[User]
<image>
Explain the two main pathways of apoptosis as shown in the diagram.

[Assistant] The diagram illustrates the two primary pathways of apoptosis: the extrinsic (death receptor) pathway and the intrinsic (mitochondrial) pathway. The extrinsic pathway is initiated when the FAS ligand binds to the CD95/FAS receptor, leading to the formation of the death-inducing signaling complex (DISC) with FADD and procaspase-8. The intrinsic pathway is triggered by mitochondrial outer membrane permeabilization (MOMP), which releases factors like cytochrome c into the cytosol. Cytochrome c then binds with APAF-1 and procaspase-9 to form the apoptosome. Both pathways converge to activate executioner caspases (caspase-3 or caspase-7), which ultimately lead to cell death.

__lib_book_Cancer_ Molecular Biology Of Cancer by Pelengaris_ Stella/img_0116.png

During apoptosis, gross morphological changes-as shown in Plate 8.1 - can be seen under a microscope. Early features of apoptosis occur within minutesof the apoptotic trigger and during this phase, mitochondria, lysosomes, and cellular membranes remain fully intact. These features include: chromatin condensation, DNA fragmentation (multiples of 180 bp), cell shrinkage, and dilatation of the endoplasmic reticulum.

Later featuresof apoptos isare completed within hours, depending on cell type and tissue: budding of cell membrane leading to the packaging of cellular components into vesicles - known as 'apoptotic bodies,' which are phagocytosed by macrophages and neighboring cellsthusavoiding an inflammatory res pons e (Plate 8.1).

In contras t, necros isaffectsgroupsof cellsor whole tissue after extended damage induced by external stimuli, such as trauma, ischemia, and

## Death receptor 'extrinsic' pathway

Fig. 8.2 The two pathways of apoptosis: death receptor (extrinsic) and mitochond


[User]
<image>
Explain the mechanism shown in the diagram regarding telomere regulation.

[Assistant] The diagram illustrates the assembly of telomeric heterochromatin. Suv39h1 and Suv39h2 histone methyltransferases catalyze the methylation of lysine 9 on histone 3 (H3K9). This methylation creates binding sites for Heterochromatin Protein 1 (HP1) isoforms (HP1alpha, HP1beta, and HP1gamma). The resulting heterochromatic structure, along with telomere-binding proteins like TRF1 and TRF2, forms a condensed chromatin state that physically impedes the access of telomerase to the telomere, thereby regulating telomere length.

__lib_book_Cancer_ Molecular Biology Of Cancer by Pelengaris_ Stella/img_0134.png

C:\Users\HARI\Desktop\DocSmile\rl\__lib_book_Cancer_ Molecular Biology Of Cancer by Pelengaris_ Stella.md

## Multiple factors regulate telomere length and function

The telomere-binding proteins TRF1 and TRF2 can also influence telomere length. Similarly, simultaneous deletion of telomerase and Ku86 in doubly deficient Terc/Ku86 mice demonstrated that Ku86 acts as a negative regulator of telomerase-mediated telomere elongation (Fig. 9.2). The study of double Terc -/ -/DNA-PKcs -/ -mice, in contrast, showed that DNA-PKcs is required for telomere length maintenance. In particular, absence of DNA-PKcs leads to a faster rate of telomere loss and to an earlier appearance of phenotypes in telomerasedeficient mice (Fig. 9.2). These findings suggest that telomere-binding proteins simultaneously regulate telomere capping and telomere length.

Aconnection between the members of the retinoblastoma family, RB, p107, and p130, and the mechanisms that regulate telomere length has been recently made (Fig. 9.2). In particular, MEFs doubly deficient in p107 and p130 (DKO), or triply deficient in p107, p130


[User]
<image>
Explain the difference between the two states of gene regulation shown in the diagram.

[Assistant] The diagram illustrates two states of gene regulation: active transcription and gene silencing. In the top panel, the gene is transcriptionally active, facilitated by the binding of RNA polymerase, transcription factors, histone acetyl transferase (HAT), and coactivator proteins. The presence of CTCF helps insulate the gene from methylation. In the bottom panel, the gene is silenced (no transcription). This occurs through DNA methylation at the promoter, which recruits methyl cytosine binding proteins, SIN3, and histone deacetylase (HDAC). HDAC promotes histone deacetylation, which represses transcription and prevents the association of the transcription activator complex.

__lib_book_Cancer_ Molecular Biology Of Cancer by Pelengaris_ Stella/img_0156.png

Fig. 11.1 Methylation can inhibit gene transcription. In the presence of CTCF the gene is 'insulated' from methylation; in this case the gene is transcriptionally active as it will remain in the unmethylated state. Conversely, in heterochromatin CpG islands in the promoter region are methylated and these regions are transcriptionally inactive. Gene silencing following methylation is reinforced by deacetylation and interactions with repressors of transcription. In fact,DNMTs,which further mediate methylation,may be actively recruited to help maintain silencing. Methylation in turn enables the binding of a complex comprising the methylcytosine binding protein (MBP) and histone deacetylase (HDAC); some MBPs (MECP2 and MBD1 and 2) can also associate with transcriptional corepressors such as SIN3,which directly bind to HDAC,and contribute to gene silencing. HDAC promotes deacteylation of histones,which contributes to organization of nucleosomes,and also more generally repression of transcri


[User]
<image>
What do the heat maps in the image represent regarding the Hes1 pathway?

[Assistant] The heat maps illustrate the spatio-temporal evolution of hes1 mRNA and Hes1 protein concentrations within a cell over time, ranging from t=150 to t=300 minutes at 30-minute intervals. These visualizations are part of a spatio-temporal model of the Hes1 intracellular signaling pathway, showing how these concentrations change in both time and space.

__lib_book_Cancer_ New Challenges for Cancer Systems Biomedicine by D_Onofrio_ A/img_0037.png

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

/STX

10

/NUL

/STX

/STX

5

10

M

/NUL

10

3

s

/NUL

/STX

10

/NUL

3

/NUL

9

1

/NUL

s

1

/SYN

d

| Table 4. Parameter | values used in the extended Hes1 model in the case |
|----------------------|-------------------------------------------------------------------------------------------|
| rate is set to zero, | and ranges over which sustained oscillatory dynamics |
| Parameter | Value in simulations which |
| | Range over |
| D i j | 3.13 /STX 10 /NUL 11 cm 2 s /NUL 1 3.33 10 /NUL 11 cm 2 s /NUL 1 to |
| ˛ m | /STX 6.25 /STX 10 /NUL 11 Ms /NUL 1 /NAK 6.87 /STX 10 /NUL 11 Ms /NUL 1 |
| O p | 1.00 /STX 10 /NUL 9 M 1.05 10 /NUL 9 M to 1.00 |
| h | /STX 5 /NAK 6 |
| /SYN m | 1.25 /STX 10 /NUL 3 s /NUL 1 1.25 /STX 10 /NUL 4 s /NUL 1 to 1.21 |
| ˛ p | 0.0555 s /NUL 1 /NAK 0.0583 s /NUL 1 |
| /SYN p | 1.25 /STX 10 /NUL 3 s /NUL 1 1.25 /STX 10 /NUL 4 s /NUL 1 to 1.21 |
| D m | 6.25 10 /NUL 12 cm 2 s /NUL 1 9.58 10 /NUL 12 cm 2 s /NUL 1 |
| D p | /STX /NAK /STX 2.08 /STX 10 /NU


[User]
<image>
Describe the information presented in this figure.

[Assistant] This figure displays four histograms illustrating the distribution of perturbed parameters in a biological system simulation. The x-axis represents the 'Ln ratio versus normal condition' across various ranges, while the y-axis indicates the 'N of perturbed parameters'. The four panels compare different scenarios: (a) all edge distances accepted, (b) one edge distance excluded, (c) one and two edge distances excluded, and (d) one, two, and three edge distances excluded. The data shows that the vast majority of perturbed parameters fall within the 0-1 Ln ratio range across all conditions.

__lib_book_Cancer_ New Challenges for Cancer Systems Biomedicine by D_Onofrio_ A/img_0065.png


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

[Assistant] These histological images illustrate the interface between dentin and the dental pulp under various experimental conditions. They demonstrate the pulp's response to external irritants, such as cavity preparation or restorative procedures, which can lead to inflammatory reactions, changes in vascularity, and alterations in the odontoblastic layer.

__lib_book_Conservative Dentistry_ Clinical Endodontics by Tronstad_ Leif 2nd Ed/img_0044.png

C:\Users\HARI\Desktop\DocSmile\rl\__lib_book_Conservative Dentistry_ Clinical Endodontics by Tronstad_ Leif 2nd Ed.md

Dehydration of the dentin may result from the heat caused by cavity or crown preparation without water, from the use of thermoplastic impression materials that are too warm, and from a prolonged and continuous blast of air to exposed dentin. As a result of dehydration, tissue fluids from the pulp will flow into the dentinal tubules toward the dentin surface. This fluid flow causes mechanical disturbances in the pulp. The odontoblasts and sometimes other cells may be sucked into the dentinal tubules, and there is an immediate increase in the bloodflow to the area of the pulp subjacent to the dehydrated dentin (Fig. 1. 35 ). There is also an increase in the number of functioning capillaries in the injured area. The injuries result in a mild

Fig. 1.34 Pulp horn in a monkey tooth with traumatic pulp exposure (complicated crown fracture). On day 7 after the injury there is evidence of severe hemorrhage in the tissue and the pulp is necrotic (hematoxylineosin)

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1

2

3

4

5


[User]
<image>
What is the clinical value of the occlusal radiographs shown in the bottom part of the image?

[Assistant] Occlusal radiographs, as shown in the bottom images, are valuable in endodontic diagnosis because they provide a more extensive view of the jaws, particularly the maxilla. They are an invaluable aid in determining the buccolingual extension of large periapical lesions.

__lib_book_Conservative Dentistry_ Clinical Endodontics by Tronstad_ Leif 2nd Ed/img_0143.png

Dyes like iodine or plaque-disclosing solutions may also be applied to teeth with suspected incomplete fractures. They should be applied

## Radiographic Examination

Modern endodontic diagnostics rely heavily on a radiographic examination. Often the radiographic findings determine the diagnosis outright. Remember, therefore, that radiographic findings are not pathognomonic for a special disease or pathological condition. A radiolucent area at the apex of a tooth is normally a sign of apical periodontitis, but it may also be indicative of a cementoma, a giant cell granuloma, various cysts, cancer metastases, and many other pathological and even normal conditions (see p. 54). The radiographic findings must, therefore, always and without exception be evaluated together with the findings of the clinical examination.

Preferably, a long cone-parallelling technique should be used for periapical examination in or-

## Tentative Diagnosis

Sometimes the clinical and radiographic examinations


[User]
<image>
What does this histological image demonstrate regarding pulp capping treatment?

[Assistant] This histological image demonstrates successful pulp capping in a tooth. Following treatment with calcium hydroxide, a hard-tissue barrier known as a dentin bridge (DB) has formed, effectively walling off the exposed pulp (E). The necrotic tissue (N) resulting from the alkaline calcium hydroxide is sharply limited, and the underlying vital pulp tissue remains healthy and free of significant inflammation.

__lib_book_Conservative Dentistry_ Clinical Endodontics by Tronstad_ Leif 2nd Ed/img_0152.png

## Wound Dressing and Tissue Reactions

A vast number of materials and medicaments have been used as pulp-capping agents: gold and silver, different types of cements, antiseptic pastes, chemotherapeutics, ivory powder, dentin chips, plaster of Paris, magnesium oxide, calcium hydroxide, and many others. It is interesting to note that both biologically inert materials like gold and silver and irritating antiseptic preparations like phenolic compounds are equally unsuitable as pulp-capping agents.

The first important progress with this type of therapy was gained in the 1920s with a paste of zinc oxide and eugenol. This material has a mild antiseptic effect and seals the cavity well. Healing of the exposed pulp without hard-tissue bridging of the pulp wound was observed. An attempt was made at obtaining hard-tissue formation at the exposure site by covering the pulp wound with dentin chips or ivory powder under the zinc oxide and eugenol paste. This approach showed some promise, but it wa


[User]
<image>
Describe the progression of treatment for the mandibular incisor shown in the figure.

[Assistant] The figure illustrates the management of a mandibular incisor with a periapical lesion. Panel (a) shows the initial radiograph with a periapical radiolucency. Panel (b) displays the histological appearance of the inflammatory tissue at the apex. Panel (c) shows the tooth following root canal treatment, and panel (d) demonstrates radiographic evidence of periapical bone healing after the endodontic intervention.

__lib_book_Conservative Dentistry_ Clinical Endodontics by Tronstad_ Leif 2nd Ed/img_0217.png

b

treatment then only follows if and when it is clear that the endodontic measures had no effect on the lesion (Fig. 6. 30 ).

When decisions such as these are made about sequencing of therapy, it is important to understand that, if a periodontal pocket is deep enough to be mistaken for an endodontic fistula originating at or near the apex of the tooth, a postponement of the periodontal treatment for 2-3 weeks will have no negative effect on the outcome of such treatment that may subsequently prove necessary.

tive or to fail, usually because of complications during conventional treatment, or when conventional treatment has failed. A common practice before placing the retrograde root filling is to remove 1-3 mm of the root end, as this part of the root is most likely to contain accessory ca-

Fig. 6.25 a Radiograph of a maxillary right central incisor with a root fracture (arrow; root canal is obliterated because of previous trauma). b The tooth was splinted for a period of 12 months


[User]
<image>
What does this composite image illustrate regarding dental health?

[Assistant] This image composite illustrates various aspects of endodontic and restorative dentistry. It includes radiographs (A, D) showing teeth with post-retained restorations and periapical status, as well as clinical photographs (B, C) of teeth with restorations and (E) a split-tooth or vertical root fracture, which is a common complication in endodontically treated teeth.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0024.png

C:\Users\HARI\Desktop\DocSmile\core_cpt\__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed.md


[User]
<image>
What does this sequence of images demonstrate regarding endodontic treatment?

[Assistant] This sequence demonstrates that standard radiographs do not always reveal the full complexity of root canal anatomy. Panel A shows the initial radiograph, panel B provides a highly magnified microscopic view of the pulp chamber floor revealing additional canal orifices, and panel C shows the completed endodontic treatment with all canals obturated.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0067.png

## Restorative Considerations

A satisfactory restoration may be jeopardized by a number of factors. Subosseous root caries (perhaps requiring crown lengthening), poor crown/root ratio, and extensive periodontal defects or misalignment of teeth may have serious effects on the final restoration. Therefore these problems must be recognized before endodontic treatment is initiated. For nonemergency complicated cases, a restorative treatment plan should be in place before starting endodontic treatment. Some teeth may be endodontically treatable but nonrestorable, or they may represent a potential restorative complication in a large prosthesis. Further, reduced coronal tooth structure under a full-coverage restoration makes endodontic access more difficult because of reduced visibility and lack of radiographic information about the anatomy of the chamber (see also Chapter 7 ). Thus it is not unusual for restorations to be compromised during endodontic access ( Fig. 4 -6 ). Whenever possible


[User]
<image>
What does this radiographic sequence demonstrate regarding endodontic treatment?

[Assistant] This radiographic sequence demonstrates the process of endodontic retreatment on a maxillary anterior tooth. The initial radiograph shows a tooth with a post and an existing root canal filling that may be inadequate, often associated with periapical pathology. The second radiograph shows the completed retreatment, with a more thorough obturation of the root canal system, which is a common procedure when addressing endodontic failure or mechanical challenges like those described in endodontic literature.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0070.png

<!--image-->

## Other Factors That May Influence Endodontic Case Selection

A variety of factors may complicate proposed endodontic therapy. Calcifications, dilacerations, and resorptive defects may compromise endodontic treatment of a tooth with potentially strategic value ( Fig. 4 -7 ). The inability to isolate a tooth is also a problem and may result in bacterial contamination of the root canal system. Extra roots and canals pose a particular anatomic challenge that radiographs do not always reveal ( Fig. 4 -8 ). Retreatment cases offer particular mechanical challenges ( Fig. 4 -9 ) and are discussed in detail in Chapter 25 . Ledges, perforations, or a post may be present, all of which complicate treatment and alter the prognosis. The dentist should recognize these potential problems and be able to manage and factor them into the decision concerning the tooth ' s prognosis, including the possibility that the patient should be referred to a specialist. An approach has been suggested


[User]
<image>
What does Figure 5-12 illustrate regarding endodontic treatment?

[Assistant] Figure 5-12 illustrates various clinical challenges in endodontic treatment, including teeth with histories of trauma, thin apical walls, complex root anatomy (such as extra roots or dilacerations), calcified canal systems, and complications like separated files or root resorption.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0095.png

Figure 5-11 Chairside darkroom allows rapid processing of endodontic working films. (Courtesy Dentsply Rinn, Elgin, IL.)

<!--image-->

To maintain the radiographic image for documentation, it is recommended that after an image has been

evaluated it be returned to the fixer for 10 minutes more and then washed for 20 minutes and dried. An alternative is to reprocess the film by means of the conventional technique. Double film packets can also be used for working films: one can be processed rapidly and the other conventionally. Regardless of what method is used for working films, a controlled time and temperature method should be used for the diagnostic qualities desired in pretreatment, posttreatment, and recall radiographs. All radiographs taken during the course of endodontic treatment should be preserved as a part of the patient ' s permanent record.

## Radiographic Interpretation in Endodontics

## Examination and Differential Interpretation

Radiographic interpretation is not str


[User]
<image>
What does the provided figure illustrate regarding endodontic anatomy?

[Assistant] The figure illustrates the classification of root canal isthmi as described by Kim et al. An isthmus is a narrow, ribbon-shaped communication between two or more root canals that contains pulp or pulpally derived tissue. The diagrams show various configurations (Types I-V) of these connections, which are critical to identify and clean during endodontic procedures to prevent them from acting as bacterial reservoirs.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0152.png

An isthmus is a narrow, ribbon-shaped communication between two root canals that contains pulp or pulpally derived tissue. All isthmi must be found, prepared, and filled during surgery, because they can function as bacterial reservoirs. Any root with two or more canals may have an isthmus. Therefore the presence of an isthmus should be suspected whenever multiple canals are seen on a resected root surface. In one study, the authors recommended that methylene blue dye be used to aid visualization of the outline of the resected root surface and thus detection of an isthmus. [22]

In one study, isthmi in the mesiobuccal root of maxillary first molars were found most often 3 to 5 mm from the root apex. [180] A complete or partial isthmus was found at the 4 mm level 100% of this time. In another study, partial isthmi were found more often than complete isthmi. [148]

Identification and treatment of isthmi are vital to the success of surgical procedures. [22] Kim et al [72] identified five t


[User]
<image>
What is the lingual shoulder in the context of endodontic access for an anterior tooth?

[Assistant] The lingual shoulder is a shelf of dentin that extends from the cingulum to approximately 2 mm apical to the canal orifice in anterior teeth. Its removal is a critical step in endodontic access preparation to achieve straight-line access, which allows for more effective cleaning and shaping of the root canal system.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0178.png

## Removal of the Lingual Shoulder and Orifice and Coronal Flaring.

Once the orifice(s) has been identified and confirmed, the lingual shoulder is removed. This is the lingual shelf of dentin that extends from the cingulum to a point approximately 2 mm apical to the orifice ( Fig. 7 -43 ). Its removal aids straight-line access and allows for more intimate contact of files with the canals walls for effective shaping and cleaning.

Figure 7-43 Lingual shoulder of the anterior tooth, extending from the cingulum to 2 mm apical to the orifice.

<!--image-->

Lingual shoulder

The lingual shoulder can be removed with a tapered safety-tip diamond or carbide bur or with Gates-Glidden burs. The tip of a fine safety-tip diamond bur is placed approximately 2 mm apical to the canal orifice and inclined to the lingual during rotation to slope the lingual shoulder. The clinician must be careful when using this bur to avoid placing a bevel on the incisal edge of the access preparation ( Fig. 7 -44 )


[User]
<image>
What does this scanning electron microscope image of an endodontic file illustrate?

[Assistant] This image is a scanning electron microscope (SEM) view of an H-type endodontic file (specifically a Hedstrom file). The arrow points to the rake angle of the file's blade. In H-type instruments, the rake angle is a critical design feature that influences the instrument's efficiency during machining strokes in the root canal.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0267.png

Figure 8-14 K-files stressed to deformation by clockwise and counterclockwise twisting ( arrow indicates deformed areas). These instruments are close to fracture.

<!--image-->

## H-Type Instruments.

An H-type instrument has spiral edges arranged to allow cutting only during a pulling stroke. An example is a Hedstrom file. H-type instruments are better for cutting than a K-type instrument because it has a more positive rake angle (see Components of a File) and a blade with a cutting rather than a scraping angle. Bending a Hedström file results in points of greater stress concentration than occurs with K-type instruments. These concentration points can lead to the propagation of cracks and fatigue failure. [121] Clinically, fatigue happens without any external physical signs of stress, such as the flute changes seen in K-type instruments ( Fig. 8 -14 ).

Currently all H-type instruments are ground from a tapered blank. Hedström files are formed by grinding a single continuous flute. C


[User]
<image>
What does this histological image show regarding the tissue response to a gutta-percha implant?

[Assistant] This histological image shows a gutta-percha implant in the subcutaneous connective tissue of a guinea pig 12 weeks after implantation. A connective tissue capsule (indicated by the arrow) has formed around the material, which is a typical biocompatible response characterized by a lack of significant inflammatory cells.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0322.png

Figure 8-67 Diaket (D) (ESPE, Seefeld, Germany) implanted in the mandible of a guinea pig. The material has necrotized the surrounding bone, which contains sequestered bone and a severe accumulation of all types of inflammatory cells.

<!--image-->

D

Gutta-percha has been extensively investigated as a root canal filling material in animals and has proved biocompatible. Compared with sealers used for root canal obturations, it clearly has the lowest tissue toxicity ( Fig. 8 -68 ). In implantation studies ranging up to 6 months ' duration, gutta-percha has been shown to heal in well, with minimal irritation. [*] Similar findings were reported with implantation in humans. After implantation gutta-percha normally is surrounded by a defined capsule rich in cells but without a significant number of inflammatory cells, although some macrophages are present ( Fig. 8 -69 ). Results from more

sensitive assays in vitro support the in vivo results, suggesting that gutta-percha used for root can


[User]
<image>
What does this micro-computed tomographic (uCT) scan illustrate regarding dental anatomy?

[Assistant] This image (Figure 9-14) displays a micro-computed tomographic (uCT) scan of the apical 5 mm of a tooth root. It provides a detailed look at the complex internal anatomy, featuring a three-dimensional reconstruction of the root's outer contour and the internal root canal system (shown in red), alongside a series of cross-sectional slices taken at 0.5 mm intervals to demonstrate the non-round and potentially complex canal morphology.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0348.png

Clinically, the landmark detected from radiographs (the radiographic apex ) does not necessarily coincide with the anatomic apex because of projection artifacts. Taken together, these observations suggest that shaping to the radiographic apex is likely to produce overinstrumentation past the apical foramen, with possible clinical sequelae of postoperative pain and inoculation of microorganisms into periapical spaces. [27][29][84][111]

Foramen diameter was also an issue in both early [109][148] and more recent studies. [41][81][176][273] The smallest canal diameter, called the apical constriction, was located 0.5 to 0.7 mm coronal to the canal terminus. [109][148] A wide range of diameters has been reported in that region, from 0.2 to about 1 mm [41][141][142][143][148][176] ; the concept of a single apical constriction has also been challenged. [81] Moreover, studies have shown that clinicians usually underestimate apical dimensions. [315] Clearly, the apical anatomy presents the clin


[User]
<image>
What is the purpose of the equipment shown in the image, and what is the recommended temperature setting for it?

[Assistant] The equipment shown is the System B unit, which is used for the continuous wave compaction technique in endodontic obturation. The recommended temperature setting for this unit is 200 degC.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0446.png

## Continuous Wave Compaction Technique

A variation of warm vertical compaction is the continuous wave compaction technique. [40] The increasing use of nickel-titanium rotary preparation techniques and the fabrication of standardized cones for files of greater taper have resulted in more clinicians using thermoplasticized techniques. The manufacturing of cones to mimic the tapered preparation permits the application of greater hydraulic force during compaction when appropriately tapered pluggers are used. The continuous wave compaction technique employs an electric heat carrier, System B unit, and #.06, #.08, #.10, and #.12 tapered stainless steel pluggers each with a tip diameter of 0.5 mm ( Fig. 10 -31 ). The #.06 tapered plugger approximates the fine conventional guttapercha cone, the #.08 plugger the fine-medium cone, the #.10 plugger the medium cone, and the #.12 plugger the medium-large cone. Pluggers are consistent with the GT Profile instruments, and Autofit gutta-percha cones


[User]
<image>
What is the purpose of the form shown in the image?

[Assistant] The image shows a standard endodontic diagnosis and treatment form (Figure 11-4). It is used by clinicians to systematically record a patient's dental and medical history, clinical and radiographic examination findings, diagnostic test results, pulpal and periapical diagnoses, and to document treatment procedures and medication logs.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0464.png

## Treatment Plan

Treatment records should contain a written plan that includes all aspects of the patient ' s oral health. Treatment plans should be coordinated, preferably in writing, with other concurrent or jointly treating clinicians. If an aspect of the patient ' s care is not under direct supervision, the clinician is proceeding improperly. Also the clinician should initiate contact with the other treating clinician. The patient should also be advised of the problem. For instance, endodontic treatment will probably fail if underlying periodontal pathosis is ignored or untreated. Therefore, the clinician should assess the patient ' s entire dentition, not just a single root canal system. The clinician should also recommend a periodontal consultation to both the patient and referring clinician if periodontal therapy is required.

## Examination

After gathering the dental and medical history, findings obtained from the various phases of the clinical and radiographic examinations


[User]
<image>
What does this series of clinical photographs demonstrate regarding dental equipment safety?

[Assistant] These photographs demonstrate a severe burn injury on a patient's lower lip caused by an inadequately maintained dental handpiece that overheated during use. This case highlights the critical importance of regular maintenance and inspection of dental equipment to prevent patient injury and potential liability.

__lib_book_Conservative Dentistry_ Cohen_s Pathways of the Pulp by Hargreaves_ KM 09th Ed/img_0476.png

nded maintenance schedule. The clinician should carefully read the manufacturer ' s instruction warnings on instruments and inform staff of any important points. Infection control in operating dental equipment is mandatory, such as updating and maintaining dental units with check valves to prevent water retraction or suck-back. The clinician should inspect check valves monthly and change clogged valves immediately. [77] Water retraction testers, at no charge to the clinician, are available from some manufacturers (A-dec [Newberg, OR], for instance). The clinician or a staff member should also disassemble the unit ' s handpiece, run water through the line for a few seconds, and then stop. If a bubble of water is visible at the end of the water hose holes, the check valve is operating properly. If a bubble of water is not visible, water may be sucked back because of an absent or clogged check valve. An absent or clogged check valve is a source of cross contamination. Therefore it is impo


[User]
<image>
Describe the clinical and radiographic progression shown in this endodontic surgery case.

[Assistant] This image illustrates a step-by-step endodontic surgical procedure on a maxillary tooth where a periapical lesion is in close proximity to the maxillary sinus. Panels (d) and (e) show the surgical site, including the management of a sinus membrane perforation. Panel (f) provides a longitudinal radiographic follow-up at 3, 6, 12, and 24 months, demonstrating the healing process of the periapical lesion over time.

__lib_book_Conservative Dentistry_ Complications in Endodontic Surgery by Tsesis_ Igor/img_0056.png

C:\Users\HARI\Desktop\DocSmile\rl\__lib_book_Conservative Dentistry_ Complications in Endodontic Surgery by Tsesis_ Igor.md

In a recent article [ 38 ], an iatrogenic perforation of the Schneiderian membrane was isolated using an absorbable hemostatic gelatin sponge. Spongostan is a gelatin-based sponge that stimulates the intrinsic clotting pathway by promoting platelet activation and subsequent release of thromboplastin and thrombin. Spongostan is indicated for hemostasis in surgical procedures (excluding ophthalmic), when control of capillary, venous, and arteriolar bleeding by pressure, ligature, and other conventional procedures is ineffective or impractical and it shows a high capability of arresting bleeding. It may be recommended for the management of perforation of the Schneiderian membrane instead of using a gauze.

In another study of the same author [ 51 ], the sponge was removed after the root-end management, and the surgical site was embedded using pure platelet-rich plasma (P-PRP) supernatant, a P-PRP clot was applied over the perforation, and another clot was used to fi ll the bone cavity. Fi


[User]
<image>
What is the clinical procedure shown in this sequence of images during endodontic surgery?

[Assistant] The images show a step-by-step process of managing a surgical site during endodontic surgery. Specifically, it demonstrates the placement of an absorbable hemostatic gelatin sponge into a bone cavity to control bleeding or shield a membrane perforation (a), followed by the removal of the sponge after the root-end management is completed (b and c).

__lib_book_Conservative Dentistry_ Complications in Endodontic Surgery by Tsesis_ Igor/img_0062.png


[User]
<image>
Describe the radiographic findings in this series of dental images.

[Assistant] The image displays a panoramic radiograph and a series of periapical radiographs documenting the endodontic treatment of a mandibular left first molar. The initial panoramic view reveals a large, well-defined radiolucent lesion associated with the roots of the molar. The subsequent periapical radiographs show the progression of root canal therapy, including the placement of filling material and the follow-up observation of the periapical area, which shows signs of healing and reduction in the size of the radiolucency.

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[User]
<image>
Describe the sequence of events shown in this series of radiographs.

[Assistant] This series of radiographs (A-D) illustrates the endodontic treatment and subsequent healing of a mandibular tooth. Panel A shows the preoperative state with a periapical radiolucency. Panel B shows the immediate postoperative result following root canal therapy. Panels C and D show follow-up radiographs demonstrating the progressive healing of the periapical bone lesion over time.

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A

B

Fig. 4.7. A . Preoperative radiograph of the maxillary first molar. The pulp chamber seems very calcified. B . The bite-wing radiograph shows the true dimensions of the pulp chamber.

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or overlying anatomical structures can be better distinguished (see Chapter 5).

A bite-wing radiograph (Fig. 4.7) can also be useful for diagnostic purposes, as it provides more precise and less distorted information about the condition of the pulp chamber (e.g., deep caries, deep filling, direct capping, pulpotomy, calcifications).

It is important to keep in mind that not all periapical lesions are radiographically visible, as occurs with lesions that extend only within the cancellous bone. In fact, as already emphasized, the lesion must also involve the cortical bone to be visible radiographically. 12 Moreover, once the lesion appears on the radiograph, the true involved zone and the extent of osseous destruction are always greater than their radiographic appearance would suggest.


[User]
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Explain how the size of the focal spot affects the sharpness of a radiographic image based on the provided diagram.

[Assistant] The diagram illustrates that the size of the focal spot directly influences the sharpness of the radiographic image by affecting the size of the penumbra. Panel A shows a larger focal spot, which creates a wider penumbra (the blurred region at the edges of the image), resulting in decreased sharpness. Panel B shows a smaller focal spot, which produces a narrower penumbra, leading to a sharper, more well-defined image (umbra).

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The collimator, comprising a ring of highly absorptive material (lead) reduces the size of the X-ray beam (6 cm in diameter, see Fig. 5.94) and thus the volume of the irradiated tissues, from which the diffuse radiation originates.

The collimator thus reduces the exposure of the patient to ionizing radiations and improves the film quality.

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����������

A

B

Fig. 5.10. A . The collimator reduces the diameter of the X-ray beam, thus diminishing the volume of the tissues irradiated and thus the production of secondary, useless, and damaging radiation. B . The metallic tube visible within the long tube collimates the X-ray beam.

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## Target-Object distance

The intensity of a beam of X-rays at a certain point (measured in number of photons x cross-sectional area x unit of time) depends on the distance from the radiographic source. 26

X-rays, like visible radiation, obey the inverse square law: for a given beam, the intensity is inversely proportional to the sq


[User]
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Describe the procedure for taking a preoperative radiograph of the upper central incisors as shown in the image.

[Assistant] To take a preoperative radiograph of the upper central incisors, a Rinn film holder is used to ensure the parallelism rule is followed. The film is positioned on the palate, parallel to the long axis of the teeth. The patient must bite down on the plastic support, often with the mandible slightly protruded, to maintain the correct position and ensure the X-rays are perpendicular to both the film and the long axis of the teeth, resulting in a clear, undistorted image.

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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 positioning (Fig. 5.50).

When the palate is particularly low, it is necessary to interpose a cotton roll between the plastic support and the incisal border of the upper incisors to maintain the parallelism between the radiograph and the tooth.

In the case of the lateral incisor, the tooth of interest must be centered in the radiograph, without superimposition of the adjacent teeth (Fig. 5.51).

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A

B

<!--image-->

����

C

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Fig. 5.49. Preoperative radiograph of the upper central incisors with the use of Rinn's film holder. A . Positioning of the film on the palate and path of the X-rays. B . Schematic representation of the use of the film holder (adapted from Rinn Cor


[User]
<image>
What procedure is being demonstrated in this image using the mandible model?

[Assistant] The image demonstrates the technique for an inferior alveolar nerve block, also known as a mandibular nerve block. This procedure involves depositing anesthetic solution near the trunk of the inferior alveolar nerve to anesthetize the mandibular teeth and surrounding tissues in that quadrant.

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To anesthetize the nerve fibers that innervate the palatal root of the upper molars or premolars, or any other tooth that has a palatal root, it is advisable to perform a palatal infiltration after the vestibular infiltration (Fig. 9.5). The palatal root is usually closer to the palatal than vestibular cortical bone; thus, a buccal infiltration alone may not suffice.

To perform a palatal infiltration, it is not necessary to reach the periostium. The palatal mucosa is so adherent and thick that it is able to limit the diffusion of the anesthetic and force the solution into the underlying bone, like the periostium of the vestibular side.

Palatal infiltration is quite painful. Therefore, it should be performed slowly by steadily depositing a small amount of anesthetic (0.5 ml) under adequate pressure. Before performing the palatal infiltration, it is advisable to achieve anesthesia of the mucosa, for example by cooling. 20

As already described in Chapter 8, special precaution is requir


[User]
<image>
What does this series of radiographs demonstrate regarding the endodontic treatment of an upper second premolar?

[Assistant] This series of radiographs (Fig. 11.49) demonstrates the endodontic treatment of an upper right second premolar. While the preoperative radiograph (A) suggests a single canal, subsequent intraoperative imaging (C) reveals a distally-oriented apical bifurcation. The final postoperative radiograph (E) confirms the successful obturation of this complex anatomy, including a lateral canal and the mesiopalatal canal of the adjacent second molar.

__lib_book_Conservative Dentistry_ Endodntics_ Volume 1 by Castellucci_ Arnaldo/img_0443.png

If the buccal bifurcation and therefore the presence of two roots remains undiagnosed, a perforation may occur during the preparation of a post space and the cementation of the post itself in what one might think to be the only buccal canal (Fig. 11.48).

For obvious reasons, it is always preferable to determine in advance the number of canals requiring treatment, even if only to plan better the treatment time required.

In the treatment of prosthetically-treated premolars, it can sometimes be difficult to determine whether the canal that one has found is the buccal or the palatal

D

Fig. 11.47. A . Preoperative radiograph of an upper right first premolar. In the presence of fused roots, it may not be easy to detect the presence of three canals. B . The first instrument introduced in what seems to be the only buccal opening appears eccentric with respect to the shadow of the root. More precisely, it appears mesially displaced: the instrument has entered the mesiobuccal canal. C . Intr


[User]
<image>
Describe the clinical and radiographic steps shown in the images for endodontic treatment of a tooth with a post.

[Assistant] The images illustrate the endodontic treatment process for a tooth with a post: (L) shows the clinical access cavity preparation through a temporary crown; (M) is a radiograph showing the post in place; (N) shows the intraoperative radiograph of the canal preparation; and (O) is the final postoperative radiograph showing the completed restoration.

__lib_book_Conservative Dentistry_ Endodntics_ Volume 1 by Castellucci_ Arnaldo/img_0566.png

Everything is cemented with zinc oxyphosphate, making certain that the cement does not obstruct the most apical part of the canal (Figs. 12.3 J, K). To prevent this, one uses a paper or gutta percha cone (Fig.

Fig. 12.3. (continued) G . The hollow post before re-lining and cementation of the temporary crown. Note that the gutta-percha cone is encased in the resin; this not only helps in finding the access cavity but in preventing obstruction of the root canal by the definitive cement. H . The abutment is lubricated with paraffin oil before re-lining of the temporary crown. I . The temporary crown previously made in the laboratory has been re-lined with the hollow post encased within. J . The temporary crown filled with oxyphosphate cement ready for cementation: note the gutta-percha cone within the hollow post. K . Radiograph at completion of cementation (continued).

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J

K

G

H

I

12.3 G) adequately inserted within the hollow post. After having removed the excess cemen


[User]
<image>
Describe the steps shown in the clinical photographs for preparing a tooth for a copper band restoration.

[Assistant] The clinical photographs illustrate the following steps for copper band pretreatment: (C) The cavity is cleansed and the pulp chamber is opened. (D) The pulp chamber is filled with thermoplastic gutta-percha to protect the canal orifices. (E) A diamond abrasive strip is used to eliminate the contact point with the adjacent tooth. (F) A diamond bur is used to remove undercuts on the tooth surface. (G) A copper band of the appropriate size is selected and tried on the tooth. (H-I) The occlusal surface is reduced to ensure it does not interfere with the opposing arch.

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A tray prepared for positioning of copper bands or orthodontic bands must contain:

- a complete series of copper bands
- orthodontic bands for molars and premolars, upper and lower

Fig. 12.4. A . Pretreatment of a lower molar with a copper band cemented with zinc oxyphosphate. B . Reconstruction of a molar crown using an orthodontic band.

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B

A

IVOR

Fig. 12.5. A . This photograph in a mannequin mouth shows a tooth requiring pretreatment using a copper band. Note that distally the carious lesion descends below the gingival margin, and that the gingiva reconstructed here in wax has proliferated into the cavity. B . Through the careful use of the electrosurgery, the gingival tissue that has invaded the carious cavity is removed (continued).

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A

B

Fig. 12.5. (continued) C . The cavity as it appears once it has been cleansed of carious tissue and the pulp chamber has been opened. D . The pulp chamber has been filled with thermoplastic gutta-percha to avoid o


[User]
<image>
What do the images in Figure 13.57 (C-L) represent in the context of endodontic instrumentation?

[Assistant] Figure 13.57 (C-L) displays the tips of LightSpeed endodontic instruments at high magnification. These instruments are characterized by a long, thin shaft for flexibility, a rounded non-cutting tip, and radial cutting blades. The images show a progression of sizes from #30 to #80, with panel L providing an S.E.M. (Scanning Electron Microscopy) view of one of these instruments.

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20 instruments in nickel titanium very similar to the Gates Glidden drills with a long shaft and a working part in the shape of a very short flame. The elevated number of instruments depends on the progression of the diameters, measured at the widest point on the working part which includes, apart from the classic ISO diameters from 20 to 100, intermediate sizes such as 22.5, 27.5, 32.5, and 37.5 etc. 36,37 The long and thin shaft ensures that the LightSpeed has an elevated flexibility but at the same time it diminishes torque stress resistance; for this reason LightSpeed instruments are made with a point of separation at 18 mm from the tip, in order to facilitate their removal incase of endocanal fracture. The length of the working part varies according to the calibre from 0.25 to 1.75 mm (Fig. 13.57); the blades present characteristic radial cutting tiers and the tip is rounded and non cutting. LightSpeed instruments available in the 21, 25 and 31 mm lengths, must be used from the sm


[User]
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What are the taper and diameter specifications for the ProTaper Finishing F3 file?

[Assistant] The ProTaper Finishing F3 file has a variable taper and diameter along its length. The taper is .09 for segments 1-3, .07 for segments 4-5, and .05 for segments 6-16. The diameter increases progressively from 30 at segment 0 to 126 at segment 16.

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[User]
<image>
What do these SEM images (Fig. 14.13) demonstrate regarding the effect of sodium hypochlorite on root canal walls?

[Assistant] These SEM images demonstrate the cleaning efficacy of sodium hypochlorite in root canals. Images A and B show untreated root canals with visible connective webs of predentin. Images C and D show root canal walls that were not mechanically shaped by instruments, yet appear free of organic material due to the digestive action of sodium hypochlorite. In image D, the presence of calcospherites (the mineralization front of predentin) confirms that the wall was not instrumented, while the lack of organic debris indicates effective chemical cleaning.

__lib_book_Conservative Dentistry_ Endodntics_ volume 2 by Castellucci_ Arnaldo/img_0100.png

Other authors 45 suggest using ethyl alcohol as a surfactant because of its ready availability. A 30% dilution of hypochlorite in alcohol has been shown to be most effective, though it has some disadvantages. The solution must be fresh, as it is labile. After 15 minutes, hypochlorite combines with ethanol to produce chloroform. Since it is particularly irritating to the pe-

Fig. 14.12. A . S.E.M. photomicrograph of an apical delta. 5% sodium hypochlorite seems to have digested the organic material (x120). B . The same area of the previous photograph as seen with different angulation (x72). C-D . Details of the preceding figure. The depressions in this canal have not been shaped by instruments, but have been cleaned by sodium hypochlorite (x500, x1,000)

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C

D

A

B

Fig. 14.13. S.E.M. photomicrograph of a lower incisor ( A ) and upper central incisor ( B ) which have not been treated endodontically. The connective web of predentin is visible. C . Distal root of a lower se


[User]
<image>
What do the diagrams in Fig. 16.26 E-J illustrate regarding endodontic instrumentation?

[Assistant] The diagrams in Fig. 16.26 E-J illustrate the use of Nickel-Titanium rotary instrumentation (specifically ProFile instruments) during the root canal enlargement phase. These instruments are used in a crown-down sequence to develop the canal shape, requiring a pilot preparation or pre-enlargement phase for safe use. The sequence involves using instruments of varying tapers and sizes to effectively prepare the canal, particularly in long, narrow, or tortuous systems.

__lib_book_Conservative Dentistry_ Endodntics_ volume 2 by Castellucci_ Arnaldo/img_0204.png

Fig. 16.26. A -D . Nickel-Titanium rotary instrumentation may also be employed during the enlargement phase (Continued).

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A

B

C

D

ProFile

ProFile

ProFile

ProFile

06 Taper

06 Taper

06 Taper

40

35

30

25

even larger instruments. Copious irrigation and recapitulation with 15 or 20 K-files is required. If the clinician is not satisfied with the contour, the sequence can be repeated. Alternating a sequence of even num- bered files with odd number files can also be useful (Figs. 16.27 A-H).

The preparation is now essentially complete with the exception of the apical finishing and refinement.

Fig. 16.26. E -J . (Continued) Safe use of these instruments requires a pilot preparation or pre-enlargement phase similar to the one already described. Utilization of handpieces that control the speed and torque are also helpful. When they are used, they are usually used in sequence from largest to smallest, i.e., in a crown-down fashion. Generally, the sequence must be rep


[User]
<image>
What does this series of radiographs demonstrate regarding endodontic treatment?

[Assistant] This series of radiographs (Fig. 17.3) demonstrates the endodontic treatment of a lower left second molar. The tooth exhibits a curvature of the entire mesial root and a marked apical curve in the distal root. Image A shows the preoperative state, while image B shows the completed root canal treatment with the obturation material following the root anatomy.

__lib_book_Conservative Dentistry_ Endodntics_ volume 2 by Castellucci_ Arnaldo/img_0209.png

Nonetheless, even if one is careful to use small excursions, the instrument tends to straighten out. It is therefore necessary to withdraw it from the canal pe-

Fig. 17.1. An upper left canine with an apical curve of about 90°, cleaned, shaped and filled according to the Schilder technique. A . Preoperative radiograph. B . Intraoperative radiograph. Note that, at the time of measurement of the working length the enlargement of the middle and coronal thirds of the canal had already been performed with the aim of achieving easier access to the apical curvature. Early enlargement of the coronal two-thirds of the canal is documented by the complete removal of old obturation material. C . Postoperative radiograph. Note the preservation of the position of the apical foramen.

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A

B

C

B

C

Fig. 17.2. A lower left third molar with an apical curve of about 90° in the distal root. A . Intraoperative radiograph. B . Postoperative radiograph. C . Two year recall (Courtesy of Dr. M


[User]
<image>
Explain the process of creating a 'monoblock' in endodontic obturation as illustrated in the image.

[Assistant] The creation of a 'monoblock' in endodontic obturation involves removing the smear layer from the root canal walls to expose the dentinal tubules. A primer is applied to penetrate these tubules, followed by the placement of a resin-based sealer and a resin core material (such as RealSeal or Resilon). This process allows the obturating material to bond to the dentin, creating a continuous, sealed 'monoblock' that minimizes microleakage compared to traditional gutta-percha.

__lib_book_Conservative Dentistry_ Endodntics_ volume 2 by Castellucci_ Arnaldo/img_0411.png

One strategic advantage that this gives the clinician is that if the patient does not get a coronal restoration as they should (assuming that the treatment has been performed correctly), Resilon is significantly resistant to leakage along its length and one of the key factors responsible for endodontic failure has been eliminated or dramatically reduced.

A recent study by Shipper et al. 142 found that comparing bacterial leakage using Streptococcus mutans and Enterococcus faecalis through both gutta-percha and Resilon over a 30 day period demonstrated that Resilon showed minimal leakage which was statistically significant compared to gutta-percha. In essence, now, Resilon endodontic obturating material can significantly diminish microleakage, a property not possessed by gutta-percha.

RealSeal is a thermoplastic synthetic resin material based on the polymers of polyester and contains a difunctional methacrylate resin, bioactive glass and radio opaque fillers.

Fig. 23.44. A . Smear la


[User]
<image>
What does this image demonstrate regarding the clinical examination of a white spot lesion?

[Assistant] This image (Figure 2.9) demonstrates the clinical examination of a white spot lesion on a molar. It illustrates that while it is useful to gently draw a sharp probe across a lesion to assess its surface texture (matt for active, shiny for arrested), using the probe with excessive force can damage the subsurface porous enamel, creating holes and potentially encouraging the progression of the carious lesion.

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A section through a white spot lesion on an occlusal surface is seen in Figure 2.6. The occlusal lesion forms on the walls of the fissure in the area of plaque stagnation. This can been seen clinically on the sloping fissure walls at the fissure entrance (Figure 2.1). The dentine is involved in the lesion in Figure 2.6, but despite this, notice that the surface enamel is not yet cavitated.

## 2.3.3 Arrest of lesions

Inactive or arrested white spot lesions have a shiny surface and may be brown in colour, having picked up exogenous stains from the mouth (Figures 1.7 and 2.7). These lesions cannot be detected by gently drawing a sharp probe across them because they feel the same as normal enamel. Histologically these lesions show wide, well-developed dark zones at the front of the lesion within the body of the lesion and at the surface of the lesion (Figure 2.8).

It is very important to realize that the carious process can be arrested by simple clinical measures such as improved plaque


[User]
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What does this cross-sectional image of endodontically treated teeth demonstrate regarding coronal leakage?

[Assistant] This image demonstrates the effect of different cementation combinations on coronal microleakage in endodontically treated teeth. The pink dye penetration shows how effectively different luting agents (such as resin cements versus zinc phosphate cement) seal the coronal restoration and prevent leakage into the root canal system. Resin cements are generally shown to provide a superior coronal seal compared to traditional cements.

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treatment and crowns contributes to long-term survival of the restored tooth, making it more resistant to coronal leakage [59]. Cementing agents may play a role as a defense line against coronal leakage at the post-core level and/or at the crown level. Zinc phosphate cement (ZPC) is one of the most frequently used cements and is considered as the gold standard to which all cements are compared. In a marginal leakage study of extracted teeth covered by cast crowns with clinical service of at least20 years, zinc phosphate cement was an effective luting agent [60]. In the last 15 years, resin cements have gained in popularity because of their improved physical properties and ability to adhere to enamel, dentin, composite, and porcelain [61]. Radiographs show that the quality of the coronal restoration is more dominant in determining periapical health than biomechanical post space preparation and root canal obturation [20, 62].

Resin cements can serve as efficient coronal sealers, prevent


[User]
<image>
Identify the labeled walls and angles in this dental cavity preparation diagram.

[Assistant] The diagram illustrates the internal components of a cavity preparation, including the gingival wall, axial wall, lingual wall, facial wall, and pulpal wall. It also highlights specific internal angles, such as the facioaxiogingival point angle and the facioaxial line angle, relative to the long axis of the anatomic crown.

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[User]
<image>
What type of dental instrument is shown in the image, and how is it classified based on its shank?

[Assistant] The image shows a straight chisel. According to Black's classification of dental instruments, this is a straight-shanked instrument where the blade is aligned with the long axis of the handle.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0205.png

Fig 6-18 Instrument handle configurations. Instrument handles are available from most manufacturers in a variety of designs and diameters. (a) Standard stainless steel handle has a diameter of approximately 6.4 mm. (b) Padded handles are available; the diameter of the illustrated padded handle is approximately 8 mm. (c) Handles with larger diameters are said to be more ergonomic; the diameter of the one illustrated is approximately 9.5 mm.

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b

Nomenclature . The terminology organized by Black 2 in the early part of the last century is still used today with minor modifications. Most names Black assigned to cutting instruments were based on the appearance of the instrument, such as hatchet , hoe , spoon , and chisel . For an instrument that did not have the appearance of a commonly used item, Black based the name on the intended use, for example, gingival margin trimmer . Black called all cutting instruments used for tooth preparation excavators , and he referred to instrum


[User]
<image>
How can a dentist assess the sharpness of a hand instrument?

[Assistant] A dentist can assess the sharpness of a hand instrument by pulling the blade across a hard plastic surface, such as the handle of a plastic mouth mirror or an evacuator tip. A sharp blade will cut into the plastic and stop, whereas a dull blade will slide across the surface.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0229.png

## Sharpening of Hand Instruments

To assess sharpness, the user of the instrument should look at the cutting edge in bright light; the presence of a 'glint' indicates that the edge is dull or rounded (Figs 6-43a and 6-43b). Alternatively, the dentist can pull the instrument across hard plastic, such as the handle of a plastic mouth mirror or an evacuator tip. A dull blade will slide across the plastic; a sharp blade will cut into the surface, stopping movement. A specially made, sterilizable, sharpness-testing stick is also available (Figs 6-44a and 6-44b) (Dalron Test Stick, American Eagle or Miltex). Sharpening is performed in different ways for different hand instruments. When chisels, hatchets, hoes, and margin trimmers are sharpened, the cutting-edge bevel is placed flat against a flat stone, which is on a stable surface, and the instrument is pushed or pulled so that the acute cutting angle is moved forward, with fairly heavy force on the forward stroke, and with little or no fo


[User]
<image>
What types of dental instruments are shown in the image?

[Assistant] The image displays three double-ended dental hand instruments, which are typically used in operative dentistry as chisels or hoes for cavity preparation and refinement. These instruments feature knurled handles for improved grip and various blade angles (such as binangle or curved designs) to access different areas of the tooth.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0237.png

Fig 6-45 Sharpening the two ends of a double-ended Wedelstaedt chisel: (a) sharpening the contrabevel end (inside or mesial bevel); (b) sharpening the bevel end (outside or distal bevel). The end bevel (for the

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a

b

primary cutting edge or working end) of each blade is placed flat on the stone; the blade will make a 45degree angle with the stone. In the primary sharpening stroke, the cutting edge is moved forward. Unless the instrument is very dull, only two or three fairly heavy forward strokes will be necessary to sharpen the cutting edge.

Fig 6-46 Sharpening the two ends of a double-ended binangle hoe: (a) sharpening the bevel end (outside or distal bevel); (b) sharpening the contrabevel end (inside or mesial bevel).The primary bevel is always flat against the stone; the face of the blade is up.

<!--image-->

a

b

<!--image-->

Blunt

Correct

Steep

(45-degree bevel)

- Fig 6-47 Bevels of sharpened cutting instruments. Working end bevels of chisels, hatchets, and


[User]
<image>
What are the instruments shown in the image and what is their primary function in operative dentistry?

[Assistant] The image shows hemostatic forceps (hemostats). In operative dentistry, hemostats are useful because they lock tightly, making them helpful for tasks such as placing or removing items used to confine amalgam for condensation.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0240.png

Explorers . Explorers are pointed instruments used to feel tooth surfaces for irregularities and to determine the hardness of exposed dentin. The explorer that is used most often is the shepherd's hook, or No. 23, explorer (Fig 6-51a). Another useful shape is a cowhorn explorer, which provides improved access for exploring proximal surfaces (Fig 6-51b). The No. 17 explorer is also useful in proximal areas (Fig 6-51c).

Periodontal probes . Periodontal probes are designed to detect and measure the depth of periodontal pockets. In operative dentistry, they are also used to determine dimensions of instruments and of various features of preparations or restorations. There are many periodontal probe designs; the differences are in the diameters, the position of the millimeter markings, the configuration of the markings (eg, whether they are notched or painted), and the design of the tip. Three commonly used probes are illustrated in Fig 6-52.

Fig 6-51 Dental explorers: (a) No. 23 explorer


[User]
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What does this diagram illustrate regarding the dentin surface after instrumentation?

[Assistant] This diagram illustrates the structure of the smear layer that forms on the dentin surface following instrumentation. It shows the smear layer as a porous structure containing water-filled channels between particles, and demonstrates how 'smear plugs' can occlude the dentinal tubules, which are surrounded by peritubular and intertubular dentin.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0415.png

A variety of instrumentation techniques can be applied to remove carious tooth structure and to make the tooth surface receptive for bonding. Cavity preparation with a diamond or tungsten carbide bur is the most common method. However, bur preparation of cavities often leads to unnecessary removal of sound tooth structure. Moreover, placement of bevels on proximal cavosurface angles is difficult, and adjacent teeth are often damaged by the bur. 76 These drawbacks of rotary instrumentation, along with the current trend toward 'minimally invasive' tooth preparation 77-79 have led to the investigation and introduction of new methods as well as the expanded use of previously neglected techniques, such as sono-abrasion, and new techniques, such as air abrasion and laser ablation (Figs 8-15 and 8-16). 75,80

## General Characteristics of the Smear Layer

Most of the time, the tooth surface is covered with a smear layer prior to bonding procedures. As stated previously, the smear layer is an


[User]
<image>
What does this diagram illustrate regarding Class 3 restorations?

[Assistant] This diagram illustrates the lingual view of a mandibular anterior tooth, highlighting the area (labeled 1) where a matrix strip and wedge are typically placed for a Class 3 resin composite restoration to help shape the restoration and manage proximal contours.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_0603.png

Microfilled veneer

Proximal view

Masking agents should be applied in thin layers to allow sufficient space for the overlying composite to restore translucency. Use of the proper accessory shades can create the appearance of dentin overlaid with enamel. Accessory shades can also be used to recreate the yellow color seen in cervical areas or the translucency that appears in incisal areas. An ochre-shaded resin composite can be used to enhance chroma in the cervical areas, gray or blue may increase the 'translucent-incisal' effect, and white can be employed to reproduce a halo. Tints may be used to imitate white or brown spots that appear on adjacent teeth, although with the current ability to bleach teeth, the spots can usually be bleached out or their appearance neutralized with bleaching (see chapter 15).

## Matrices

## For Class 3 Restorations

With Class 3 restorations, the most commonly used matrix is the clear plastic strip (Figs 9-24a and 9-24b). The clear plastic matrix, when


[User]
<image>
What does this chart illustrate regarding dental restorative materials?

[Assistant] This chart (Fig 13-2) illustrates the compressive strengths of various fluoride-releasing dental restorative materials measured at different setting times: 7 minutes, 1 hour, 24 hours, and 1 week. It demonstrates that the compressive strength of these materials generally increases over time as they set.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_1011.png

Table 132 Composition, form supplied, and setting reaction of the materials in the fluoride-releasing materials continuum

| Glass ionomer | Resin-modified glass ionomer | Compomer | Resin composite |
|--------------------|--------------------------------|--------------|--------------------------|
| Contains water | Contains water | No water | No water |
| Powder-liquid only | Powder-liquid or paste-paste | VLC paste | VLC paste or paste-paste |
| Acid-base only | Acid-base and radical | Radical only | Radical only |

## Table 13-3 Representative products in each category of the fluoride-releasing materials continuum

| Glass ionomer | Resin-modified glass ionomer | Compomer | Resin composite |
|-----------------|--------------------------------|--------------|-------------------|
| Ketac-Fil* | Photac-Fil* | Dyract AP † | Heliomolar ‡ |
| Fuji II § | Fuji II LC § | Hytac* | Tetric ‡ |
| Ketac-Molar* | Vitremer* | Compoglass ‡ | Solitaire II |
| Fuji IX § | | F 2000 * | SureFil † |

*3


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

[Assistant] This diagram illustrates the path of insertion for a complete-coverage (full veneer) crown. The vertical arrows indicate the direction in which the crown is placed onto or removed from the prepared tooth. A slight taper of the external walls of the tooth preparation is necessary to provide this path of insertion while maintaining retention.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_1323.png

eral factors. The degree of convergence toward the occlusal (extracoronal walls) or divergence toward the occlusal (intracoronal walls) and the length of the walls are the most important factors. One long wall opposed by a short wall provides retention equivalent only to that imparted by the short wall. The longer 42 and more nearly parallel the walls, the greater the retention. The further apart the opposing walls and the greater the surface areas, the more retentive the restoration will be. 43 Certain implant internal connections have utilized these principles creating an effective self-locking morse taper configuration. In practice, the taper achieved bears little resemblance to those traditionally advocated in textbooks (a combined 6 to 12 degrees), and most teeth are prepared with a taper in excess of 12 degrees with clinical success. 44-46 Although a rapid loss of retention occurs as the taper progresses from 5 to 10 degrees for each wall, 47 a total convergence up to 16 degrees


[User]
<image>
What does this illustration represent in the context of a partial-coverage crown preparation?

[Assistant] This illustration depicts a variation of an occlusobuccal finish line for a maxillary partial-coverage crown. Such designs, including flat bevels, contrabevels, or knife-edged margins, are used to provide adequate resistance form and finish for the restoration while protecting the tooth structure.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_1363.png

Fig 19-35 Limited reduction of the mesiofacial incline of the facial cusp and greater reduction of the distofacial incline of a maxillary tooth provide some protection to the cusp while limiting the display of gold in a partial-coverage restoration.

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(

## Lingual Reduction

The axial wall of the lingual surface is reduced with a round-ended tapered diamond bur. Close attention must be paid to the desired path of insertion to establish parallelism. A two-plane reduction of the tooth is needed to maintain natural contours. Because of the anatomic differences in the lingual contours of the maxillary and the mandibular teeth, the second plane on the lingual surface of a maxillary tooth will be more pronounced. The gingival portion of the lingual surface should have a 3- to 5-degree convergence occlusal to the path of insertion (Fig 19-39), and the second plane should be offset about 30 degrees.

Fig 19-36 The diamond bur is held at the same angle as the natural slope of the


[User]
<image>
Describe the technique for facial and lingual reduction in a full-coverage crown preparation as shown in the image.

[Assistant] For a full-coverage crown preparation, the facial and lingual surfaces are reduced in two planes to allow for the reproduction of normal tooth contours. The first plane, extending occlusally from the gingival finish line, is prepared with a 3- to 5-degree taper to the path of insertion. A second plane is then added at a 30- to 45-degree angle to the first plane, typically involving the occlusal third of the centric holding cusp and the occlusal fourth of the noncentric cusp.

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_1382.png

## Facial and Lingual Reduction

The facial and lingual surfaces are each reduced in two planes to allow reproduction of normal contours in the restoration. The first plane, extending occlusally from the gingival finish line, should have a 3- to 5-degree taper to the path of insertion (Fig 19-51). The second plane should be angled at 30 to 45 degrees to the first plane to allow desired facial and lingual contours to be reestablished (Figs 19-52 and 19-53). This second plane should begin at the occlusal third of the wall for the centric cusp and the occlusal fourth for the noncentric cusp. A round-ended, tapered diamond is used to make these reductions. A modified conservative full-coverage preparation, involving supragingival margins on both lingual and buccal aspects, has shown excellent long-term results. 100

Fig 19-50a Use of a thin, flame-shaped diamond bur is recommended to initiate the proximal reduction of the preparation for a complete-coverage restoration.

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Fig


[User]
<image>
What does this diagram illustrate regarding the restoration of a mandibular molar?

[Assistant] This diagram illustrates a mandibular molar that lacks a sufficiently large pulp chamber for adequate core retention. Consequently, a post is placed in the distal canal to provide the necessary retention for the core buildup, which is then prepared to support a crown (indicated by the dashed outline).

__lib_book_Conservative Dentistry_ Fundamentals of Operative Dentistry by Summitt_ James B 3rd Ed/img_1394.png

Although a post is not commonly required to retain the core in a posterior tooth, a post may be indicated when the tooth is to serve as an abutment for a removable partial denture. 30 In this circumstance, the forces that play on the tooth are not physiologic, and coronal reinforcement may be necessary (Fig 20-3). In maxillary molars, a post is generally placed only in the palatal canal, and in mandibular molars, in the distal canal.

Fig 20-1 Mandibular molar with post perforation in the mesial concavity of the distal root.

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Fig 20-2a Amalcore with adequate chamber retention.

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Fig 20-2b Amalcore preparation in a maxillary second molar.

Fig 20-2c Definitive amalcore restoration in the maxillary second molar.

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Fig 20-3 Mandibular molar that does not have a large enough pulp chamber for chamber retention of the core buildup. A post is used for retention of the core.

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Fig 20-4 (a) Preoperative view of an endodontically


[User]
<image>
What does this diagram and accompanying photograph illustrate regarding endodontic laser treatment?

[Assistant] This image illustrates the thermal effects produced by the contact of a laser fiber with the dentin walls of a root canal during conventional laser irradiation in dry mode. The diagram on the left shows the fiber position, while the photograph on the right displays the resulting 'hot spots' or charred areas on the canal surface caused by the laser energy.

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0122.png

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

In this case, the near-infrared lasers activate the irrigant solutions via heating (warming), and this procedure increases the effi cacy of the irrigation [ 69 ]. The irradiation with near-infrared laser, diode laser (2.5 W, gated mode), and Nd:YAG laser (1.5 W, pulsed mode at 15 Hz), performed after irrigation in a fl uid fi lled canal, produces a dentin pattern, more similar to the

Fig. 5.18 SEM image (1222×) 7 mm shorter of the apex after conventional chemo-mechanical rotary instrumentation and irradiation with an 810 nm diode laser in dry mode at 2.5 W, 20 ms ton/20 mstoff, four times ×5 s. The smear layer is not removed and mainly occludes the dentin surface; presence of superfi cial thermal damage with fl akes and detached particles including debris and smear layer

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Fig. 5.20 SEM image (1000×) of the root canal surface after conventional chemo-mechanical rotary instrumentation and Nd:YAG laser irradiation in dry mode, 1.5 W, 15 Hz, 100 mJ, four times ×5 s. The cana


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

[Assistant] This is a panoramic radiograph, also known as an orthopantomogram (OPG). It provides a wide-view X-ray of the entire mouth, including the teeth, upper and lower jaws, and surrounding structures.

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0196.png


[User]
<image>
What does this diagram illustrate regarding laser-activated irrigation (LAI) in endodontics?

[Assistant] This diagram illustrates six different protocols (a-f) for positioning laser tips within a root canal during laser-activated irrigation (LAI). The protocols vary based on the depth of the tip insertion and movement within the canal, ranging from stationary positioning at specific distances from the apex (a) to hovering over the canal orifice (f).

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0213.png

Data reported in Table 10.2 show the inconsistency in fi bre/tip-end position in the root canal. In order to prevent extrusion, the laser fi bre/tip should be kept away from the apex. On the other hand, effi cient and safe cleaning and disinfection of the root canal have to be ensured. At present there are two approaches: the one moving or keeping the fi bre tip stationary in the root canal and the other using the fi bre tip stationary in the pulp chamber. The difference between the conventional approach (fi bre in the root canal) and the PIPS protocol (fi bre out of the root canal) will be explained in more detail in the next chapter (Fig. 10.9 ).

Blanken and Verdaasdonk (2007) reported the formation of the vapour bubbles up to 4.5 mm distance from the 200 μ m fl at tip using an Er:Cr:YSGG with a 200 μ m fl at tip [ 14 ] and Blanken et al. (2009) at 3.0-3.5 mm using the same wavelength and parameters [ 15 ].

Fig. 10.9 LAI advocates positioning the tip inside the canal fi lled with i


[User]
<image>
What is the clinical significance of the access preparations shown in these images?

[Assistant] These images illustrate various endodontic access preparations. The clinical goal of these preparations is to achieve straight-line access to the root canal system, allowing for the complete excavation of carious lesions and the selective removal of pulp tissue. Proper access design, which is related to the health of the remaining tissue and the specific position of the canal orifices, ensures that all orifices can be visualized and confirmed with an endodontic explorer, facilitating subsequent cleaning and shaping procedures.

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0297.png

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a

b

c

remove the coronal pulp tissues. Upon complete excavation of carious lesions and the selective removal of pulp tissue in the chamber, the remaining canal orifi ces can be visualized and confi rmed with an endodontic explorer (Fig. 11.78a-c ). Creating an appropriate convenience form during access preparation (straight-line access) is always preferred and advised (Fig. 11.79a-d ). For this purpose the ultrasonic instruments with a diamond tip work very well because of their long, curved, and thin stem design allowing for a very precise and controlled application while using a microscope. The cavity walls are consequently fl ared, rounded, and smoothed to facilitate easy and straight access into the root canal [ 55 ] (Figs. 11.80 , 11.81 , 11.82 , 11.83 , 11.84 , and 11.85 ). The design and size of the access opening are related to the health of the remaining tissue and to the position of the canal orifi ces (Fig. 11.86ac ); however, in case of coronal destruction,


[User]
<image>
What does this diagram illustrate regarding root canal treatment?

[Assistant] This diagram illustrates the sequential instrumentation of a root canal, showing the use of a hand file (size 20) followed by rotary files to shape the canal system.

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0302.png

subsequent fi les will be instrumented to. Irrespective of the instrumentation technique used, after each fi ling step, continuous laseractivated irrigation (PIPS) of 30s with sodium hypochlorite will digest the vital and/or necrotic tissue in the canal. NaOCl is left in the chamber as a lubricant, and instrumentation from here forward is always done with adequate hydration and never in a dry fi eld. Instrumentation is always performed sequentially until reaching a size 20 or 25 ISO (Figs. 11.98 , 11.99 , 11.100 , and 11.101 ). This can be done by hand, rotary, or combination. Patency is confi rmed between each fi le using the smallest hand fi le possible (typically a .06.08 ISO hand fi le) (Fig. 11.102 ).

## 11.15.3 Shaping the Root Canal

Whatever the canal length is determined to be, that value is shortened by 1 mm to which all the

The authors fi nd that a combination of hand .06, .08, and .10 rotary glide path fi les (#13/02 and #16/02 or #10/02 to #20/02) and fi nally a rotary s


[User]
<image>
Describe the steps shown in Figure 11.129 for the endodontic retreatment of a lower central incisor.

[Assistant] Figure 11.129 illustrates the endodontic retreatment process for a lower central incisor: (a) shows the pre-treatment state with a metal post; (b) shows the tooth after the post has been removed, revealing a previously untreated lingual canal; (c) shows the completed root canal obturation; and (d) provides the post-operative radiograph confirming the treatment.

__lib_book_Conservative Dentistry_ Lasers in Endodontics by Olivi_ Giovanni/img_0339.png

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a

b

Fig. 11.124 ( a ) Pre-treatment upper fi rst molar; ( b ) 1 year post-treatment (Courtesy Dr. Tom McClammy Scottsdale, Arizona, USA)

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a

b

Fig. 11.125 ( a ) Pre-treatment upper fi rst molar; ( b ) 1 year post-treatment

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a

b

Fig. 11.126 ( a ) Pre-treatment upper second bicuspid; ( b ) 6 months post-treatment

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a

b

Fig. 11.127 ( a ) Pre-treatment upper fi rst bicuspid; ( b ) 1 year post-treatment

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a

b

## 11.16 PIPS Protocol for Endodontic Retreatment

Removing failed endodontic material from previous therapies requires the use of hand and rotary fi les in combination with PIPS. PIPS and continuous water between instruments are used in an alternating pattern until dislodging and cleaning of previous material occur (Figs. 11.128a-d , 11.129 , 11.130 , and - 11.131a, b ). PIPS standard settings are used with the handpiece water feature 'on' at 2 water/0 air. Use of alcohol and hydrogen peroxide with PIPS aids


[User]
<image>
Explain the progression of the carious lesion shown in the image.

[Assistant] The image illustrates the ecological changes in a carious lesion. Panels (a) and (d) show a 'closed' lesion with undermined enamel, representing an active, highly cariogenic environment. Panels (b) and (e) show the lesion after the undermined enamel has been removed, exposing the soft, yellow, and wet carious dentin. Panels (c) and (f) demonstrate the lesion after a sealing period, where the environment has changed, resulting in the carious dentin becoming darker, harder, and drier, indicating a slower-progressing or arrested ecosystem.

__lib_book_Conservative Dentistry_ Management of Deep Carious Lesions by Schwendicke_ Falk/img_0022.png

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

The relevance of the ecological plaque hypothesis can be well demonstrated when assessing the changes in the dental ecosystem in so-called 'closed lesions' compared to 'open (cavitated) lesions,' with carious dentin being soft light yellow and wet in the first stage; while after the breakdown of the undermined enamel (Fig. 3.1a-c), the environment within the lesion markedly changes, leading to different clinical appearances of the carious dentin. Similar signs of environment change can be seen during when carious lesions are sealed as briefly discussed in the previous chapter, with soft, moist and yellow dentin being transformed into dark, hard and drier dentin after a sealing period (Fig. 3.1d-f). A third example of 'natural' lesion arrest following breakdown of undermined enamel can often be shown in an upper front teeth (Fig. 3.2), as has also been demonstrated in Chap. 1.

3

Fig. 3.1 Principle illustration of a so-called 'closed' lesion environment defining an active cariogenic en


[User]
<image>
Describe the different dental arch relationships shown in the diagram.

[Assistant] The diagram illustrates various aspects of dental occlusion and arch relationships. It shows the alignment of cusps and fossae within the dental arches, the concept of maximum intercuspation (MI) where opposing teeth are in maximal contact, and the classification of molar and skeletal relationships into Classes I, II, and III. Class I represents a normal relationship, while Class II and Class III represent different types of malocclusions based on the anterior-posterior positioning of the dental arches and skeletal structures.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0072.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 factors that determine the superior border of the incisor point tracing and the separation of posterior teeth during mandibular movement as shown in the diagram.

[Assistant] As illustrated in the diagram, the superior border of the incisor point tracing near Maximum Intercuspation (MI) is primarily determined by canine guidance. Conversely, the separation of the posterior teeth on the nonworking side during lateral mandibular movement is determined by the slope of the articular eminence (posterior guidance).

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0110.png

movements is simulated by the Bennett

adjustment (b).

wall

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A Observed pathways

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80% between

and 4

20% between 2 and 3

Mean

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<!--image-->

Effect of adjustment

- C Working condyle point (a) movement

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E, F, and G illustrate the combined effect of anterior and posterior guidance on the superior border of molar point. The angulation of the posterior guidance is indicated in degrees for each figure. The absence of anterior guidance is indicated by a and presence of anterior guidance by b. The tracing of the movement of the mesiolingual cusp of the maxillary molar is made on the grid in each figure. Note that the absence of anterior guidance reduces the separation of the posterior teeth, but has the greatest effect when the posterior guidance is shallow.

<!--image-->

p Nonworking condyle point (e) movement

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209

FIG. 2-58 Horizontal condylar guidance. (A modified from Lundeen HC, Wirth CG: Condylar m


[User]
<image>
What are the components shown in the image used for in dentistry?

[Assistant] The components shown in the image, including the capsules, pestles, and the amalgamator, are used for the automatic mixing of dental amalgam constituents (alloy and mercury) to prepare restorative material.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0215.png

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B

mixed manually (Fig. 4-22, A). To proportion and mix amalgam more carefully, manufacturers later recommended the use of alloy pellets, mercury dispensers, reusable mixing capsules and pestles, and amalgamators (Fig. 4-22, B). A typical reusable capsule (Fig. 4-23, A) was a hollow tube with rounded ends constructed as two pieces that could be friction-fit or screwed together. Amalgam alloy was dispensed into the capsule as a pellet of pressed powder of standard weight. Mercury was dispensed into the capsule as a standard-sized droplet from an automatic dropper bottle. A small metal or plastic pestle (Fig. 4-23, B) was added to the capsule and it was closed. The capsule and its contents were then automatically mixed using an amalgamator. The typical amalgamator has been designed to grasp the ends of the capsule in a claw that is oscillated in a figure-eight pattern. This accelerates the mixture toward each end of the capsule during each throw and impacts the mixture with


[User]
<image>
What does this transmission electron micrograph (TEM) illustrate regarding the resin-dentin interface?

[Assistant] This TEM micrograph illustrates the resin-dentin interface formed with a self-etching primer (specifically Clearfil SE Bond). It highlights the hybrid layer (H), which is the zone where the adhesive resin has infiltrated the demineralized dentin, and the underlying residual dentin (D).

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0335.png

FIG. 5-16 Bonding to dentin using a self-etching primer.

<!--image-->

Self-Etching Primer

Adhesive + Composite

Dentin Smear Layer

No Rinsing

Composite

Prepared With Bur

Primer

Dentin Adhesive

Hybrid

Layer

Resin-

Impregnated

Smear

Plug

promised because a perfect marginal integrity is not achieved .102,210

A clinical study using Clearfil Liner Bond 2 ( Kuraray, Osaka, Japan), a self-etching primer, has demonstrated excellent retention in Class V restorations at three years, but 47% of the restorations had a score of "bravo" for marginal integrity."' An in vitro study involving the same adhesive material resulted in enamel bond strengths statistically similar to those obtained with the concomitant use of a separate acid etchant before the application of the primer. 112 However, when the fitting surface was observed under the SEM, the use of the self-etching primer resulted in a shallower etching pattern than when a conventional acid etchant was used. 232 Nevertheless, som


[User]
<image>
What is shown in this image?

[Assistant] This image displays a dental rotary cutting instrument, commonly known as a bur. Part A shows the side profile of the bur with its fluted cutting head, while part B provides a cross-sectional view of the blade geometry. The letters x, y, z, v, and w represent various design parameters such as blade angles, flute depth, and dimensions critical to the instrument's cutting efficiency.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0427.png


[User]
<image>
What clinical procedure is being demonstrated in this series of photographs?

[Assistant] This series of photographs demonstrates the clinical procedure of rubber dam isolation for a posterior tooth. The images show the placement and adjustment of a rubber dam clamp to isolate the operating site, which is a standard technique in operative dentistry to maintain a clean, dry field.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0620.png


[User]
<image>
Describe the clinical procedure shown in this series of photographs.

[Assistant] This series of clinical photographs (A-L) illustrates the step-by-step process of placing direct composite veneers on the maxillary anterior teeth. The procedure includes preoperative assessment (A-B), isolation (C), application of bonding agents (D), incremental placement and contouring of composite resin (E-F), finishing and polishing to achieve proper anatomy and surface texture (G-I), and the final aesthetic result (J-L).

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0867.png


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

[Assistant] This sequence illustrates the clinical procedure for a porcelain-fused-to-metal (PFM) resin-bonded bridge used to replace missing maxillary central incisors. It shows the initial edentulous state, the preparation of the abutment teeth, the design of the bridge framework with metal wings for bonding, and the final cemented restoration.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0899.png


[User]
<image>
What does this figure illustrate regarding the preparation of a tooth for a restoration?

[Assistant] This figure illustrates the clinical procedure for removing residual pit-and-fissure caries and infected dentin from the pulpal floor of a tooth preparation. It shows the initial state with remnants (A), the use of burs and spoon excavators to remove the infected tissue, and the final preparation design, which includes a peripheral seat.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0955.png


[User]
<image>
Describe the steps shown in the image for a dental cavity preparation.

[Assistant] The image illustrates the progression of a dental cavity preparation on a tooth model: (A) Initial entry into the occlusal surface with a bur, (B) deepening the preparation, (D) establishing the initial outline form along the central groove, and (E) the final cavity preparation. The bottom image provides a side-by-side comparison of an unprepared tooth and the finished preparation.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_0996.png


[User]
<image>
Describe the steps shown in the image for placing a Barton matrix during an OL amalgam restoration.

[Assistant] The image illustrates the Barton matrix technique used for an occlusolingual (OL) amalgam restoration: (A) The Tofflemire matrix band is placed. (B) A stainless steel matrix segment is inserted to adapt to the lingual surface. (C) A toothpick wedge is prepared with green compound. (D) The compound-coated wedge is inserted to secure the matrix. (E) A burnisher is used to press the compound gingivally for a rigid seal. (F) The completed amalgam restoration. (G) The final occlusal view of the restoration.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_1171.png

## Restorative Technique

Placing a Sealer or Adhesive System. As presented previously, after any indicated liner or base or both is placed, regardless of the depth of the excavation, either a dentin desensitizer or dentin-bonding system is placed. A desensitizer is usually indicated in conservative preparations. A dentin-bonding system may be indicated in more extensive preparations. Either is used instead of varnish.

Placing a Matrix (if Necessary). Using a rigid matrix to support the lingual portion of the restoration during condensation is occasionally necessary. A matrix is helpful to prevent "land-sliding" during condensation and to ensure marginal adaptation and strength of the restoration. The Tofflemire matrix retainer is used to secure a matrix band to the tooth (as described later in this chapter). Because this type of matrix band does not intimately adapt to the lingual groove area of the tooth (Fig. 17-39, A), an additional step may be necessary to provide a matrix that i


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

[Assistant] This diagram illustrates an incorrect technique for placing a threaded dental pin. Panel A shows an improper approach angle with the insertion instrument. Panels B and C demonstrate how this incorrect angulation can lead to excessive stress on the surrounding tooth structure, resulting in a sharp bend in the pin and chipped dentin.

__lib_book_Conservative Dentistry_ Sturdevant_s Art and Science of Operative Dentistry by Roberson_ TM 4th Ed/img_1210.png

Pin insertion. Two instruments for insertion of threaded pins are available: conventional latch-type contra-angle handpiece (Fig. 19-32), and TMS hand wrenches (see Fig. 19-30). Studies conflict as to which method of pin insertion produces the best results. The latch-type handpiece is recommended for the insertion of the Link Series and the Link Plus pins. The hand wrench is recommended for the insertion of standard pins.

When using the latch-type handpiece, insert a Link Series or a Link Plus pin into the handpiece and place the pin in the pinhole. Activate the handpiece at low speed until the plastic sleeve shears from the pin. Then, remove the sleeve and discard it. For low-speed handpieces with a low gear, the low gear should be used. Using low gear increases the torque and increases the tac-

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FIG 19-32 Conventional latch-type contra-angle handpiece.

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FIG 19-33 A, Use of hand wrench to place pin. B, Thread pin to bottom of pinhole, and then reverse wren