type of digital image receptor which is used: [ 36 ]
The potential faults associated with the choice of image receptor used have been covered, it should also be noted that other faults elsewhere in the process of formulating an ideal diagnostic radiograph can occur. The majority of these have already been mentioned due to other faults but due to processing inaccuracies alone these may occur:
The training of staff is also an area which can lead to faults in the formulation of an ideal diagnostic radiograph. If someone is not adequately trained this can lead to discrepancies in pretty much any aspect in the process of achieving a diagnostic radiographic image. Below are some examples: [ 37 ]
It is inevitable that some faults may occur despite the efforts of prevention, so a set of criteria for what is an acceptable image has been created. This has to be implemented so that the amount of re-exposure to a patient is minimal in order to get a diagnostic image and to improve the manner in which radiographs are taken in practice.
When considering the quality of a radiographic image there are many factors which come into play. These can be split into sub-categories such as: Radiographic Technique, Type of image receptor (film or digital) and/or the processing of the image. [ 38 ] A combination of all these factors are taken into account alongside the quality of the image itself to determine a specific grade for the image to determine if it is up to a standard for diagnostic use or not.
The following grades have since been updated but may still be used in literature and by some clinicians: [ 39 ]
In 2020, FGDP updated guidance on a simplified system for image quality rating and analysis. [ 40 ] The new system has the following grades:
The targets for Grade A radiographs are no less than 95% for digital, and no less than 90% for film imaging. Hence, the targets for Grade N radiographs are no more than 5% for digital, and no more than 10% for film imaging. [ 40 ]
To maintain a high standard of images, each radiograph should be examined and appropriately graded. In simplistic terms as depicted by the World Health Organisation, "this is a well designed quality assurance programme which should be comprehensive but inexpensive to operate and maintain." The aim of the quality assurance is to continually achieve diagnostic radiographs of consistently high standards, therefore reducing the number of repeat radiographs by determining all sources of error to allow their correction. This, in turn, will then reduce the exposure to the patient keeping the doses as low as reasonably possible, as well as keeping a low cost.
Quality assurance consists of close monitoring of image quality on a day to day basis, comparing each radiograph to one of a high standard. If a film does not reach this standard it goes through the process of film reject analysis. This is where diagnostically unacceptable radiographs are examined to determine the reason for their faults, to ensure the same mistakes are not made again. The X-ray equipment is also something to acknowledge and ensure that it is always compliant with the current regulations. [ 39 ]
There are numerous risks associated with the taking of dental radiographs. Even though the dose to the patient is minimal, the collective dose needs to be considered in this context as well. Therefore, it is incumbent on the operator and prescriber to be aware of their responsibilities when it comes to exposing a patient to ionizing radiation . These dental radiographies have been indicated as a risk factor for cancer of salivary gland and for intracranial tumors due to improper protection from radiation. [ 41 ] It is believed that children are more at risk from these effects of radiographic examination due to their increased rate of cellular division. [ 41 ] Children are also more at risk due to the number of dental radiographs that are encountered during adolescence. [ 41 ] The United Kingdom has two sets of regulations related to the taking of X-rays . These are the Ionizing Radiations Regulations of 2017 (IRR17) and the Ionizing Radiations Medical Exposures Regulations of 2018 (IRMER18). IRR17 principally relates to the protection of workers and the public, along with the equipment standards. IRMER18 is specific for patient protection. [ 42 ] These regulations replace the previous versions which were being followed for many years (IRR99 and IRMER2000). This change has come primarily due to Basic Safety Standards Directive 2013 (BSSD; also known as European Council Directive 2013/59/Euratom), which all European Union member states are legally required to transpose into their national laws by 2018. [ 43 ]
The above regulations are specific to the United Kingdom; the EU and USA are principally governed by the directive 2013/59/Eurotam [ 44 ] and The Federal Guidance For Radiation Protection, respectively. [ 45 ] The goal of all these standards, including others governing other countries, is primarily to protect the patient, operators, maintain safe equipment and ensure quality assurance. The UK's Health and Safety Executive (HSE) has also published an accompanying Approved Code of Practice (ACoP) and associated guidance, which gives practical advise on how to comply with the law. [ 42 ] Following the ACoP is not obligatory. However, compliance with it can prove very beneficial for the legal person if they were to face any negligence or lack of compliance to the law issues, as it will confirm that the said legal person has been implementing good practice.
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Dental restoration , dental fillings , or simply fillings are treatments used to restore the function, integrity, and morphology of missing tooth structure resulting from caries or external trauma as well as the replacement of such structure supported by dental implants . [ 1 ] They are of two broad types— direct and indirect —and are further classified by location and size. Root canal therapy , for example, is a restorative technique used to fill the space where the dental pulp normally resides and are more hectic than a normal filling.
In Italy evidence dated to the Paleolithic, around 13,000 years ago, points to bitumen used to fill a tooth [ 2 ] and in Neolithic Slovenia, 6500 years ago, beeswax was used to close a fracture in a tooth. [ 3 ] Graeco-Roman literature, such as Pliny the Elder's Naturalis Historia (AD 23–79), contains references to filling materials for hollow teeth. [ 4 ]
Restoring a tooth to good form and function requires two steps:
The process of preparation usually involves cutting the tooth with a rotary dental handpiece and dental burrs , a dental laser , or through air abrasion (or in the case of atraumatic restorative treatment , hand instruments ), to make space for the planned restorative materials and to remove any dental decay or portions of the tooth that are structurally unsound. If permanent restoration cannot be carried out immediately after tooth preparation, temporary restoration may be performed.
The prepared tooth, ready for placement of restorative materials, is generally called a tooth preparation . Materials used may be gold , amalgam , dental composites , glass ionomer cement , or porcelain , among others.
Preparations may be intracoronal or extracoronal. Intracoronal preparations are those which serve to hold restorative material within the confines of the structure of the crown of a tooth. Examples include all classes of cavity preparations for composite or amalgam as well as those for gold and porcelain inlays . Intracoronal preparations are also made as female recipients to receive the male components of removable partial dentures . Extracoronal preparations provide a core or base upon which restorative material will be placed to bring the tooth back into a functional and aesthetic structure. Examples include crowns and onlays , as well as veneers .
In preparing a tooth for a restoration, a number of considerations will determine the type and extent of the preparation. The most important factor to consider is decay . For the most part, the extent of the decay will define the extent of the preparation, and in turn, the subsequent method and appropriate materials for restoration.
Another consideration is unsupported tooth structure. When preparing the tooth to receive a restoration, unsupported enamel is removed to allow for a more predictable restoration. While enamel is the hardest substance in the human body, it is particularly brittle, and unsupported enamel fractures easily.
A systematic review concluded that for decayed baby (primary) teeth, putting an off‐the‐shelf metal crown over the tooth ( Hall technique ) or only partially removing decay (also referred to as "selective removal" [ 5 ] ) before placing a filling may be better than the conventional treatment of removing all decay before filling. [ 6 ] For decayed adult (permanent) teeth, partial removal (also referred to as "selective removal" [ 5 ] ) of decay before filling the tooth, or adding a second stage to this treatment where more decay is removed after several months, may be better than conventional treatment. [ 7 ]
This technique involves placing a soft or malleable filling into the prepared tooth and building up the tooth. The material is then set hard and the tooth is restored. Where a wall of the tooth is missing and needs to be rebuilt, a matrix should be used before placing the material to recreate the shape of the tooth, so it is cleansable and to prevent the teeth from sticking together. Sectional matrices are generally preferred to circumferential matrices when placing composite restorations in that they favour the formation of a contact point. This is important to reduce patient complaints of food impaction between the teeth. However, sectional matrices can be more technique sensitive to use, so care and skill is required to prevent problems occurring in the final restoration. [ 8 ] The advantage of direct restorations is that they are usually set quickly and can be placed in a single procedure. The dentist has a variety of different filling options to choose from. A decision is usually made based on the location and severity of the associated cavity. Since the material is required to set while in contact with the tooth, limited energy (heat) is passed to the tooth from the setting process.
In this technique the restoration is fabricated outside of the mouth using the dental impressions of the prepared tooth. Common indirect restorations include inlays and onlays , crowns , bridges , and veneers . Usually a dental technician fabricates the indirect restoration from records the dentist has provided. The finished restoration is usually bonded permanently with a dental cement . It is often done in two separate visits to the dentist. Common indirect restorations are done using gold or ceramics.
While the indirect restoration is being prepared, a provisory/ temporary restoration is sometimes used to cover the prepared tooth to help maintain the surrounding dental tissues.
Removable dental prostheses (mainly dentures ) are sometimes considered a form of indirect dental restoration, as they are made to replace missing teeth. There are numerous types of precision attachments (also known as combined restorations) to aid removable prosthetic attachment to teeth, including magnets, clips, hooks, and implants which may themselves be seen as a form of dental restoration.
The CEREC method is a chairside CAD/CAM restorative procedure. An optical impression of the prepared tooth is taken using a camera. Next, the specific software takes the digital picture and converts it into a 3D virtual model on the computer screen. A ceramic block that matches the tooth shade is placed in the milling machine. An all-ceramic, tooth-colored restoration is finished and ready to bond in place.
Another fabrication method is to import STL and native dental CAD files into CAD/CAM software products that guide the user through the manufacturing process. The software can select the tools, machining sequences and cutting conditions optimized for particular types of materials, such as titanium and zirconium, and for particular prostheses, such as copings and bridges. In some cases, the intricate nature of some implants requires the use of 5-axis machining methods to reach every part of the job. [ 9 ]
Greene Vardiman Black classification:
G.V. Black classified the cavities depending on their site: [ 10 ]
Graham J. Mount's classification:
Mount classified cavities depending on their site and size. [ 11 ] The proposed classification was designed to simplify the identification of lesions and to define their complexity as they enlarge.
Site:
Size:
The following casting alloys are mostly used for making crowns, bridges and dentures. Titanium , usually commercially pure but sometimes a 90% alloy, is used as the anchor for dental implants as it is biocompatible and can integrate into bone.
Amalgams are alloys formed by a reaction between two or more metals, one of which is mercury . It is a hard restorative material and is silvery-grey in colour. One of the oldest direct restorative materials still in use, dental amalgam was widely used in the past with a high degree of success, although recently its popularity has declined due to a number of reasons, including the development of alternative bonded restorative materials, increase in demand for more aesthetic restorations and public perceptions concerning the potential health risks of the material.
The composition of dental amalgam is controlled by the ISO Standard for dental amalgam alloy (ISO 1559). [ 12 ] The major components of amalgam are silver, tin and copper. [ 12 ] Other metals and small amounts of minor elements such as zinc, mercury, palladium, platinum and indium are also present. [ 12 ] Earlier versions of dental amalgams, known as 'conventional' amalgams consisted of at least 65 wt% silver, 29 wt% tin, and less than 6 wt% copper. [ 12 ] Improvements in the understanding of the structure of amalgam post-1986 gave rise to copper-enriched amalgam alloys, which contain between 12 wt% and 30 wt% copper and at least 40 wt% silver. [ 12 ] The higher level of copper improved the setting reaction of amalgam, giving greater corrosion resistance and early strength after setting.
Possible indications for amalgam are for load-bearing restorations in medium to large sized cavities in posterior teeth, and in core build-ups when a definitive restoration will be an indirect cast restoration such as a crown or bridge retainer. Contraindications for amalgam are if aesthetics are paramount to patient due to the colour of the material. Amalgams should be avoided if the patient has a history of sensitivity to mercury or other amalgam components. Besides that, amalgam is avoided if there is extensive loss of tooth substance such that a retentive cavity cannot be produced, or if excessive removal of health tooth substance would be required to produce a retentive cavity.
Advantages of amalgam include durability - if placed under ideal conditions, there is evidence of good long term clinical performance of the restorations. Placement time of amalgam is shorter compared to that of composites and the restoration can be completed in a single appointment. The material is also more technique-forgiving compared to composite restorations used for that purpose. Dental amalgam is also radiopaque which is beneficial for differentiating the material between tooth tissues on radiographs for diagnosing secondary caries. The cost of the restoration is typically cheaper than composite restorations.
Disadvantages of amalgam include poor aesthetic qualities due to its colour. Amalgam does not bond to tooth easily, hence it relies on mechanical forms of retention. Examples of this are undercuts, slots/grooves or root canal posts. In some cases this may necessitate excessive amounts of healthy tooth structure to be removed. Hence, alternative resin-based or glass-ionomer cement-based materials are used instead for smaller restorations including pit and small fissure caries. There is also a risk of marginal breakdown in the restorations. This could be due to corrosion which may result in "creep" and "ditching" of the restoration. Creep can be defined as the slow internal stressing and deformation of amalgam under stress. This effect is reduced by incorporating copper into amalgam alloys. Some patients may experience local sensitivity reactions to amalgam.
Although the mercury in cured amalgam is not available as free mercury, concern of its toxicity has existed since the invention of amalgam as a dental material. It is banned or restricted in Norway, Sweden and Finland. See dental amalgam controversy .
Direct gold fillings were practiced during the times of the Civil War in America.
Although rarely used today, due to expense and specialized training requirements, gold foil can be used for direct dental restorations.
Dental composites, commonly described to patients as "tooth-colored fillings", are a group of restorative materials used in dentistry. They can be used in direct restorations to fill in the cavities created by dental caries and trauma, minor buildup for restoring tooth wear (non-carious tooth surface loss) and filling in small gaps between teeth (labial veneer). Dental composites are also used as indirect restoration to make crowns and inlays in the laboratory.
These materials are similar to those used in direct fillings and are tooth-colored. Their strength and durability is not as high as porcelain or metal restorations and they are more prone to wear and discolouration. As with other composite materials, a dental composite typically consists of a resin-based matrix, which contains a modified methacrylate or acrylate. Two examples of such commonly used monomers include bisphenol A - glycidyl methacrylate (BISMA) and urethane dimethacrylate (UDMA), together with tri-ethylene glycol dimethacrylate (TEGMA). TEGMA is a comonomer which can be used to control viscosity, as Bis GMA is a large molecule with high viscosity, for easier clinical handling. [ 12 ] Inorganic filler such as silica , quartz or various glasses, are added to reduce polymerization shrinkage by occupying volume and to confirm radio-opacity of products due to translucency in property, [ clarification needed ] which can be helpful in diagnosis of dental caries around dental restorations. The filler particles give the composites wear resistance as well. Compositions vary widely, with proprietary mixes of resins forming the matrix, as well as engineered filler glasses and glass ceramics. A coupling agent such as silane is used to enhance the bond between resin matrix and filler particles. An initiator package [ clarification needed ] begins the polymerization reaction of the resins when external energy (light/heat, etc.) is applied. For example, camphorquinone can be excited by visible blue light with critical wavelength of 460-480 nm to yield necessary free radicals to start the process.
After tooth preparation , a thin primer or bonding agent is used. Modern photo-polymerised composites are applied and cured in relatively thin layers as determined by their opacity. [ 13 ] After some curing, the final surface will be shaped and polished.
A glass ionomer cement (GIC) is a class of materials commonly used in dentistry as direct filling materials and/or for luting indirect restorations. GIC can also be placed as a lining material in some restorations for extra protection. These tooth-coloured materials were introduced in 1972 for use as restorative materials for anterior teeth (particularly for eroded areas). [ 12 ]
The material consists of two main components: Liquid and powder. The liquid is the acidic component containing polyacrylic acid and tartaric acid (added to control the setting characteristics). The powder is the basic component consisting of sodium alumino-silicate glass. [ 14 ] The desirable properties of glass ionomer cements make them useful materials in the restoration of carious lesions in low-stress areas such as smooth-surface and small anterior proximal cavities in primary teeth.
Advantages of using glass ionomer cement: [ 12 ]
Disadvantages of using Glass ionomer cement: [ 12 ]
Resin Modified Glass Ionomer
Resin modified glass ionomer was developed to combine the properties of glass ionomer cement with composite technology. It comes in a powder-liquid form. The powder contains fluro-alumino-silicate glass, barium glass (provides radiopacity), potassium persulphate (a redox catalyst to provide resin cure in the dark) and other components such as pigments. The liquid consists of HEMA (water miscible resin), polyacrylic acid (with pendant methacrylate groups) and tartaric acid. This can undergo both acid base and polymerisation reactions. It also has photoinitiators present which enable light curing. [ 14 ]
The ionomer has a number of uses in dentistry. It can be applied as fissure sealant, placed in endodontic access cavity as a temporary filling and a luting agent. It can also be used to restore lesions in both primary and permanent dentition. They are easier to use and are a very popular group of materials.
Advantages of using RMGIC: [ 12 ]
Disadvantages of using RMGIC: [ 12 ]
GIC and RMGIC are used in dentistry, there will be times when one of these materials is better than the other but that is dependent upon the clinical situation. However, in most cases the ease of use is deciding factor.
Dental compomers are another type of white filling material although their use is not as widespread. [ 15 ] [ 16 ] [ 17 ]
Compomers were formed by modifying dental composites with poly-acid in an effort to combine the desirable properties of dental composites, namely their good aesthetics, and glass ionomer cements, namely their ability to release fluoride over a long time. Whilst this combination of good aesthetics and fluoride release may seem to give compomers a selective advantage, their poor mechanical properties (detailed below) limits their use. [ 15 ] [ 16 ] [ 17 ]
Compomers have a lower wear resistance and a lower compressive, flexural and tensile strength than dental composites, although their wear resistance is greater than resin-modified and conventional glass ionomer cements. [ 15 ] [ 16 ] Compomers cannot adhere directly to tooth tissue like glass ionomer cements; they require a bonding agent like dental composites. [ 15 ] [ 16 ] [ 17 ]
Compomers may be used as a cavity lining material and a restorative material for non-load bearing cavities. [ 15 ] [ 16 ] In Paediatric dentistry, they can also be used as a fissure sealant material. [ 17 ]
The luting version of compomer may be used to cement cast alloy and ceramic-metal restorations, and to cement orthodontic bands in Paediatric patients. [ 16 ] [ 17 ] However, compomer luting cement should not be used with all-ceramic crowns. [ 15 ] [ 16 ]
Full-porcelain dental materials include dental porcelain (porcelain meaning a high-firing-temperature ceramic), other ceramics , sintered- glass materials, and glass-ceramics as indirect fillings and crowns or metal-free "jacket crowns". They are also used as inlays, onlays, and aesthetic veneers . A veneer is a very thin shell of porcelain that can replace or cover part of the enamel of the tooth. Full-porcelain restorations are particularly desirable because their color and translucency mimic natural tooth enamel.
Another type is known as porcelain-fused-to-metal , which is used to provide strength to a crown or bridge. These restorations are very strong, durable and resistant to wear, because the combination of porcelain and metal creates a stronger restoration than porcelain used alone.
One of the advantages of computerized dentistry (CAD/CAM technologies) involves the use of machinable ceramics which are sold in a partially sintered , machinable state that is fired again after machining to form a hard ceramic. [ 18 ] Some of the materials used are glass-bonded porcelain (Vitablock), lithium disilicate glass-ceramic (a ceramic crystallizing from a glass by special heat treatment), and phase stabilized zirconia (zirconium dioxide, ZrO 2 ). Previous attempts to utilize high-performance ceramics such as zirconium-oxide were thwarted by the fact that this material could not be processed using the traditional methods used in dentistry. Because of its high strength and comparatively much higher fracture toughness, sintered zirconium oxide can be used in posterior crowns and bridges, implant abutments, and root dowel pins. Lithium disilicate (used in the latest Chairside Economical Restoration of Esthetic Ceramics CEREC product) also has the fracture resistance needed for use on molars. [ 19 ] Some all-ceramic restorations, such as porcelain-fused-to-alumina set the standard for high aesthetics in dentistry because they are strong and their color and translucency mimic natural tooth enamel.
Cast metals and porcelain-on-metal were the standard material for crowns and bridges for long time. The full ceramic restorations are now the major choice of patients and are of commonly applied by dentists.
The US National Institute of Dental Research and international organizations as well as commercial suppliers conduct research on new materials. In 2010, researchers reported that they were able to stimulate mineralization of an enamel-like layer of fluorapatite in vivo . [ 23 ] Filling material that is compatible with pulp tissue has been developed; it could be used where previously a root canal or extraction was required, according to 2016 reports. [ 24 ]
Dental implants are anchors placed in bone, usually made from titanium or titanium alloy. They can support dental restorations which replace missing teeth. Some restorative applications include supporting crowns, bridges, or dental prostheses .
When a deep cavity had been filled, there is a possibility that the nerve may have been irritated. [ citation needed ] This can result in short term sensitivity to cold and hot substances, and pain when biting down on the specific tooth. It may settle down on its own. If not, then alternative treatment such as root canal treatment may be considered to resolve the pain while keeping the tooth.
In situations where a relatively larger amount of tooth structure has been lost or replaced with a filling material, the overall strength of the tooth may be affected. This significantly increases the risk of the tooth fracturing off in the future when excess force is placed on the tooth, such as trauma or grinding teeth at night, leading to cracked tooth syndrome .
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A dental school ( school of dental medicine , school of dentistry , dental college ) is a tertiary educational institution —or part of such an institution—that teaches dental medicine to prospective dentists and potentially other dental auxiliaries . Dental school graduates [ 1 ] receive a degree in Dentistry, Dental Surgery, or Dental Medicine, which, depending upon the jurisdiction, might be a bachelor's degree , master's degree , a professional degree , or a doctorate . Schools can also offer postgraduate training in general dentistry , and/or training in endodontics , oral and maxillofacial surgery , oral pathology , oral and maxillofacial radiology , orthodontics , pedodontics , periodontics , prosthodontics , dental public health , restorative dentistry , as well as postgraduate training for dental hygienists and dental technicians .
Other oral health professionals including dental hygienists , dental technicians and denturists , dental therapists and oral health therapists, Dental assistants or dental nurses , and other members of the dental auxiliary including orthodontic auxiliaries may be trained at dental schools, or at universities of applied science or polytechnics.
Sometimes dental education is done within medical schools , as in Pakistan ; the separation between medical and dental educations is also blurred within certain sub-specialties, such as oral and maxillofacial surgery .
High enrollment in dental schools occurred during the 1980–81 academic year, when there were approximately 23,000 students enrolled in U.S. dental schools. In the mid-1980s, enrollment began to decline. Several dental schools have closed and the number of new dentists has dwindled for some time. As of March 2010, there were more than 19,000 students per year enrolled in dental schools training dentists. [ 2 ] [ 3 ]
Before applying to dental school, you must have completed an undergraduate degree in science disciplines such as biology, chemistry, and physics. [ 4 ] [ 5 ] This knowledge is necessary to understand the complex nature of dental procedures and treatments. In addition, some dental schools may have prerequisite courses required.
The Dental Admission Test (DAT) is a standardized exam that assesses the academic ability and scientific knowledge of applicants to dental schools. [ 6 ] [ 7 ] [ 8 ] You must score high enough on the DAT exam to get into dental school. The exam consists of multiple-choice questions on a variety of subjects including biology, general chemistry, organic chemistry, reading comprehension, and quantitative reasoning.
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This dentistry article is a stub . You can help Wikipedia by expanding it .
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Dental sealants (also termed pit and fissure sealants , [ 1 ] or simply fissure sealants ) [ 2 ] are a dental treatment intended to prevent tooth decay . [ 3 ] [ 4 ] Teeth have recesses on their biting surfaces; the back teeth have fissures (grooves) and some front teeth have cingulum pits . [ 5 ] [ 6 ] [ 7 ] It is these pits and fissures that are most vulnerable to tooth decay because food and bacteria stick in them and because they are hard-to-clean areas. Dental sealants are materials placed in these pits and fissures to fill them in, creating a smooth surface which is easy to clean. Dental sealants are mainly used in children who are at higher risk of tooth decay, and are usually placed as soon as the adult molar teeth come through.
Dental caries is an upset of the balance between loss and gain of minerals from a tooth surface. [ 8 ] The loss of minerals from the teeth occurs from the bacteria within the mouth, fermenting foods and producing acids, whereas the tooth gains minerals from our saliva and fluoride that is present within the mouth. [ 8 ] When this balance is skewed due to frequent intake of fermentable carbohydrates, poor oral hygiene, and lack of fluoride consumption, there is a continuous loss and little gain of minerals over a long period of time, which can ultimately cause what is known as tooth decay. [ 8 ]
Dental sealants are a preventive treatment that is part of the minimal intervention dentistry approach to dental care. [ 9 ] These sealants are a plastic material placed in the pits and fissures (the recesses on the chewing surfaces) of primary (baby) or permanent (adult) molar and premolar teeth at the back of the mouth. These molar teeth are considered the most susceptible teeth to dental caries due to the anatomy of the chewing surfaces of these teeth, which inhibits protection from saliva and fluoride and instead favours plaque accumulation. [ 10 ] This approach facilitates prevention and early intervention, in order to prevent or stop the dental caries process before it reaches the ends stage of the disease, which is also known as the "hole" or cavitation of a tooth. [ 9 ] Once the tooth is cavitated, it requires a dental restoration in order to repair the damage, which emphasizes the importance of prevention in preserving teeth for a lifetime of chewing.
Preventing tooth decay from the pits and fissures of the teeth is achieved by dental sealants providing a physical barricade to protect natural tooth surfaces and grooves, inhibiting build-up of bacteria and food trapped within such fissures and grooves. Dental sealants also provide a smooth surface that is easily accessible for both the natural protective factor, saliva and the toothbrush bristles when cleaning the teeth. [ 11 ] As dental sealants are clear or white, they are only visible upon close inspection.
Multiple oral health care professionals including dentists, dental therapists , dental hygienists , oral health therapists and dental assistants (in some states in the US) are able to apply dental sealants to teeth. [ 11 ]
There have been many attempts made within past decades to prevent the development of caries , in particular occlusal caries as it was once generally accepted that pits and fissures of teeth would become infected with bacteria within 10 years of erupting into the mouth. [ 12 ] G.V. Black , the creator of modern dentistry , informed that more than 40% of caries incidences in permanent teeth occurred in pits and fissures due to being able to retain food and plaque . [ 13 ]
One of the first attempts to prevent occlusal caries occurred as early as 1905 by Willoughby D. Miller . [ citation needed ] Miller, a pioneer of dentistry , was applying silver nitrate to surfaces of teeth, chemically treating the biofilm with its antibacterial functions against both Streptococcus mutans and Actinomyces naeslundii , which are both carious pathogens. [ 12 ] [ 13 ] [ 14 ] Silver nitrate , which was also being practiced by H. Klein and J.W. Knutson in the 1940s, was being used in attempt to prevent and arrest occlusal caries . [ 13 ] [ 15 ]
In 1921, T.P. Hyatt, a pioneer researcher, was the first person to recommend prophylactic odontotomy (preventive operation). [ 13 ] [ 16 ] This procedure involved creating Class 1 cavity preps of teeth that were considered at risk of developing occlusal caries , which included all pits and fissures. [ 13 ] [ 16 ] The widening of the pits and fissures were then filled with amalgam . [ 13 ] [ 16 ]
C.F Bödecker, a dentist and researcher, also made attempts to prevent occlusal caries . Initially, in 1926 Bödecker would use a large round bur to smooth out the fissures. 1929, Bödecker attempted to prevent occlusal caries by cleaning the pit and fissures with an explorer and then sealing the pits and fissures with dental cement , such as oxyphosphate cement. [ citation needed ] Bödecker then later became an advocator for prophylactic odontotomy procedures (preventive operations). [ 16 ]
It was in 1955, that M.G. Buonocore gave insight to the benefits of etching enamel with phosphoric acid . [ 12 ] [ 13 ] His studies demonstrated that resin could be bonded to enamel through acid etching, increasing adhesion whilst also creating an improved marginal integrity of resin restorative material . [ 13 ] It was this bonding system that led to the future successful creation of fissure sealants. [ 12 ] [ 16 ]
In 1966, E.I. Cueto created the first sealant material, which was methyl cyanoacrylate . [ 1 ] However, this material was susceptible to bacterial breakdown over time, therefore was not an acceptable sealing material. [ citation needed ] Bunonocore made further advances in 1970 by developing bisphenol-a glycidyl dimethacrylate, which is a viscous resin commonly known as BIS-GMA . [ 1 ] This material was used as the basis for many resin-based sealant/composite material developments in dentistry, as it is resistant to bacterial breakdown and forms a steady bond with etched enamel. [ 1 ]
In 1974, glass ionomer cement fissure seals (GIC) were introduced by J.W. McLean and A.D. Wilson. [ 1 ]
Modern dental sealants generally are either resin based or glass ionomer based. [ 1 ]
It is customary to refer to the development of resin based sealants in generations: [ 1 ] [ 17 ]
As part of the wider debate over the safety of bisphenol A (BPA), concerns have been raised over the use of resin based sealants. [ 1 ] BPA is a xenoestrogen, i.e. it mimics the relative bioactivity of estrogen , a female sex hormone. Pure BPA is rarely present in dental sealants, however they may contain BPA derivatives. [ 1 ] There is very little research about the potential estrogen-like effects of BPA derivatives. [ 1 ] A transient presence of BPA in saliva has been reported immediately following placement of some resin based sealants. [ 1 ] The longest duration of salivary BPA was 3 hours after placement, so there is little risk of chronic low-dose BPA exposure. The currently available evidence suggests that there is no risk of estrogen-like side effects with resin based sealants. [ 1 ] Several national dental organizations have published position statements regarding the safety of resin based dental materials, e.g. the American Dental Association , [ nb 1 ] the Australian Dental Association , [ nb 2 ] the British Dental Association , [ nb 3 ] and the Canadian Dental Association . [ nb 4 ]
GIC materials bond both to enamel and dentine after being cleaned with polyacrylic acid conditioner. [ citation needed ] Some other advantages GICs have is that they contain fluoride and are less moisture sensitive, with suggestions being made that despite having poor retention, they may prevent occlusal caries even after the sealant has fallen out due to their ability to release fluoride . [ 1 ] [ 18 ]
There is evidence that GIC sealant that were exposed to thermo-light curing [ 19 ] with a LED polymerization unit (60 s) had comparable sealing ability and superior sealing characteristics compared to the conventional resin-based sealant. [ 20 ]
It was shown that GIC materials were more effective in prevention of development of caries despite the higher non-successful rate compared to resin based sealants. [ 21 ] This may be accounted for due to the fluoride-releasing property of GIC which increases salivary fluoride level that may aid in preventing dental caries.
Resin-based sealants are normally the preferred choice of material for denture sealants. GIC material may be used as a provisional protective material when there are concerns regarding adequate moisture control. [ 22 ]
Dental sealants are accepted as an effective preventive method for cavities and as long as the sealant remains adhered to the tooth, cavities can be prevented. It is for this reason that sealant success is now measured by the length of time a sealant remains on the tooth, rather than the decay experienced in sealed and unsealed teeth. The ability of a pit and fissure sealant to prevent dental caries is highly dependent on its ability to retain on the tooth surface.
It has been demonstrated that the use of adhesive systems before applying dental sealants improves retention. [ citation needed ] Traditional retention of a sealant on tooth surface is through acid etching .
The most common reason for sealant failure is salivary contamination during sealing placement. Other factors include clinician inexperience, lack of client co-operation, and less effective sealant material used. [ 23 ]
Sealants may be applied in conjunction with fluoride varnish as a preventive method which is shown to be more successful (low certainty evidence) than fluoride varnish alone. [ 24 ]
Various factors can help contribute to the retention of fissure sealants. These include:
Although dental sealants do wear naturally and may become damaged over time, they usually last for around five to ten years, despite the heavy pressures endured by teeth during chewing each day. Longevity of dental sealants is also dependent on the type of material used. [ 26 ] It is not uncommon for dental sealants to be retained well into adulthood. [ citation needed ] It is believed that bacteria and food particles may eventually become entrapped under dental sealants, and can thus cause decay in the very teeth intended to be protected. [ medical citation needed ] Dental sealants are inspected during routine dental visits to ensure that they are retained in the fissures of the teeth. Damaged sealants can simply be repaired by adding new sealant material. One of the major causes of the loss of sealants in the first year is salivary contamination. [ 25 ]
On the basis of limited evidence both GIC and resin materials are equally acceptable in caries prevention, however retention rates between GIC and Resin have been shown to differ. [ 18 ] Resin has been shown to be the superior product for retention. A 2-year clinical trial comparing GIC and Resin for dental sealants demonstrated that the GIC had a total loss rate of 31.78%, in contrast to the resin which had a total loss rate of 5.96% The study did acknowledge that GIC had its therapeutic advantages other than retention, this included the benefit of fluoride release and its use on partially erupted teeth. [ 27 ] Though GIC has poorer retention rates, the fact that they release active fluoride in the surrounding enamel is very important. They can exert a cariostatic effect and increased release of fluoride, and for these reasons GIC is more of a fluoride vehicle rather than a traditional fissure sealant. [ 28 ] All three materials are as effective as each other if the correct techniques are used to complete the procedure. [ 18 ]
Although dental sealants are recommended to be placed in all children as soon as possible following eruption of permanent molars there are specific indications for when they are required to be placed. These indications mainly stem from issues that would cause a patient to be considered high caries risk, in order to prevent dental caries.
These indications are:
There are no specific contraindications to placing dental sealants. For resin fissure sealants to be successful excellent moisture control is needed during placement of the fissure sealant. In cases where moisture control cannot be achieved then Glass Ionomer fissure sealants should be placed until a time where moisture control is adequate enough to place resin fissure sealants.
The exact technique depends on the material used and a good application technique will increase retention, which means sealants can last longer on the teeth. [ 33 ] Generally, each quadrant is treated separately by using four-handed technique with an assistant and to follow the manufacturer's recommendations. [ 33 ] The patient should wear safety glasses for protection from chemicals and curing light. Once the patient is prepared, the surface of the tooth must be cleaned to allow maximum contact of the etch and the dental sealant with the enamel surface. A rubber dam may be used to prevent saliva from contaminating the intended site to be sealed, although often these are not used, especially for younger children. Moisture control is more of an issue with resin based sealants than with glass ionomer sealants. The surface is cleaned and dried.
Resin sealants require a phosphoric acid solution ("etch") to create microscopic porosity into which the sealant material can flow thereby increasing retention, increasing surface area and improving the strength of the bond between the sealant and the tooth surface. [ 34 ] Etching time varies from 15 to 60 seconds, depending on the product. After that, the tooth must be rinsed and dried thoroughly for 15 to 20 seconds. Chalky appearance on the dried tooth means the tooth has been properly etched. If the tooth does not have this chalky appearance, the etching process must be repeated. The sealant is then applied to the tooth by carefully placing the sealant material into the prepared pits and fissures by using a disposable instrument provided by the manufacturer. Overfilling on the tooth should be prevented to minimize occlusal adjustment. The material is left for 10 seconds after the placement prior to curing to allow optimum penetration of the sealant material into the pores created by the etching procedure. Finally, the sealant is hardened by a curing light, which usually takes 20 to 30 seconds. Glass ionomer does not require light curing, however it will set faster with the usage of a curing light. [ 35 ]
Resin-based sealants require an absolutely dry surface until polymerization is complete, so it is essential to avoid salivary contamination of the sealant site. A rubber dam or cotton roll isolation technique can be used to isolate the sealant site from saliva which is the common reason for sealant failure. Glass ionomer sealants have the advantage of not needing a dry field to be effective. In fact, the application procedure for glass ionomers can involve pressing a saliva-moistened finger onto the occlusal surface to push the sealant material into the pits and fissures.
Compared to a typical dental filling, where an injection of local anesthetic and the use of a dental drill may be involved, the application of dental sealants is significantly less invasive and generally considered quick and easy. The procedure is entirely painless, although a minor level of discomfort may be experienced by the patient. The etching gel may temporarily leave a sour taste in the mouth.
Pits and fissure sealants are used as effective controls in preventing caries. Sealants create a barrier which removes the biofilm from the occlusal surface. There are 4 sealant materials that can be used for the purpose of sealing pits and fissures. The materials are: [ 36 ]
Resin-based sealant
Glass-ionomer (GI)
Polyacid-modified resin sealants
Resin-modified glass ionomer sealants
Historically methods such as; zinc phosphate cement, mechanical fissure eradication, prophylactic odontotomy, or chemical treatment with silver nitrate, were used to seal pits and fissures. These techniques are no longer used in modern-day practice. Placement techniques for sealants rely on the type of material being used. However a common factor for all is that moisture control must be achieved. The maintenance of moisture control increases the treatment time and could be counter productive. [ 37 ]
For partially erupted teeth which are difficult to isolate some will use GIC (doesn't need etching) as an interim option. GIC may have an advantage of fluoride release.
In the US, 42% of children aged 6–11 and 48% of adolescents aged 12–19 had fissure sealants on permanent teeth during 2011–2016. [ 38 ]
In Greece, in a study from 2011, 8.3% of 12 year olds and only 8% of 15 year olds had at least one dental sealant on a molar tooth. When sealants were applied, DMFS scores were reduced by 11% in the 12 year olds and 24% in the 15 year olds. [ 39 ]
In Portugal, a study has shown that over half (58.8%) of adolescents had a fissure sealant applied on at least one tooth. [ 40 ]
In Denmark, 66% of 15-year-old children had at least one sealed molar. [ 41 ]
In the UK in 2003, 13% of 8 year olds, 25% of 12 year olds and 30% of 15 year olds had at least one fissure sealant. [ 42 ] In Ireland, the rates were 47%, 70% and 69% comparatively. [ 43 ]
In Slovenia, around 94% of 12 year olds have at least one sealed molar. [ 44 ]
Around 25% of Japanese children have at least one sealed molar. [ 45 ]
A study surveying fissure sealants and dental caries in primary school girls in Saudi Arabia in 2017 found that only 1.3% of the children had at least 1 fissure sealant applied, [ 46 ] but in another study, the overall figure was 9%. [ 47 ]
Dental sealants have been around us for a very long time and have been proven in research to be a safe and effective technique for preventing dental caries, especially on occlusal surfaces where teeth are particularly susceptible to decay. [ 48 ] Through acting as a physical barrier to food and bacteria, dental sealant can prevent food from sticking to grooves in teeth and providing a place for bacteria to colonize. This is how dental sealants prevent that initial carious lesion. [ 49 ] The materials used are resins, glass ionomers and hybrids; the effect of the materials used and retention rate depend on the type of material you use. [ 50 ] But they are all effective in doing what they are used for, which is to prevent caries. Additionally, proper application, such as the tooth preparation, acid etch and adhesive also needs to be considered, otherwise, if they are applied incorrectly, it might resulted in unexpected and unfavorable clinical outcomes. [ 51 ]
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A dental spa is a dental facility supervised by a licensed oral health care provider in which dental services are provided alongside spa treatments. [ 1 ]
"Spa dentistry" refers to dental practices that offer many services not normally associated with dental care: facials , paraffin wax hand treatment, reflexology , micro-dermabrasion , massage therapy, Botox and Restylane treatment, and many other treatments. The administration of Botox and Restylane is based on each respective state's dental board approval.
The American Dental Association notes that the consumer media have coined the term "dental spa", but many practices offer services and amenities specifically designed to relax patients without considering themselves a "spa". [ 2 ] The loose definition of "dental spas" makes it difficult to know how many dental spas exist in the United States. [ 2 ]
In 2003, Lynn Watanabe, DDS of the Dental Spa in Pacific Palisades, California , and the Day Spa Association defined a dental spa as "a facility whose dental program is run under the strict supervision of a licensed Oral Health Care Provider, which might be a Dentist or an Independent Dental Hygienist . Services are provided that integrate both traditional and non-traditional dental and spa treatments such as massage therapy , skincare and body treatments". [ 3 ] [ 4 ]
Ancient civilizations such as the Greeks and Chinese all used certain methods to relax a person suffering from ailments such as a toothache . The " barber surgeon " in the 18th and 19th century allowed barbers to perform some dental procedures as well as shaves and haircuts . [ 4 ] The term "spa dentistry" (synonymous to dental spa) was used during the 18th century to describe dental practitioners in Bath, England . [ 5 ] Ms. Curris, a female dentist in 18th century Bath likely created the first dental spa, offering patients dentistry with skin and body care. [ 5 ]
The terms "dental spa" and "spa dentistry" began to be more publicly used in the late 1990s. [ 6 ] In 1998, Lorin Berland DDS reserved the name DallasDentalSpa.com. [ 7 ]
1994: London's The Guardian has identified the Atlanta Center for Cosmetic Dentistry as "one of the first of these new dental spas." [ 8 ] The February 19, 2007 edition reported that Debra Gray King, DDS, began providing spa services at the Atlanta Center for Cosmetic Dentistry in 1994. [ 9 ]
1996: Lorin Berland DDS began providing a massage therapist on staff. [ 10 ]
1999: On July 11, 1999, The New York Times reported several Long Island dentists were offering "distraction techniques" by offering massage therapy to their patients. The article reports that massage services were offered since early 1999. [ 11 ]
2001: On October 1, 2002, Salt Lake Magazine reported that the Dental Spa in Sugar House provided patients with complimentary spa services such as temple massage, hand treatments, eye masks , and other techniques aimed at calming the patients. The spa services were provided since the Spa's inception in 2001. [ 12 ]
2002: On August 12, 2002, the Los Angeles Times reported Lynn Watanabe, DDS, one of the field's "pioneers," opened "Dental Spa" in Pacific Palisades, California , with a full-time esthetician and full-time massage therapist. [ 13 ]
In 2003, the American Dental Association reported that more than 50% of 427 practicing dentists surveyed at their annual session offered some sort of spa or office amenity. [ 14 ] In 2005, as many as 5% of the American Dental Association's more than 152,000 members had declared themselves "dental spas". [ citation needed ] In 2007, the ADA estimated that possibly that one in every 20 dental offices in the United States actually offers, to some extent, some spa dentistry services to their patients. [ 15 ]
In 1978, the Holistic Dental Association was formed to focus on the mind-body connection and the dental patient's well-being. Spa dentistry is recognized by the International Medical Spa Association and the Day Spa Association, but similar to the field of cosmetic dentistry, it is not recognized as a specialty practice area by the American Dental Association. In 2002, Lynn Watanabe, DDS, founded the first dental spa association with the creation of the International Dental Spa Association. [ 16 ] The New York Times reported in 2006 that "it now has ten members and is coming up with guidelines for what services constitute a dental spa." [ 17 ]
One of the main reasons people avoid visiting the dentist is dental anxiety . [ 18 ] [ 19 ] Dental anxiety drives some people to create more dental problems by not visiting the dentist on a regular basis. Patients who are high in dental anxiety have the greatest likelihood of avoiding dental treatment . [ 18 ] Dental anxiety, or dental fear, is estimated to affect approximately 36% of the population, with a further 12% suffering from extreme dental fear. [ 20 ]
The first known scientific study on dental fear occurred in 1954. [ 21 ] Dental anxiety has been a well-studied phenomenon since the late 1960s. [ 18 ] Since then, studies and several books report successful treatment of patients with dental fear using behavioral methods. [ 22 ] [ 23 ] [ 24 ]
Variations of the dental spa concept typically combine cosmetic, general, and restorative dentistry with amenities designed to create a comfortable and relaxing experience for patients. [ 25 ]
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In the United States and Canada , there are twelve recognized dental specialties in which some dentists choose to train and practice, in addition to or instead of general dentistry . In the United Kingdom and Australia , there are thirteen. [ 1 ] [ 2 ]
To become a specialist requires training in a residency or advanced graduate training program. Once a residency is completed, the doctor is granted a certificate of specialty training. Many specialty programs have optional or required advanced degrees such as a master's degree , such as the Master of Science (MS or MSc), Master of Dental Surgery/Science (MDS/MDSc), Master of Dentistry (MDent), Master of Clinical Dentistry (MClinDent), Master of Philosophy (MPhil), Master of Medical Science (MMS or (MMSc); doctorate such as Doctor of Clinical Dentistry (DClinDent), Doctor of Medical Science/Sciences (DMSc), or PhD ;or medical degree : Doctor of Medicine / Bachelor of Medicine, Bachelor of Surgery (MD/MBBS) specific to maxillofacial surgery and sometimes oral medicine ).
Specialists in these fields are designated "registrable" (in the United States , "board eligible") and warrant exclusive titles such as dentist anesthesiologist, orthodontist, oral and maxillofacial surgeon, endodontist, pediatric dentist, periodontist, or prosthodontist upon satisfying certain local (U.S., "Board Certified"), ( Australia and New Zealand : Fellow of the Royal Australasian College of Dental Surgeons , designated by the post-nominal "FRACDS"), or ( Canada : Fellow of the Royal College of Dentists , designated by the postnominal "FRCD(C)") registry requirements.
The American Board of Dental Sleep Medicine (ABDSM) provides board-certification examinations annually for qualified dentists. These dentists collaborate with sleep physicians at accredited sleep centers and can provide oral appliance therapy and upper airway surgery to treat sleep-related breathing disorders. [1] While Diplomate status granted by the ABDSM is not one of the recognized dental specialties, it is recognized by the American Academy of Sleep Medicine (AASM). (See sleep dentistry in the section of sleep medicine about the US.)
A few other post-graduate formal advanced education programs: GPR, GDR, MTP residencies (advanced clinical and didactic training with intense hospital experience) and AEGD, SEGD, and GradDipClinDent programs (advanced training in clinical dentistry) are recognized but do not lead to specialization. There are CODA (Council on Dental Accreditation) programs in Orofacial Pain at more than ten Dental Schools in the USA.
Other dental education exists where no postgraduate formal university training is required: cosmetic dentistry , dental implant , temporo-mandibular joint therapy . These usually require the attendance of one or more continuing education courses that typically last for one to several days. There are restrictions on allowing these dentists to call themselves specialists in these fields. The specialist titles are registrable titles and controlled by the local dental licensing bodies.
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A dental technician is a member of the dental team who, upon prescription from a dental clinician, constructs custom-made restorative and dental appliances. [ 1 ] [ 2 ]
There are four major disciplines within dental technology. These are fixed prosthesis including crowns , bridges and implants ; removable prosthesis , including dentures and removable partial dentures ; maxillofacial prosthesis , including ocular prosthesis and craniofacial prosthesis ; and orthodontics and auxiliaries , including orthodontic appliances and mouthguards . [ 3 ]
The dentist communicates with the dental technician with prescriptions, drawings, and measurements taken from the patient. The most important aspect of this is a dental impression into which the technician flows a gypsum dental stone to create a replica of the patient's anatomy known as a dental cast. A technician can then use this cast for the construction of custom appliances. [ 4 ]
A fixed dental restoration is an appliance designed to replace a tooth or teeth that may have been lost or damaged by injury, caries or other oral diseases. These restorations are distinguished from other restorations by the fact that once they have been placed by a dentist the patient can not remove them. [ 5 ] Such restorations include crowns, bridges, veneers, fixed implant restorations, pivot teeth , inlays and onlays. [ 6 ] [ 7 ]
Removable restorations are dental appliances to replace one or more teeth that have been completely lost. These restorations ideally remain stable in normal function but can be removed by the patient for cleaning and at night. Removable restorations are either retained by the patients soft tissue as in full dentures, [ 8 ] anchored and stabilized by other teeth as with partial dentures and overdentures [ 9 ] or on implant attachments as with implant-retained overdentures and partial dentures.
Orthodontic technicians make removable orthodontic appliances with wires, springs, and screws on prescription from an orthodontist to either move teeth to form a more harmonious occlusion and aesthetic appearance of teeth or to maintain the position of previously moved teeth.
Training to become a dental technician requires a combination of academic study as well as experience gained from working on the job. Therefore, regardless of the country that they are from, after becoming a qualified technician (so long as the title of “dental technician” exists there) one has finished their studies, but not their training since these crafts take years of experience to master.
Depending on the position held by the dental technician, their specific title could differ as well (“ceramicist”, “polisher”, “orthodontist”, etc.). In fact, due to the complexity of the work that is carried out by dental technicians, a professional generally specializes in one field of dental prosthesis. Since the range of devices to design and create is extremely varied, it would be impossible to make all of them with the same set of skills, further, to completely master any technique may require years of experience.
In general, the first step a dental technician makes is to “master the plaster”, meaning that they first start in the part of the lab where dental impressions are made, cutting models, and mounting articulators. The dental technician may acquire the ability to carry out various and disparate tasks in the lab, being able to even execute most steps in the production of various prosthetics, such as removable partial dentures , complete and partially made of resin, and orthodontic devices (including braces and retainers). Nevertheless, as mentioned previously, dental technicians need to specialize; in fact, there are many specific dental labs that exist for each and every type of prosthesis.
The distinct specialties are described below:
A polisher is a dental technician who dedicates themselves to the setup of teeth, either in making removable prosthetics made of resin or metal, molding the neck of the tooth, or loading the resin. Within their profession, they can also be referred to as a waxer.
A metalworker is a dental technician who is in charge of casting dental rods, which means they mold the metal and obtain the metallic frames for fixed prostheses , similar to the removable prosthetics made of resin. They are also in charge of processing and reworking said metal. These professionals can also be in charge of designing the wax patterns of removable metallic prostheses, such as the copings of crowns and fixed bridges. Among other things, this depends on the dental technician and the lab in which they work.
It is very common to differentiate a prosthetist who works with removable orthodontics , as it is normal to find professionals who specialize in this field. Removable equipment consists of a variety of different devices, each with specific naming and characteristics. Prosthetic orthodontists should be both agile and precise when handling different pliers and manipulating wires.
A ceramicist is a dental physician who has specialized in the final stage of making fixed prosthetics , which consists of the assembly of ceramic on different prosthetic structures such as: bridges , crowns , prosthetic implants or prosthetic attachments. This technique is complex and requires artistic talent, so much so that dental technicians can achieve different levels of ability, developing their creativity to a greater or lesser extent to give your teeth the most natural look possible. As such, ceramicists are often considered valued professionals.
Dental technicians predominantly make dentures , or similarly, create artificial parts that are intended to basically replace the natural, missing teeth of the patient.
Therefore, dental technicians make complete resin prosthetics (commonly called dentures ), partial prosthetics (being metallic or made of resin ), bridges and crowns of any type ( fixed prosthetics , also called dental implants ), and mixed prosthetic devices. Further, dental technicians also make all removable orthodontic devices (removable orthodontics), dental splints , individual compression trays , temporary resin prosthetics, bite plates, as well as study models. Dental technicians are also in charge of making composites (the repairing of prosthetics in case they break) and relining (the readjustment of prosthetics when they are too big or become flimsy in the mouth due to the reabsorption of alveolar bone over time). All of these, concerning the plaster models or instructor models, being a crime that acts on the patient's mouth.
In every country that legally regulates the profession of dental technicians, the prosthetist is the only professional trained and authorized by law to make the previously mentioned products.
By law, dental technicians can never, even if there is a medical prescription, take impressions - the client of the prosthetists is legally the dentist, and it is considered an intrusive crime by the Penal Code [ which? ] if a prosthetist touches the mouth of the patient.
The goal of a dental technician can be summarized as restoring functionality, health, and aesthetic of the mouth.
The only goal of a prosthetist is not just to create a prosthetic, but rather to restore the loss of functionality of a patient's mouth, from mastication and swallowing to speaking and correct phonetics . Through the work of a prosthetist, a patient's oral health, mechanical function, hygiene, and comfort are revamped, including the aesthetic of the mouth and face.
This objective is a combined effort between clinical and lab members, an effort that is, in part, coordinated and achieved by the dentist and the prosthetist. That said, the only one in charge of the creation of prosthetics is the prosthetist, being a handcrafted, personalized, unique item designed in the dental lab.
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A dental therapist is a member of the dental team who provides preventive and restorative dental care for children and adults. The precise role varies and is dependent on the therapist's education and the various dental regulations and guidelines of each country.
More than 50 countries allow dental therapists to provide some dental services. [ 1 ] [ 2 ] In the United States, dental therapists are allowed to operate in 13 states. [ 2 ] [ 3 ] The American Dental Association , the largest professional association of dentists in the United States, has lobbied against allowing dental therapists to practice while the Federal Trade Commission has advocated that more dental therapists would enable greater access to oral care and strengthen competition in dental services. [ 2 ] Research shows that dental therapists provide greater access to dental care without undermining the quality of care or undermining health outcomes. [ 1 ] [ 3 ] [ 4 ]
In 1913, Dr Norman K. Cox , the President of the New Zealand Dental Association, proposed a system of school clinics operated by the state and staffed by 'oral hygienists' to address the dental needs of children between the ages of 6 and 14 years. At the time, the idea was considered to be unorthodox, but in 1920, at a special meeting of the New Zealand Dental Association, 16 members voted for the adoption of school dental nurses with 7 opposed to the proposal. Such a drastic change in the voting could be accredited to the refusal of New Zealand troops during the first world war . The recruits were rejected due to rampant and uncontrolled dental diseases. [ 5 ]
School dental nurses were to provide diagnostic and restorative services to children '...in a rigidly structured set of methods and procedures which spare her the anxiety of making choices'. [ 6 ] In Great Britain , during the first world war, 'dental dressers' were used to carry out examinations and treatment for children in parts of England. Their role was eliminated by the Dentist Act of 1921 because of hostility to the role on the part of the dentist profession. They were later re-introduced, on the strength of the New Zealand scheme, as dental therapists when the high dental needs of children were 'rediscovered' in the 1960s, carrying out similar services but under the prescription of a dentist who carried out the examination and care plan. [ 7 ]
The success of New Zealand's program was so significant that many countries facing similar needs adopted programs which mirrored the ones initially established in New Zealand. [ 5 ] School dental services which followed similar training became popular in countries such as Canada , South Africa , the Netherlands (temporarily), Fiji , Hong Kong , Malaysia and the Philippines and in 2000, 28 countries around the world utilised dental therapists. In today's modern day practices, in all previously mentioned countries dental therapists are becoming more recognised and employable due to the identifiable need for dental professionals in underserved areas. [ 5 ]
Dental therapists are no longer trained in Australia , and instead oral health therapists are being trained. An oral health therapist is trained as both a dental therapist and a dental hygienist with a focus on health promotion and disease prevention. [ 8 ]
Oral health therapy training occurs at university level and therefore completion of secondary schooling to a high standard is mandatory, including certain pre-requisite subjects that differ between states/territories and between the universities that offer the courses themselves. [ 9 ]
The training varies, depending on what is offered at each university, but the golden rule is that once graduated an oral health therapist can only perform what they have been formally trained in. [ 8 ] [ 9 ]
Oral health therapists are trained to perform: [ 8 ]
Dental therapists use number of different tools and technology to complete their dental tasks such as X-ray equipment, hand powered tools such as drills and polishers along with the use of computers and printers to record and store data. [ 10 ]
The average salary of a dental therapist in Australia is generally $1150.00 per week being full-time and before tax. A benefit of working in this profession is that dental therapists work normal business hours. [ 10 ]
From 2002 [ 11 ] –2016, dental therapists were trained at either University of Otago in Dunedin (at New Zealand's only Dental School ) or at Auckland University of Technology . [ 12 ] Until 2016, the qualification (Bachelor of Oral Health at Otago, Bachelor of Health Science in Oral Health at AUT) enabled graduates to register and practise as both a dental therapist and dental hygienist. [ 11 ]
Development of the dental therapists began in New Zealand. They were initially trained as 'school dental nurses', providing preventive and simple restorative care to children aged up to 12 years old. They were employed to treat children at a school dental service including treatment of preschool children. [ 13 ]
From 1921 to 1990 the Department of Health ran the Wellington School for Dental Nurses, which offered a two-year certificate. [ 11 ] In 1952 this programme was extended with the creation of the Auckland School for Dental Nurses, and in 1956 it was again extended by opening the Christchurch School for Dental Nurses. [ 11 ] Both Auckland and Christchurch Schools closed in 1981. [ 11 ] In 1991, the profession was renamed from 'school dental nurse' to 'dental therapist' to align with overseas designations, and training was taken over by the Department of Education . [ 11 ] Training continued in Wellington , at Wellington Polytechnic . The qualification offered was a two-year Certificate in Dental Therapy, which in 1995 was changed to a two-year Diploma in Dental Therapy. [ 11 ]
In 1999 University of Otago took over the two-year Diploma in Dental Therapy, which was offered until the introduction of the BOH degree in 2007. [ 11 ]
In 2002, both University of Otago and AUT debuted three-year Bachelor of Health Science degrees. [ 11 ] The Otago degree was endorsed in dental therapy, while the AUT degree was in oral health, but still only allowed for registration as a therapist. [ 11 ] At Otago, this was offered in addition to the two-year diploma. [ 11 ] Both degrees were discontinued in 2007. [ 11 ] The current 'dual degree' was introduced at AUT in 2006 and at Otago in 2007. [ 11 ] [ 14 ] This was in response to a shortage and increased legislative requirements. [ 11 ]
In order to practise, all therapists must annually register with the Dental Council. [ 15 ] For the 2014–2015 cycle, the cost of this is $758.23. [ 16 ] One therapist is represented on the council for a three-year term. [ 17 ]
Dental therapists in New Zealand work exclusively with children under 18 years old. Their duties include examination and routine dental treatment and prevention work, such as fillings, fissure sealants and extractions of first teeth. Duties may also include giving local anaesthetic and taking X-rays. Therapists also advise patients and their parents how to care for the patient's mouth. [ 18 ]
Dental therapists generally work for a local District Health Board (DHB), but some work in private practice. [ 19 ]
Dental therapists could become members of the New Zealand Dental & Oral Health Therapists Association [ 20 ] until its merger with the New Zealand Dental Hygienists' Association into the New Zealand Oral Health Association 2021. The association was founded in 1935, as the New Zealand State Dental Nurses' Institute. [ 20 ]
Some of the procedures carried out by UK dental therapists include examinations, taking radiographs ( X-rays ), fillings (restorations), implementing preventive strategies ( fluoride application, dental sealants (fissure seals), oral hygiene instruction) and dental health education. [ 21 ]
Alaska began its dental therapist program 2004, the first in the United States, to address gaps in rural dental healthcare using a model developed after New Zealand's. [ 22 ] An early sponsor, the W.K. Kellogg Foundation, then funded similar programs in Kansas, New Mexico, Ohio, Vermont and Washington. [ 23 ] However, Minnesota was the next state to pass legislation authorizing dental therapists and the first to approve a non-tribal program. [ 24 ] Dental therapists are allowed to operate in 13 states as of 2025 [update] : Alaska , Arizona , Colorado , Connecticut , Idaho , Michigan , Minnesota , Maine , New Mexico , Nevada , Oregon , Vermont , Washington , and Wisconsin . [ 2 ] [ 3 ] [ 25 ] [ 26 ] This is an increase from 2013, when only Alaska and Minnesota permitted dental therapists to practice. [ 27 ] The American Dental Association , the largest professional association of dentists in the United States, has lobbied against allowing dental therapists to practice while the Federal Trade Commission has advocated that more dental therapists would enable greater access to oral care and strengthen competition in dental services. [ 2 ] Research shows that dental therapists provide greater access to dental care without undermining the quality of care or undermining health outcomes. [ 1 ] [ 3 ] [ 4 ]
A 2013 report by an advisory panel of academics, assembled by the non-profit consumer advocacy group Community Catalyst, stated that, "As members of the oral health team, dental therapists provide restorative dental treatment services, disease prevention and oral health promotion programs to maintain and improve health." [ 27 ] The panel recommended several specific "minimum standards of quality" for use by educational programs for aspiring dental therapists. [ 27 ]
Scope of practice varies by state; some states distinguish between the scope of practice of dental therapists (DTs) and advanced dental therapists (ADTs). [ 28 ]
The following tasks are regularly performed by dental therapists:
The dental profession involves the study, diagnosis, prevention and treatment of diseases, disorders and conditions involving the oral cavity and surrounding structures. [ 30 ] Dental therapists practice in a team situation alongside a practising dentist and have a tradition of being part of the dental team primarily to provide dental care to children through school dental services. [ 30 ]
The dental therapists role in the dental team can include the provisions of oral health assessment, treatment planning, management and prevention for children, adolescents and adults, which is dependent on their training. [ 30 ] In many practices dental therapists are limited to the provision of restorative dental care and extractions to those aged 25 and under, however there are some settings where the dental or oral health therapist can provide these services to someone of any age where the clinician has developed his or her scope of practice.
In Australia, dental therapists have been practicing under guidance of dentists providing diagnostic, preventive, restorative and health promotion services to children and adolescents. [ 31 ]
Common procedures performed by dental therapists include examination, prescribing and exposing intra and extra oral dental xrays, administration of local anaesthesia, preparation and restoration of carious lesions, pulpal therapies, extraction of deciduous teeth and preventive therapies such as fissure sealants and fluoride application. [ 31 ] Oral health education and promotion also plays a large part in the dental therapists role. [ 31 ]
Professional support for the role of the dental therapist in the dental team has been widely accepted in Australia and New Zealand, where their role came about in response to population need from the rising numbers of caries prevalence in children. [ 32 ] This same support has not followed in all countries, with the United States referring to dental therapists as "lower level practitioners" with a study showing 75% of US paediatric dentists not knowing what a dental therapist was and 71% of them disagreeing to add them as part of the dental team. [ 32 ]
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Dental vibration appliances are devices that aim to speed up the process of straightening teeth or correcting a person's bite during orthodontic treatment. The goal is to reduce the time it often takes to move teeth safely and also reduce the risk of side effects such as problems with normal tooth mineralization and inflammatory root resorption . [ 1 ] These devices also aim to improve compliance by shortening the time needed for orthodontic care. [ 1 ]
Dental vibration appliances are proposed to work by applying vibration called "micropulses" to dental braces . The goal of this vibration is to stimulate bone cell remodelling and result in faster tooth movement during orthodontic treatment. Evidence as of the effectiveness and safety of this treatment approach is not clear. There is weak evidence to suggest that the vibrational forces associated with these devices does not provide a benefit or reduce the amount of time a person requires orthodontic treatment. [ 1 ]
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The dentinoenamel junction or dentin-enamel junction ( DEJ ) is the boundary between the enamel and the underlying dentin that form the solid architecture of a tooth . [ 1 ]
It is also known as the amelo - dentinal junction, or ADJ. [ 2 ]
The dentinoenamel junction is thought to be of a scalloped structure which has occurred as an exaptation of the epithelial folding that is undergone during ontogeny. This scalloped exaptation has then provided stress relief during mastication and a reduction in dentin-enamel sliding and has thus, not been selected against, making it an accidental adaptation.
The crown of a human tooth, or more precisely, the tooth's dentin, is coated in enamel. Derived from the mesoderm, dentin is a mineralised, flexible tissue with a weight percentage of 70% inorganic material, 20% organic material, and 10% fluid. On the other hand, enamel, which comes from ectoderm, is an extremely brittle tissue that is mainly made up of water (about 3%), trace organic matrix (approximately 1%), and the mineral hydroxyapatite (~96%). The contact between two mineralised tissues with distinct compositions and biomechanical characteristics is known as the dentin-enamel junction (DEJ). [ 3 ]
The dentino-enamel junction is thought to be a scalloped structure, which has occurred as an exaptation of the epithelial folding undergone during ontogeny. This scalloped exaptation has then provided stress relief during mastication and a reduction in dentin-enamel sliding and has, thus, not been selected against, making it an accidental adaptation [ 3 ]
It has been proposed that the DEJ is crucial in preventing the progression of cracks from enamel to dentin and averting additional severe tooth fractures
The dentino-enamel junction (DEJ) is an intricate biomechanical interface that forms the boundary between the highly mineralised enamel and the collagen-rich dentin. Enamel is the hardest tissue in the human body, consisting predominantly of hydroxyapatite crystals. At the same time, dentin is a more flexible tissue with a lower mineral content, providing structural support to enamel. The DEJ plays an essential role in ensuring the integration of these two mechanically different tissues, allowing for the dissipation of stresses during mastication and preventing crack propagation that could otherwise lead to tooth failure.
The molecular structure of the DEJ is designed to accommodate the stark differences in composition and mechanical properties between enamel and dentin. The specialised architecture of the DEJ not only strengthens the bond between these tissues but also distributes mechanical loads in a way that maximises the durability and functionality of the tooth. [ 3 ]
Primary mechanical role of DEJ is to act as a transitional buffer between enamel and dentin. The molecular architecture of the DEJ ensures that stress concentrations are minimized at the junction, preventing the formation of cracks that could compromise the structural integrity of the tooth.
Cracks formed in the enamel has tendency to not pass through dentin due to existence of DEJ. This crack-stopping ability is largely attributed to the nano-interlocking structures within the DEJ, which dissipate the energy of the crack and prevent it from spreading further. In this way, the DEJ functions as a protective barrier, ensuring the longevity of the tooth under repeated mechanical stress. [ 4 ]
The molecular structure of the DEJ has important clinical implications, particularly in the field of restorative dentistry. Dental restorations, such as crowns and fillings, must be designed to mimic the natural mechanical transition between enamel and dentin. Understanding the molecular architecture of the DEJ can inform the development of advanced biomaterials that better integrate with the remaining tooth structure, improving the success rate and longevity of restorative treatments. [ 5 ]
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A dentist , also known as a dental doctor , dental physician , dental surgeon , is a health care professional who specializes in dentistry , the branch of medicine focused on the teeth , gums , and mouth . The dentist's supporting team aids in providing oral health services. The dental team includes dental assistants , dental hygienists , dental technicians , and sometimes dental therapists .
In China as well as France, the first people to perform dentistry were barbers. They have been categorized into 2 distinct groups: guild of barbers and lay barbers. The first group, the Guild of Barbers, was created to distinguish more educated and qualified dental surgeons from lay barbers. Guild barbers were trained to do complex surgeries. The second group, the lay barbers, were qualified to perform regular hygienic services such as shaving and tooth extraction as well as basic surgery. However, in 1400, France made decrees prohibiting lay barbers from practicing all types of surgery. In Germany as well as France from 1530 to 1575 publications completely devoted to dentistry were being published. Ambroise Paré , often known as the Father of Surgery, published his own work about the proper maintenance and treatment of teeth. Ambroise Paré was a French barber surgeon who performed dental care for multiple French monarchs. He is often credited with having raised the status of barber surgeons. [ 1 ] [ 2 ]
Pierre Fauchard of France is often referred to as the "father of modern dentistry" because in 1728 he was the first to publish a scientific textbook on the techniques and practices of dentistry. [ 3 ] Over time, trained dentists immigrated from Europe to the Americas to practice dentistry, and by 1760, America had its own native born practicing dentists. Newspapers were used at the time to advertise and promote dental services. In America from 1768 to 1770 the first application of dentistry to verify forensic cases was being pioneered; this was called forensic dentistry . With the rise of dentists, there was also the rise of new methods to improve the quality of dentistry. These new methods included the spinning wheel to rotate a drill and chairs made specifically for dental patients. [ 4 ]
In the 1840s, the world's first dental school and national dental organization were established. Along with the first dental school came the establishment of the Doctor of Dental Surgery degree, often referred to as a DDS degree. In response to the rise in new dentists as well as dentistry techniques, the first dental practice act was established to regulate dentistry. In the United States, the First Dental Practice Act required dentists to pass each specific state medical board exam in order to practice dentistry in that particular state. However, because the dental act was rarely enforced, some dentists did not obey the act. From 1846 to 1855, new dental techniques were being invented such as the use of ester anesthesia for surgery, and the cohesive gold foil method which enabled gold to be applied to a cavity. The American Dental Association was established in 1859 after a meeting with 26 dentists. Around 1867, the first university-associated dental school was established, Harvard Dental School. Lucy Hobbs Taylor was the first woman to earn a dental degree.
In the 1880s, tube toothpaste was created which replaced the original forms of powder or liquid toothpaste. New dental boards, such as the National Association of Dental Examiners, were created to establish standards and uniformity among dentists. [ 4 ] In 1887, the first dental laboratory was established; dental laboratories are used to create dentures and crowns that are specific to each patient. [ 5 ] In 1895, the dental X-ray was discovered by a German physicist, Wilhelm Röntgen . [ 6 ]
In the 20th century, new dental techniques and technology were invented such as the porcelain crowns (1903), Novocain (a local anesthetic) 1905, precision cast fillings (1907), nylon toothbrushes (1938), water fluoridation (1945), fluoride toothpaste (1950), air driven dental tools (1957), lasers (1960), electric toothbrushes (1960), and home tooth bleaching kits (1989) were invented. Inventions such as the air driven dental tools ushered in a new high-speed dentistry. [ 4 ] [ 7 ]
By nature of their general training, a licensed dentist can carry out most dental treatments such as restorative ( dental restorations , crowns , bridges ), orthodontics ( braces ), prosthodontic ( dentures , crown /bridge), endodontic ( root canal ) therapy, periodontal (gum) therapy, and oral surgery (extraction of teeth), as well as performing examinations, taking radiographs (x-rays) and diagnosis. Additionally, dentists can further engage in oral surgery procedures such as dental implant placement. Dentists can also prescribe medications such as antibiotics , fluorides , pain killers , local anesthetics , sedatives / hypnotics and any other medications that serve in the treatment of the various conditions that arise in the head and neck.
All DDS and DMD degree holders are legally qualified to perform a number of more complex procedures such as gingival grafts , bone grafting , sinus lifts , and implants , as well as a range of more invasive oral and maxillofacial surgery procedures, though many choose to pursue residencies or other post-doctoral education to augment their abilities. A few select procedures, such as the administration of General anesthesia , legally require postdoctoral training in the US. While many oral diseases are unique and self-limiting, poor conditions in the oral cavity can lead to poor general health and vice versa; notably, there is a significant link between periodontal, cardiovascular, and endocrine diseases. [ 8 ] [ 9 ] Conditions in the oral cavity may also be indicative of other systemic diseases such as osteoporosis, diabetes , AIDS , and various blood diseases, including malignancies and lymphoma. Dentists can also prescribe medicines. [ 10 ]
Several studies have suggested that dentists and dental students are at high risk of burnout . During burnout, dentists experience exhaustion, alienate from work and perform less efficiently. [ 11 ] [ 12 ] A systemic study identified risk factors associated with this condition such as practitioner's young age, personality type, gender, the status of education, high job strain, working hours, and the burden of clinical degrees requisites. The authors of this study concluded that intervention programs at an early stage during the undergraduate level may provide practitioners with a good strategy to prepare for and cope with this condition. [ 13 ]
Depending on the country, all dentists are required to register with their national or local health board, regulators, and professional indemnity insurance, in order to practice dentistry. In the UK, dentists are required to register with the General Dental Council. In Australia, it is the Dental Board of Australia, while in the United States, dentists are registered according to the individual state board. The main role of a dental regulator is to protect the public by ensuring only qualified dental practitioners are registered, handle any complaints or misconduct, and develop national guidelines and standards for dental practitioners to follow. [ 14 ]
For many countries, after satisfactory completion of post-graduate training, dental specialists are required to join a specialist board or list, in order to use the title 'specialist'.
In the US, dental specialties are recognized by the American Dental Association (ADA) or the American Board of Dental Specialties (ABDS) [ 15 ] Currently, the ADA lists twelve dental specialties, who are recognized by the National Commission on Recognition of Dental Specialties and Certifying Boards, [ 16 ] while the ABDS recognizes four dental specialty boards. [ 17 ]
List of Dental Specialties under the ADA: [ 16 ]
List of Dental Specialties under the ABDS: [ 17 ]
Specialists in these fields are designated "registrable" (in the United States , "board eligible") and warrant exclusive titles such as dentist anesthesiologist, orthodontist, oral and maxillofacial surgeon, endodontist, pediatric dentist, periodontist, or prosthodontist upon satisfying certain local accreditation requirements (U.S., "Board Certified")
In the UK, the specialties are recognized by the General Dental Council (GDC). Currently the GDC lists 13 different dental specialties: [ 19 ]
European Union legislation recognizes two dental specialties: Oral and Maxillofacial Surgery (A degree in dentistry and medicine being compulsory) [ 20 ] and Orthodontics. [ citation needed ]
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[ 1 ] [ nb 1 ]
Dentistry , also known as dental medicine and oral medicine , is the branch of medicine focused on the teeth , gums , and mouth . It consists of the study, diagnosis , prevention, management, and treatment of diseases , disorders, and conditions of the mouth, most commonly focused on dentition (the development and arrangement of teeth) as well as the oral mucosa . [ 2 ] Dentistry may also encompass other aspects of the craniofacial complex including the temporomandibular joint . The practitioner is called a dentist .
The history of dentistry is almost as ancient as the history of humanity and civilization, with the earliest evidence dating from 7000 BC to 5500 BC. [ 3 ] Dentistry is thought to have been the first specialization in medicine which has gone on to develop its own accredited degree with its own specializations. [ 4 ] Dentistry is often also understood to subsume the now largely defunct medical specialty of stomatology (the study of the mouth and its disorders and diseases) for which reason the two terms are used interchangeably in certain regions. However, some specialties such as oral and maxillofacial surgery (facial reconstruction) may require both medical and dental degrees to accomplish. In European history, dentistry is considered to have stemmed from the trade of barber surgeons . [ 5 ]
Dental treatments are carried out by a dental team, which often consists of a dentist and dental auxiliaries (such as dental assistants , dental hygienists , dental technicians , and dental therapists ). Most dentists either work in private practices ( primary care ), dental hospitals, or ( secondary care ) institutions (prisons, armed forces bases, etc.).
The modern movement of evidence-based dentistry calls for the use of high-quality scientific research and evidence to guide decision-making such as in manual tooth conservation, use of fluoride water treatment and fluoride toothpaste, dealing with oral diseases such as tooth decay and periodontitis , as well as systematic diseases such as osteoporosis , diabetes , celiac disease , cancer , and HIV/AIDS which could also affect the oral cavity. Other practices relevant to evidence-based dentistry include radiology of the mouth to inspect teeth deformity or oral malaises, haematology (study of blood) to avoid bleeding complications during dental surgery, cardiology (due to various severe complications arising from dental surgery with patients with heart disease), etc.
The term dentistry comes from dentist , which comes from French dentiste , which comes from the French and Latin words for tooth. [ 6 ] The term for the associated scientific study of teeth is odontology (from Ancient Greek : ὀδούς , romanized : odoús , lit. 'tooth') – the study of the structure, development, and abnormalities of the teeth.
Dentistry usually encompasses practices related to the oral cavity. [ 7 ] According to the World Health Organization , oral diseases are major public health problems due to their high incidence and prevalence across the globe, with the disadvantaged affected more than other socio-economic groups. [ 8 ]
The majority of dental treatments are carried out to prevent or treat the two most common oral diseases , which are dental caries (tooth decay) and periodontal disease (gum disease or pyorrhea). Common treatments involve the restoration of teeth , extraction or surgical removal of teeth, scaling and root planing , endodontic root canal treatment, and cosmetic dentistry . [ 9 ]
By nature of their general training, dentists, without specialization, can carry out the majority of dental treatments such as restorative (fillings, crowns , bridges ), prosthetic ( dentures ), endodontic (root canal) therapy, periodontal (gum) therapy, and extraction of teeth, as well as performing examinations, radiographs (x-rays), and diagnosis. Dentists can also prescribe medications used in the field such as antibiotics , sedatives , and any other drugs used in patient management. Depending on their licensing boards, general dentists may be required to complete additional training to perform sedation, dental implants, etc.
Dentists also encourage the prevention of oral diseases through proper hygiene and regular, twice or more yearly, checkups for professional cleaning and evaluation. Oral infections and inflammations may affect overall health, and conditions in the oral cavity may be indicative of systemic diseases, such as osteoporosis , diabetes , celiac disease or cancer . [ 7 ] [ 10 ] [ 13 ] [ 14 ] Many studies have also shown that gum disease is associated with an increased risk of diabetes, heart disease , and preterm birth . The concept that oral health can affect systemic health and disease is referred to as "oral-systemic health".
John M. Harris started the world's first dental school in Bainbridge, Ohio , and helped to establish dentistry as a health profession. It opened on 21 February 1828, and today is a dental museum . [ 15 ] The first dental college, Baltimore College of Dental Surgery , opened in Baltimore, Maryland, US in 1840. The second in the United States was the Ohio College of Dental Surgery , established in Cincinnati, Ohio, in 1845. [ 16 ] The Philadelphia College of Dental Surgery followed in 1852. [ 17 ] In 1907, Temple University accepted a bid to incorporate the school.
Studies show that dentists who graduated from different countries, [ 18 ] or even from different dental schools in one country, [ 19 ] may make different clinical decisions for the same clinical condition. For example, dentists that graduated from Israeli dental schools may recommend the removal of asymptomatic impacted third molar (wisdom teeth) more often than dentists that graduated from Latin American or Eastern European dental schools. [ 20 ]
In the United Kingdom, the first dental schools, the London School of Dental Surgery and the Metropolitan School of Dental Science, both in London, opened in 1859. [ 21 ] The British Dentists Act of 1878 and the 1879 Dentists Register limited the title of "dentist" and "dental surgeon" to qualified and registered practitioners. [ 22 ] [ 23 ] However, others could legally describe themselves as "dental experts" or "dental consultants". [ 24 ] The practice of dentistry in the United Kingdom became fully regulated with the 1921 Dentists Act, which required the registration of anyone practising dentistry. [ 25 ] The British Dental Association , formed in 1880 with Sir John Tomes as president, played a major role in prosecuting dentists practising illegally. [ 22 ] Dentists in the United Kingdom are now regulated by the General Dental Council .
Dentists in many countries complete between five and eight years of post-secondary education before practising. Though not mandatory, many dentists choose to complete an internship or residency focusing on specific aspects of dental care after they have received their dental degree. In a few countries, to become a qualified dentist one must usually complete at least four years of postgraduate study; [ 26 ] Dental degrees awarded around the world include the Doctor of Dental Surgery (DDS) and Doctor of Dental Medicine (DMD) in North America (US and Canada), and the Bachelor of Dental Surgery/Baccalaureus Dentalis Chirurgiae (BDS, BDent, BChD, BDSc) in the UK and current and former British Commonwealth countries.
All dentists in the United States undergo at least three years of undergraduate studies, but nearly all complete a bachelor's degree. This schooling is followed by four years of dental school to qualify as a " Doctor of Dental Surgery " (DDS) or " Doctor of Dental Medicine " (DMD). Specialization in dentistry is available in the fields of Anesthesiology, Dental Public Health, Endodontics, Oral Radiology, Oral and Maxillofacial Surgery, Oral Medicine, Orofacial Pain, Pathology, Orthodontics, Pediatric Dentistry (Pedodontics), Periodontics, and Prosthodontics. [ 27 ]
Some dentists undertake further training after their initial degree in order to specialize. Exactly which subjects are recognized by dental registration bodies varies according to location. Examples include:
Tooth decay was low in pre-agricultural societies, but the advent of farming society about 10,000 years ago correlated with an increase in tooth decay (cavities). [ 32 ] An infected tooth from Italy partially cleaned with flint tools, between 13,820 and 14,160 years old, represents the oldest known dentistry, [ 33 ] although a 2017 study suggests that 130,000 years ago the Neanderthals already used rudimentary dentistry tools. [ 34 ] In Italy evidence dated to the Paleolithic, around 13,000 years ago, points to bitumen used to fill a tooth [ 35 ] and in Neolithic Slovenia, 6500 years ago, beeswax was used to close a fracture in a tooth. [ 36 ] The Indus valley has yielded evidence of dentistry being practised as far back as 7000 BC, during the Stone Age . [ 37 ] The Neolithic site of Mehrgarh (now in Pakistan's south western province of Balochistan ) indicates that this form of dentistry involved curing tooth related disorders with bow drills operated, perhaps, by skilled bead-crafters. [ 3 ] The reconstruction of this ancient form of dentistry showed that the methods used were reliable and effective. [ 38 ] The earliest dental filling , made of beeswax , was discovered in Slovenia and dates from 6500 years ago. [ 39 ] Dentistry was practised in prehistoric Malta , as evidenced by a skull which had a dental abscess lanced from the root of a tooth dating back to around 2500 BC. [ 40 ] The practice of dentistry dates back thousands of years, with evidence of dental procedures such as tooth extraction and fillings found in ancient civilizations like the Egyptians and the Greeks. One notable historical figure is Pierre Fauchard , often referred to as the 'father of modern dentistry,' who wrote the first comprehensive book on the subject in 1728.
An ancient Sumerian text describes a " tooth worm " as the cause of dental caries . [ 41 ] Evidence of this belief has also been found in ancient India, Egypt , Japan, and China. The legend of the worm is also found in the Homeric Hymns , [ 42 ] and as late as the 14th century AD the surgeon Guy de Chauliac still promoted the belief that worms cause tooth decay. [ 43 ]
Recipes for the treatment of toothache, infections and loose teeth are spread throughout the Ebers Papyrus , Kahun Papyri , Brugsch Papyrus , and Hearst papyrus of Ancient Egypt . [ 44 ] The Edwin Smith Papyrus , written in the 17th century BC but which may reflect previous manuscripts from as early as 3000 BC, discusses the treatment of dislocated or fractured jaws. [ 44 ] [ 45 ] In the 18th century BC, the Code of Hammurabi referenced dental extraction twice as it related to punishment. [ 46 ] Examination of the remains of some ancient Egyptians and Greco-Romans reveals early attempts at dental prosthetics . [ 47 ] However, it is possible the prosthetics were prepared after death for aesthetic reasons. [ 44 ]
Ancient Greek scholars Hippocrates and Aristotle wrote about dentistry, including the eruption pattern of teeth, treating decayed teeth and gum disease, extracting teeth with forceps , and using wires to stabilize loose teeth and fractured jaws. [ 48 ] Use of dental appliances, bridges and dentures was applied by the Etruscans in northern Italy, from as early as 700 BC, of human or other animal teeth fastened together with gold bands. [ 49 ] [ 50 ] [ 51 ] The Romans had likely borrowed this technique by the 5th century BC. [ 50 ] [ 52 ] The Phoenicians crafted dentures during the 6th–4th century BC, fashioning them from gold wire and incorporating two ivory teeth. [ 53 ] In ancient Egypt, Hesy-Ra is the first named "dentist" (greatest of the teeth). The Egyptians bound replacement teeth together with gold wire. Roman medical writer Cornelius Celsus wrote extensively of oral diseases as well as dental treatments such as narcotic-containing emollients and astringents . [ 54 ] The earliest dental amalgams were first documented in a Tang dynasty medical text written by the Chinese physician Su Kung in 659, and appeared in Germany in 1528. [ 55 ] [ 56 ]
During the Islamic Golden Age Dentistry was discussed in several famous books of medicine such as The Canon in medicine written by Avicenna and Al-Tasreef by Al-Zahrawi who is considered the greatest surgeon of the Middle Ages , [ 57 ] Avicenna said that jaw fracture should be reduced according to the occlusal guidance of the teeth; this principle is still valid in modern times. Al-Zahrawi invented over 200 surgical tools that resemble the modern kind. [ 58 ]
Historically, dental extractions have been used to treat a variety of illnesses. During the Middle Ages and throughout the 19th century, dentistry was not a profession in itself, and often dental procedures were performed by barbers or general physicians . Barbers usually limited their practice to extracting teeth which alleviated pain and associated chronic tooth infection . Instruments used for dental extractions date back several centuries. In the 14th century, Guy de Chauliac most probably invented the dental pelican [ 59 ] (resembling a pelican 's beak) which was used to perform dental extractions up until the late 18th century. The pelican was replaced by the dental key [ 60 ] which, in turn, was replaced by modern forceps in the 19th century. [ 61 ]
The first book focused solely on dentistry was the "Artzney Buchlein" in 1530, [ 48 ] and the first dental textbook written in English was called "Operator for the Teeth" by Charles Allen in 1685. [ 23 ]
In the United Kingdom, there was no formal qualification for the providers of dental treatment until 1859 and it was only in 1921 that the practice of dentistry was limited to those who were professionally qualified. The Royal Commission on the National Health Service in 1979 reported that there were then more than twice as many registered dentists per 10,000 population in the UK than there were in 1921. [ 62 ]
It was between 1650 and 1800 that the science of modern dentistry developed. The English physician Thomas Browne in his A Letter to a Friend ( c. 1656 pub. 1690) made an early dental observation with characteristic humour:
The Egyptian Mummies that I have seen, have had their Mouths open, and somewhat gaping, which affordeth a good opportunity to view and observe their Teeth, wherein 'tis not easie to find any wanting or decayed: and therefore in Egypt, where one Man practised but one Operation, or the Diseases but of single Parts, it must needs be a barren Profession to confine unto that of drawing of Teeth, and little better than to have been Tooth-drawer unto King Pyrrhus, who had but two in his Head.
The French surgeon Pierre Fauchard became known as the "father of modern dentistry". Despite the limitations of the primitive surgical instruments during the late 17th and early 18th century, Fauchard was a highly skilled surgeon who made remarkable improvisations of dental instruments, often adapting tools from watchmakers , jewelers and even barbers , that he thought could be used in dentistry. He introduced dental fillings as treatment for dental cavities . He asserted that sugar -derived acids like tartaric acid were responsible for dental decay , and also suggested that tumors surrounding the teeth and in the gums could appear in the later stages of tooth decay. [ 63 ] [ 64 ]
Fauchard was the pioneer of dental prosthesis , and he invented many methods to replace lost teeth. He suggested that substitutes could be made from carved blocks of ivory or bone . He also introduced dental braces , although they were initially made of gold, he discovered that the teeth position could be corrected as the teeth would follow the pattern of the wires. Waxed linen or silk threads were usually employed to fasten the braces. His contributions to the world of dental science consist primarily of his 1728 publication Le chirurgien dentiste or The Surgeon Dentist. The French text included "basic oral anatomy and function, dental construction, and various operative and restorative techniques, and effectively separated dentistry from the wider category of surgery". [ 63 ] [ 64 ]
After Fauchard, the study of dentistry rapidly expanded. Two important books, Natural History of Human Teeth (1771) and Practical Treatise on the Diseases of the Teeth (1778), were published by British surgeon John Hunter . In 1763, he entered into a period of collaboration with the London-based dentist James Spence. He began to theorise about the possibility of tooth transplants from one person to another. He realised that the chances of a successful tooth transplant (initially, at least) would be improved if the donor tooth was as fresh as possible and was matched for size with the recipient. These principles are still used in the transplantation of internal organs . Hunter conducted a series of pioneering operations, in which he attempted a tooth transplant. Although the donated teeth never properly bonded with the recipients' gums, one of Hunter's patients stated that he had three which lasted for six years, a remarkable achievement for the period. [ 65 ]
Major advances in science were made in the 19th century, and dentistry evolved from a trade to a profession. The profession came under government regulation by the end of the 19th century. In the UK, the Dentist Act was passed in 1878 and the British Dental Association formed in 1879. In the same year, Francis Brodie Imlach was the first ever dentist to be elected President of the Royal College of Surgeons (Edinburgh), raising dentistry onto a par with clinical surgery for the first time. [ 66 ]
Long term occupational noise exposure can contribute to permanent hearing loss, which is referred to as noise-induced hearing loss (NIHL) and tinnitus . Noise exposure can cause excessive stimulation of the hearing mechanism, which damages the delicate structures of the inner ear. [ 67 ] NIHL can occur when an individual is exposed to sound levels above 90 dBA according to the Occupational Safety and Health Administration (OSHA). Regulations state that the permissible noise exposure levels for individuals is 90 dBA. [ 68 ] For the National Institute for Occupational Safety and Health ( NIOSH ), exposure limits are set to 85 dBA. Exposures below 85 dBA are not considered to be hazardous. Time limits are placed on how long an individual can stay in an environment above 85 dBA before it causes hearing loss. OSHA places that limitation at 8 hours for 85 dBA. The exposure time becomes shorter as the dBA level increases.
Within the field of dentistry, a variety of cleaning tools are used including piezoelectric and sonic scalers, and ultrasonic scalers and cleaners. [ 69 ] While a majority of the tools do not exceed 75 dBA, [ 70 ] prolonged exposure over many years can lead to hearing loss or complaints of tinnitus. [ 71 ] Few dentists have reported using personal hearing protective devices, [ 72 ] [ 73 ] which could offset any potential hearing loss or tinnitus.
There is a movement in modern dentistry to place a greater emphasis on high-quality scientific evidence in decision-making. Evidence-based dentistry (EBD) uses current scientific evidence to guide decisions. It is an approach to oral health that requires the application and examination of relevant scientific data related to the patient's oral and medical health. Along with the dentist's professional skill and expertise, EBD allows dentists to stay up to date on the latest procedures and patients to receive improved treatment. A new paradigm for medical education designed to incorporate current research into education and practice was developed to help practitioners provide the best care for their patients. [ 74 ] It was first introduced by Gordon Guyatt and the Evidence-Based Medicine Working Group at McMaster University in Ontario, Canada in the 1990s. It is part of the larger movement toward evidence-based medicine and other evidence-based practices , especially since a major part of dentistry involves dealing with oral and systemic diseases. Other issues relevant to the dental field in terms of evidence-based research and evidence-based practice include population oral health, dental clinical practice, tooth morphology etc.
Like other medical disciplines, dentistry is strongly influenced by the digital transformation of healthcare. Processes are changing fundamentally, affecting the effectiveness and accuracy of patient treatment. [ 75 ] [ 76 ]
Various technologies are being used in dentistry, including CAD/CAM systems in combination with 3D printing , artificial intelligence (AI) , and electronic health records . [ 77 ] [ 78 ] The degree of implementation of such technologies varies significantly across dental practices. [ 79 ]
Research shows that larger dental centers are adopting digital solutions more rapidly. Younger dentists, as well as those who regularly participate in digital training programs, show a higher willingness to implement new technologies. However, financial constraints and the lack of comprehensive training opportunities for the digitalization of dentistry currently represent major barriers to implementation. [ 80 ]
Dentistry is unique in that it requires dental students to have competence-based clinical skills that can only be acquired through supervised specialized laboratory training and direct patient care. [ 81 ] This necessitates the need for a scientific and professional basis of care with a foundation of extensive research-based education. [ 82 ] According to some experts, the accreditation of dental schools can enhance the quality and professionalism of dental education. [ 83 ] [ 84 ]
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Dentistry for babies is a branch of pediatric dentistry provided to children from birth to around 36 months of age, aiming to maintain or re-establish a good oral health status and create a positive attitude in parents and children about dentistry. [ 1 ] [ 2 ] Although concerns about dental treatment directed to babies have been reported at the beginning of the twentieth century, only recently has the dental community started to focus on this area of dentistry, due to the high dental caries (decay) prevalence observed in young children.
The first [ citation needed ] setting for providing dental care exclusively to babies started in 1986, at Londrina's State University (Brazil), [ 3 ] changing the concept from early treatment of carious lesions and their consequences to early educative-preventive attention. These concepts were disseminated throughout the entire country introducing new clinics with a similar philosophy such as the Baby Clinic of Araçatuba Dental School, São Paulo State University (UNESP), [ 4 ] and also abroad.
The general aim is to provide dental assistance to 0-3-year-old children, through an educative-preventive oral health program directed to parents and children comprising the diagnosis, prevention, treatment, and control of the most common clinical situations at this age range ( dental caries , dental trauma , alterations of tooth development, etc.).
At the Baby Clinic of Araçatuba Dental School, parents are required to enroll their babies from birth up to 6 months of age. Prior to the first clinical session, parents attend a lecture providing general information about:
Meetings occur on a regular basis. At the end of them, parents are shown how to clean the baby's mouth and how to use a fluoridated solution. Afterward, the baby's first appointment is booked.
A general clinical examination evaluates the baby's health as a whole. If necessary, the baby is referred to professionals in other areas for further examination. Caries risk is determined by correlating information gathered through anamnesis , clinical examination, and environmental factors:
Specific educative orientation will be directed to parents according to the needs of the baby's caries risk. Caries risk must be determined in this first appointment. The type of assistance to be provided to the baby will depend on the risk.
For low caries risk children, the aim is to maintain the baby's oral health. Clinical sessions include hygiene with hydrogen peroxide (1 part of H 2 O 2 + 3 parts of boiled or filtered water) and application of 0.1% sodium fluoride (NaF) solution using cotton swab. At home, parents and caregivers are instructed to keep the same dietary and hygiene habits, and apply a 0.05% NaF solution once per day with a cotton swab at night time before the baby sleeps. Follow-up appointments are booked quarterly. At the first follow-up session, the caregiver is asked to perform the hygiene procedures and to apply the fluoridated solution under professional supervision to evaluate how skilled they are in performing those tasks, as well as to correct possible mistakes. If caries risk remains low, a quarterly scheme can be kept.
For high caries risk children, the aim is to revert the baby's caries risk, as well as to increase tooth resistance. Clinical sessions include the identification and reversion of risk factors for caries – parents are oriented on how to control (either eliminating or reducing) caries risk factors. Tooth resistance will be increased by applying a 0.1% NaF solution over all tooth surfaces. At home, parents and caregivers will adopt measures for oral hygiene and diet control, as well as eliminate bad oral hygiene and dietary habits that increase the risk of caries development. Daily application of a 0.05% NaF solution is also recommended. Follow-up appointments are booked every 1 or 2 months. As with low caries risk children, the caregiver will be asked to perform the hygiene procedures and to apply the fluoridated solution under professional supervision to evaluate how skilled they are in performing those tasks, as well as to correct possible mistakes. Caries risk must be evaluated again. Parents will be evaluated on how the recommendations done in the first session are being followed, which could potentially reduce the baby's caries risk.
For children with caries lesions, the aims are to re-establish oral equilibrium, by eliminating or reducing causal factors, as well as by increasing tooth resistance. Four clinical sessions, with a 1-week interval, are performed, so the dentist is able to act over causal factors (instructing parents), to increase tooth resistance (hygiene with diluted H 2 O 2 solution and gauze; application of fluoride varnish over white spot lesions and softened carious lesions), as well as to restore tooth cavities with glass ionomer cement (atraumatic restorative treatment). At home, parents and caregivers will adopt measures for oral hygiene and diet control, as well as daily application of a 0.05% NaF solution. The first follow-up appointment is booked after 1 month, when caries risk must be re-evaluated to determine the appropriate periodicity for checkups. At the first follow-up session, the caregiver will be asked to perform the hygiene procedures and to apply the fluoridated solution under professional supervision to evaluate how skilled they are in performing those tasks, as well as to correct possible mistakes. [ citation needed ]
Caries risk assessment will be performed on a regular basis regardless of the initial caries risk evaluation, so changes in the protocol can be implemented whenever necessary.
"Pediatric Dentistry: A Clinical Approach" [ 5 ] aims to provide information about dental problems, and related conditions. The developments of oral health in infants impacts the overall risks, health conditions and issues.
Dental caries are the most significant cause of health problems among babies. The meta analysis of dental caries in children, a sample size of 80,405 was 46.2% (95% CI: 41.6–50.8%), and the prevalence of dental caries in permanent teeth in children in the world with a sample size of 1,454,871 was 53.8% (95% CI: 50–57.5%). [ 6 ]
“Early Childhood caries update: A review of causes, diagnoses, and treatments” [ 7 ] aim is the factors and causes to treat adolescents early dental care. “Tooth extraction is a common and necessary treatment for advanced carries of one or more decayed” found in a child 72 months of age or younger.
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Dentistry developed during the early parts of Roman history , which may be due to the arrival of a Greek doctor named Archagathus . Ancient Roman oral surgical tools included the curettes , osteotomes , cauteries , scalpels , bone forceps , [ 1 ] and bone levers . [ 2 ] The ancient Romans invented the usage of narcotics during dental surgery . These tools were used to treat conditions such as toothache and to extract teeth . It was believed in ancient Rome that the cause of the conditions that necessitated such treatment was a " tooth worm ."
According to Pliny the Elder , a 1st-century Roman writer, an established medical community was absent for much of Roman history . During this time, medicine was confined to popular homemade remedies rather than professionally trained doctors. The profession of medicine was introduced to the Romans by the Greek doctor Archagathus , who traveled to Rome and established himself as a physician. [ 3 ] Eventually, he garnered a reputation for violent use of steel and fire costing him his reputation and granting him the title of "butcher." Archaeological and historical evidence disputes this narrative.
The Twelve Tables —the set of legislation forming the basis of Roman law —mention teeth laden with gold, [ 4 ] implying that dentistry had been practiced at this point in history. Other evidence includes the finding of prosthetic materials designed to treat dental and oral health conditions in Roman cities such as Teano . [ 5 ] Dental tools have been unearthed at various Roman archaeological sites, indicating that dentistry became commonplace throughout the Roman world. [ 6 ] It is unclear which Roman profession or professions would have performed dentistry . There may have been medical specialists trained to perform dental procedures, it is also possible that dentistry was practiced as a subset of other professions, such as barbery . [ 2 ]
In the 3rd century, Saint Dionysius described the story of Saint Apollonia , who was allegedly brutally beaten by a mob of pagans . According to Saint Dionysius, the pagans knocked out her teeth and threatened to burn her if she did not blaspheme God . In response, she is said to have thrown herself into the fire. Afterwards, she became the patron saint of dentistry in Christian tradition. [ 7 ] Analysis of teeth samples from the Roman era and the Early Middle Ages , shortly following the collapse of Rome , indicate the prevalence of dental lesions and caries rose during the transition to the Middle Ages . [ 8 ] Similar evidence from Late Antique and Early Medieval Croatia suggests that rates of abscesses , caries, tooth loss , posterior teeth decay, and alveolar resorption rose during the early medieval period. However, the same evidence indicated that Late Antique Romans suffered from higher rates of anterior teeth decay, possibly due to non-dietary factors. [ 9 ]
The Roman anatomist Galen commented on Hippocrates' work, classifying teeth as bones, noting their distinct characteristics compared to other bones. He was the first to discover nerves in teeth and identified seven cranial nerves in his research. [ 10 ]
The ancient Romans whitened their teeth using toothpaste made from human urine and goat milk . [ 11 ] Scribonius Largus , a 1st-century Roman physician, claims Messalina —the wife of Emperor Claudius —used toothpaste made from mastic , salammoniac , and calcified stag horns . Toothpicks, known to the Romans as dentiscalpia , were also used for teeth cleaning; they were typically made of lentisk wood , although in some cases quill or gold were used instead. Pliny claims that toothpicks made from porcupine quills would harden the teeth, while vulture quills would sour the breath. [ 12 ]
Dental prosthetics were first developed by the ancient Etruscan civilization in the 7th century BCE; in the following centuries, gold prosthetics remained in use throughout Etruria and Rome. However, gold dental prosthetics disappeared from the archaeological record by the Late Republic . [ 13 ] The 1st-century Roman medical writer Celsus described a process in which physicians utilized gold or silk threads to tie teeth to the gums, allowing for dental implants to replace lost teeth. [ 14 ] This same process could also be used to replace missing parts of existing teeth. The usage of golden implants is further depicted by Martial , who described the repair of broken teeth using golden stoppings. [ 15 ] Cicero , a 1st-century BCE Roman politician, mentions a law forbidding corpses from being buried with gold, unless they had golden dental implants. [ 4 ] Doctor of dental surgery and historian Bernhard Wolf Weinberger believed that such legislation indicated that golden implants were common, as otherwise he argues there would have been no need to specify it as an exception. [ 16 ]
Celsus mentioned the possibility of replacing teeth using real teeth extracted from the corpses of the dead. [ 17 ] [ 18 ] Archaeological evidence of false Roman teeth dating to the 1st or 2nd century was possibly unearthed in a Gallo-Roman necropolis by the hamlet of Chantambre in Essonne , France . Excavators discovered the remains of an around 30-year-old Roman man with a metal implant by the second upper-right premolar tooth. The excavators argued that it was made of iron or non- alloy steel , although they believed it contained traces of calcium and silicon . Certain sections of the implant are more oxidized than other areas; the researchers believe this discrepancy indicates that the piece may have been forged through hammering and folding. [ 19 ] However, the veracity of this find has been heavily criticized by archaeologist Dr. Marshall J. Becker , who argued that the finding was more likely a natural tooth stained with iron oxide . [ 20 ] In his Epigrams , Martial often derides others for utilizing fake teeth: he ridicules a one-eyed prostitute for utilizing fake teeth and a wig, [ 21 ] ridicules an old lady for her fake teeth made of bone and ivory , [ 12 ] and mocks a girl named Maximina for her fake teeth made of boxwood and pitch . [ 21 ] Martial describes a physician named Cascellius who worked by the Aventine Hill in Rome in the 1st-century CE; this dentist is described as filling teeth with lead. [ 15 ]
According to the Hippocratic text , De Carnibus , teeth were considered bones since they extended from the bones inside the head and mouth . [ 22 ] The 2nd-century CE Roman surgeon Galen stated that the human body contained 32 teeth divided equally between the upper and lower jaw . [ 23 ] He grouped these teeth into three categories: molars , canines , and incisors . Incisors, as described by Galen, were wide and sharp teeth used to cut through food. Galen wrote that there were four incisors in the front part of each jaw. There were also only four canine teeth; they had a wide base and were located on both sides of the jaws. Their name derives from supposed similarities to the teeth of dogs. Although Galen noticed the molar teeth, he failed to distinguish between molars and premolars . Galen further documented cases of individuals with 4 molars in each part of the jaw instead of 5, incidents of birth defects that resulted in abnormalities in molar teeth, as well as cases of people with excess molars. [ 24 ] According to Galen, the formation of teeth begun inside the uterus and that their growth was completed after the skull bones had been shaped. Galen incorrectly claimed that teeth were the only example of innervated hard tissue . [ 25 ]
Pliny the Elder's Naturalis Historia (AD 23–79), contains references to filling materials used as fillers in hollow teeth. [ 26 ] Roman gold crowns dated to 100 BC have been found at the Satricum excavation. [ 27 ]
Galen distinguished between diseases of the root and of the pulp in his work De ossibus , the same text in which he also identified the medical issue of a toothache . [ 22 ] Around 100 CE, the physician Archigenes stated that tooth pain could be caused by a disease of the interior tooth leading to an inflammation of the gums. He attempted to treat this phenomenon by applying a small drill to the dental crown . [ 15 ] Other Roman doctors believed that toothaches were caused by a " toothworm ." [ 28 ] Scribonius Largus believed that this condition could be treated by applying a scalpel to cut away at the infected teeth. [ 15 ]
Treatments for toothaches were popular and widely desired due to the intense pain and dental decay this condition caused. In his work Natural History , the 1st-century Roman writer Pliny the Elder discussed therapies for tooth pain. He described various concoctions such as the ashes of burned earthworms , ashes of burned mice mixed with fenned roots and honey , sparrow feces wrapped in wool ; snakeskin mixed with oil , resin , and pitch-pine and then poured into an ear. [ 29 ] Pliny further describes a patient who, after receiving a treatment for a toothache consisting of wax and asafoetida , committed suicide . [ 30 ] Celsus advises patients with toothaches apply a pad of wool and a sponge to the afflicted teeth, while abstaining from drinking wine and food initially; they would proceed to only eat soft foods to avoid irritating the gums. [ 31 ] Medicaments such as saffron , opium , spider eggs , fried worms , pepper , and nardus paste may have been used as painkillers for toothaches. [ 32 ]
Archaeological evidence from the house of Julius Polybius in Pompeii revealed that amongst 11 skulls and 145 teeth, only 2 osteolytic lesions and 10 caries were identified. Another study on the skeletons of 41 adults and 12 children from Herculaneum revealed that only 3.8% of the 1275 teeth were carious. The relatively low rate of carious lesions amongst these samples could be attributed to the fluorine -rich water near each settlement. [ 33 ] Analysis of a separate sample of 700 skeletons from the Via Latina revealed that although the majority of teeth were not carious, 70% of the samples had at least one carious lesion. Furthermore, 80% of the skeletons had tartar presence in the teeth and 26% had abscesses in the alveoli . [ 34 ] Archaeological evidence from 77 skeletons in Viminacium dating to the 2nd to 4th centuries found that the dental health of the studied sample was comparable to modern data, with only 3.9% of the skeletons having carious lesions. [ 35 ] Around 64% of the skeletons were afflicted with tooth abrasion , the most prevalent condition amongst the sample. [ 36 ]
Excavations of a taberna by the Temple of Castor and Pollux unearthed a deposit of 86 teeth most of which are afflicted with carious lesions . [ 37 ] Each tooth was unbroken, suggesting that they had been removed by a skilled dentist. Further analysis of these teeth revealed that the front of the cavities had hypermineralized areas, possibly indicating the usage of analgesics . [ 38 ] Many of the teeth likely had the soft part of their carious sections removed prior to surgical treatment, leaving the cavities uniquely round or circular. [ 32 ] Some examples of teeth from this site have the remains of dentin along the sections of pulp impacted by caries, suggesting that the pulp was preserved throughout the procedure until it was entirely exposed. [ 39 ] Evidence from 1st-4th century Roman skeletons from a rural community in the province of Macedonia found extremely high rates of periodontitis and calculus , although low rates of caries. [ 40 ] Similar studies on other rural Roman communities have found high rates of periodontitis , caries, periapical cavities, calculus, and tooth decay. [ 41 ] Differences in the oral health between communities was likely strongly influenced by geography; different subsentence strategies affected diets and thus oral health. [ 41 ] [ 42 ] Menaeum , an ancient Roman community in Sicily , suffered from high rates of caries and calculus likely due to protein and carbohydrate -rich diets. [ 43 ] However, evidence from the necropolis near Vallerano revealed low rates of caries amongst it sample likely due to a primarily agricultural diet centered around products. [ 44 ]
External stressors can lead to tooth decay by disrupting enamel development creating Wilson bands, a deformed type of Striae of Retzius . [ 45 ] Analysis of 127 Roman skeletons from a Roman necropolis at Isola Sacra indicates that the Wilson bands were most prevalent from 2-5 and 6-9 months after birth, correlating with infant mortality rates in ancient Rome. [ 46 ] Harsh external conditions can also lead to enamel hypoplasia , a condition defined by a lack of enamel . This defect is extremely common amongst Roman skeletons from Vallerano, most frequently appearing in the remains of individuals between 2 and 4 years old. These results indicate that the sampled skeletons were exposed to severe and stressful experiences in childhood. [ 47 ] Comparisons of skeletons from the rural community of Lucus Feroniae and urban settlement of Isola Sacra revealed that the rates of enamel hypoplasia were similar, a fact possibly attributable to similar levels of metabolic stress affecting dental development. [ 48 ] The urban population may have experienced similar harsh conditions to the rural settlement due to the effects of higher population density in urban sites such as increased disease spread . [ 49 ]
Tooth extraction is an oral surgical procedure conducted to remove teeth. In ancient Rome, it may have been practiced by specialists who were not associated with any other Roman medical professionals. [ 6 ] This practice presented numerous dangers for patients and challenges for physicians. Celsus recommends that physicians remove teeth straight to avoid risking the bone being broken by the roots. [ 50 ] Extraction of teeth in the maxilla risked damaging the eyes and the temples ; Celsus advises addressing this issue by making an incision into the gingiva , clearing the gum and bone around the tooth thus allowing for it to be extracted either by hand or using a forceps. [ 51 ] The danger of this practice also resulted in it becoming rare; [ 2 ] Celsus cautions physicians against the technique, advising that it should only be employed in herbal remedies had failed to address the issue. [ 52 ]
Another practice involved cutting the gum to expose the root before extraction, followed by cauterization . Celsus advises that the cautery should be applied lightly, imposing little pressure on the gums. Afterward, the gums were covered with honey and washed with mead . [ 52 ] According to Celsus, physicians should refuse to extract children's teeth unless they were preventing adult teeth from growing. [ 53 ] [ 54 ] If the adult tooth began to grow before the primary tooth had fallen out, then Celsus recommends the removal of the original tooth and for the new tooth to be pushed further into place by hand each day. [ 55 ] He further writes that, if the root had been left behind, the physician should remove it utilizing a pair of forceps called a rhizaga . The rhizaga could also be used to remove a cavity, although according to Celsus this procedure should be performed after the cavity had been filled with a lead amalgam to ensure the dental crown remained intact. [ 50 ] Celsus describes other tools called the specillum , a type of probe, and the vulsellum , used as a type of probe. [ 31 ]
Ancient Roman medical writers believed that teeth could become loose due to root weakness or gum disease . They would treat this by cauterizing the gums, then covering it in honey swilled with mead . Afterwards, medication was placed on the teeth. If the tooth became painful it would be extracted. This procedure would be conducted by "scraping" the tooth in "round order" and then shaking the tooth until it could be safely removed. [ 56 ] Celsus described a treatment for gum bleeding that involved chewing purslane and another therapy for mouth bleeding that involved drinking undiluted wine or vinegar . He further recommends that patients could chew on either apples and pears or vinegar to contain the juices within their gums. [ 57 ] [ 58 ] Pedanius Dioscorides , a 1st-century Greek physician, documented herbal remedies that functioned as drugs for gum disease and toothaches. [ 59 ]
As early as the 7th century BC, Etruscans in northern Italy made partial dentures out of human or other animal teeth fastened together with gold bands. [ 60 ] [ 61 ] The Romans had likely borrowed this technique by the 5th century BC. [ 60 ] A text by Martial (c. AD 40-103) referenced Cascellius, who extracted or repaired painful teeth. H. L. Strömgren (1935), postulated that by repairing it was meant tooth replacement and not tooth filling. [ 62 ]
Celsus described treatments for the medical condition known as cleft lip and palate . He wrote that applying a suture and abrasions to the lips was Celsus' suggested method of treating small defects. Larger and more problematic defects were treated using a surgical procedure known as flaps . Galen , another Roman doctor likely described either coloboma or facial cleft . To treat this condition, he recommended scarifying the skin and unifying the disparate parts of the skin, removing callouses, and then finishing the procedure through sewing and glue. It was believed that a healthy palate was necessary for proper speech. [ 56 ]
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Dentomandibular sensorimotor dysfunction (DMSD) is a medical condition involving the mandible (lower jaw), upper three cervical (neck) vertebrae , and the surrounding muscle and nerve areas.
There is a concentrated nerve center in this area called the trigeminal nucleus . This major pathway of nerves controls pain signals from the teeth, face, head, and neck, and carries them to the brain. DMSD is a condition in which an individual experiences chronic pain or stiffness from these nerve inputs as a result of dental force imbalances. [ 1 ]
There are many symptoms associated with DMSD conditions. The most commonly reported are: [ 2 ]
This condition affects all ages and both genders. However, females are more likely to suffer from DMSD. Individuals who have experienced chronic headaches and/or migraines without finding lasting relief through traditional medicine can be assessed for DMSD through a combination of objective tests, evaluations, and a comprehensive discussion of their symptoms, medical history, headache history, pharmacological background, and head health. Research used in sports medicine and rehabilitation allows dentists to address the population with DMSD symptoms.
The dental foundation consists of teeth, muscles, and joints in the dentofacial (head and neck) area. The dental foundation is considered to be out of balance when one or more of the following conditions apply:
The protocol for assessment of the condition is typically done in several stages:
This tool is used for digital force analysis to measure the presence and amount of imbalance at closing of the mouth, during closure, and during mastication (chewing). The computer displays the results of how the forces in the mouth spread along the arch, the center of force, the center of force trajectory, and the left/right force balance. This means the dentist can show patients which teeth are generating the most force, and facilitates the dentist’s knowledge of what adjustments need to be made to teeth and soft tissue to create a stable dental foundation. [ citation needed ]
This test digitally measures an individual’s cervical range of motion from a standing position and displays the results in terms of flexion and extension , left and right lateral flexion, and left and right rotation. Limited cervical range of motion is a disability , and being able to understand what is normal—and where their own mouth, head and neck are during the examination—helps people see how this disability is affecting their condition.
This is also when the amount a person can open their mouth is measured. Along with normal opening movement, the jaw should slide symmetrically from left to right at least 25% of the total mouth opening distance.
Finally, during the range of motion assessment, a record of jaw joint vibrations and sounds are made. Normal jaw joints glide without noise or vibrations.
Depending on the assessment findings, patients are classified as needing 1 of 4 levels of care (see Table 1: Levels of Dental Headache Care) to treat and manage their pain and balance their dental foundation. Every level has a regimented therapy protocol designed to provide the most effective, long-lasting care for each individual.
Once the type of headache pain and extent of dental foundation imbalance is determined, treatment options are discussed.
Historically, the treatments for headache pain included one or a combination of herbal remedies, stress-reduction exercises, massage , acupuncture , non-steroidal anti-inflammatory drugs (NSAID), narcotic pain relievers, anti-seizure medications , chiropractic adjustments, anti-depressants or sedatives .
The combination of advanced dentistry techniques and sports rehabilitation-derived therapies used in treating dental force imbalances in dental headache care has resulted in a dentist reported 93% success rate in providing patients with real, lasting relief from their DMSD symptoms. The methods used control muscle force and force balance, restore proper function and range of motion, and change the way the brain perceives stimuli, so pain levels, dysfunction, and improper muscle activity
return to normal. By balancing the muscles, joints, and teeth, and controlling the way the body feels pain in the head and neck
areas, long lasting pain relief can be achieved.
Once the individual has had the proper dental adjustments to restore normalcy to the dental foundation, and has been prescribed and fitted for their at-home orthotic (worn in the mouth for the short term, typically only during the 4- to 12-week rehabilitation period) for muscle re-training, the sports rehabilitation-derived components of therapy begin.
The goal of therapeutic ultrasound treatment is to restore circulation to sore, strained muscles through increased blood flow and heat. Another objective is to break up scar tissue and deep adhesions (areas where connective tissue fibers have formed over muscle) through sound waves . Therapeutic exposure to ultrasound reduces trigger point sensitivity and is considered a useful clinical tool for managing myofascial pain. Moreover, the ultrasound has also been shown to lessen the stiffness and discomfort of trigger points. [ 4 ]
Sub-threshold micro-current stimulation reduces muscle spasms and referral pain through a low electrical signal that decreases lactic acid buildup and encourages healthy nerve stimulation. Micro-current electrotherapy is known to significantly aid in increasing mouth opening. [ 5 ]
Low-level laser therapy , sometimes called light therapy for short, decreases pain and inflammation , accelerates the healing of muscle and joint tissues by 25%-35%, and reconnects the brain stem ’s neurological pathways, effectively inhibiting pain. Low-level laser therapy combined with electrical stimulation improves mouth opening in patients diagnosed with TMJ/D. The musculoskeletal system 's natural healing ability decreases pain and promotes TMJ stability. [ 6 ]
Manual trigger-point therapy , also known as manual muscle therapy , decreases and eliminates pain and tension in the trigger points by breaking up muscle knots and increasing blood flow. This decreases inflammation and pain in the muscles. [ 7 ]
As part of their in-office treatment, a dentist-monitored homecare system/deprogrammer and intraoral orthotic device are given to patients for their own personal use on their own time.
Patients will typically need: [ 8 ]
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In medicine, denudation refers to the loss of surface layers, such as the epithelium . Denudation coupled with peeling and cracking of skin gives rise to a "crazy pavement dermatosis" pattern seen in Kwashiorkor or Kwashiorkor-Marasmus complex.
In occupational asthma , the denudation of the bronchial mucosa can occur in the setting of nonimmunologic exposures (i.e., chemical spill, chlorine, ammonia), causing irritation.
Clostridioides difficile is known to cause formation of pseudomembranes in the intestines that is formed by denuded epithelium, neutrophilic infiltrate, fibrin , and bacteria due to the effects of its toxins: Toxin A (TcdA) and Toxin B (TcdB), which disrupt cellular cytoskeletons and tight junctions leading to cell death. [ 1 ]
This medical article is a stub . You can help Wikipedia by expanding it .
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The Department of Forest Biomaterials at North Carolina State University (NC State) is an academic department specializing in the study and development of forest-based materials, bioenergy, and sustainability. [ 3 ] [ 4 ] [ 5 ] [ 6 ] The department is part of the College of Natural Resources.
Undergraduate and graduate programs (#1 in Wood Science & Wood Products/Pulp & Paper Technology in 2024 in the United States [ 14 ] [ 15 ] ), including Bachelor's, Master's, and Ph.D. degrees. Courses cover topics such as wood science, bioenergy, sustainable biomaterials, and environmental sustainability. [ 16 ]
The Department of Forest Biomaterials collaborates with various institutions, organizations, and industries:
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https://en.wikipedia.org/wiki/Department_of_Forest_Biomaterials
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In physiology and medicine , depression [ 1 ] refers to a lowering, in particular a reduction in a specific biological variable or the functions of an organ . It is the opposite of elevation. For example, it is possible to refer to "depressed thyroid function" or to a depression of blood flow in a particular area.
Further examples:
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https://en.wikipedia.org/wiki/Depression_(physiology)
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Derealization is an alteration in the perception of the external world, causing those with the condition to perceive it as unreal, distant, distorted, or in other ways falsified. Other symptoms include feeling as if one's environment lacks spontaneity, emotional coloring, and depth. [ 1 ] Described as "Experiences of unreality or detachment with respect to surroundings (e.g., individuals or objects are experienced as unreal, dreamlike, foggy, lifeless or visually distorted") in the DSM-5 , it is a dissociative symptom that may appear in moments of severe stress. [ 2 ] [ 3 ]
Derealization is a subjective experience pertaining to a person's perception of the outside world, while depersonalization is a related symptom characterized by dissociation from one's own body and mental processes. The two are commonly experienced in conjunction but can also occur independently. [ 4 ]
Chronic derealization is fairly rare, and may be caused by occipital – temporal dysfunction. [ 5 ] Experiencing derealization for long periods of time or having recurring episodes can be indicative of many psychological disorders, and can cause significant distress. Chronic derealization is estimated to occur in between 0.95% and 2.4% of the general population. [ 6 ] Derealization is equally prevalent amongst men and women, while the onset usually occurs in adolescence; only 5% of cases of chronic derealization occur in those older than 25. [ 7 ] Temporary derealization symptoms are commonly experienced by the general population a few times throughout their lives, with a lifetime prevalence of 26%–74% and a prevalence of 31%–66% at the time of a traumatic event . [ 8 ]
Derealization is linked to childhood trauma, with its severity correlating directly with the reported severity of childhood maltreatment. [ 9 ]
The experience of derealization can be described as feeling as if a substance separates a person from the outside world, such as a sensory fog, pane of glass, or veil. The person may feel as if they are viewing their surroundings through VR glasses, through glass, or on a movie screen. Some report that what they see lacks vividness and emotional coloring. [ 10 ] Emotional response to visual recognition of loved ones may be significantly reduced. Feelings of déjà vu or jamais vu are common. One may not be sure whether what one perceives is real. The world may seem as if it were going through a dolly zoom effect. Such perceptual abnormalities may also extend to hearing, taste, and smell. An important differentiation between hallucination and derealization is that one does not hear, see, or experience things that are not real or visible during derealization; rather, one experiences their surroundings as distant or dreamlike. During this state of altered perception, one is aware of the feeling's subjective nature. [ 11 ]
The degree of familiarity one has with their surroundings is among one's sensory and psychological identity , memory foundation, and history when experiencing a place. People experiencing derealization block this identifying foundation from recall. This "blocking effect" creates a discrepancy of correlation between one's perception of one's surroundings during derealization and what one would perceive in its absence.
Frequently, derealization occurs in the context of constant worrying or " intrusive thoughts " that one finds hard to switch off. In such cases it can build unnoticed along with the underlying anxiety attached to these disturbing thoughts, and be recognized only in the aftermath of a realization of crisis, often a panic attack , subsequently seeming difficult or impossible to ignore. This type of anxiety can be crippling to the affected and may lead to avoidant behavior. Those who experience this phenomenon may feel concern over the cause of their derealization. It is often difficult to accept that such a disturbing symptom is simply a result of anxiety, and one may think the cause must be something more serious. This can, in turn, cause more anxiety and worsen the derealization. Derealization has also been shown to interfere with the learning process, with cognitive impairments demonstrated in immediate recall and visuospatial deficits. [ 12 ] This can be best understood as the feeling of seeing events in third person. [ 13 ]
Derealization can accompany the neurological conditions of epilepsy (particularly temporal lobe epilepsy ), migraine , and mild TBI ( head injury ). [ 14 ] There is a similarity between visual hypo-emotionality, a reduced emotional response to viewed objects, and derealization. This suggests a disruption of the process by which perception becomes emotionally colored. This qualitative change in the experiencing of perception may lead to reports of anything viewed being unreal or detached. [ 5 ]
The instances of recurring or chronic derealization among those who have experienced extreme trauma and/or have post-traumatic stress ( PTSD ) have been studied closely in many scientific studies, whose results indicate a strong link between the disorders, with a disproportionate amount of post traumatic stress patients reporting recurring feelings of derealization and depersonalization (up to 30% of those with the condition) in comparison to the general populace (only around 2%), [ 15 ] especially in those who experienced the trauma in childhood. Many possibilities have been suggested by various psychologists to help explain these findings, the most widely accepted including that experiencing trauma can cause individuals to distance themselves from their surroundings and perception, with the aim of subsequently distancing themselves from the trauma and (especially in the case of depersonalisation) their emotional response to it. This could be either as a deliberate coping mechanism or an involuntary, reflexive response depending on circumstance. [ 16 ] This possibly not only increases the risk of experiencing problems with derealization and its corresponding disorder, but with all relevant dissociative disorders. In the case of childhood trauma, not only are children more likely to be susceptible to such a response as they are less able to implement more healthy strategies to deal with the emotional implications of experiencing trauma, there is also a lot of evidence that shows trauma can have a substantial detrimental effect on learning and development, especially since those who experience trauma in childhood are far less likely to have received adequate parenting. [ 16 ]
Some neurophysiological studies have noted disturbances arising from the frontal-temporal cortex, which could explain the correlation found between derealization symptoms and temporal lobe disorders. This is further supported by reports of people with frontal lobe epilepsy , with those with epilepsy of the dorsal premotor cortex reporting symptoms of depersonalization, while those with temporal lobe epilepsy reported experiencing derealization symptoms. [ 17 ]
Derealization is a common psychosomatic symptom seen in various anxiety disorders, especially hypochondria . [ 18 ]
One study suggested multiple explanations for derealisation, one of which being the “intrusions of sleep elements into waking consciousness”, [ 19 ] because derealisation has been described as “dream-like”, and because derealisation is related to low levels of norepinephrine, a neurotransmitter regulating alertness, in the urine. These all suggest a link between derealisation and depersonalisation and abnormalities in sleep and wakefulness. Another explanation in the same vein is poor sleep quality, which contributes to rumination— repetitively focusing on one’s own distress and the circumstances surrounding such distress— and seems to either bring about or increase symptoms of derealisation. Rumination and derealisation were found to be linked, as those individuals who had high levels of rumination were more likely to report symptoms of derealisation. Finally, the study suggested that maladaptive emotional regulation was linked to derealisation, and that poor emotional regulation, when combined with high levels of rumination and poor sleep quality, could be the cause of derealisation and depersonalisation disorder. [ 19 ]
There is a positive correlation between fatigue and derealisation symptoms. Emotional suppression is also linked to derealisation symptoms. A study by Tibubos et al. showed that those who reappraised their emotions, meaning those who changed the way they assessed their situation and their capacity to manage it, thus altering its emotional impact, were less likely to experience derealisation. Conversely, those who suppressed their emotions were both more fatigued and more likely to experience derealisation and depersonalisation symptoms. [ 20 ]
Derealisation is often comorbid with depression and anxiety. Symptoms of derealisation are associated with symptoms of both depression and anxiety in the long-term, and those who experience chronic derealisation seem to be more likely to experience depressive and anxious symptoms. [ 21 ] Even when controlling for factors like treatment history, family history of mental disorders, childhood trauma, and sociodemographic status, many people who experience derealization also suffer from depression and/or anxiety disorders. However, those who experience derealization are also less likely to experience bodily symptoms of anxiety, compared to those who suffer from anxiety but not derealization, which may reflect the feelings of detachment from the body caused by derealization. [ 22 ]
Researchers used brain fMRI to check the neural responses of those suffering from derealisation and depersonalisation to both aversive and neutral images. They found that the derealised patients “rated the aversive, disgusting scenes as less emotive than control subjects and, in response to these stimuli, showed reduced activation in structures implicated in the perception of disgust.” While the derealised patients understood the content of the aversive pictures they were shown, they did not experience an emotional response, while the control group did, showing that the neural and behavioural responses of those experiencing derealization and depersonalisation were impaired. [ 23 ]
Derealization and dissociative symptoms have been linked by some studies to various physiological and psychological differences in individuals and their environments. It was remarked that labile sleep-wake cycles (labile meaning more easily roused) with some distinct changes in sleep, such as dream-like states, hypnogogic, hypnopompic hallucinations, night-terrors and other disorders related to sleep could possibly be causative or improve symptoms to a degree. [ 24 ] Derealization can also be a symptom of severe sleep disorders and mental disorders like depersonalization disorder , borderline personality disorder , bipolar disorder , schizophrenia , dissociative identity disorder , and other mental conditions. [ 25 ]
Cannabis , [ 26 ] psychedelics , dissociatives , antidepressants , caffeine , nitrous oxide , albuterol , and nicotine can all produce feelings of derealization, or sensations mimicking them, [ 27 ] particularly when taken in excess. It can also result from alcohol withdrawal or benzodiazepine withdrawal . [ 28 ] Tramadol withdrawal can also cause feelings of derealization, often alongside psychotic symptoms such as anxiety , paranoia and hallucinations. [ 29 ] Generally, when derealisation is induced by cannabis, symptoms do not last longer than the period of intoxication, generally subsiding within about 2 hours of exposure. However, a small group of those who use cannabis may experience derealization symptoms lasting weeks, months, or years, even after they stop using cannabis. The most significant factor for this chronic cannabis-induced derealisation seems to be a history of anxiety, and young, anxiety-prone males who use cannabis under “marked distress” are particularly at risk. [ 30 ]
Derealisation symptoms may also be experienced after playing video games, particularly after using virtual-reality headsets. A study of 40 participants found that those who used VR headsets while playing the game Skyrim reported significantly more derealisation symptoms than those who played on a PC. Researchers hypothesised that using VR headsets, as opposed to the PC, induced “stronger levels of realness towards the newly experienced virtual world, which casts into doubt the so far experienced ordinary world." [ 31 ]
Interoceptive exposure exercises have been used in research settings as a means to induce derealization, as well as the related phenomenon depersonalization, in people who are sensitive to high levels of anxiety. Exercises with documented successes include timed intervals of hyperventilation or staring at a mirror, dot, or spiral. [ 32 ]
In the past, treatments like anticonvulsants, stimulants, and electroconvulsive therapy were tested, but were not effective in reducing symptoms. [ 33 ]
There is evidence to suggest that cognitive behavioural therapy is effective in treating derealisation symptoms, especially through cognitive reappraisal of catastrophizing thoughts, reducing avoidance behavior, and self-observation. Therapy has been shown to reduce the severity of chronic derealisation and other comorbidities, like anxiety and depression, in the long-term. [ 20 ] [ 33 ]
Currently, chronic derealisation is generally treated using medication. These drugs include antidepressants, antiepileptics, and antipsychotics. Serotonin reuptake blockers (SSRIs) may be prescribed. They mediate serotonergic dysregulation, which is when the body does not have enough serotonin, thought to be a possible cause of derealisation-depersonalisation disorder. [ 34 ]
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The DermIS ( Dermatology Internet Service or Dermatology Information System ) is a web site providing images and information on diagnosis in dermatology. [ 1 ] [ 2 ] It is a project of the Department of Clinical Social Medicine of the University of Heidelberg and the Department of Dermatology of the University of Erlangen , and provides information in seven languages: Turkish, Japanese, Portuguese, Spanish, French, German and English. [ 3 ] It includes the Dermatology Online Atlas (DOIA), a database of images of conditions. [ 4 ]
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https://en.wikipedia.org/wiki/DermIS
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Dermatologic Surgery is a monthly peer-reviewed journal that deals with the subject matter of dermatology. The journal is published by American Society for Dermatologic Surgery , Lippincott , Williams & Wilkins According to the Journal Citation Reports , the journal has a 2022 impact factor of 2.4.
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https://en.wikipedia.org/wiki/Dermatologic_Surgery_(journal)
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Dermatologic surgical procedures are treatments aimed at managing a wide range of medically necessary and cosmetic conditions, with a long history dating back to ancient times.
Medically necessary dermatologic surgical procedures include curettage and electrosurgery , and Mohs surgery for the treatment of skin cancer, as well as skin grafting for repairing damaged skin. Cosmetic dermatologic surgeries comprise anti-ageing procedures , and mole and scar removal surgeries. The former include Botulinum toxin treatments and face lifts , while the latter include shave excision and dermabrasion .
Although all dermatologic surgical procedures require post-operative treatment and present common risks and complications, the future development of dermatologic surgical procedures involving the use of technology shows promising improvements in patient outcomes.
Dermatologic surgery has a long history and has evolved significantly over time. Ancient civilizations such as Egyptians, Greeks, and Romans practiced early forms of dermatologic surgery, employing techniques such as tissue excision, cautery, and scarification for therapeutic and cosmetic purposes. [ 1 ]
The 19th century marked the emergence of dermatologic surgery as a distinct speciality, [ 1 ] where significant advancements in surgical techniques and instruments were made. For instance, the development of aseptic techniques and anesthesia allowed for infection-free and pain-free procedures respectively, while instruments such as forceps , retractors , and cauteries improved the precision and safety of dermatological surgical procedures. [ 2 ] The applications and safety of sutures were also enhanced by William Stewart Halsted , as he emphasized on the role of sutures in sterile tissue closure, managing hemorrhage and wound healing. [ 3 ]
In the early 20th century, electrosurgery and cryosurgery were introduced, [ 4 ] and surgical techniques continued to evolve from mid to late 20th century, with the introduction of surgical procedures such as skin grafting , laser surgery and Mohs microscopic surgery . [ 3 ] The establishment of dermatology surgery societies and training programs, such as the “ American College of Mohs Surgery ” founded by Frederic Mohs in 1967, as well as postgraduate courses on dermabrasion and chemical peels , also contributed to the progression of surgical techniques. [ 3 ] These advancements expanded the range of treatment options available in dermatologic surgery.
Skin cancer is the uncontrolled proliferation of abnormal skin cells, usually developing on skin exposed to ultraviolet radiation. Squamous cell carcinoma , basal cell carcinoma , and melanoma are the three main types of skin cancer, [ 5 ] with the former two being non-melanoma skin cancer.
Most small, low-risk and superficial skin cancers, such as basal cell carcinoma and squamous cell carcinoma, could be treated by curettage and electrosurgery . [ 6 ] A clinical margin which includes areas around the lesion site is marked out, and local anesthesia or numbing medicine is applied. A curette , consisting of a fenestrated head with a semi-sharp blade, is used to debride the malignant tumour. This is done by mechanically scraping or peeling at the lesion until all cancerous tissues are removed. Electrodesiccation is followed up after each curettage by applying a high-voltage electric current to the tumour site. The heat could destroy the remaining tumours not eliminated by curettage, induce inflammatory response in tumour cells, and aid in hemostasis . [ 7 ] Treating small and superficial skin cancers with curettage and electrosurgery presents a high cure rate of over 90%. [ 8 ]
Mohs surgery could target non-melanoma and melanoma skin cancers, and is recommended as a first-line treatment for large, high-risk tumours in anatomically critical areas. [ 9 ] After local anesthesia is applied, visible tumours are first excised using a scalpel . Then, a thin piece of tissue is removed circumferentially around the tumour and sectioned with a cryostat microtome . This is followed by tissue processing and viewing under a microscope. If any residual tumour could be identified microscopically, the tumour site could be marked for further tissue removal. This process is repeated until the absence of tumours is confirmed by these histological methods. [ 10 ] In most patients treated with Mohs surgery, complete elimination of cancerous cells, maximal conservation of healthy tissues, and high cure rates of up to 99% are observed. [ 11 ]
Skin grafting is a surgical procedure where a piece of healthy skin, also known as the donor site, is taken from one body part and transplanted to another, often to cover damaged or missing skin. [ 12 ] Before surgery, the location of the donor site would be determined, and patients would undergo anesthesia. [ 13 ]
FTSGs are the most frequently used grafts in dermatology, [ 14 ] which involves surgical removal of the epidermis and dermis layers of the skin. After the skin graft is harvested, the donor site is stitched close, and the graft is trimmed of any underlying hair or fat tissue, as well as contoured to match the size and shape of the defect. [ 15 ] The graft is then immediately placed onto the wound site and sutured. Finally, a bolster, which is a type of dressing, is placed over the graft to secure it in place. [ 16 ]
STSGs are suitable for large wounds and relatively avascular sites where FTSGs would have a high risk of failure. Only a portion of the skin, namely the epidermis and part of the dermis, is removed from the donor site using a powered dermatome . [ 17 ] If desired, meshing of the harvested skin graft allows it to be elongated. The graft is then applied to the defect and secured using skin staples or dissolvable sutures . [ 17 ] A bolster is placed over the graft to conclude the procedure, while for areas where bolstering is difficult, a negative pressure wound vacuum could reduce air pressure on the wound to promote healing. [ 18 ]
Composite grafts are used to repair defects that require contouring and support due to a loss of underlying muscle or bone. These grafts usually consist of different tissue layers, such as the skin, cartilage , and fat, and are frequently utilized to reconstruct structures such as the nose, ears, and fingertips. [ 14 ] Skin from the donor site is first excised precisely and contoured as needed, then the donor site is closed in multiple layers. The graft is subsequently placed over the wound and secured by suturing, followed by the application of a bolster if necessary. Typically, minor revisions of the graft are required after the initial surgery for fine-tuning and adjustment of the graft's shape and appearance. [ 19 ]
Botulinum toxin is a neurotoxin with cosmetic and dermatologic applications, such as treating hyperhidrosis , removing facial lines and wrinkles. Among the serotypes A to G, Botulinum toxin type A is the major type used for aesthetic and clinical purposes. Before injection, it has to be reconstituted using sterile saline as a diluent . The reconstituted solution should be refrigerated and used within 4 hours to prevent its loss of function. Then, by using a hollow teflon -coated, 30-gauge 1-inch needle, the toxin could be injected directly into the affected muscles. The dose of toxin for each injection is determined by the muscle mass, [ 20 ] while the injection site should be localized to overactive smooth muscles to induce muscle weakness. Overactive muscles can be determined by measuring the muscle's maximal response to a nervous stimuli with electromyography. [ 20 ] Botulinum toxin could be used to relax the corrugator and procerus muscles, orbicularis oculi , and the frontalis muscle to relieve glabellar lines (frown lines), lateral canthal lines (Crow's feet) and forehead lines respectively. [ 21 ]
Rhytidectomy is a surgical method, often used for making the skin look smoother and younger. This is done by first making an incision at the temples that extend around the ear, then separating the skin from the underlying fascial layers and muscles, and removing the sagging facial skin. [ 22 ] [ 23 ] The remaining skin is subsequently pulled backward and upward, and sutured to a new position to achieve a tightened appearance. During this process, facial muscles might be tightened, while facial fat might be removed or redistributed. Sometimes, a jaw lift is performed in the same surgery by making an incision under the chin and tightening the skin of the jaw and neck. Immediately after the surgery, a drainage tube is used to remove excess fluid from the wound. [ 23 ] [ 24 ]
Mole removal surgeries are performed for various reasons. Atypical mole removal is performed when moles look dysplastic , as this is associated with an increased risk of melanoma ; Cosmetic mole removal is performed when moles are non-cancerous, but are preferred to be eliminated due to aesthetic or practical considerations. [ 25 ]
Shave excision is the most frequently used method for mole removal. Anesthesia is first administered to the area around the mole. With the use of a sharp razor, multiple horizontal cuts are then made to remove the mole. This is followed by electrosurgical feathering, where a small dermal loop electrode is used to gently shape the edges of the wound. This not only ensures any remaining cells of the mole are removed, but also minimizes scarring as the edges of the wound are blended with the surrounding skin. [ 26 ] At last, the surgical site is cleaned, applied with antibiotic ointment, and covered with a sterile bandage to prevent infection.
Scar revisions are cosmetic treatments to improve the appearance of scars, [ 27 ] with dermabrasion being a surgical procedure most often used for individuals with skin concerns such as scars caused by acne , surgery or injury. [ 28 ] This skin-resurfacing procedure makes use of dermabraders, a rapidly rotating device to exfoliate the outer layer of the skin, [ 28 ] thereby promoting the growth of new skin that is smoother in texture.
First, local or general anesthesia is employed. Next, the area to be treated is marked out, and a suitable dermabrasion tip is chosen to be used during the procedure. During dermabrasion, the skin being treated is held taut with one hand to maintain tension while the dermabrader is moved across the skin uniformly and gently. [ 29 ] Proper manipulation, appropriate pressure and precise control of the dermabrader is crucial to ensure the accurate layer of the skin is targeted and to reduce adverse effects. Following dermabrasion, a saline-soaked gauze coupled with occlusive ointment are applied to the treated skin to prevent infection and facilitate wound healing. [ 29 ]
For skin cancer surgeries, most wounds are relatively small. After removal of the dressing, the wound can be cleaned by washing with clean soapy water, and should be kept moist. It is also suggested to apply prescribed antibiotic ointments or any other medications to the wound, and protect the scar formed. [ 30 ]
For skin grafts, the newly grafted skin is fragile to damage. Slight bleeding may occur, which can be managed by removing serosanguineous material or necrotic debris using hydrogen peroxide. If eschar is present which affects the grafted skin, debridement should only be done when the area of necrosis is clearly defined. [ 31 ]
Immediately after a dermatologic cosmetic surgery, it is generally recommended for the surgical site to be elevated to reduce swelling and maintain blood flow. [ 23 ] Analgesics , antibiotics and anesthetics are usually prescribed to relieve pain, inflammation and swelling. Patients should refrain from vigorous exercise for the first few days after surgery and exercise caution when gradually resuming their normal activities. [ 32 ] Showering should also be avoided during the first few days after surgery. Patients are also advised against submerging their wound in water for at least two weeks after surgery. [ 23 ]
During dermatologic surgery, dissecting errors may give rise to damaged structures adjacent to the surgical site, such as nerves, glands, and blood vessels. This may result in numbness, muscle weakness or paralysis . Patients with risk factors such as blood clotting abnormalities or long-term use of certain medications may experience excessive bleeding at the incision site. This would prolong the healing process and increase the risk of bacterial wound infection. [ 33 ] Moreover, though uncommon, allergic reactions to anesthesia during surgery may also occur in some patients. [ 24 ]
After dermatologic surgery, the presence of suture materials at the wound site can cause redness and swelling, yet these suture reactions may not necessarily indicate allergy or infection. Other common complications include hypertrophic or keloid scars, bruises, suture marks, and skin color changes, which may be temporary or permanent. [ 34 ]
Throughout the past 10 years, minimally invasive dermatological procedures have shown significant advancements, with the emergence of intradermal fillers , botulinum toxin injections and chemical peels. [ 35 ] These techniques require smaller incisions , which could lessen scarring and trauma, and decrease surgical complications. [ 36 ] Compared with traditional surgical methods, minimally invasive procedures are more likely to result in high patient satisfaction and treatment efficacy. [ 35 ] With the introduction of three-dimensional bioprinting [ 37 ] and robotic-assisted surgeries for tissue repair and reconstruction, [ 38 ] future technological advancements might continue to diminish recovery time and improve patient outcomes.
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A dermatome is an area of skin that is mainly supplied by afferent nerve fibres from the dorsal root of any given spinal nerve . [ 1 ] [ 2 ] There are 8 cervical nerves (C1 being an exception with no dermatome),
12 thoracic nerves ,
5 lumbar nerves and 5 sacral nerves .
Each of these nerves relays sensation (including pain) from a particular region of skin to the brain .
The term is also used to refer to a part of an embryonic somite .
Along the thorax and abdomen , the dermatomes are like a stack of discs forming a human, each supplied by a different spinal nerve. Along the arms and the legs, the pattern is different: the dermatomes run longitudinally along the limbs. Although the general pattern is similar in all people, the precise areas of innervation are as unique to an individual as fingerprints.
An area of skin innervated by a single nerve is called a peripheral nerve field .
The word dermatome is formed from Ancient Greek δέρμα 'skin, hide' and τέμνω 'cut'.
A dermatome is an area of skin supplied by sensory neurons that arise from a spinal nerve ganglion. Symptoms that follow a dermatome (e.g. like pain or a rash) may indicate a pathology that involves the related nerve root . Examples include somatic dysfunction of the spine or viral infection. Certain skin problems tend to orient the lesions in the dermatomal direction.
In referred pain , sensory nerve fibers such as that from dermatomes may come together at the same spinal cord level as the general visceral afferent fibers such as that from the heart .
When the general visceral sensory fiber is stimulated, the central nervous system does not clearly discern whether the pain is coming from the body wall or from the viscera , so it perceives the pain as coming from somewhere on the body wall, e.g. left arm/hand pain, jaw pain.
So the pain is "referred to" the related dermatomes of the same spinal segment. [ 3 ]
Viruses that lie dormant in nerve ganglia (e.g. varicella zoster virus , which causes both chickenpox and shingles ), often cause either pain, rash or both in a pattern defined by a dermatome (a zosteriform pattern). However, the symptoms may not appear across the entire dermatome.
Following is a list of spinal nerves and points that are characteristically belonging to the dermatome of each nerve: [ 4 ]
Following is a list of cranial nerves responsible for sensation from the face:
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A dermatome is a surgical instrument for producing thin slices of skin from a donor area, for use in skin grafts . One of its main applications is for reconstituting skin areas damaged by third degree burns or trauma .
Dermatomes can be operated either manually or electrically. The first drum dermatomes, developed in the 1930s, were manually operated. Afterwards, dermatomes which were operated by air pressure, such as the Brown dermatome, achieved higher speed and precision. Electrical dermatomes are better for cutting out thinner and longer strips of skin with a more homogeneous thickness.
Those are manual dermatomes and the term knife or scalpel is used to describe them. Their disadvantages are harvesting of grafts with irregular edges and grafts of variable thickness. Their operator has to be experienced in their use for optimal results. [ 1 ]
There are several types of dermatomes, usually named after their inventor.
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https://en.wikipedia.org/wiki/Dermatome_(instrument)
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Dermatopathology (from Greek δέρμα , derma 'skin' + πάθος , pathos 'fate, harm' + -λογία , -logia 'study of') is a joint subspecialty of dermatology and pathology or surgical pathology that focuses on the study of cutaneous diseases at a microscopic and molecular level. It also encompasses analyses of the potential causes of skin diseases at a basic level. Dermatopathologists work in close association with clinical dermatologists , with many possessing further clinical training in dermatology. [ 1 ] The field was founded by German dermatologist and physician Gustav Simon , who published the first textbook on dermatopathology, 'Skin Diseases Illustrated by Anatomical Investigations' ( Die Hautkrankheiten durch anatomische Untersuchungen erläutert ), in 1848. [ 2 ] [ 3 ]
Dermatologists are able to recognize most skin diseases based on their appearances, anatomic distributions, and behavior. Sometimes, however, those criteria do not allow a conclusive diagnosis to be made, and a skin biopsy is taken to be examined under the microscope or are subject to other molecular tests. That process reveals the histology of the disease and results in a specific diagnostic interpretation. In some cases, additional specialized testing needs to be performed on biopsies, including immunofluorescence , immunohistochemistry , electron microscopy , flow cytometry , and molecular-pathologic analysis. [ 4 ]
One of the greatest challenges of dermatopathology is its scope. More than 1500 different disorders of the skin exist, including cutaneous eruptions (" rashes ") and neoplasms (dermatological oncology deals with pre-cancers, such as an actinic keratosis ; and cancers, including both benign masses, and malignant cancers- such as basal cell carcinoma , squamous cell carcinoma , and most dangerously, malignant melanoma ). Non-cancerous conditions include vitiligo , impetigo , purpura , pruritus , spider veins , warts , moles , oral or genital herpes, chancre sores of syphilis , exposure to poison ivy and similar plants or other venom sources, rashes, cysts , abscesses , corns, and dermabrasions or cases dealing with wrinkles, peeling skin, or autoimmune attacks on the skin. Therefore, dermatopathologists must maintain a broad base of knowledge in clinical dermatology, and be familiar with several other specialty areas in Medicine . [ 5 ]
Certification in dermatopathology in the United States and several other countries requires the completion of a medical degree , followed by residency training of 3 years in dermatology or 3 years in anatomic pathology (often completed as part of a 4-year combined residency in anatomic pathology and clinical pathology). Thereafter, an additional 1 or 2 years of post-residency education in dermatopathology is undertaken. For trainees with a primary background in pathology, the fellowship experience includes the equivalent of 6 months of clinical dermatology, and for those whose training is primarily in dermatology, 6 months of the fellowship are devoted to anatomic pathology. In the United States, dermatopathologists are first certified by the American Boards of Pathology or Dermatology , or the American Osteopathic Boards of Pathology or Dermatology , in the United Kingdom dermatopathologist are certified by the Royal College of Pathologist, and in the rest of the world by the International Board of Dermatopathology. Trainees then obtain subspecialty certification (termed "special competence") or Diploma in dermatopathology by written examination. [ 6 ] [ 7 ] Since 2003, the International Board of Dermatopathology (IBDP)—headquartered in Graz, Austria—also has certified candidates from countries around the world. This is done by IBDP review of applicants' professional qualifications, and a written and practical examination that is given in Europe each year. [ 8 ] [ 9 ]
In the United States, dermatopathology is practiced in a variety of settings. Some biopsies are interpreted by the dermatologists who obtained them, some are sent to pathology laboratories and interpreted either by general pathologists or dermatopathologists, while others are interpreted at specialized dermatopathology laboratories. Only a few of the latter exist outside of the United States.
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https://en.wikipedia.org/wiki/Dermatopathology
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Des-gamma carboxyprothrombin (DCP) , also known as protein induced by vitamin K absence/antagonist-II (PIVKA-II), is an abnormal form of the coagulation protein, prothrombin . Normally, the prothrombin precursor undergoes post-translational carboxylation (addition of a carboxylic acid group) by gamma-glutamyl carboxylase in the liver prior to secretion into plasma . DCP/PIVKA-II may be detected in people with deficiency of vitamin K (due to poor nutrition or malabsorption ) and in those taking warfarin or other medication that inhibits the action of vitamin K.
A 1984 study first described the use of DCP as a marker of hepatocellular carcinoma (HCC); it was present in 91% of HCC patients, while not being detectable in other liver diseases. The DCP level did not change with the administration of vitamin K, suggesting a defect in gamma-carboxylation activity rather than vitamin K deficiency. [ 1 ] A number of subsequent studies have since confirmed this phenomenon. [ 2 ] [ 3 ] [ 4 ]
A 2007 comparison of various HCC tumor markers found DCP the least sensitive to risk factors for HCC (such as cirrhosis ), and hence the most useful in predicting HCC. [ 5 ] It differentiates HCC from non-malignant liver diseases. [ 6 ] Moreover, it has been demonstrated that a combined analysis of DCP and Alpha-fetoprotein (AFP) can lead to a better prediction in early stages of HCC. [ 7 ]
Despite many years of use in Japan , only did a 2003 American study reevaluate its use in an American patient series. It also identified HCC at an earlier stage. [ 4 ]
A 1987 report described the use of DCP determination in the detection of intoxication with acenocoumarol , a vitamin K antagonist. [ 8 ]
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https://en.wikipedia.org/wiki/Des-gamma_carboxyprothrombin
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Descriptive psychiatry is based on the study of observable symptoms and behavioral phenomena rather than underlying psychodynamic processes. In descriptive psychiatry, the clinical psychiatrist focuses on empirically observable behaviors and conditions, such as words spoken or actions taken.
Modern works sometimes refer to it as biological psychiatry . [ 1 ] It was championed by Emil Kraepelin in the early 20th century and is sometimes called Kraepelinian psychiatry. [ 1 ] One major work of descriptive psychiatry is the Diagnostic and Statistical Manual of Mental Disorders . [ 1 ]
Its focus on observable symptoms contrasts with dynamic psychiatry 's emphasis on emotional processes and the mental mechanisms underlying them. The relative popularity of these two basic approaches to psychiatry changes over time. [ 2 ] Descriptive psychiatry was seen at its low points as "narrow, bloodless, and without real significance." [ 2 ] At its high points, it is considered orderly, systematic, and scientific. Most modern psychiatrists believe that it is most helpful to combine the two complementary approaches in a biopsychosocial model . [ 3 ]
This psychiatry -related article is a stub . You can help Wikipedia by expanding it .
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https://en.wikipedia.org/wiki/Descriptive_psychiatry
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1674
13346
ENSG00000175084
ENSMUSG00000026208
P17661
P31001
NM_001927
NM_010043
NP_001369641 NP_001369642
NP_034173
Desmin is a protein that in humans is encoded by the DES gene . [ 5 ] [ 6 ] Desmin is a muscle-specific, type III intermediate filament [ 7 ] that integrates the sarcolemma , Z disk , and nuclear membrane in sarcomeres and regulates sarcomere architecture. [ 8 ] [ 9 ]
Desmin is a 53.5 kD protein composed of 470 amino acids, encoded by the human DES gene located on the long arm of chromosome 2 . [ 10 ] [ 11 ] There are three major domains to the desmin protein: a conserved alpha helix rod, a variable non alpha helix head, and a carboxy-terminal tail. [ 12 ] Desmin, as all intermediate filaments , shows no polarity when assembled. [ 12 ] The rod domain consists of 308 amino acids with parallel alpha helical coiled coil dimers and three linkers to disrupt it. [ 12 ] The rod domain connects to the head domain. The head domain 84 amino acids with many arginine, serine, and aromatic residues is important in filament assembly and dimer-dimer interactions. [ 12 ] The tail domain is responsible for the integration of filaments and interaction with proteins and organelles. Desmin is only expressed in vertebrates, however homologous proteins are found in many organisms. [ 12 ] Desmin is a subunit of intermediate filaments in cardiac muscle , skeletal muscle and smooth muscle tissue. [ 13 ] In cardiac muscle, desmin is present in Z-discs and intercalated discs . Desmin has been shown to interact with desmoplakin [ 14 ] and αB-crystallin . [ 15 ]
Desmin was first described in 1976, [ 16 ] first purified in 1977, [ 17 ] the gene was cloned in 1989, [ 6 ] and the first knockout mouse was created in 1996. The function of desmin has been deduced through studies in knockout mice. Desmin is one of the earliest protein markers for muscle tissue in embryogenesis as it is detected in the somites . [ 12 ] [ 18 ] Although it is present early in the development of muscle cells, it is only expressed at low levels, and increases as the cell nears terminal differentiation. A similar protein, vimentin , is present in higher amounts during embryogenesis while desmin is present in higher amounts after differentiation. This suggests that there may be some interaction between the two in determining muscle cell differentiation. However desmin knockout mice develop normally and only experience defects later in life. [ 13 ] Since desmin is expressed at a low level during differentiation another protein may be able to compensate for desmin's function early in development but not later on. [ 19 ]
In adult desmin-null mice, hearts from 10 week-old animals showed drastic alterations in muscle architecture, including a misalignment of myofibrils and disorganization and swelling of mitochondria; findings that were more severe in cardiac relative to skeletal muscle. Cardiac tissue also exhibited progressive necrosis and calcification of the myocardium. [ 20 ] A separate study examined this in more detail in cardiac tissue and found that murine hearts lacking desmin developed hypertrophic cardiomyopathy and chamber dilation combined with systolic dysfunction. [ 21 ] In adult muscle, desmin forms a scaffold around the Z-disk of the sarcomere and connects the Z-disk to the subsarcolemmal cytoskeleton. [ 22 ] It links the myofibrils laterally by connecting the Z-disks. [ 12 ] Through its connection to the sarcomere, desmin connects the contractile apparatus to the cell nucleus , mitochondria , and post-synaptic areas of motor endplates. [ 12 ] These connections maintain the structural and mechanical integrity of the cell during contraction while also helping in force transmission and longitudinal load bearing. [ 22 ] [ 23 ]
In human heart failure, desmin expression is upregulated, which has been hypothesized to be a defense mechanism in an attempt to maintain normal sarcomere alignment amidst disease pathogenesis. [ 24 ] There is some evidence that desmin may also connect the sarcomere to the extracellular matrix (ECM) through desmosomes which could be important in signalling between the ECM and the sarcomere which could regulate muscle contraction and movement. [ 23 ] Finally, desmin may be important in mitochondria function. When desmin is not functioning properly there is improper mitochondrial distribution, number, morphology and function. [ 25 ] [ 26 ] Since desmin links the mitochondria to the sarcomere it may transmit information about contractions and energy need and through this regulate the aerobic respiration rate of the muscle cell.
Desmin-related myofibrillar myopathy (DRM or desminopathy) is a subgroup of the myofibrillar myopathy diseases [ 27 ] and is the result of a mutation in the gene that codes for desmin which by changing the protein structure [ 28 ] prevents it from forming protein filaments , and rather, forms aggregates of desmin and other proteins throughout the cell. [ 8 ] [ 12 ] Desmin ( DES ) mutations have been associated with restrictive, [ 29 ] dilated, [ 30 ] [ 31 ] idiopathic, [ 32 ] [ 33 ] arrhythmogenic [ 34 ] [ 35 ] [ 36 ] [ 37 ] and non-compaction cardimyopathy. [ 38 ] [ 39 ] Even within the same family the observed cardiac phenotype could be broad and diverse. The N-terminal part of the 1A desmin subdomain is a genetic hot spot region for mutations affecting filament assembly. [ 40 ] [ 41 ] Some of these DES mutations cause an aggregation of desmin within the cytoplasm . [ 41 ] [ 42 ] [ 43 ] Some mutations like p.A120D or p.R127P were discovered in families, where several members had sudden cardiac death. [ 44 ] In addition, DES mutations cause frequently cardiac conduction diseases. [ 45 ]
Desmin has been evaluated for role in assessing the depth of invasion of urothelial carcinoma in TURBT specimens. [ 46 ]
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https://en.wikipedia.org/wiki/Desmin
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In medicine , desmoplasia is the growth of fibrous connective tissue . [ 1 ] It is also called a desmoplastic reaction to emphasize that it is secondary to an insult . Desmoplasia may occur around a neoplasm , causing dense fibrosis around the tumor, [ 1 ] or scar tissue ( adhesions ) within the abdomen after abdominal surgery. [ 1 ]
Desmoplasia is usually only associated with malignant neoplasms , which can evoke a fibrotic response invading healthy tissue. Invasive ductal carcinomas of the breast often have a stellate appearance caused by desmoplastic formations.
Desmoplasia originates from the Ancient Greek δεσμός desmos , 'knot, bond' and πλάσις plasis , 'formation'. It is usually used in the description of desmoplastic small round cell tumors .
Neoplasia is the medical term used for both benign and malignant tumors, or any abnormal, excessive, uncoordinated, and autonomous cellular or tissue growth.
Desmoplasia refers to growth of dense connective tissue or stroma . [ 2 ] This growth is characterized by low cellularity with hyalinized or sclerotic stroma and disorganized blood vessel infiltration. [ 3 ] This growth is called a desmoplastic response and occurs as result of injury or neoplasia. [ 2 ] This response is coupled with malignancy in non-cutaneous neoplasias, and with benign or malignant tumors if associated with cutaneous pathologies. [ 3 ]
The heterogeneity of tumor cancer cells and stroma cells combined with the complexities of surrounding connective tissue suggest that understanding cancer by tumor cell genomic analysis is not sufficient; [ 4 ] analyzing the cells together with the surrounding stromal tissue may provide more comprehensive and meaningful data.
Normal tissues consist of parenchymal cells and stromal cells. The parenchymal cells are the functional units of an organ. In contrast, the stromal cells provide the structure of the organ and secrete extracellular matrix as supportive, connective tissue. [ 3 ] In normal epithelial tissues, epithelial cells, or parenchymal cells of epithelia, are highly organized, polar cells . [ 5 ] These cells are separated from stromal cells by a basement membrane that prevents these cell populations from mixing. [ 5 ] A mixture of these cell types is recognized, normally, as a wound , as in the example of a cut to the skin. [ 6 ] Metastasis is an example of a disease state in which a breach of the basement membrane barrier occurs. [ 7 ]
Cancer begins as cells that grow uncontrollably, usually as a result of an internal change or oncogenic mutations within the cell. [ 8 ] Cancer develops and progresses as the microenvironment undergoes dynamic changes. [ 9 ] The stromal reaction in cancer is similar to the stromal reaction induced by injury or wound repair: increased extracellular matrix (ECM) and growth factor production and secretion, which consequently cause growth of the tissue. [ 10 ] In other words, the body reacts similarly to a cancer as it does to a wound, causing scar -like tissue to be built around the cancer. As such, the surrounding stroma plays a very important role in the progression of cancer. The interaction between cancer cells and surrounding tumor stroma is thus bidirectional, and the mutual cellular support allows for the progression of the malignancy.
Stroma contains extracellular matrix components such as proteoglycans and glycosaminoglycans which are highly negatively charged, largely due to sulfated regions, and bind growth factors and cytokines , acting as a reservoir of these cytokines. [ 5 ] In tumors, cancer cells secrete matrix degrading enzymes, such as matrix metalloproteinases (MMPs) that, once cleaved and activated, degrade the matrix, thereby releasing growth factors that signal for the growth of cancer cells. [ 11 ] MMPs also degrade ECM to provide space for vasculature to grow to the tumor, for the tumor cells to migrate, and for the tumor to continue to proliferate. [ 3 ]
Desmoplasia is thought to have a number of underlying causes.
In the reactive stroma hypothesis, tumor cells cause the proliferation of fibroblasts and subsequent secretion of collagen . [ 3 ] The newly secreted collagen is similar to that of collagen in scar formation – acting as a scaffold for infiltration of cells to the site of injury. [ 12 ] Furthermore, the cancer cells secrete matrix degrading enzymes to destroy normal tissue ECM thereby promoting growth and invasiveness of the tumor. [ 3 ] Cancer associated with a reactive stroma is typically diagnostic of poor prognosis. [ 3 ]
The tumor-induced stromal change hypothesis claims that tumor cells can dedifferentiate into fibroblasts and, themselves, secrete more collagen. [ 3 ] This was observed in desmoplastic melanoma, in which the tumor cells are phenotypically fibroblastic and positively express genes associated with ECM production. [ 13 ] However, benign desmoplasias do not exhibit dedifferentiation of tumor cells. [ 3 ]
A desmoplastic response is characterized by larger stromal cells with increased extracellular fibers and immunohistochemically by transformation of fibroblastic-type cells to a myofibroblastic phenotype. [ 2 ] Myofibroblastic cells in tumors are differentiated from fibroblasts for their positive staining of smooth-muscle actin (SMA). [ 2 ] Furthermore, an increase in total fibrillar collagens, fibronectins , proteoglycans, and tenascin C are distinctive of the desmoplastic stromal response in several forms of cancer. [ 14 ] Expression of tenascin C by breast cancer cells has been demonstrated to allow for metastasis to the lungs and cause the expression of tenascin C by the surrounding tumor stromal cells. [ 15 ] In addition, tenascin C is found extensively in pancreatic tumor desmoplasia as well. [ 16 ]
While scars are associated with the desmoplastic response of various cancers, not all scars are associated with malignant neoplasms. [ 3 ] Mature scars are usually thick, collagenous bundles arranged horizontally with paucicellularity, vertical blood vessels, and no appendages. [ 3 ] This is distinguished from desmoplasia in the organization of the tissue, the appendages, and orientation of blood vessels. Immature scars are more difficult to distinguish due to their neoplastic origins. [ 3 ] These scars are hypercellular with fibroblasts, myofibroblasts, and some immune cells present. [ 3 ] The immature scars can be distinguished from desmoplasia by immunohistochemical staining of biopsied tumors that will reveal the type and organization of cells present as well as whether recent trauma has occurred to the tissue. [ 17 ]
Source: [ 3 ]
The stroma of the prostate is characteristically muscular. [ 2 ] Due to this muscularity, detecting the myofibroblastic phenotypic change indicative of reactive stroma is difficult in an examination of patient pathologic slides. [ 2 ] A diagnosis of reactive stroma associated with prostate cancer is one of poor prognosis. [ 2 ]
Clinical presentation of a lump in the breast is histologically viewed as a collagenous tumor or desmoplastic response created by myofibroblasts of the tumor stroma. [ 18 ] Proposed mechanisms of activation of myofibroblasts are by immune cytokine signaling, microvascular injury, or paracrine signaling by tumor cells. [ 18 ]
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https://en.wikipedia.org/wiki/Desmoplasia
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In medicine , a desmoplastic fibroma is a low-grade malignant , locally aggressive, fibrous and rare tumor of the bone, affecting children and young adults, potentially resulting in cortical bone destruction. It usually affects craniofacial bones, mandible most frequently, long bones (metaphyseal femur, tibia, humerus). [ 1 ] The World Health Organization, 2020, reclassified these tumors as specific benign tumors in the category of fibroblastic and myofibroblastic tumors . [ 2 ]
Although it does not tend to metastatize , it has a high local recurrence and infiltrative growth. [ 3 ] Treatment consists in wide local excision to prevent otherwise frequent recurrences. [ 4 ] The role of radiotherapy and chemotherapy in this tumor still is unclear. [ 5 ]
Some cases have been described, in which an osteosarcoma has arisen from a desmoplastic fibroma. [ 6 ]
A famous occurrence of this particular form of the disease involved Italo-Australian Riccardo Torresan in 2011, with 18 cm of femur needing to be removed with the now widely recognized method of "aggressive curettage" being employed. [ 7 ]
This oncology article is a stub . You can help Wikipedia by expanding it .
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https://en.wikipedia.org/wiki/Desmoplastic_fibroma
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Desperate Remedies: Psychiatry's Turbulent Quest to Cure Mental Illness by sociologist Andrew Scull is a critical history of two hundred years of treatment of mental disorders in the United States. From the "birth of the asylum" in the 1830s to the drug trials and genetic studies of the 2000s, Scull catalogues efforts by psychoanalysts, psychologists, neuroscientists and social reformers to diagnose and treat mental maladies.
Scull maps out the progression of the treatment of mental disorders, beginning in the 19th century with state asylums or state hospitals whose inhabitants, “poor and the friendless”, reached a population of half a million by 1950. The wealthy, on the other hand, got treated at home with often dangerous substances such as morphine and strychnine. Scull details the personalities and progress behind other treatments like Hydrotherapy , electrotherapy, insulin shock therapy , injections of Camphor, Metrazol, electroconvulsive or “shock” therapy, as well as frequently deadly surgical interventions such as colectomy , and lobotomy . He also explores the progression of disease models from humorism to the biochemical model of mental illness, and the advent of psychopharmacology and the development and travails of the Diagnostic and Statistical Manual of Mental Disorders .
Initial reaction was positive amongst legacy media . Richard McNally called the book "an indisputable masterpiece" in the Wall Street Journal . [ 1 ] Rebecca Lawrence of the Guardian said it was, "meticulously researched and beautifully written, and even funny at times, despite the harrowing content." [ 2 ] [ 3 ] [ 4 ]
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https://en.wikipedia.org/wiki/Desperate_Remedies:_Psychiatry's_Turbulent_Quest_to_Cure_Mental_Illness
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