[User]
<image>
Describe the structural components of an antibody molecule as shown in the diagram.

[Assistant] The antibody molecule is a Y-shaped protein consisting of two heavy chains and two light chains held together by disulfide bonds (S-S). It features a variable region at the N-terminal ends, which contains the antibody binding site (paratope) responsible for antigen specificity. The tail end is the constant region, which includes the Fc (fragment crystallizable) region and a complement binding site. The hinge region provides flexibility to the molecule.

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- Antigen-binding fragment (Fab).
- -It is the region of antibody which has specificity to antigen. It is composed of two constant domains (CH and CL) and two variable domains (VH and VL) toward N-terminal. Variable domains possess antigen-binding site called as 'paratope.' The antigen contains a specific site that attaches to the antibody and is called as 'epitope.' It is the antigen determinant.
- Fragment crystallization region (Fc).
- -This region is located toward the tail end of antibody. It is composed of three constant domains (CH-2-4 ) in each H-chain. This region interacts with cell surface receptors of immune cell. Fc region is helpful in the activation and regulation of immune response.
- Enzymatic proteolysis of immunoglobulin.
- -Papain enzyme breaks immunoglobulin molecule into three similar-sized fragments. Two fragments are named as 'Fab,' and the third fragment is named as 'Fc.'
- -Pepsin enzyme cleavages Ig molecule below hinge region and yields a large fragment call


[User]
<image>
What is the chemical structure shown in the image, and what is its biological significance?

[Assistant] The image shows the 5' cap structure of a eukaryotic messenger RNA (mRNA) molecule. It consists of a 7-methylguanosine residue linked via a triphosphate bridge to the 5' end of the mRNA strand. This cap, along with the 2'-O-methylpurine modification, is added post-transcriptionally to protect the mRNA from degradation and facilitate its recognition by the translation machinery.

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C:\Users\HARI\Desktop\DocSmile\rl\__lib_book_Biochemistry_ Harper_s Illustrated Biochemistry by Harper 26th Ed.md

The components of the mammalian ribosome, which has a molecular weight of about 4.2 × 10 6 and a sedimentation velocity of 80S (Svedberg units), are shown in Table 35-2. The mammalian ribosome contains two major nucleoprotein subunits-a larger one with a molecular weight of 2.8 × 10 6 (60S) and a smaller subunit with a molecular weight of 1.4 × 10 6 (40S). The 60S subunit contains a 5S ribosomal RNA (rRNA), a 5.8S rRNA, and a 28S rRNA; there are also probably more than 50 specific polypeptides. The 40S subunit is smaller and contains a single 18S rRNA and approximately 30 distinct polypeptide chains. All of the ribosomal RNA molecules except the 5S rRNA are processed from a single 45S precursor RNA molecule in the nucleolus (Chapter 37). 5S rRNA is independently transcribed. The highly methylated ribosomal RNA molecules are packaged in the nucleolus with the specific ribosomal proteins. In the cytoplasm, the ribosomes remain quite stable and capable of many translation cycles. The func


[User]
<image>
Based on the provided chemical structure, what are the components of a triacylglycerol molecule?

[Assistant] A triacylglycerol molecule is composed of a glycerol backbone esterified to three fatty acid chains. In the provided diagram, the triacylglycerol is shown breaking down into one glycerol molecule and three specific fatty acids: palmitate, oleate, and stearate.

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Fats are lipids composed of triacylglycerols (also called triglycerides). A triacylglycerol molecule contains 3 fatty acids esterified to one glycerol moiety (Fig. 1.6).

Fats contain much less oxygen than is contained in carbohydrates or proteins. Therefore, fats are more reduced and yield more energy when oxidized. The complete oxidation of triacylglycerols to CO 2 and H2O in the body releases approximately 9 kcal/g, more than twice the energy yield from an equivalent amount of carbohydrate or protein.

The food 'calories' used in everyday speech are really 'Calories,' which = kilocalories. 'Calorie,' meaning kilocalorie, was originally spelled with a capital C, but the capitalization was dropped as the term became popular. Thus, a 1-calorie soft drink actually has 1 Cal (1 kcal) of energy.

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Table 1.1. Caloric Content of Fuels

| | kcal/g |
|--------------|----------|
| Carbohydrate | 4 |
| Fat | 9 |
| Protein | 4 |
| Alcohol | 7 |

<!--image-->

An analysis of Ann O'Re


[User]
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Explain the cellular consequences of ethanol metabolism in the liver as shown in the diagram.

[Assistant] Ethanol metabolism in the liver involves several pathways, primarily mediated by alcohol dehydrogenase (ADH) and the microsomal ethanol oxidizing system (MEOS). This process produces acetaldehyde, which is highly toxic. Acetaldehyde can form adducts with proteins and glutathione, leading to impaired protein secretion and cellular damage. Additionally, the metabolism generates reactive oxygen species (ROS) that cause lipid peroxidation and free radical injury. These metabolic disturbances contribute to the accumulation of lipids (triacylglycerols and VLDL), cell swelling, and the release of liver enzymes like ALT and AST, which are markers of hepatic injury.

__lib_book_Biochemistry_ Marks_ Basic Medical Biochemistry A Clinical Approach_ 2nd Edition/img_1396.png

Ethanol metabolism may result in alchohol-induced liver disease , including hepatic steatosis (fatty liver), alcohol-induced hepatitis , and cirrhosis . The principal toxic products of ethanol metabolism include acetaldehyde and free radicals. Acetaldehyde forms adducts with proteins and other compounds. The hydroxyethyl radical produced by MEOS and other radicals produced during

Fig. 25.1. The major route for metabolism of ethanol and use of acetate by the muscle. (ADH, alcohol dehydrogenase; ALDH, acetaldehyde dehydrogenase; ACS, acetyl-CoA synthetase).

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Liver

Muscle

Blood

Ethanol

Acetaldehyde

Acetaldehyde

Acetate

Acetate

CH3CH2OH

CH3

C

H

O

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NADH

+ H +

Acetyl CoA

3NADH,

3H +

FAD

(2H)

CO2

TCA

cycle

Acetate

NAD +

NADH

+ H +

CH3

C

OH

O

ADH

ALDH

ACS

inflammation cause irreversible damage to the liver. Many other tissues are adversely affected by ethanol, acetaldehyde, or by the consequences of hepatic dysmetabolism and injury. Geneti


[User]
<image>
Describe the chemical differences between Type A, Type B, and Type O blood group antigens as shown in the diagram.

[Assistant] The diagram illustrates the structural basis of ABO blood types, which are determined by specific sugar modifications to the H substance (Type O). Type O consists of the H substance core (Gal, GlcNAc, Fuc, and R). Type A is distinguished by the addition of an N-acetylgalactosamine (GalNAc) sugar to the terminal galactose of the H substance. Type B is distinguished by the addition of a galactose (Gal) sugar to the terminal galactose of the H substance.

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[User]
<image>
Describe the biochemical pathway shown in the diagram for the synthesis of serine.

[Assistant] The diagram illustrates the biosynthesis of serine starting from 3-phosphoglycerate, an intermediate of glycolysis. The pathway involves three main steps: 1) Oxidation of 3-phosphoglycerate to 3-phosphohydroxypyruvate by 3-phosphoglycerate dehydrogenase (using NAD+). 2) Transamination of 3-phosphohydroxypyruvate to 3-phospho-L-serine, utilizing glutamate and the cofactor PLP. 3) Dephosphorylation of 3-phospho-L-serine to serine by the enzyme phosphoserine phosphatase. The diagram also depicts alternative metabolic routes, including the conversion of serine to hydroxypyruvate and glycerate.

__lib_book_Biochemistry_ Marks_ Basic Medical Biochemistry A Clinical Approach_ 2nd Edition/img_2026.png


[User]
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Describe the metabolic pathways involving glycine as shown in the diagram.

[Assistant] The diagram illustrates several metabolic pathways involving glycine. Glycine can be synthesized from threonine (via a PLP-dependent reaction) or from serine (via serine hydroxymethyltransferase). Glycine can be degraded to CO2 and NH4+ by the glycine cleavage enzyme, or it can be converted into glyoxylate through the action of D-amino acid oxidase or transaminases. Glyoxylate, in turn, can be oxidized to oxalate or processed via TPP-dependent pathways to form alpha-hydroxy-beta-ketoadipate, eventually leading to CO2 and H2O.

__lib_book_Biochemistry_ Marks_ Basic Medical Biochemistry A Clinical Approach_ 2nd Edition/img_2027.png


[User]
<image>
Describe the metabolic pathways shown in this diagram of a red blood cell.

[Assistant] This diagram illustrates several key metabolic pathways in a red blood cell: 1) Glycolysis, which converts glucose to lactate while generating ATP and NADH. 2) The HMP shunt (pentose phosphate pathway), which branches from glucose-6-phosphate to produce NADPH, essential for maintaining reduced glutathione to protect against oxidative stress. 3) The Rapoport-Lueberin shunt, which diverts 1,3-bisphosphoglycerate to form 2,3-BPG, a regulator of hemoglobin oxygen affinity. 4) The cytochrome b5 reductase pathway, which uses NADH to reduce methemoglobin (Fe3+) back to functional hemoglobin (Fe2+).

__lib_book_Biochemistry_ Marks_ Basic Medical Biochemistry A Clinical Approach_ 2nd Edition/img_2250.png


[User]
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Explain the biochemical pathway shown in the diagram for the regulation of glycogen metabolism in muscle.

[Assistant] The diagram illustrates the signaling cascade initiated by epinephrine in muscle cells to promote glycogenolysis. 1) Epinephrine binds to a receptor, activating adenylate cyclase, which converts ATP to cAMP. 2) cAMP activates protein kinase A. 3) Active protein kinase A phosphorylates and activates phosphorylase kinase, a process also stimulated by Ca2+-calmodulin. 4) Active protein kinase A simultaneously phosphorylates and inactivates glycogen synthase, preventing glycogen synthesis. 5) Activated phosphorylase kinase converts inactive phosphorylase b to active phosphorylase a. 6) Phosphorylase a catalyzes the breakdown of glycogen into glucose-1-phosphate, which is then converted to glucose-6-phosphate and metabolized to provide energy (lactate or CO2 + H2O) for the muscle.

__lib_book_Biochemistry_ Marks_ Basic Medical Biochemistry A Clinical Approach_ 2nd Edition/img_2392.png


[User]
<image>
Explain the experimental procedure shown in the diagram for determining the half-life of Flag-Snail protein.

[Assistant] The diagram illustrates a protein degradation assay. MCF-7 cells are cotransfected with pCMV2-Flag-Snail and pEGFP. After 36 hours, cells are treated with cycloheximide (CHX), a protein synthesis inhibitor, to stop new protein production. Cells are then lysed at specific time points (0, 1, 3, 5, 7, and 9 hours). The lysates are analyzed via SDS-PAGE and immunoblotting to measure the remaining levels of Flag-Snail protein relative to Beta-Actin. Finally, the degradation kinetics are quantified to determine the protein's half-life.

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One day before transfection, plate 200,000 MCF-7 cells (controlshRNA and DEDD-shRNA) into a 35 mm culture dish containing 2 mL of culture medium. Each kind of cells is seeded for six dishes. Dilute 24 μ g DNA (12 μ g pCMV2-Flag-Snail + 12 μ g pEGFP) in 1,200 μ L DMEM-serum free medium. Pipet 60 μ L FuGENE ® HD transfection reagent directly into the medium containing DNA without allowing contact with the walls of the plastic tubes. Vigorously tap the tube or vortex for 1-2 s to mix the transfection complex, and then incubate for 15 min at room temperature. Add 100 μ L/dish of transfection complex to the cells in a drop-wise manner. Swirl the wells to ensure distribution over the entire plate surface. Incubate at 37 ºC for 36 h ( see Note 29 ).

Replace the medium containing transfection complex with 2 mL fresh complete DMEM medium. Add 2 μ L CHX (20 mM) to the transfected cells to a fi nal concentration of 20 μ M. Incubate at 37 ºC. After the cells are treated with CHX for the indicated


[User]
<image>
Explain the molecular mechanism shown in the diagram that regulates the transition from G1 to S phase in the cell cycle.

[Assistant] The diagram illustrates the regulation of the G1 to S phase transition. In the absence of growth signals, the RB protein binds to the transcription factor E2F and recruits HDAC (histone deacetylase), which represses the transcription of S-phase genes. When growth factors are present, they stimulate the expression of MYC, which leads to the production of Cyclin D. Cyclin D complexes with CDK4 to phosphorylate RB. This phosphorylation, along with subsequent phosphorylation by Cyclin E/CDK2, causes RB to release E2F and HDAC. Once released, E2F is free to bind to the E2F site and initiate the transcription of S-phase genes, allowing the cell to progress into the S phase and replicate its DNA.

__lib_book_Cancer_ Molecular Biology Of Cancer by Pelengaris_ Stella/img_0034.png

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[User]
<image>
Describe the signaling pathways initiated by Receptor Tyrosine Kinases (RTKs) as shown in the diagram.

[Assistant] Receptor Tyrosine Kinases (RTKs) initiate signaling pathways upon ligand binding, which triggers receptor dimerization and tyrosine autophosphorylation. This leads to the activation of several downstream cascades: 1) The RAS-RAF-MEK-ERK (MAPK) pathway, which regulates gene transcription (e.g., c-MYC, c-FOS, c-JUN) to promote cellular replication and growth. 2) The JAK-STAT pathway, where JAK kinases phosphorylate receptors, recruiting STAT transcription factors that translocate to the nucleus. 3) The RAC pathway, which is involved in actin cytoskeleton remodeling.

__lib_book_Cancer_ Molecular Biology Of Cancer by Pelengaris_ Stella/img_0062.png

results in deregulated activity of the usual repertoire of RET targets. The different downstream activities of the mutant RET account for the phenotypic differences between MEN2A and MEN2B and thus produce a different portfolio of endocrine tumors.

MEN1 is associated with hyperplasia or tumors of several endocrine glands, including the parathyroids, the pancreas, and the pituitary. The most frequent problem in MEN1 is hyperparathyroidism. Hyperplasia of the parathyroid glands and excess production of parathyroid hormone result in elevated blood calcium levels, kidney stones, constipation, weakened bones, and depression. Almost all MEN1 patients show parathyroid symptomsbyage40. Variousgutand pancreatic endocrine tumors are also common in MEN1 (including gastrinomas that can result in excess secretion of gastrin and gastrointestinal ulcers and insulinomas that cause inappropriate secretion of insulin resulting in lowered blood glucose levels). The anterior pituitary and the adrenal gla


[User]
<image>
Explain the cooperative relationship between MYC and RAS in oncogenesis as illustrated in the diagram.

[Assistant] The diagram illustrates that MYC and RAS oncogenes have opposing effects on cell fate. Individually, deregulated MYC often triggers apoptosis, while activated RAS often induces growth arrest or senescence, serving as protective tumor-suppressor mechanisms. However, when both MYC and RAS are activated, they cooperate to bypass these checkpoints: RAS suppresses MYC-induced apoptosis (via the PI3K/AKT pathway), and MYC suppresses RAS-induced growth arrest (by inhibiting p21). This cooperation allows the cell to avoid programmed death and senescence, thereby promoting uncontrolled proliferation and tumor development.

__lib_book_Cancer_ Molecular Biology Of Cancer by Pelengaris_ Stella/img_0073.png

arrest/senescence, respectively. Deregulated activation of c-MYC alone may preferentially lead to apoptosis rather than cell division, while activated RAS alone may lead to cellular senescence - these outcomes serve to protect the organism from cancer-inherent tumor-suppressor activity. However, when RAS and MYC are both activated, these 'in-built' tumor suppressor activities are lost: RAS suppresses MYC-induced apoptosis and MYC suppresses RAS-induced growth arrest. It is such cooperation between oncogenes that promotes tumor development. (b) Activation of RAS and MYC results in potential engagement of both replication and growth but also of apoptosis and possibly senescence. If either MYC or RAS levels are excessive (as might occur during oncogenesis) or other proapoptotic signals are received then the balance may be tipped away from replication. RAS can promote senescence through either p16 INK4a or ARF, which activate RB or p53 pathwaysres pectively, while MYC can inhibit growth ar


[User]
<image>
Based on the provided charts, how does the distribution of phosphorylated EGFR differ among the three branches of the pathway?

[Assistant] According to the study, the PLC and Shc-Grb-SOS branches exhibit a spike in phosphorylated EGFR concentration when EGF concentrations are high (20 nM and 2 nM). In contrast, the Grb-SOS branch does not contribute to this initial spike; instead, it slowly leads to an accumulation of phosphorylated EGFR, eventually reaching a steady-state concentration higher than that of the other two branches.

__lib_book_Cancer_ New Challenges for Cancer Systems Biomedicine by D_Onofrio_ A/img_0054.png

C:\Users\HARI\Desktop\DocSmile\rl\__lib_book_Cancer_ New Challenges for Cancer Systems Biomedicine by D_Onofrio_ A.md

those bound to proteins in the cytoplasm) by varying the

EGF concentration (20 nM,

2 nM and 0.2 nM)

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Modelling Biochemical Pathways with the Calculus of Looping Sequences

Deterministic simu-

20

30

40

50

60

70

80

Total phosphorylated EGFR (nM)

10

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0

0

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TIME (s)

Stochastic simulations

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Total phosphorylated EGFR (nM)

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20 nM EGF

2 nM EGF

0.2 nM EGF

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20 nM EGF

2 nM EGF

0.2 nM EGF

100

117

120

120

TIME (s) are rather high and stochastic simulation can exhibit sensitivity of the pathway to stochastic noise. In this case the macroscopic dynamics obtained by the stochastic approach is essentially the same coming from deterministic simulations. In fact, there is only a slight difference in the shape of the spike caused by the higher concentration of EGF, which in the stochastic simulation has a wider amplitude. This comparison is not repeated for the other simulations wher


[User]
<image>
What do the panels in this figure represent regarding a simulated tumor?

[Assistant] This figure provides a three-dimensional visualization of the simulated response of a clinical glioblastoma (GBM) tumor to one cycle of chemotherapy. Panels (a) and (b) show the external surface and internal structure of the tumor before the start of chemotherapy, respectively. Panels (c) and (d) show the predicted external surface and internal structure of the tumor 20 days after the beginning of the chemotherapy treatment.

__lib_book_Cancer_ New Challenges for Cancer Systems Biomedicine by D_Onofrio_ A/img_0120.png

## apy. The pseudo-coloring criterion proposed and utilized is described in the caption

of Fig. 3.

4.2 Model B: Tumor Response to Radiotherapeutic Schedules Model B is a spatiotemporal simulation model of in vivo tumor growth and response to radiotherapy exemplified by the special case of imageable GBM treated by the treatment modality under consideration. The main constitutive processes of the model can be summarized as follows. A discretizing cubic mesh is superimposed upon a three dimensional virtual reconstruction of the tumor including its necrotic region and the surrounding anatomical features based on imaging data. In a way analogous to Model A, within each geometrical cell of the mesh a number of biological cell equivalence classes are defined based i.a. on the biological cell distribution over the various phases within or out of the cell cycle for the various mitotic potential categories. Sufficient registers are used in order to store the current state of each equivalence c


[User]
<image>
Describe the process shown in the provided dental diagrams.

[Assistant] The image illustrates the clinical steps for restoring a tooth after root canal therapy. The top row (G, H) shows the preparation of the root canal space to receive a post, including the temporary restoration phase. The bottom row (I, J) shows the final restoration, featuring the placement of a post, core, and crown, with the diagram indicating the presence of healed periapical bone.

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[User]
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Describe the steps shown in the illustration for performing an endodontic access cavity preparation.

[Assistant] The illustration depicts the sequential steps for an endodontic access cavity preparation in a posterior tooth: (A) initial assessment of the tooth with a carious lesion, (B) penetration of the pulp chamber roof, (C) refinement of the access, (D) cross-sectional view of internal dentin removal, (E) clinical retraction of the gingiva, and (F) final shaping of the access cavity to allow straight-line access to the root canals.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0188.png

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C F

L 0

Figure 7-56 A, Evaluation of the preoperative radiograph. B, Clinical evaluation of the tooth. C, Penetration of the pulp roof. D, Removal of the pulp roof/pulp horns with a round carbide bur. E, Location of the orifice with Mueller or LN bur. F, Exploration of the canal with a small K-file. G-I, Flaring of the orifice/coronal third of the mesial canal with Gates-Glidden burs. J, Flaring of the orifice/coronal third of the distal canal with a #.12 taper nickel-titanium rotary file. K, Flaring of the orifice/coronal third of the distal canal with a Gates-Glidden bur. L, Funneling of the mesial axial wall from the cavosurface margin to the mesial orifice. M, Funneling of the distal axial wall from the cavosurface margin to the distal orifice. N, Completed access preparation. O, Verification of straight-line access.

## Straight-Line Access Determination.

As with anterior teeth, straight-line access is paramount to successful shaping. Files must have unimpeded acc


[User]
<image>
What type of dental instrument is shown in this SEM image?

[Assistant] The image displays the working ends of Gates-Glidden burs, which are rotary instruments used in endodontic procedures. These instruments are characterized by their fluted design and rounded safety tips, which help guide the instrument and reduce the risk of lateral cutting or perforation during root canal preparation.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0280.png

<!--image-->

50 pm

## Low-Speed Rotary Instruments

Many types of rotary instruments are used during endodontic procedures. In addition to regular burs adapted for endodontics, various types of root canal reamers are used to prepare the root canal or to place or remove root canal filling materials and to prepare the post space.

## Burs.

In addition to conventional burs, burs with extended shanks for low-speed contraangle handpieces ( Fig. 8 -28 ) are useful for providing good visibility during deep preparation of the pulp chamber. After access to the pulp chamber has been achieved, straight-line access to the initial point of curvature traditionally has been accomplished using rotary instruments such as Gates-Glidden burs and Peeso instruments. These reamers are available in a 32 mm length and a 28 mm length for posterior teeth ( Fig. 8 -29 ). Use of these instruments should be limited to the straight portion of the canal preparation. The risk of perforation with these instruments


[User]
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What does this diagram illustrate regarding endodontic rotary instruments?

[Assistant] This diagram (Figure 8-47) compares the manufacturers' illustrated cross-sectional designs (left) with the actual cross-sectional shapes of various endodontic rotary instruments (Profile, Pro taper, Hero, RaCe, Quantec, and K3) at different levels along the working surface (1 mm, 6 mm, and 14 mm from the tip).

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0297.png

Figure 8-43 LightSpeed rotary NiTi instruments, size #20 (LightSpeed Technologies) . The working head is slightly larger than the shaft, and the radial lands are poorly defined.

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## Quantec.

The Quantec instrument (SybronEndo, Orange, CA) has double helical, asymmetric flutes separated by lands, the width of which is reduced by a relief. The Quantec also has positive cutting blades on the working portion. The lands of the instrument are said to enhance the instrument ' s strength ( Fig. 8 -44 ). The Quantec file is available with two tip designs, a cutting tip ( Fig. 8 -45 ) and a safety cutting tip. Instruments come in #.02, #.03, #.04, #.05, #.06, #.08, #.10, and #.12 taper. The instruments are available in #.02 taper in sizes #15 to #60.

Figure 8-44 Quantec rotary NiTi instrument, size #10 with a #.02 taper (Analytic Endodontics, Orange, CA) . Note the double land that characterizes the Quantec instrument. The higher marginal land (wide white bar) machines the root c


[User]
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What do these images demonstrate regarding nickel-titanium (NiTi) endodontic instruments?

[Assistant] These images demonstrate the physical properties of nickel-titanium (NiTi) endodontic rotary instruments, specifically their superelasticity and susceptibility to plastic deformation. The first two panels show instruments with permanent plastic deformation (indicated by arrows), while the third panel illustrates the superelastic behavior of the alloy, allowing the instrument to maintain a significant curve without breaking.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0356.png

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10.0 kV Imn

12

A

B

22

n

Most of the instruments described in this section are manufactured by a grinding process, although some are produced by laser etching. Precision at the surface quality is not really at a high level, whereas the tolerances are. Surface quality also is an important detail (see Fig. 9 -21 ), because cracks that arise from superficial defects play a role in instrument fracture. [11] Superficial defects such as metal flash and rollover are common in unused NiTi instruments. [83][170][336]

Attempts have been made to improve surface quality by electropolishing the surface and by coating it with titanium nitride. [217][235] The latter process also seems to have a beneficial effect on cutting efficiency. [235]

In essence, two properties of the NiTi alloy are of particular interest in endodontics: superelasticity ( Fig. 9 -22 ) and high resistance to cyclic fatigue (discussed later). These two properties allow continuously rotating instruments to be


[User]
<image>
Describe the endodontic procedure shown in the image.

[Assistant] The image illustrates the lateral compaction technique for root canal obturation in a mandibular molar. This process involves using a finger spreader to create space alongside the master gutta-percha cone, followed by the insertion of accessory gutta-percha cones to fill the canal space. The sequence concludes with radiographic verification of the obturation's length, density, and taper.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0441.png

Bookmark URL: /das/book/view/65969511-3/1357/78.html/top

Use of this content is subject to the Terms and Conditions of the MD Consult web site.

Cohen: Pathways of the Pulp, 9th ed. , Copyright © 2006 Mosby, An Imprint of Elsevier

## METHODS OF OBTURATION

## Lateral Compaction

Lateral compaction is a common method for obturation ( Fig. 10 -26 ). [45] The technique can be used in most clinical situations and provides for length control during compaction. [92] A disadvantage is the technique may not fill canal irregularities [291] as well as warm vertical compaction. [288] The procedure can be accomplished with any of the acceptable sealers.

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GH

Figure 10-26 Left first mandibular molar. A , Preoperative radiograph. B , Working length radiograph. C , Coronal access opening and demonstrating the prepared mesiobuccal canal. D , Standardized master cones with coronal reference marked. E , Standardized master cones fit to length as they exhibit minimal taper and permit deep


[User]
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What endodontic procedure is illustrated in this sequence of images?

[Assistant] This sequence illustrates the warm vertical compaction technique for root canal obturation. The process involves selecting a master gutta-percha cone, using a heated instrument to soften and remove excess coronal material, and then using a plugger to compact the plasticized gutta-percha apically. This is followed by back-filling the coronal portion of the canal with segments of gutta-percha, which are also heated and compacted to ensure a three-dimensional seal of the radicular space.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0444.png

n the prepared canal. Conventional cones that closely replicate the canal taper are best because they permit the development of hydraulic pressure during compaction. Following the adaptation of the master cone it is removed and sealer applied. The cone is placed in the canal and the coronal portion removed. Heat is applied with a heated spreader or plugger that removes portions of the coronal gutta-percha and softens the remaining material in the canal. The Touch ′ n Heat (SybronEndo) ( Fig. 10 -30 ) is an alternative to applying heat with a flameheated instrument because it permits temperature control. A plugger is inserted into the canal and the guttapercha condensed, forcing the plasticized material apically. The process is repeated until the apical portion has been filled. The coronal canal space is back-filled using small pieces of gutta-percha. The sectional method consists of placing 3 to 4 mm sections of gutta-percha approximating the size of the canal into the

root, applying


[User]
<image>
What do these scanning electron microscopy (SEM) images demonstrate regarding a dental needle?

[Assistant] These SEM images (Figure 11-32) illustrate the fracture of a dental needle. Such analysis is used to determine if a broken instrument resulted from excessive operator trauma or a manufacturing defect. In this case, the fracture patterns, including ductile dimple voids and bending deformation, typically indicate a combination of low-cycle bending fatigue and tensile overload, often occurring when a needle strikes a hard object like the ramus during a mandibular block.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0491.png

## Pneumomediastinum (Air Embolus)

When performing endodontic surgery a surgical handpiece should be used that ventilates air through the back of the handpiece rather than an air turbine that directs air into open tissue spaces. Pneumomediastinum, also known as mediastinal emphysema, may result from air embolisms dissecting down the neck facial planes from air forced into the submandibular or sublingual spaces contiguous with neck spaces. [19][119]

## Broken Needle

Scanning electron microscopy (SEM) with an energy dispersive x-ray spectrometer attachment can analyze whether a broken instrument is due to excessive operator trauma or manufacturing defect. Fig. 11 -30 represents a combination of low-cycle bending fatigue and tensile overload. Accordingly, the local anesthetic needle likely fractured because of bending deformation as it struck the ramus.

Figure 11-30 Tensile overload shown elongated ductile dimple voids.

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Obsd

Ductile rupture in metals results from shear


[User]
<image>
What do the microscopic images in this figure demonstrate regarding endodontic root-end preparation?

[Assistant] These images demonstrate the microscopic assessment of root-end preparations. The top images show the root-end surface, with an arrow highlighting a dentinal crack. The bottom images are scanning electron microscopy (SEM) views; the left shows the prepared root-end cavity, and the right shows the interface between the root dentin and the filling material, illustrating the quality of the seal and potential for cracks caused by instrumentation like ultrasonic tips.

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The ultrasonic cavities produced more parallel walls and deeper depths for retention. In addition, the ultrasonic tips followed the direction of the canals more closely than those prepared by burs. Scanning electron microscopic examination of the cavity walls showed presence of cleaner surfaces of root-end cavities prepared by ultrasonic tips than those made with burs [ 17 ].

Ultrasonic diamond-coated tips preparation is easier and faster, but the tips should be used cautiously to avoid over-preparation or perforation of the root end [ 18 ].

Several simple indications may help a safe and effective use of ultrasonic endodontic tips. First, the lighter the touch, the more effi cient the cutting will be, while the use of a greater pressure may cause fracture of the tips and perforations. Then the correct amount of water is very important. In fact, if too much spray is used, visibility and cutting effi ciency are both decreased. On the contrary, if too little water is used, the necessary


[User]
<image>
Describe the histological features of the developing tooth germ shown in the image.

[Assistant] The image displays the cap stage of tooth development. Key structures include the inner enamel epithelium (IE), which consists of columnar cells lining the concavity, the outer enamel epithelium (OE), the stellate reticulum (SR) characterized by a loose network of cells, and the underlying dental papilla (DP) composed of dense mesenchymal cells.

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Fig. 2.1. Frontal section through head of a human 10-week embrio. A . x20. B . x200. C . x250. The 'tooth bud stage': the epithelial cells of the dental lamina proliferate and begin to deepen in the underlying mesenchyme (Courtesy of Prof. A. Bloom, Boston University).

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A

C

B

lution in which, by means of a continuous and gradual proliferation of cells, the teeth begin their slow, progressive formation.

Very early in the 'tooth bud stage', which represents the primordia of the enamel organ,* two types of epithelial cells differentiate. One covers the internal surface of the bud, the other the external surface; they are the 'inner epithelium' and 'outer epi-

A

thelium', respectively, of the enamel organ (Fig. 2.2). Concurrently, there is marked proliferation of the mesenchymal cells which face the inner epithelium of the enamel organ, from which the 'dental papilla' (Fig. 2.3) will derive. This mesenchymal proliferation tends to dip within the epithelial proliferation


[User]
<image>
What does this figure illustrate regarding the management and diagnosis of a periapical lesion?

[Assistant] This figure illustrates a clinical case involving a maxillary incisor with a periapical radiolucency. Panels A through E show the progression of endodontic treatment, including the initial lesion, instrumentation, and obturation. Panels F and G show the histopathological examination of the excised lesion, revealing a cystic structure lined by epithelium, consistent with a radicular (periapical) cyst.

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[User]
<image>
Describe the technique for taking a periapical radiograph of an upper lateral incisor as shown in the figure.

[Assistant] To take a periapical radiograph of an upper lateral incisor, the film must be positioned deeply in the palate to ensure the apices are included. The film should be parallel to the long axis of the tooth. The patient should bite on the plastic support of the film holder, keeping the mandible slightly protruded to maintain the correct position. The tooth of interest must be centered in the radiograph to avoid superimposition of adjacent teeth.

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Fig. 5.45. In this case, in view of the lesion's extensiveness, a panoramic radiograph was obtained to visualize the limits of the radiolucency.

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Fig. 5.46. The radiograph was not rinsed properly. At the level of the clip, there are large streaks of the fixer solution, evidently still present in the rinsing water.

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Fig. 5.47 Ultraspeed radiographs DF 57 contain two films inside the envelop.

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Fig. 5.48. Positioning of the film using the patient's finger doesn't give reproducible results (taken from McCoy, 1923).

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## Upper incisors

The film must be positioned deeply enough in the palate, so that the apices are included in the radiograph.

The midline of the radiograph must coincide with the midline of the dental arch. The plane of the film must be parallel to the long axis of the teeth. For this reason, the patient must bite the plastic support, holding the mandible in a slightly protruded position (Fig. 5.49) to avoid improper pos


[User]
<image>
Explain the technique for taking a dental radiograph of the upper central incisors as shown in the image.

[Assistant] To take a radiograph of the upper central incisors using a film holder, the film must be positioned deeply in the palate so that the apices are included. The midline of the radiograph should coincide with the midline of the dental arch, and the plane of the film must be parallel to the long axis of the teeth. The patient should bite the plastic support while holding the mandible in a slightly protruded position to ensure the holder remains stable and the X-rays are correctly aligned.

__lib_book_Conservative Dentistry_ Endodntics_ Volume 1 by Castellucci_ Arnaldo/img_0161.png


[User]
<image>
What do these histological images show regarding the dental pulp?

[Assistant] These histological images show various forms of pulpal calcifications, commonly known as pulp stones or pulpal calculi. These structures can be free-floating within the pulp chamber or adherent to the dentinal walls, and they represent a common finding in dental pulp histology.

__lib_book_Conservative Dentistry_ Endodntics_ Volume 1 by Castellucci_ Arnaldo/img_0256.png

The etiology of these pulp calcifications is unknown. They can occur around nests of cellular degeneration, in the form of dystrophic degeneration, but in the absence of such tissue degeneration, their cause remains obscure. They have even been described in still-unerupted teeth, which have not been influenced by the same functional stresses. 36

There is undoubtedly a cause-and-effect relationship

Fig. 7.7. A Radiographic appearance of a normal pulp in a second molar with an immature apex. B . Histologic appearance of a normal pulp in a molar with immature apices (courtesy of Prof. A. Bloom, Boston University).

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Fig. 7.8. Radiographic appearance of a normal pulp in an elderly patient. Note the sizes of the pulp chamber and of the canals of the upper right second molar.

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B

Fig. 7.9. A . Large free-false pulpal calculus (concentric layers, without tubular elements) (courtesy of Dr. N. Perrini). B . Small free-false pulpal calculus with four concentric calci


[User]
<image>
What does this diagram illustrate regarding dental anesthesia?

[Assistant] This diagram illustrates the technique of local infiltration anesthesia in dentistry. It shows the needle being introduced vestibularly at the mucogingival junction, with the anesthetic solution deposited near the root apices of the teeth to block nerve impulses in the treatment area.

__lib_book_Conservative Dentistry_ Endodntics_ Volume 1 by Castellucci_ Arnaldo/img_0326.png

the patient anticipates endodontic treatment with great anxiety. What is most frightening is the fear of experiencing pain. It is the dentist's responsibility to calm the patient and elicit the maximal cooperation by successful anesthesia. Nonetheless, one must not abuse anesthetics as tranquillizers. If the planned treatment is definitely painless, such as the cleaning and shaping of a necrotic root canal or the filling procedure of a canal, it is perfectly useless, if not in fact contraindicated, to administer anesthetics. There are several reasons for this. In the case of the necrotic tooth, the preparation of the access cavity corresponds to the very important 'cavity test', and if one is working under anesthesia, one may realize too late that a lesion that originally seemed to be of endodontic origin was rather of periodontal origin, and thus that the pulp was vital. Furthermore, if one uses anesthetics when not indicated, one excludes the admittedly minimal and not always reliabl


[User]
<image>
Describe the sequence of radiographs shown in Figure 11.137 for the endodontic treatment of a lower molar.

[Assistant] Figure 11.137 illustrates the endodontic treatment of a lower molar with complex canal anatomy: (A) shows the preoperative radiograph, (B) shows the initial instrumentation of the canals, (C) shows the placement of instruments confirming the canal configuration, and (D) shows the final postoperative radiograph after obturation.

__lib_book_Conservative Dentistry_ Endodntics_ Volume 1 by Castellucci_ Arnaldo/img_0539.png

<!--image-->

C

D

A

B

E

F

G

This bizarre type of endodontic anatomy is easily explained by examining an extracted tooth (Fig. 11.137). Seen from the buccal side (Fig. 11.137 E), the tooth appears singlerooted, while from the lingual side (Fig. 11.137 F) the tooth demonstrates the normal anatomy of a lower molar: two roots, one of which is mesial, the other distal, separated by a va- riable interradicular bony septum. The molar with a 'C-shaped' canal is therefore a singlerooted tooth with a kidney shaped root. The canal contained within also has a kidney shaped appearance which can be preserved unaltered throughout its coronoapical length or which can branch into individual canals at various levels.

B

D

Fig. 11.137. A . Radiographically, the lower second molar seems to have the classical endodontic anatomy. B . Careful examination of the pulp chamber floor indicates a C-shaped canal. C . The introduction of instruments into the respective canals confirms the diagnosis. Note t


[User]
<image>
Describe the clinical steps shown in this image sequence for the endodontic retreatment of a lower molar.

[Assistant] The image sequence (Fig. 11.159) illustrates the endodontic retreatment of a lower molar: (A) Preoperative radiograph showing previous treatment. (B) The occlusal surface shows two separate composite restorations. (C) Removal of the composite reveals an enamel bridge separating two distinct access cavities. (D) The bridge is removed to visualize the pulp chamber floor. (E) The access cavity is fully prepared with cleaned and shaped canals. (F) Postoperative radiograph showing the completed root canal treatment.

__lib_book_Conservative Dentistry_ Endodntics_ Volume 1 by Castellucci_ Arnaldo/img_0556.png

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Fig. 11.154. A . Preoperative radiograph of the lower left second molar which necessitates retreatment. B . After the removal of the old composite filling, the access cavity made by the previous dentist is evident. C . The residual roof has been removed. D . One year recall.

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C

D

A

B

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C

B

A

Fig. 11.155. A . Part of the roof of the pulp chamber is still in place. B . The roof has been removed. C . Access cavity after cleaning and shaping the root canals.

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A

B

Fig. 11.156. A . The previous dentist forgot to remove part of the pulp chamber roof. B . Now the root canals are ready for packing.

A

B

Fig. 11.157. A . The root canal treatment of this upper first molar has been made through three holes made in the pulp chamber roof. B . The bleeding from the palatal canal is caused by some remaining vital pulp tissue!

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A

C

E

<!--image-->

Fig. 11.158. A , B and C-E . More examples of root canal treatments misdiag


[User]
<image>
Describe the design characteristics of the ProFile endodontic instrument shown in the image.

[Assistant] The ProFile endodontic instrument is characterized by a 'triple U' cross-sectional design featuring three radial lands. These radial lands are flat cutting surfaces that provide structural support while increasing the instrument's flexibility, which is beneficial for shaping curved canals.

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The rotary ProFiles are now available in .02, .04 and .06 taper, and in the ISO diameters from 15 to 45 (.02 taper) and from 15 to 80 (.04 and .06 taper) and in 21, 25 and 30 mm lengths. ProFiles all present a working surface of 16 mm and a round non cutting tip (Fig. 13.52); furthermore along the shaft there are 'depth gages' that are dark grooves placed at 18, 19, 20, 22 and 24 mm from the tip, that facilitate the positioning of the silicone stop and allow an accurate control of the depth of instrument placement. The handle of the ProFile in nickel plated and has a small ISO standard coloured rings which are useful to identify both the diameter and the taper (one small ring for the .02 series, two small rings for the .04 series, and three small rings for the .06 series) (Fig. 13.53).

ProFiles can be used on their own or in hybrid sequences to finish off the canals prepared with more resistant instruments such as the ProTaper. In the 'pure' instrument sequences ProFiles are used in a


[User]
<image>
What are the instruments shown in the image and how are they categorized?

[Assistant] The image shows GT Rotary Files and their corresponding GT Obturators. They are organized into three series based on their tip diameter: the Small 20 Series (0.20 mm tip), the Medium 30 Series (0.30 mm tip), and the Large 40 Series (0.40 mm tip). Within each series, the instruments are further categorized by their taper, ranging from .04 to .10.

__lib_book_Conservative Dentistry_ Endodntics_ volume 2 by Castellucci_ Arnaldo/img_0067.png

esent a non cutting tip, a prefixed tip diameter and a prefixed maximum flute diameter (MFD), multiple tapers and a blade length inversely proportional to the taper. Rotary and Hand GT Files however, also present substantial differences, the most evident of which being the blade direction which is clockwise in the Rotary GT and counter-clockwise in the Hand GT; furthermore, the Rotary GT blades are classical 'radial lands' (Fig. 13.59) without the sharp cutting angles found in the Hand GT Files (Fig. 13.36). 6,7 The clockwise direction of the blades and the radial cutting planes are fundamental because they make it possible to use the Rotary GT in continual clockwise rotation without screw in. Like the ProFiles, the Rotary GT Files are hardly efficient in lateral cutting and they tend to imprint their shape into the canal; on the basis of the last GT brought to the working length, the operator can predetermine the final diameter and tapers of the preparation and choose the correspondin


[User]
<image>
Describe the procedure shown in the diagrams for navigating an apical impediment in a root canal.

[Assistant] The diagrams illustrate a technique for bypassing an apical impediment in a root canal using pre-bent endodontic files. After initial shaping with K-files (F, G), a GT Hand File is used (H). Because NiTi files have shape memory, they are dramatically overbent (H, I) to achieve a residual 35-45 deg bend. This pre-bent file is then introduced into the canal (J) and rotated counter-clockwise without apical pressure to pull the instrument into the canal walls, similar to tapping a screw thread (K), allowing it to traverse the impediment.

__lib_book_Conservative Dentistry_ Endodntics_ volume 2 by Castellucci_ Arnaldo/img_0329.png

Again, rotate the GT File counter-clock-wise to feed it back in, push on it, and make the cut in a clock-wise direction (Figs. 20.15 M-P). After three to five of these cutting cycles, the file will stop advancing in counterclock-wise rotation because the flutes are full of debris. Rotate the file counter-clock-wise as it is retrieved from the canal to keep the debris loaded on the file flutes.

Quite often the impediment will be gone at this point and conefit is straightforward (Fig. 20.16). In cases where the impediment remains after shaping and conefit is impossible, a GT Obturator is indicated as filling material can be effectively pushed ahead of carriers but not ahead of gutta-percha cones.

Fig. 20.15. (Continued) F . A pre-bent # 25 K-file cuts to 0.5 mm short of terminal length. G . A pre-bent # 30 K-file is watch-wound to about 1 mm short of terminal length. H . A GT Hand File of adequate taper (a 20-.08 in this case) is brought in at this point because pre-bending and directe


[User]
<image>
What are the instruments shown in the image and what is their purpose?

[Assistant] The image displays a set of Axxess Flares, which are endodontic instruments used in root canal procedures. These files are designed with varying tapers, ranging from .12 down to .02, allowing for efficient coronal flaring and canal preparation.

__lib_book_Conservative Dentistry_ Endodntics_ volume 2 by Castellucci_ Arnaldo/img_0360.png

Fig. 22.9. The Quantec File™ is available with cutting tips for negotiating canals with diameters smaller than the tip and non-cutting tips for canals with larger diameters.

<!--image-->

Non-cutting tip

Cutting tip

Fig. 22.10. The Quantec File™ is available with the standard length handle and the Axxess™ handle that is 4 mm shorter.

<!--image-->

Standard Handle

Quantec AxxessTM Handle

## The Quantec™ series by Analytic

The Quantec™ series of instruments is comprised of files having the same .25 mm tip size but different tapers ranging from a .12 taper to a .02 taper that can be used with either a crown-down or step-back technique (Fig. 22.11). The series is supplemented with ISO sizes.

By progressively changing the tapers of files, the Quantec™ Series provides the means to reduce the surface area engaged and thus the torque required for rotation. A larger tapered file initially engages only the coronal portion of a canal prepared by a smaller tapered file of the same tip size


[User]
<image>
Describe the endodontic procedure shown in the radiographs and diagram in Figure 24.79.

[Assistant] Figure 24.79 illustrates the endodontic treatment of a molar with a canal confluence. Panel G shows the completed compaction of the mesial canal. Panel H is the postoperative radiograph, demonstrating the successful filling of the confluence after the compaction of the mesial canal cone. Panel I shows the tooth at a two-year recall, indicating stable results.

__lib_book_Conservative Dentistry_ Endodntics_ volume 2 by Castellucci_ Arnaldo/img_0501.png

<!--image-->

A

C

E

Fig. 24.79. A . Preoperative radiograph of a lower right second molar. The tooth shows a single root with only two root canals, one distal and one mesial, which converge at a common apex. B . The drawing represents the root of figure A. C . Radiograph of the cone fit: the distal cone descends to the end of the preparation, while the mesial stops against the preceding one. D . Schematic drawing. E . Radiograph of the apical condensation of the distal canal: note that the mesial cone has been introduced into the canal but has not yet been compacted. It will be compacted after this radiograph has been checked for the distal canal. F . Schematic drawing (continued).

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B

D

F

apically and the obturation appears compacted), can the operator proceed with the compaction of the second cone of gutta-percha that will be pushed, heated, and compacted against the gutta-percha of the first canal (Fig. 24.79 G). If, instead of using this important trick, we perfo


[User]
<image>
What are the instruments shown in the image and how are they typically packaged?

[Assistant] The image shows Thermafil obturators, which are used in endodontic procedures for root canal obturation. They consist of a plastic carrier coated with gutta-percha. These instruments are typically available in various sizes and are commonly sold in packs of 6 or in assorted sizes for anterior and posterior teeth.

__lib_book_Conservative Dentistry_ Endodntics_ volume 2 by Castellucci_ Arnaldo/img_0532.png

Fig. 26.1. Thermafil Obturator: The carrier in plastic is roughly wrapped in gutta-percha for about 16 mm.

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Thermafil Obturator

Gutta-percha

Plastic Carrier

- rotary files with the only exception that the carrier taper is slightly less than that of the GT file to prevent contact of the carrier with the canal walls and to leave space for the flow of gutta-percha and sealer (Fig. 26.4). The GT Thermafil are available in the following four series (Fig. 26.5):
- series 20 consisting of 4 obturators with taper .04, .06, .08 and .10 with the tip diameter of 0.20 mm and a maximum diameter of 1.00 mm
- series 30 consisting of 4 obturators with taper .04, .06, .08 and .10 with the tip diameter of 0.30 mm and a maximum diameter of 1.00 mm for the GT
- Thermafil 30 .04, .06 and .08 and 1.25 for the GT Thermafil 30 .10
- series 40 consisting of 4 obturators with taper .04, .06, .08 and .10 with the tip diameter of 0,40 mm and a maximum of 1.00 mm for GT Thermafil 40 .04, .06 and .


[User]
<image>
What does this graph illustrate regarding dental health trends in developed countries between 1967 and 1983?

[Assistant] This graph illustrates the decline in DMFT (Decayed, Missing, and Filled Teeth) scores among 12-year-old children in various developed countries between 1967 and 1983. The data shows a consistent downward trend in caries prevalence across all listed nations, reflecting a significant improvement in dental health during this period, which experts largely attribute to the regular use of fluoridated toothpastes.

__lib_book_Conservative Dentistry_ Essentials of Dental Caries by Kidd_ E A M 3rd ed/img_0021.png

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## 1.7.4 Caries prevalence 5

Dental caries is ubiquitous in modern humans, and is the main cause of tooth loss in people of all ages. For most of the twentieth century caries was seen as a disease of economically developed countries, with a low prevalence in the developing world. By the late twentieth century this pattern was changing in two ways:

- There was evidence of a rise in caries experience in some developing countries. To give an example, studies in the 1990s show dental caries as a major problem in the former socialist countries of eastern Europe. These countries can be considered 'developing' in the economic sense, and the use of fluoride toothpastes and toothbrushes there is still low.
- By the late 1970s a marked reduction in caries experience among children and young adults was obvious in developed countries (Figure 1.12) although in 1983 there were considerable differences between countries. 6

Figure 1.12, DMFT data from 12-year-old children of many countries demonstr


[User]
<image>
Describe the clinical and radiographic presentation of the maxillary central incisors shown in the image.

[Assistant] The image displays a clinical case of a patient with discolored and exposed crown margins on both maxillary central incisors. Panel (a) shows the preoperative clinical state, panel (b) shows the teeth after crown removal, revealing the underlying buildup and remaining tooth structure, and panel (c) provides a periapical radiograph showing the root canal treatments, posts, and associated periapical pathology.

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The most critical restorative aspect is the remaining external and internal tooth structure. After removal of old restorations and caries, the remaining tooth structure is evaluated to assess structural integrity and the margins of a future permanent restoration. Preparation of defined

Fig. 6.1 A 49-year-old female patient, presenting to prosthodontist, discolored and exposed crown margins of both central maxillary incisors. Case demonstrates that although the patient's primary concern was a simple esthetic issue, the decision-making for a new permanent restoration had to include endodontic, periodontal, restorative, and esthetic aspects, as well as weigh the prognosis of teeth with endodontic re-treatment and permanent restoration versus the prognosis of an implant-supported restoration. ( a ) Preoperative clinical situation; ( b ) situation after crown removal, exposing calculus, buildup, and amount of remaining tooth structure; ( c ) radiograph

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a

c

b

revealing the


[User]
<image>
Describe the clinical sequence shown in this image series regarding the replacement of a maxillary incisor.

[Assistant] The image series illustrates a clinical case involving the replacement of a failing endodontically treated maxillary incisor with a dental implant. Panel (a) shows the preoperative radiograph with periapical pathology. Panel (b) shows the clinical presentation of the tooth with compromised margins. Panel (c) shows the surgical site after implant placement. Panel (d) shows the gingival tissue, and panel (e) shows the final radiographic appearance of the implant-supported restoration.

__lib_book_Conservative Dentistry_ Evidence Based Decision Making in Dentistry by Eyal Rosen_ Carlos E/img_0041.png

including biological, technical, or esthetic [120]. The same authors also demonstrated a declining survival rate of restorations on dental implants in comparison to the actual implant fixtures. They reported that after 5 years 95.4 % and after 10 years 92.8 % of implant fixtures were in function, whereas after 5 years 95.0 %, but after 10 years only 86.7 % of the prosthodontic abutments were still in place. Although implant designs, surfaces, techniques, and restoration types have changed in the past decade, these complication rates have not significantly changed. Recently, Zembic et al. reported incidence rates for technical complications of 11.8 % (95 % CI 8.5-16.3 %) and biologic complications of 6.4 % (95 % CI 3.3-12.0 %) [121]. The authors did not address esthetic complications in their study. Pjetursson et al. stated that although higher survival rates and lower complication rates were reported in more recent clinical studies, the actual incidence rate of esthetic, biologic, and


[User]
<image>
When is CBCT imaging recommended for the assessment of mandibular third molars prior to extraction?

[Assistant] CBCT imaging is typically recommended for mandibular third molar extraction when panoramic radiographs show signs of close contact between the tooth roots and the mandibular canal, and when the CBCT findings are expected to change the treatment plan or outcome.

__lib_book_Conservative Dentistry_ Evidence Based Decision Making in Dentistry by Eyal Rosen_ Carlos E/img_0044.png

Another recently published study [43] evaluated the efficacy of CBCT for assessment of mandibular third molars using the hierarchical model by Fryback and Thornbury [41] and reported that only few high-evidence studies on the efficacy of CBCT for radiographic examination of mandibular third molars currently exist [43]. They stated that 'periapical or panoramic examination is sufficient in most cases before removal of mandibular third molars. However, CBCT may be suggested when one or more signs for a close contact between the tooth and the canal are present in the two-dimensional image if it is believed that CBCT will change the treatment or the treatment outcome for the patient' [43] (Fig. 7.1).

In a recent study [12], a systematic review of the literature was performed to identify and analyze studies evaluating the use of CBCT in endodontics. Initially 485 possible relevant articles were identified. However, following the application of strict inclusion criteria, only 58 articles (1


[User]
<image>
What are the key components of a cavity preparation shown in this diagram?

[Assistant] The diagram illustrates the nomenclature for a cavity preparation, identifying the following walls and margins: the gingival wall, axial wall, distal wall, mesial wall, incisal wall, and the cavosurface margin. It also indicates the long axis of the anatomic crown and the relative directions (distal, mesial, and incisal) on the tooth.

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Incisors and canines are referred to as anterior teeth , regardless of the arch; premolars and molars are posterior teeth .

In addition to quadrants, the mouth may also be divided into sextants , or sixths. There are three sextants in each arch, with divisions between the canines and first premolars-the maxillary right, anterior , and left sextants and the mandibular right, anterior, and left sextants.

Fig 6-1 Nomenclature of directions and tooth surfaces.

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Midline -

10

Facial

6

11

12

Mesial

surace

Maxillary

13

arch

14

Facial

Lingual

15

Distal

16

surface

Right

Left

quadrani

quadrant

3

Fig 6-2 Tooth-numbering systems and nomenclature.

<!--image-->

21 Central incisor

12

22 Lateral incisor

14

10

24 First premolar

Outside numbers)

FDI system

15

12

25 Second premolar

13

16

26 First molar

17

Inside numbers

27 Second Molar

Universal

15

system

18

16

28 Third molar

Permanent

dentition

48

38 Third molar

47

31

18

37 Second Mol


[User]
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What information is provided in Table 6-1 regarding dental carbide burs?

[Assistant] Table 6-1 provides a reference for various shapes of regular carbide burs used in tooth preparation. For each shape-such as round, inverted cone, straight fissure, tapered fissure, and pear-the table lists the corresponding US bur size numbers and their specific head diameters in millimeters.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0254.png

A positive rake angle would produce a more acute edge angle. Positive rake angles may be used to cut softer , weaker substances, such as soft carious dentin. If a blade with a positive rake angle were used to cut a hard material, such as sound enamel or dentin, it would dig in, leaving an irregularly cut surface, and the cutting edges of the blades would chip and dull rapidly.

The basic shapes of tooth-preparation burs used in operative dentistry are shown in Fig 6-66. Many other shapes are available; most are modifications of these five. Numbering systems have been introduced to describe the shapes of dental burs. The original system, introduced by SS White Dental Manufacturing, had nine shapes based on the burs available at that time. 10 That system has been modified and expanded as new burs have been developed. The American National Standards Institute/American Dental Association (ANSI/ADA) specification 11 provides standard characteristics for dental burs; this specification lists


[User]
<image>
Describe the technique shown in the illustration for isolating a fixed partial denture with a rubber dam.

[Assistant] The illustration depicts the ligation method for isolating a three-unit fixed partial denture. In this technique, holes are punched in the rubber dam for the abutment teeth and the pontic. A ligature is then threaded through the abutment hole on the facial aspect, passed under the retainer-pontic connector, and through the lingual aspect of the same hole. It is then looped around the septum, passed through the pontic hole, and back under the connector to the facial aspect to secure the dam tightly around the restoration.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0379.png

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Fig 7-44a A four-unit fixed partial denture extends from the mandibular first premolar to the second molar.

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Fig 7-44b The holes for the abutment teeth are connected with an arched cut. Note small piece of dam material at bottom that will be used as shown in Figs 7-44c and 7-44d.

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Figs 7-44c and Fig 7-44d A small piece of dam is glued in place.

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d

Fig 7-44e A No. W8A clamp is positioned on the second molar.

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Fig 7-44f The dam is carried to place.

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Fig 7-44g The tongue of dam material is tucked under the pontics with a periodontal probe.

Fig 7-44h The tongue of material is grasped and pulled lingually with a hemostat.

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Fig 7-44i Glue is applied for attachment of the rubber dam tongue.

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Fig 7-44j The tongue is held in place with a hemostat and a cotton-tipped applicator while the glue sets.

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Fig 7-44k Isolation is complete.

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Fig 7-45


[User]
<image>
How do different instrumentation techniques affect the dentin surface as seen in SEM?

[Assistant] Different instrumentation techniques produce distinct surface characteristics on dentin. Traditional rotary instrumentation, such as a diamond bur, typically creates a smear layer-a layer of cutting debris that covers the dentin surface and occludes the tubules. In contrast, laser ablation (such as Er:YAG) can remove this debris and modify the surface, often resulting in the exposure of open dentinal tubules, which changes the surface's receptivity to adhesive bonding.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0413.png

Sclerotic dentin usually contains few, if any, patent tubules and therefore has low permeability 62,63 and tends to be insensitive to external stimuli. 58,59,61,62 The odontoblastic processes associated with sclerotic dentin often exhibit partial atrophy and mineralization. 48,54,64 Heavily sclerotic dentin has areas of complete hypermineralization 60,65 without tubule exposure, even when etched with an acid (Fig 8-12). Some areas show abundant mineral sclerotic casts, which extend from the tubule orifices above the dentin surface and represent mineralized odontoblastic processes (Fig 8-13).

All of these morphologic and structural transformations of dentin, induced by physiologic and pathologic processes, result in a dentinal substrate that is less receptive to adhesive treatments than is normal dentin. 57,58,60,66-68

Fig 8-12 Scanning electron photomicrographs demonstrating heavily sclerotic dentin without exposed tubules, despite treatment with 10% citric acid. Bar = 20 µm. (From V


[User]
<image>
What does this diagram illustrate regarding dental cavity preparation?

[Assistant] This diagram illustrates a cavity preparation for a dentinal caries lesion. The proximal view shows the location of the contact area, while the mesiodistal section demonstrates that the axial wall of the preparation extends into the dentin and the external enamel margins are beveled to reduce enamel fracture and improve esthetics.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0529.png

## Cavitated Enamel Caries Lesions

When the enamel surface is cavitated, it is past the point of remineralization. If the cavitation is very shallow and deeper enamel has been remineralized, a restoration may not be necessary unless the lesion is esthetically displeasing. If the lesion is confined to enamel, enameloplasty or recontouring may be sufficient. If necessary, a conservative cavity preparation may be accomplished with a round tungsten-carbide or diamond bur used in a high-speed handpiece. The finished preparation resembles a saucer and has no retentive undercuts (Fig 9-4). Adhesion to acid-etched enamel provides the necessary retention. Both laboratory and 3-year clinical data have demonstrated the durability of

Fig 9-4 Saucer-shaped preparation in enamel. The caries lesion is usually located slightly gingival to the contact area. Every attempt should be made to maintain natural tooth contact between the adjacent teeth during restoration. If no cavitation is present, remine


[User]
<image>
What does this diagram illustrate regarding dental enamel?

[Assistant] This diagram illustrates the microscopic appearance of dental enamel, highlighting different surface conditions. It shows a cross-section of a tooth with magnified callouts depicting a fracture within the enamel and the appearance of etched enamel, as well as indicating the presence of cracks on the tooth surface.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0623.png


[User]
<image>
What is the purpose of the technique shown in this illustration during a Class 2 cavity preparation?

[Assistant] The illustration shows the use of a hand instrument to fracture the thin plate of proximal enamel during a Class 2 cavity preparation. This technique is used to remove the enamel plate safely without using a bur, which helps prevent accidental nicking, scarring, or damage to the adjacent tooth.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0792.png

d there is evidence that the patient will reduce his or her caries risk status, consideration should be given to stopping the extension of the preparation short of removing some superficial demineralized enamel. After the amalgam restoration has been placed, the demineralized enamel can be treated with fluoride to enhance remineralization, or it can be acid etched and coated with light-cured resin for at least short-term protection from further demineralization. 86 Alternatively, the demineralized enamel can be removed with a round bur or hand instrument; then the sound enamel walls of the dished-out area can be etched and the area can be restored to contour with bonded resin composite. The Class 2 restoration necessitated only because of a proximal caries lesion and having an occlusal outline limited to the marginal ridge area will be referred to in this chapter and others as a slot restoration . If it involves the distal surface with access from the occlusal surface, it will be calle


[User]
<image>
What does this diagram illustrate regarding the etiology of noncarious cervical lesions?

[Assistant] This diagram illustrates the abfraction theory of noncarious cervical lesion (NCCL) formation. It shows how occlusal forces (represented by the lightning bolts) cause tooth flexure, which leads to the loosening and eventual loss of enamel rods at the cervical region of the tooth.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_1020.png

## Etiology

The entire etiology of noncarious cervical lesions has not been determined. While the various possible causes and their degree of involvement may be controversial, there is overwhelming evidence that the cause is multifactorial. 5 Erosion , the loss of tooth structure from chemical dissolution, abrasion , the loss of tooth structure by mechanical or frictional forces, and abfraction or stress corrosion , the loss of cervical tooth structure due to occlusal forces, have all been implicated in the formation of NCCLs. Patients should be informed of the possible etiologies, implications of the presence of lesions, prevention methods, treatment alternatives, and expected outcomes. Failure to appropriately prevent and treat NCCLs can result in progression of tooth structure loss; tooth sensitivity; the need for endodontic therapy; tooth loss; and the occurrence of additional lesions. 6

Fig 14-1a Numerous stained Class 5 caries lesions.

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Fig 14-1b The


[User]
<image>
What does this diagram illustrate in the context of restorative dentistry?

[Assistant] This diagram illustrates a dental post and core system. The post is designed to be placed into the root canal of an endodontically treated tooth to provide retention for the core, which in turn supports a definitive crown restoration.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_1423.png


[User]
<image>
What do these images represent in the context of dental anatomy?

[Assistant] These images show the occlusal (a) and proximal (b) views of lower premolars. The first set represents a lower first premolar, while the second set represents a lower second premolar, illustrating their typical crown and root morphology.

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0035.png

C:\Users\HARI\Desktop\DocSmile\rl\__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni.md

## 1.7.1 Lower First Premolar

The lower fi rst premolar erupts sometimes months before and at times after the lower canine and is the

Fig. 1.31 Anatomical tables from Hess and Keller: upper single-root premolars presenting two canals with separated termini, one apically and the other lateral [ 2 ] (Image reprint with permission from Perrini [ 1 ])

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smallest of all the premolars. The crown has two cusps, one very big and similar to that of the canine. The other is shorter by about 2 mm in correspondence with the canine's lingual cingulum (Fig. 1.33 ).

About 21-22 mm in length, it generally has one root with one canal (73-74 %). Sometimes it has one root with two canals (19 %) (Fig. 1.34a, b ), two roots with two canals (6 %) (Fig. 1.35a, b ) or three canals (1-2 %).

The root often has a distal curvature in 35 % of cases and a bayonet curvature in 7 % of cases. The shape of the access cavity of the pulp chamber is oval shaped, extending from the main cusp to the top of


[User]
<image>
What do these 3D reconstructions represent in the context of endodontic anatomy?

[Assistant] These images are 3D reconstructions (often derived from CT scans) of lower molar root canal systems. They illustrate the complex and variable morphology of the pulp space, including variations in canal branching, curvature, and apical anatomy, which are critical considerations for successful endodontic treatment.

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0053.png

Fig. 1.48 Upper third molar with severe 3D root curvature

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be two different apical foramina (38 %) or just one (62 %) (Figs. 1.50 , 1.51 and 1.52 ) (Figs. 1.53 and 1.54 ).

All the roots, on the buccal side, present a moderate distal inclination. The pulp chamber is triangular or square, depending on the number of canals (3 or 4), and it is located in the centre of the crown, in the mesial-lingual area. Because of this peculiarity, during the opening of the access cavity of the pulp chamber, it is important to be careful not to remove precious dental tissue in the distal area.

The design of the access cavity must be triangular or trapezoidal with the larger base towards the mesial ridge of the occlusal surface and the smaller base (or the apex of the triangle if the distal canal is just one) slightly distal of the central occlusal fossa (Figs. 1.55 and 1.56 ).

In the case of a third root, its orifi ce can be found looking along the fl oor of the pulp chamber in the corn


[User]
<image>
What do these images illustrate regarding dental anatomy?

[Assistant] These images illustrate the complex and variable apical anatomy of teeth, including fine ramifications, delta-like terminations, and multiple apical foramina, which are often difficult to assess preoperatively and can complicate endodontic treatment.

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0063.png

Fig. 1.55 Lower molar: access cavity to three canals (Courtesy of Giovanni Olivi, Rome, Italy)

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The access cavity to the pulp chamber is located in the middle of the mesial-lingual area, and it has a trapezoidal design. Because of the dimensions of the pulp chamber and its proximity to the mesial-lingual wall, we advise attention during the opening of the chamber in order to avoid unnecessary destruction of dental substance (see Figs. 1.55 and 1.56 ).

## 1.9.3 Third Lower Molar

It erupts after the age of 17 years and usually at the age of 25 years. Also called 'wisdom tooth,'

Fig. 1.56 Lower molar: trapezoidal access cavity to four canals (Courtesy of Giovanni Olivi, Rome, Italy)

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Fig. 1.57 Variegated occlusal morphology of third lower molars can have four to fi ve cusps

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Fig. 1.58 ( a ) Lower third molar with curved mesial root fused to the distal. ( b ) Lower third molar: distal root

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a

b

Fig. 1.59 ( a ) Lower third molar s


[User]
<image>
What procedure is being demonstrated in this four-part clinical image sequence?

[Assistant] This image sequence demonstrates sonic-activated irrigation in the pulp chamber during endodontic treatment. Panels (a) and (c) show the use of sonic activation tips within the pulp chamber, while (b) and (d) show the state of the chamber during the cleaning process.

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0081.png

## 3.4.2 Sonic Activation

Sonic-activated irrigation can be performed using sonic handpieces that can drive instruments at sonic frequencies (Fig. 3.2). Traditionally only cutting files were available. Today, there are also several new sonic activation systems available on the market like the EndoActivator system or the Vibringe. The EndoActivator system allows a variation in driving power, frequency, and the size of polymer tips that do not cut into the root canal wall. The suggested manufacturer use advises delivery of the irrigant into the root canal by syringe irrigation after creating a 'fully tapered shape.' The irrigant is activated for 30-60 s using a pumping action in short 2-3 mm strokes.

Vibringe system uses a sonically oscillating needle to deliver the irrigant into the root canal. The Vibringe can be used throughout the complete root canal treatment procedure.

## 3.4.3 Ultrasonic Activation

For ultrasonic activation, most of the devices already present in the clinic ca


[User]
<image>
What do the SEM images (b-e) demonstrate regarding the root canal surface after PIPS treatment?

[Assistant] The SEM images demonstrate that after PIPS (Photon Induced Photoacoustic Streaming) laser-activated irrigation, the root canal surfaces are clean and free of debris and smear layers. The images show open dentin tubules and the presence of calcospherites, which are globular formations representing the mineralization front of predentin. The presence of these structures indicates that while the dentin wall may not have been extensively shaped by mechanical instrumentation, the PIPS technique effectively cleaned the surface.

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0290.png

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a

b

Fig. 11.73 ( a -e ) Upon examination of the complex morphologies associated with premolars, it is apparent that the isthmus remains untouched during canal preparation. However after two 30s cycles of sodium hypochlorite irrigation and one 30s cycle of EDTA activated by PIPS, the surfaces are clean and bacteria-free (Image of Dr. Giovanni Olivi, Rome (Italy))

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a

b

c

e

d

Wd

Spol Magn

WD

WD

SE

SE

Acc V

Spot Magn

Dot

WD

SE

Giovann

It is important to know that the PIPS technique can be applied regardless of the type of shaping and instrumentation method chosen to prepare the canal system. It is very effective at removing both vital and necrotic tissue. It has also been demonstrated to be effective at open- ing and helping negotiate calcifi ed canals and removing separated or fractured instruments and antibiotics and medication pastes (Figs. 11.76a, b and 11.77a, b ).

The following protocols for the correct use of PIPS are described later o


[User]
<image>
What does the radiographic follow-up in this figure demonstrate regarding the use of dental sealants?

[Assistant] The radiographic follow-up in Fig. 7.3 demonstrates that sealed maxillary first molars show no lesion progression over a 2-year period, whereas non-sealed mandibular first molars show clear evidence of caries progression during the same timeframe. This supports the clinical efficacy of sealants in arresting the development of non-cavitated and microcavitated carious lesions.

__lib_book_Conservative Dentistry_ Management of Deep Carious Lesions by Schwendicke_ Falk/img_0049.png

C:\Users\HARI\Desktop\DocSmile\rl\__lib_book_Conservative Dentistry_ Management of Deep Carious Lesions by Schwendicke_ Falk.md

The evidence supporting sealing of non-cavitated lesions to arrest lesion development is also strong. When carious lesions are traditionally sealed with opaque sealant materials, lesion arrest is measured over time by looking at bacterial counts (i.e., bacterial counts significantly decrease after sealant placement, leading to a more leathery, less wet dentin over time) or radiographs (Fig. 7.3). Examples of reviews are provided next.

- In 1983, a National Institutes of Health (NIH) sponsored Consensus Development Conference on dental sealants [5] concluded sealants are highly effective and safe, are underutilized, their use should be expanded together with use of fluoride strategies, and they are urgently needed to control dental caries in high- risk population groups. These conclusions are identical to ones we could develop today. In addition, even though sealants had only been available for a little over a decade, it was concluded the evidence was 'overwhelming' that the vitality o


[User]
<image>
Describe the clinical management of the occlusal carious lesion shown in the image.

[Assistant] The image illustrates the management of an occlusal carious lesion in a primary molar. Panel (a) shows the radiographic assessment of the lesion. Panel (b) displays the clinical appearance of the tooth before treatment. Panel (c) shows the tooth after selective removal of soft carious dentin using hand instruments and restoration with a glass ionomer material.

__lib_book_Conservative Dentistry_ Management of Deep Carious Lesions by Schwendicke_ Falk/img_0056.png

## 8.8 Fissure Sealants; Why Sealing Is an Option, but Sealants Might Not Do It

Fissure sealing has evidence to support its use for managing both proximal [12] and occlusal lesions [3, 15, 16]. However, evidence for sealants over carious lesions has mainly been obtained from studies of shallow lesions where there is no cavitation of the lesion. As discussed in Chap. 2 and the last chapter, fissure sealants are low- filled resins and when taken in a thin section are very brittle. The properties of the materials mean that they are not currently suitable for use in lesions where demineralisation of enamel and dentin have taken place to such an extent that the ability of the tooth to withstand biting forces has been compromised. Sealants will provide protection from the ingress of bacteria but will not add much to the strength of the tooth. In cases where the lesion is very deep, the sealant will usually not prevent the tooth beneath it from breaking down if the

Fig. 8.2 Management of an


[User]
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Describe the structures visible in this histological image of a tooth.

[Assistant] This photomicrograph displays the interface between enamel and dentin in a tooth. The upper portion shows the enamel, characterized by its rod structure. Below this is the dentino-enamel junction (DEJ), which acts as the boundary between the enamel and the underlying dentin. The lower portion shows the dentin, containing dentinal tubules, with the cell bodies of odontoblasts visible along the pulpal surface of the dentin.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0033.png

C:\Users\HARI\Desktop\DocSmile\core_cpt\__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed.md


[User]
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Explain the role of the canine in the mandibular movement shown in the diagram.

[Assistant] In a right lateral movement, the working side canine acts as a guide, controlling the final closing path of the mandible. This is evidenced by the coincidence of the closure tracing with the superior border of the movement path, indicating that the canine provides the necessary guidance during this functional movement.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0089.png

Types of Motion. Centric relation ( CR) is the position of the mandible when the condyles are positioned superiorly in the fossae in healthy TMJs. In this position the condyles articulate with the thinnest avascular portion of the disks and are in an anterior-superior position

## A Maxillary arch

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The maxillary arch is larger than the mandibular arch causing the maxillary facial line (nonsupporting cusps) to overlap the mandibular teeth.

- C Molar teeth in occlusion
- E Views of left dental arches in occlusion showing interdigitation of nonsupporting cusps

Maxillary nonsupporting cusp overlapping mandibular tooth

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Mandibular nonsupporting cusp overlapping maxillary tooth

208

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## B Maxillary left quadrant

Synonyms for nonsupporting cusps include:

1. Noncentric cusps
2. Nonholding cusps

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Facial occlusal line

Maxillary nonsupporting cusps are located on the facial occlusal line.

## D Mandibular left quadrant

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Ma


[User]
<image>
What does the provided figure illustrate regarding oral plaque communities?

[Assistant] The figure illustrates the significant differences in the microbial composition of plaque communities across four distinct oral habitats: coronal plaque, gingival crevice, tongue dorsum, and buccal mucosa. Each pie chart shows the relative proportions of various bacterial species, such as Streptococcus species, Gram-positive filaments, and Veillonella, demonstrating that the oral cavity is not a uniform environment for bacterial colonization.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0131.png

n of enamel in A. Enamel rods interlock with each other in a head-to-tail orientation. The rod heads are visible on the surface as slight depressions on the perikymata ridges. The enamel rods are composed of tightly packed crystallites. The orientation of the crystallites changes from being parallel to the rod in the head region to being perpendicular to the rod axis in the tail end. Striae of Retzius form a descending diagonal l ine, descending cervically. C, Drawings 1 through 5 illustrate the various stages in colonization duri ng plaque formation upon the shaded enamel block shown in B. The accumulated mass of bacteria on the tooth surface may become so thick that it is visible to the unaided eye. Such plaques are gelatinous and tenaciously adherent; they readily take up disclosing dyes, aiding in their visualization for oral hygiene instruction. Thick plaques (4 and 5) are capable of great metabolic activity when sufficient nutrients are available. The gelatinous nature of the pla


[User]
<image>
Explain the key mechanical properties shown in the stress-strain diagram.

[Assistant]
The stress-strain diagram illustrates several critical mechanical properties of a material:

1. **Modulus (Elastic Modulus/Stiffness):** Represented by the slope of the initial linear portion of the curve, indicating the material's resistance to elastic deformation.
2. **Elastic Limit (Proportional Limit/Yield Point):** The point where the material transitions from elastic (reversible) to plastic (permanent) deformation.
3. **Ultimate Strength (Breaking Strength):** The maximum stress the material can withstand before fracture.
4. **Resilience:** The area under the curve up to the elastic limit, representing the energy a material can absorb without permanent deformation.
5. **Toughness:** The total area under the entire curve up to the point of fracture, representing the total energy the material can absorb before failing.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0203.png

As loading continues, the structure is deformed. At first this deformation (or strain) is completely reversible (elastic strain). However, increased loading finally produces some irreversible strain as well (plastic strain), which causes permanent deformation. The point of onset of plastic strain is called the elastic limit (proportional limit, yield point). This is indicated on the stress-strain diagram (see Fig. 4-11) as the point at which the straight line starts to become curved. Continuing plastic strain ultimately leads to failure by fracture. The highest stress before fracture is the ultimate strength (see Fig. 4-11, C). The total plastic tensile strain at fracture is called the elongation. This also may be expressed as the percent elongation. Materials that undergo extensive plastic deformation before fracture are called ductile (in tension) or malleable (in compression). Those that undergo very little plastic deformation are called brittle.

The slope of the linear portion (co


[User]
<image>
Describe the lifecycle and disposal pathways of dental amalgam as shown in the diagram.

[Assistant] The diagram illustrates the lifecycle of dental amalgam, starting from its consumption in dental practices. Amalgam is used for new fillings, while surplus triturated amalgam and carved surplus/minor particles are generated during procedures. These materials are managed through collection and recycling (often using an amalgam separator) or may enter the drain/sewage system as sludge. Additionally, the removal of old fillings, the disposal of extracted teeth containing amalgam, and the management of amalgam in deceased persons (via interment or cremation) represent further pathways in the dental amalgam waste cycle.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0239.png

As individual political entities (countries, states or provinces, counties, towns) examine their own pollution problems, they will adopt restrictions that intend to limit future contributions of toxic metallic and organic wastes to the environment. The problem of pollution is less one of the concentration or amount of individual disposal, but rather one of accumulation of waste within a relatively closed system.

Small amounts of mercury, silver, lead, or other toxic heavy metals are accumulated as part of an everincreasing load to the local environment. This is

F I G . 4-40 Cycle of mercury in dentistry in dental amalgam (From Hoersted-Bindslev P et al: Dental amalgam-a health hazard? Copenhagen, Denmark, 1991, Munksgaard.)

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New amalgam

fillings

Surplus of

Consumption

triturated

In

amalgam

dental practices

Collection

Amalgam

recycling

separator

Carved surplus

of amalgam

Sludge

Drain/sewage

Minor amalgam

particles

Central vacuum

Removal of old

system


[User]
<image>
What structures are visible in the lower panel of this scanning electron microscopy image?

[Assistant] The lower panel (B) of the scanning electron microscopy image shows the cross-sectional view of dentin, specifically highlighting the openings of dentinal tubules.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0257.png


[User]
<image>
Explain the concept of interfacial interlocking in the context of dental amalgam bonding as shown in the image.

[Assistant] The image illustrates the concept of interfacial interlocking, which is a mechanism used to improve the retention of dental amalgam to tooth structure. Part A shows a schematic representation where the bonding system penetrates the irregularities of the prepared enamel or dentin surface, creating a mechanical interlock. This is further supported by the SEM image in Part B, which demonstrates the physical interface between the bonding system and the dental amalgam, showing how the two materials interdigitate at the microscopic level to provide a stable bond.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0260.png


[User]
<image>
Describe the process of dentin bonding as shown in the diagram.

[Assistant] The diagram illustrates the three-stage process of dentin bonding: 1) The initial state shows a dentin surface covered by a smear layer created by a bur, which blocks the dentinal tubules. 2) After acid-etching and rinsing, the smear layer is removed, exposing the collagen fibers and opening the dentinal tubules. 3) Finally, the application of primer/adhesive and composite results in the formation of a hybrid layer, where the adhesive infiltrates the exposed collagen network and tubule openings to bond the composite to the dentin.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0326.png

5

FIG . 5-8 Composition of enamel and dentin by volume percentage.

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Enamel

Dentin

Organic

2%

Organic

259

Mineral

50%

Water

2596

Water

10%

88%

FIG . 5-9 Scanning electron micrograph of dentin that was fractured longitudinally.

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and heat created by the preparation procedure. Submicron porosity of the smear layer still allows for diffusion of dentinal fluid .219

The removal of the smear layer and smear plugs with acidic solutions may result in an increase of the fluid flow onto the exposed dentin surface. This fluid may interfere with adhesion, because hydrophobic resins do not adhere to hydrophilic substrates even if resin tags are formed in the dentin tubules.

Several additional factors affect dentin permeability. Besides the use of vasoconstrictors in local anesthetics, which decrease pulpal pressure and fluid flow in the tubules, other factors such as the radius and length of the tubules, the viscosity of dentin fluid, the pressure gradient,


[User]
<image>
What do these diagrams illustrate regarding dental restorations?

[Assistant] These diagrams illustrate the cross-sectional anatomy of a tooth with a restoration, focusing on the marginal interface. The detailed insets (C and D) highlight the relationship between the restorative material and the tooth structure, using labels and arrows to represent potential stress vectors, marginal adaptation, or leakage pathways at the restoration-tooth interface.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0352.png


[User]
<image>
Describe the clinical steps shown in this sequence of images.

[Assistant] This sequence of images illustrates a clinical dental procedure involving occlusal assessment and restorative treatment. Panels A and B show the use of a bite registration or occlusal clearance tool. Panel C shows the inspection of a cavity preparation using an explorer, and Panel D shows the final restoration with arrows indicating the margins.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0507.png


[User]
<image>
Describe the clinical procedure shown in this sequence of images.

[Assistant] This image sequence illustrates a clinical dental procedure involving the placement of a multi-unit restoration (likely a bridge or splint). The patient is isolated with a rubber dam, and the images show the progression from checking the fit of the restoration to the final seating process using dental instruments.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0558.png


[User]
<image>
Describe the dental preparation designs shown in the image.

[Assistant] The image illustrates two types of dental preparations for composite restorations. The top diagrams (Fig 11-22) show a Class III preparation design that extends onto the root surface, featuring a beveled enamel margin, a retention groove in the dentin, and a 90-degree root-surface margin. The bottom diagrams (Fig 11-23) illustrate a conventional Class II composite tooth preparation, shown from both the occlusal and proximal perspectives.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0612.png


[User]
<image>
What does this figure illustrate regarding dental bur usage?

[Assistant] This figure illustrates the correct (B) and incorrect (C) angulation of a dental bur when preparing a proximal surface of a tooth. The correct technique ensures the bur does not damage the adjacent tooth structure, while the incorrect technique shows the bur cutting into the neighboring tooth.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0639.png


[User]
<image>
What does this image illustrate regarding dental clinical procedures?

[Assistant] This image illustrates two distinct dental topics. The top row shows examples of extrinsic tooth staining: image A shows natural surface stains in a young patient, and image B shows intentional 'exotic' decoration of teeth using etching and black pigment. The bottom row demonstrates a clinical polishing procedure, where a prophy cup is used to clean or polish the teeth, followed by the use of a shade guide to evaluate the tooth color.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0840.png