endodontics Flashcards

Question

"Endodontic Disinfection for Orthograde Root Canal Treatment in Veterinary Dentistry". Laura Sasser. JVD 2020:37(1). what is the smear layer? how does the smear layer complicate disinfection of the root canal?

Answer 1

The smear layer is an ultrafine layer of inorganic and organic substances, dentin particles, remnants of vital or necrotic pulp tissue, microorganisms, and retained irrigants formed by shaping and irrigating the root canal space. 1-5 µm. The smear layer seals dentinal tubules and is resistant to chemomechanical removal, leading to entrapment of microorganisms in the dentinal tubules. The presence of a smear layer has adverse effects on the final outcome because it harbors microorganisms, reduces dentin permeability, compromises adequate disinfection by limiting the diffusion of endodontic disinfectants inside the dentinal tubules, and is a potential channel for microleakage.

Answer 2

The fundamental goals of root canal irrigation: * to dissolve vital or necrotic pulp tissues * disrupt endodontic biofilms * eradicate microorganisms * remove the smear layer

Answer 3

* mechanical objective: the ability of the irrigant to reach the entire root canal system. * chemical objective: depends on the properties of the irrigant, concentration of the irrigant, area of contact, and the length of time the irrigant has contact with the contents of the root canal. * biologic objective: directly related to the antimicrobial effects of the irrigant against anaerobic and facultative microorganisms in their planktonic and sessile state.

Answer 4

* increasing concentration (0.5-6%) * increasing the temperature of the solution: heating 0.5% NaOCl to 113°F=45°C dissolved pulp tissue as well as room temperature 5.25% NaOCl. elevating the temperature to 140°F=60°C resulted in complete dissolution of pulp tissue. * increasing the volume of the solution * increasing contact time in the root canal * utilizing agitation/activation methods

Answer 5

* heating 0.5% NaOCl to 113°F (45°C) dissolved pulp tissue as well as room temperature 5.25% NaOCl. * elevating the temperature to 140°F (60°C) resulted in complete dissolution of pulp tissue

Answer 6

A 5.25% solution compared to a 0.5% solution decreases the elastic modulus and flexural strength of dentin due to the proteolytic action of the concentrated hypochlorite on the collagen matrix of dentin potentially weakening the tooth structure.

Answer 7

substantivity: CHX is readily adsorbed onto the hydroxyapatite crystals of dentin and released back into the environment, which could be important when treating residual bacterial in the root canal space.

Answer 8

* bactericidal at high concentrations and bacteriostatic at low concentrations * activity against Gram-positive and Gram-negative bacteria and yeasts * substantivity * CHX differs from NaOCl, in that it does not remove collagen fibrils and can significantly improve the resin–dentin bond stability disadvantages: * inability to dissolve organic debris compared to NaOCl * CHX cannot destroy the resistant biofilm structure

Answer 9

When CHX is used with NaOCl, an insoluble precipitate, parachloroaniline (PCA), can be produced. * This precipitate is carcinogenic * can penetrate into the dentinal tubules and interfere with obturation and the root canal sealer *When CHX is used with EDTA a white salt can be produced.* *EDTA and NaOCl should be used separately:* * *EDTA retains its calcium-complex ability when mixed with NaOCl* * *NaOCl loses its tissue-dissolving capacity (no free chlorine detected in the mixture).*

Answer 10

EDTA removes the inorganic mineralized components of the smear layer (NaOCl removes the organic components). The use of EDTA as the final rinse when utilizing a resin-based root canal sealer improves binding of the resin base sealer to dentin.

Answer 11

The actual exchange of fluids with passive irrigation occurs within 1-1.5 mm apical to the needle tip

Answer 12

Intracanal medicaments * impede bacterial regrowth * supply continued disinfection * create a physical barrier in the root canal system

Answer 13

Advantages of Calcium hydroxide: * a high pH * broad-spectrum antimicrobial activity * possesses the ability to sustain antimicrobial action * has the capability to dissolve necrotic tissue remnants, bacteria, and their by-products disadvantages of CaOH2: * incomplete removal of the residue at the second appointment * the residue’s effects on the canal sealer

Answer 14

* an aqueous solution of 3% doxycycline, 4.25% citric acid as a demineralizing agent, and 0.5% polysorbate 80 as a detergent * The cumulative effects of doxycycline, citric acid, and the detergent have a synergistic effect on the disruption of bacterial cell walls and cytoplasmic membranes * effective against resistant E faecalis (not as effective as NaOCl) * an alternative to EDTA as a final rinse, with reported capabilities of removing both the smear layer and the organic debris from the infected root canal.

Answer 15

TAP (1:1:1 mixture of ciprofloxacin, metronidazole, minocycline) is more cytotoxic to stem cells then CaOH2. * at 1 g/ml no apical papila stem cells (SCAP) survive. * at 1 mg/mL TAP has no effect on SCAP survival. * the effective antibacterial concentration of TAP is 1-10 mg/mL.

Answer 16

A-delta nerve fibers

Answer 17

planar imaging-based studies have resulted in an overestimation of successful outcomes, compared to CBCT assessments, because apical periodontitis confined within the cancellous bone or lesions covered by a thick cortex may be undetectable with conventional radiographic assessments

Answer 18

the groove in the working surface used to collect soft tissue and dentin chips from the wall of the canal. Its effectiveness depends on its depth, width, configuration, and surface finish.

Answer 19

The surface with the greatest diameter that follows the groove (where the flute and land intersect) as it rotates forms the leading (cutting) edge or the blade of the file

Answer 20

rake angle: the angle formed by the leading edge and the radius of the file through the point of contact with the radicular wall perpendicular to the long axis of the file. * positive = cutting * neutral * negative = scraping

Answer 21

a feature between trailing and cutting edge that forms a larger contact area with the radicular wall. * reduces the tendency of the file to thread into the canal * supports the cutting edge and limits the depth of cut * landed files are typically less cutting efficient compared with triangular cross sections

Answer 22

the distance between a point on the leading edge and the corresponding point on the adjacent leading edge (the distance from one “spiral twist” to the next)

Answer 23

Coronal flaring (orifice modification): the extension of an access cavity into the coronal most portion of the root canal. * If a canal is constricted, mineralized, or difficult to access, enlargement of the coronal portion prior to any deep entry into the root canal is beneficial * Tools for preflaring include Gates-Gliddens and dedicated NiTi instruments

Answer 24

The file that has reached the apical foramen has already formed a so-called glide path (securing an open pathway to the canal terminus that subsequent engine-driven instruments can follow).

Answer 25

The same WL for all instruments introduced into the canal -> the inherent shape of the instruments imparts the final shape to the canal. Files are advanced to WL and worked until a next larger instrument may be used.

Answer 26

Apical to coronal direction. WLs decrease in a stepwise manner with increasing instrument size (typically in 1 or 0.5 mm steps) -> prevents less flexible instruments from creating ledges in apical curves while producing a taper for ease of obturation.

Answer 27

* Step-down: determine WL, instrumentation coronal to apical (file size decreases). * Crown-down: instrumentation coronal to apical (file size decreases), until reaching WL (which is determined later in the procedure).

Answer 28

* Step-down: determine WL, instrumentation from coronal to apical (decreasing file sizes). * Crown-down: instrumentation from coronal to apical (decreasing file sizes), until WL is reached. WL is determined later in the procedure (after coronal flaring).

Answer 29

transformational elasticity; the ability to return to its original shape without showing signs of permanent deformation (shape memory). martensite phase can accomodate greater stress without increasing the strain.

Answer 30

0.5-6%. * higher concentrations have better tissue-dissolving ability * lower concentrations used in high volumes can be equally effective

Answer 31

the antimicrobial effectiveness of NaOCl is based on its high pH (>11), similar to the mechanism of action of CaOH2. The high pH interferes in cytoplasmic membrane integrity due to: * irreversible enzymatic inhibition * biosynthetic alterations in cellular metabolism * phospholipid degradation observed in lipidic peroxidation

Answer 32

Adsorption of CHX to dentin with gradual and prolonged release (because of the cationic nature of its molecule) depends on * Concentration with 0.005-0.01% a monolayer is adsorbed on the tooth surface. with 0.02% a multilayer is formed providing a reservoir of CHX that can rapidly release into the environment as CHX concentration in the surrounding environment decreases * Contact time with dentin

Answer 33

removing the smear layer * allows irrigants, medications, and sealers penetrate dentinal tubules and improve disinfection keeping the smear layer: * protection for bacterial invasion, apical and coronal microleakage, bacterial penetration of the tubules * adaptation of root canal materials

Answer 34

EDTA is a chelator * forms a stable complex with calcium * removing the mineralized portion of the smear layer

Answer 35

Heating EDTA is not desirable (decreases calcium binding capacity)

Answer 36

EDTA and NaOCl should be used separately * EDTA retains its calcium-complex ability when mixed with NaOCl * NaOCl loses its tissue-dissolving capacity (no free chlorine detected in the mixture)

Answer 37

combining 2% CHX with NaOCl results in the formation of a red toxic precipitate, parachloroaniline (PCA), that may harm tissues. * The higher the concentration of NaOCl, the larger the precipitate * The precipitate might interfere with the seal of the root obturation

Answer 38

An aqueous solution, mixture of: * antibiotics (3% doxycycline) * demineralizing agent (citric acid) * a detergent this irrigant is capable of removing both the smear layer and organic tissue from the infected root canal system. MTAD has been recommended as a final rinse. there is no significant difference between EDTA and MTAD in smear layer removal efficacy.

Answer 39

* Torsional fracture: an instrument tip is locked in a canal while the shank continues to rotate, exerting enough torque to fracture the tip. * Flexural fracture: cyclic loading leads to metal fatigue. Stainless steel develops fatal fatigue after only a few cycles (precludes its use for rotary endodontic instruments); NiTi can withstand several hundred flexural cycles before they fracture.

Answer 40

both are epoxy resin sealers. * AH-26 is a slow-setting epoxy resin that releases formaldehyde when setting. * AH Plus is a modified AH-26 in which formaldehyde is not released.

Answer 41

Monoblock: the idealized scenario in which the canal space becomes perfectly filled with a gap-free, solid mass consisting of different materials and interfaces, with the advantages of simultaneously improving the seal and fracture resistance of an obturated root canal.

Answer 42

silicone sealers

Answer 43

* **Persistent or reintroduced intraradicular microorganisms**: If initial RCT does not render the canal space free of bacteria, if the obturation does not adequately entomb those that may remain, or if new microorganisms can reenter the cleaned and sealed canal space, then posttreatment disease will occur. * **Extraradicular infection**: Bacterial cells can invade periradicular tissues by direct spread of infection from the root canal space, via contaminated periodontal pockets that communicate with the apical area, extrusion of infected dentin chips, or by contamination with overextended, infected endodontic instruments. * **Foreign body reaction**: foreign material in the periradicular area can induce inflammatory responses. Lentil beans and cellulose fibers from paper points. Extruded root canal filling material (GP and sealers are usually well tolerated by apical tissues -> if the tissues have not been inoculated with microorganisms, healing can still occur). * **True cysts**: form in the periradicular tissues when retained embryonic epithelium (rests of Malassez) proliferate due to the presence of chronic inflammation (an attempt to separate the inflammatory stimulus from the surrounding bone). The periapical true cyst: a cavity/lumen contained within a continuous epithelial lining; does not heal following nonsurgical RCT (requires surgical enucleation).

Answer 44

they disintegrate

Answer 45

an interplay between stem cells, growth factors, and scaffolds. * stem cells of the apical papilla (SCAP), dental pulp stem cells (DPSC) * growth factors: dentin is composed of collagen fibers (90%, collagen type I) and non collagenous matrix molecules (proteoglycans, phosphoproteins, and phospholipids). The collagen fibers act as a scaffold upon which mineralization can occur. The matrix is a reservoir of growth factors and cytokines, secreted by odontoblasts during primary dentinogenesis, becoming sequestered and trapped in the matrix after biomineralization. demineralization of the matrix promotes the release of these factors (EDTA, CaOH2, acid etching, MTA, Biodentine). * scaffold: evoked bleeding creates a blood clot (serves as a protein scaffold, permitting 3D ingrowth of tissue), PRP/PRF, Colla-Plug (collagen based)

Answer 46

disinfection is primarily chemical rather than the chemomechanical approach used in conventional nonsurgical RCT * Minimal to no instrumentation is performed (concerns regarding potential fracture of thin incompletely developed roots) * relies on copious irrigation for maximum antimicrobial and tissue dissolution effects, with irrigating needle placed at working length (1 mm from root end) ## Footnote *"Regenerative Endodontics". Feigin & Shope. JVD 2017.* * 1.5% NaOCl (low concentration) using an irrigating needle positioned about 1 mm from the root end, to minimize cytotoxicity to stem cells in the apical tissues. * Followed with irrigation with 17% EDTA (promotes survival of apical papilla stem cells, exposes a reservoir of growth factors from the dentin). * After drying the canal, calcium hydroxide (promotes MSCs survival) or a low concentration of triple antibiotic paste (TAP; 1:1:1 ratio of ciprofloxacin, metronidazole, and minocycline to a final concentration of 0.1-1.0 mg/mL) is placed in the canal. The antibiotic paste eliminates bacteria in dentinal tubules. Toxic concentrations of antibiotics reduce viable stem cells in the apical papilla. These effects can be avoided at 1 mg/mL.

Answer 47

Treatment of dentin with NaOCl results in an indirect cytotoxic effect on stem cells -> lower concentration (1.5%) of NaOCl followed by EDTA (releases growth factors from dentin, promotes stem cell survival and differentiation) is the standard irrigation for REPs. Chlorhexidine should be avoided because it does not have tissue dissolution capability and is cytotoxic to stem cells.

Answer 48

intracanal medicaments are used to disinfect the canal. * triple antibiotic paste (TAP) (1:1:1 mixture of ciprofloxacin, metronidazole, minocycline) * CaOH2 The ability to remove the medicament from the canal space is an important consideration. Drugs remaining within dentin are likely to have an effect on the fate of stem cells in contact with the treated dentin. * TAP is harder to remove (>80% remaining, extending >350 μm into the dentinal tubules) * CaOH2 (>80% removed, with the remaining medicament present superficially within dentin).

Answer 49

The odontoblast layer in the coronal pulp contains more cells per unit area than in the radicular pulp (fewer dentinal tubules per unit area in the root than in the crown).

Answer 50

Tertiary dentin: irregular dentin formed in response to abnormal stimuli. Reactionary dentin: tertiary dentin formed by the original odontoblasts that made secondary dentin. The formation rate is increased, the tubules remain continuous with the secondary dentin. Reparative dentin: If the provoking stimulus caused destruction of the original odontoblasts, newly differentiated odontoblast-like cells form new, less tubular, more irregular tertiary dentin. In reparative dentin the tubules are usually not continuous with those of secondary dentin.

Answer 51

The distinctive difference between nonsurgical and surgical endodontic therapy: * the goal of nonsurgical RCT is to remove primary microbial etiology from the root canal * the goal of surgical endodontic therapy is to seal microbial etiology within the root canal by root-end filling

Answer 52

7.1% How soon a periapical lesion is detected on a radiograph usually depends on how soon cortical bone is involved, which will depend on the proximity of the root apex to the cortex.

Answer 53

100% in intact 70% in teeth with pulp exposure

Answer 54

85-134 ## Footnote *"Scanning Electron Microscopic Evaluation of Tooth Root Apices in the Dog". Sabás Z. Hernández, Viviana B. Negro, Georgina de Puch, Paula G. Toriggia. JVD 2014*

Answer 55

71% (78/110) had pulp alterations: * fibrosis (26%) * calcification (14%) * necrosis associated with absence of odontoblasts (14%) * presence of predentin and dentin inside the cavity (8%) * odontoblastic hyperplasia (3%) * pigmentation (3%) * pulpitis (2%) * pulp stones (1%)

Answer 56

49/81 (60.5%) maxillary teeth and all of the mandibular teeth had pulp alterations. Premolars were most affected by pulp alterations, molars least affected.

Answer 57

MTA consistently performed as well or better than other commercially available products in terms of calcific barrier formation and biocompatibility. * 89% of teeth capped with CH contained tunnel defects, most of which appeared to be patent. These patent tunnels fail to provide a hermetic seal to the underlying pulp against infection due to microleakage. * MTA produces more histomorphologically favorable calcific barriers than CH, with earlier formation of hard tissue bridges, larger daily dentin increases and few tunnel defects. * Three of the studies included in this review demonstrated that PMTA was superior to CH regarding calcific barrier formation and degree of pulpal inflammation. * As for different types of MTA, it seems to be beneficial to have a material that releases a relatively high amount calcium and hydroxyl ions at the start, but quickly tapers off as prolonged release may have a negative impact due to chronic pulp inflammation.

Answer 58

Advantages: * excellent antibacterial properties due to its high pH Disadvantages: * irritation and necrosis of the pulp directly beneath the capping material * high solubility in oral fluids * dissolution over time * lack of inherent adhesive properties * the presence of tunnel defects within the calcific barrier lead to a failure to produce a hermetic seal to the underlying pulp against bacteria due to microleakage

Answer 59

Advantages: * excellent biocompatibility, bioactivity and sealing ability with the capacity to bond to dentin (an initial mechanical bond between MTA and dentin with a chemical bond being produced over time) * a high pH, resulting in extraction of growth factors from dentin thought to promote calcific barrier formation * ability to set is not affected by the presence of blood or serum * once set, MTA is nonabsorbable, unlike CaOH2 which can degrade and dissolve, allowing potential ingress of microorganisms and bacterial contamination of the pulp through tunnel defects in the calcific barrier * produces more histomorphologically favorable calcific barriers than CaOH2, with earlier formation of hard tissue bridges, larger daily dentin increases and few tunnel defects Disadvantages: * long setting time * tooth discoloration * high cost * difficult handling characteristics

Answer 60

MTA performed as well or better than other MTA-like cements in terms of the calcific barrier formation and biocompatibility. One notable difference between MTA and the MTA-like cements was that Biodentin (BMTA) formed significantly thicker calcific barriers than MTA. * BMTA has a greater release of calcium and hydroxyl ions during the initial setting of the material, with reduced ion release over time creating more favorable conditions for pulp repair * while it is widely accepted that the release of calcium hydroxide from pulp capping materials induces a beneficial inflammatory reaction contributing to formation of the calcific barrier, prolonged release of calcium and hydroxyl ions may have a negative impact due to chronic pulpal inflammation

Answer 61

* 98.18% (54/55) success/NEF 92.7% (51/55) success 5.45% (3/55) NEF * 1.82% (1/55) failure

Answer 62

Teeth with PAL were more likely to result in NEF or failure (40%) than those without (0%). EIRR did not affect outcome, unless it was combined with PAL (the 1/55 that failed had PAL+EIRR).

Answer 63

They didn't change outcome, except with PAL. crowned teeth were sig more likely to resolve the PAL (71% vs 33% without crowns)

Answer 64

obturation materials: * thermoplastic gutta percha (TGP) 61.82% (34/55) * single cone with flowable gutta percha 36.36% (20/55) * warm lateral compaction of gutta percha with a root canal sealer 1.8% (1/55) Obturation material NOT significantly associated with outcome. If a PAL was present at the time of treatment, this lesion was less likely to improve or resolve with TGP obturation (85% success) than with single-cone gutta percha with flowable gutta percha (100% success). File separation with intra-canal retention of the file segment in 7.14% (4/56). no impact on outcome. separated file tips were entombed in obturation meterial.

Answer 65

early 1990s the first-generation ProFile system became available 1992

Answer 66

* 55 wt% Ni * 45 wt% Ti

Answer 67

Austenite phase: Strong and hard. The flexibility of the A-phase allows the file to be inserted readily within a curved canal. Transforms under stress (during root canal instrumentation). Martensite phase: More elastic, greater tensile strength. Once the stress is released, M-phase transforms back to A-phase. If the austenite phase is not present, the superelastic behavior does not exist. Without the martensite phase, a plastic strain recovery or shape memory would not transpire.

Answer 68

It is a transitional Rhombohedral distortion occuring during phase shift, with a lower modulus of elastisticity than austenite. It may enhance flexibility but is not always present (present when precipitates or dislocations exist such as in aging NiTi files).

Answer 69

* 55 wt% Ni * 45 wt% Ti

Answer 70

The elastic modulus of NiTi is 1/4 to 1/5 that of stainless steel, contributing to increased flexibility in comparison to stainless steel.

Answer 71

Super flexibility, also described as superelasticity, is the ability of a material to resist stress without permanent deformation. NiTi’s ability to return to its original shape without showing signs of permanent deformation is described as shape memory effect. NiTi's flexibility allows better navigation of a curved root canal while minimizing canal transportation. This results in fewer procedural errors such as ledging, zipping, elbows and perforations commonly seen with stainless steel files.

Answer 72

A is correct. * NiTi alloy is comprised of 55 wt% Ni and 45 wt% Ti. * NiTi is far more flexible than stainless-steel, which has an inherent stiffness and tendency to straighten a curved canal. The elastic modulus of NiTi is 1/4 to 1/5 that of stainless steel, contributing to increased flexibility in comparison to stainless steel. * NiTi’s thermodynamic properties are due to its ability to phase change (metallurgical transformation). NiTi alloy exists in two main predominant conformations, austenite (A-phase) and martensite (M-phase). Phase (crystallographic) changes occur either due to stress during procedures or due to changes in temperature during manufacturing. The A-phase is a hexagonal lattice that is quite strong and hard. The flexibility of the A-phase allows the file to be inserted readily within a curved canal. Once stress is encountered, as the file is in contact with the canal, a shearing transformation occurs, transforming the hexagonal lattice to a body-centered cubic lattice. This transformation gives rise to the M-phase which is more elastic and has greater tensile strength than the A-phase. Once the stress is released, M-phase transforms back to A-phase. If the A-phase is not present, superelastic behavior does not exist. Without the M-phase, a plastic strain recovery or shape memory would not transpire.

Answer 73

1st generation: U-shaped tips, radial lands, fixed tapers (0.02, 0.04, 0.06) and neutral or slightly positive rake angles (ProFile, LightSpeed systems). 2nd generation: Active cutting edges without radial lands, increased taper control, and improved cutting efficiency (K3, ProTaper). 3rd generation: Heat treatment of NiTi alloy to increase flexibility and cyclic fatigue resistance (M-Wire, Vortex Blue, Twisted Files). 4th generation: Introduction of reciprocating motion (SAF, Wave One). 5th generation: Offset center of rotation, creating a mechanical wave motion to reduce contact with dentinal walls and minimize torsional stress (ProTaper Next)

Answer 74

* Cyclic fatigue: from repeated compression/tension, more frequent in curved canals * Torsional failure: When the file tip binds the canal but the shaft continues to rotate Fractures occurred due to torsional failure with smaller files (55.7%), while larger files were prone to fracture from cyclic fatigue (44.3%).

Answer 75

The master apical rotary file is determined when a file requires 12 pecking motions to reach working length

Answer 76

up to 6 bacterial species per root canal, average 1.9. number of bacterial species significantly lower when duration of fracture was longer than 12 months.

Answer 77

* in 15/31 (48%), the primary root canal within the apical delta could be clearly identified * in 16/31 (52%) the primary root canal was indiscernible All canine teeth depicted an apical delta with various configurations except for 2 teeth that showed a single canal exiting at the apex. No teeth had lateral canals.

Answer 78

234.19 μm diameters of the apical foramina of the maxP4, manM1, and maxC showed no significant differences.

Answer 79

current evidence supports the contention that the prognosis for surgical treatment is approximately the same as that for nonsurgical retreatment

Answer 80

* fibroblasts * endothelial cells

Answer 81

granulation tissue

Answer 82

Undifferentiated ectomesenchymal cells in the perivascular tissue and fibroblasts in the adjacent connective tissue migrate into the wound

Answer 83

begin after 3 days, peak after 7 days

Answer 84

fibroblast growth factor [FGF] insulin-like growth factor 1 [IGF-1] platelet-derived growth factor [PDGF]

Answer 85

produce most of the structural proteins (collagen) involved in wound healing

Answer 86

type III collagen made first, type I made later

Answer 87

myofibroblast

Answer 88

48-72 hours after injury

Answer 89

All the cytokines! low oxygen tension vascular endothelial growth factor (VEGF) basic fibroblast growth factor (bFGF) acidic FGF (aFGF) transforming growth factors alpha and beta (TGF-α, TGF-β) epidermal growth factor (EGF) interleukin 1 (IL-1) tumor necrosis factor alpha (TNF-α) lactic acid

Answer 90

0.5-1mm/day

Answer 91

21-28 hours after closure

Answer 92

5-7 days after injury

Answer 93

Epithelial seal: * a single complete layer of epithelial cells covering the surface of the fibrin clot * Epithelium migrates 0.5-1 mm/day across the fibrin clot from both sides of the wound * in wounds healing by primary intention, formation of an epithelial seal typically takes 21-28 hours after reapproximation of the wound margins. Epithelial barrier: * the monolayer of cells forming the epithelial seal differentiates and undergoes mitosis and maturation to form a definitive layer of stratified squamous epithelium. * typically forms by 36-42 hours after suturing of the wound * characterized by a significant increase in wound strength.

Answer 94

36-42 hours (maturation of the epithelial seal formed by 21-28 hours)

Answer 95

MTA, followed by Retroplast, appear to have a clear advantage over the other available materials

Answer 96

PDT uses a photosensitizer (azulene in this study) that when activated by a low-intensity laser such as gallium-aluminum-arsenide lasers (diode, 720-904 nm), generates reactive oxygen species that destroy microorganisms. may be an excellent adjunctive in endodontics due to: * efficacy * low cost * lack of systemic effects * absence of microbial resistance * can reduce working time * improve some biological aspects of the treatment (such as enamel and dentin morphological alterations) * significantly reduce the microbiota within root canals, leading to a more successful outcome

Answer 97

* unspecified bacteria * enterococcus spp * yeast species (Candida spp) PDT or CSP alone provided a significant reduction in bacterial contamination both by unspecified organisms and enterococci. Yeast contamination was reduced by PDT or CSP alone, but no significant difference between pre- and post-treatment data was observed. Can be due to the relatively small baseline fungal burden.

Answer 98

standard chemical-surgical preparation: * 77.7% reduction in total bacterial load * 71.4% reduction in Enterococcus spp * 100% elimination of yeast PDT alone: * 90% reduction in total bacterial load * 100% elimination of Enterococcus spp. * 100% elimination of yeast chemical-surgical preparation 1st, PDT 2nd -> all remaining Enterococcus spp. were eliminated PDT 1st, chemical-surgical preparation 2nd -> the last remaining bacteria were eliminated

Answer 99

* 29/29 (100%) treated teeth maintained their stability and did not require extraction. * 7/29 teeth had a PAL prior to RCT, 0/29 teeth at follow up.

Answer 100

* 23/29 (79.3%) sustained no additional damage. * 5/29 (17.2%) had an enamel fracture requiring additional treatment to the crown after the initial treatment * 1/29 (3.4%) had additional abrasion but did not require treatment 29/29 (100%) treated teeth maintained their stability and did not require extraction.

Answer 101

10/19 (52.6%) dogs sustained trauma to other teeth at follow up (abrasion, UCF, CCF). 8 previously untreated canine teeth (in 7 dogs) fractured at follow up. 2 of these 8 fractured canine teeth involved the contralateral canine tooth.

Answer 102

No. Possibly. * 10/19 (52.6%) dogs had trauma (abrasion, UCF, CCF) to other teeth at follow up * 8 previously untreated canine teeth (in 7 dogs) fractured at follow up. Only 2 of these 8 (25%) fractured canine teeth involved the contralateral canine tooth

Answer 103

tooth transillumination (TTI) * sensitivity 0.59 (identified 59% (13/22) of the nonvital teeth) * specificity 0.95 (identified 95% (20/21) of the vital teeth) * PPV 0.94 * NPV 0.67 * accuracy 0.76 often failed to detect necrotic teeth

Answer 104

* step-down: determining WL, then shaping from coronal to apical. * crown-down: shaping from coronal to apical until WL is reached. in both techniques file size decreases. the difference is determination of WL at the begining or later.

Answer 105

Best filling at 2000 rpm, additionally improved by using a master GP cone. * results cannot be directly applied for guttaflow and other sealers (AH Plus Jet used in this study) * Higher than 2000 RPM was not tested. * Human studies have shown that higher speeds (10,000 and 20,000 RPM) have an increased risk for apical extrusion compared to 5000 RPM.

Answer 106

* The backfill technique: placing the rotating Lentulo spiral filler apically until backfill of flowable sealer cement is seen at the access site. Once backfill is seen, the instrument is slowly withdrawn from the canal with continued rotation. * The pumping method: placing the rotating Lentulo spiral filler at the apical region and applying slight pumping motion prior to withdrawing completely. The pumping technique with placement of the master gutta percha cone had a higher probability of success as compared to the backfill technique, but this finding lacked significance.

Answer 107

* success/NEF 99.16% success 90.83% NEF 8.33% * failure 0.83% ## Footnote *"Outcomes of root canal treatments with three different sealers for 120 fractured maxillary fourth premolar teeth in small-to medium-sized dogs". Daehyun Kwon et al. FVETS 2024.*

Answer 108

There were no significant differences between the three different sealers. ## Footnote *"Outcomes of root canal treatments with three different sealers for 120 fractured maxillary fourth premolar teeth in small-to medium-sized dogs". Daehyun Kwon et al. FVETS 2024.*

Answer 109

average working length: * 17.89 mm for the mesiobuccal root * 14.15 mm for the mesiopalatal root * 16.25 mm for the distal root The WL of each root tended to increase with increasing body weight. ## Footnote *"Outcomes of root canal treatments with three different sealers for 120 fractured maxillary fourth premolar teeth in small-to medium-sized dogs". Daehyun Kwon et al. FVETS 2024.*

Answer 110

* success/NEF 95.84% success 54.17% NEF 41.67% * failure 4.16% (significantly reduced success) ## Footnote *"Outcomes of root canal treatments with three different sealers for 120 fractured maxillary fourth premolar teeth in small-to medium-sized dogs". Daehyun Kwon et al. FVETS 2024.*

Answer 111

average master apical file (MAF) sizes: * mesiobuccal root 45 * mesiopalatal root 45 * distal root 60 MAF increased as body weight increased ## Footnote *"Outcomes of root canal treatments with three different sealers for 120 fractured maxillary fourth premolar teeth in small-to medium-sized dogs". Daehyun Kwon et al. FVETS 2024.*

Answer 112

Sealing off all potential routes of microbial escape from the root canal system is the goal of both nonsurgical and surgical treatment

Answer 113

Fungi and viruses recently have also emerged as potential causes of RCT failure and may play either a primary or secondary role in persistent periradicular pathosis

Answer 114

* hemotasis/inflammatory phase * proliferation phase * maturation/remodelling phase

Answer 115

Neutrophils * begin showing up after 6 hours * peak at 24-48 hours role is decontamination by phagocytosis of bacteria

Answer 116

Macrophages * after 48 hours * usually peak by 3-4 days function: * phagocytosis of bacteria and tissue debris * process and present antigen to T cells * secrete an array of cytokines

Answer 117

contact inhibition from opposite side

Answer 118

* reduction in fibroblasts, vascular channels, and extracellular fluids * upregulation of collagen fibrogenesis * collagen gradually reorganizes; this requires degradation and reaggregation of the collagen

Answer 119

approx 6 days

Answer 120

16 weeks (remodelling of the cortical plate will take longer)

Answer 121

After 10-12 days

Answer 122

About 8 weeks after surgery

Answer 123

root end filling/condensation

Answer 124

various carriers for placement of root end fillings

Answer 125

pre-forming MTA pellets for placement in root ends

Answer 126

The round bur has the best shape for removing osseous tissue. * Produces a wound site with less thermal damage and heals faster. * This type of bur also readily allows access of coolant to the actual cutting surfaces.

Answer 127

* Collagen-Based Materials - stimulate platelets and activate clotting cascade * Surgicel - physical barrier becomes a sticky mass and serves as an artificial clot * Gelfoam - stimulates intrinsic clotting pathway by promoting platelet disintegration * Bone Wax - mechanically plugs bleeding osseous sites * Ferric Sulfate - necrotizing agent that helps form a surface coagulum * Calcium Sulfate - allowed to set then mostly carved away. produces a physical barrier * Epinephrine Pellets - powerful local vasoconstrictor

Answer 128

From a biologic perspective the most appropriate angle of root-end resection is perpendicular to the long axis of the tooth

Answer 129

* citric acid * tetracycline * ethylenediamine tetraacetic acid (EDTA)

Answer 130

The ideal preparation is a class I cavity prepared along the long axis of the tooth to a depth of at least 3 mm

Answer 131

* zinc oxide eugenol cements (IRM and SuperEBA) * glass ionomer cement * Diaket * composite resins (Retroplast) * resin–glass ionomer hybrids (Geristore) * mineral trioxide aggregate (ProRoot-MTA)

Answer 132

The main constituents of this material are * calcium silicate (CaSiO4) * bismuth oxide (Bi2O3) * calcium carbonate (CaCO3) * calcium sulfate (CaSO4) * calcium aluminate (CaAl2O4)

Answer 133

extended setting time of 2h 45 mins + continues setting for weeks

Answer 134

Cementum regeneration adjacent to/overtop of MTA The importance of the presence of cementum-like tissue adjacent to MTA cannot be understated. Cementum deposition is essential to regeneration of the periodontal apparatus.

Answer 135

largest reduction in tooth stiffness results from additional preparation, especially the loss of marginal ridges. possible decrease in tooth strength can be attributed to dentin aging and to a smaller extent to dentin alteration by endodontic irrigants

Answer 136

reactionary (left), reparative (right) * reactionary: made by existing odontoblasts and is tubular * reparative: made by newly differentiated odontoblast like cells and is atubular

Answer 137

* necrosis of adjacent pulp * inflammation of contiguous tissue * beneath region of coagulation necrosis odontoblast like cells differentiate and produce dentin matrix

Answer 138

The often profuse bleeding that occurs is controlled by lavaging the pulp with NaOCl * antimicrobial * appears to have no adverse effects on pulpal healing, odontoblastic cell formation, or dentinal bridging …Does anyone do this??? it sounds crazy. it’s on page 840 if you’re interested.

Answer 139

Apexogenesis: saves some vital pulp tissue in the root end and allows the tooth to mature it’s own root. Apexification: has no vital pulp tissue left and is based on creating an external apical stop in the form of a cementoid or osteoid layer on the outside of the tooth.

Answer 140

Apexogenesis

Answer 141

If it fails or even if it succeeds but still need RCT treatment later on MTA is cement and very challenging to remove/work through.

Answer 142

Apexification

Answer 143

Will not cause any continued root development in the form of increased length or wall thickness.

Answer 144

need to replace CaOH every 3 months for 9-24 months

Answer 145

significantly shorter treatment period - MTA barrier is allowed to set, then after a few weeks obturation may be completed and hard tissue barrier will grow externally over time. N.B. There is a JVD describing a modified technique in a cat where a hard floor of glass ionomer was put over the MTA and treatment completed in a single appointment.

Answer 146

Stem cells of the apical papilla (SCAPs)

Answer 147

* Persistent or reintroduced intraradicular microorganisms * Extraradicular infection * Foreign body reaction * True cysts

Answer 148

* chloroform * methylchloroform * eucalyptol * halothane * rectified turpentine * xylene

Answer 149

If the separated instrument extends into the straight coronal portion of the canal retrieval is likely

Answer 150

if the instrument has separated deep in the canal and the entire broken segment is apical to the canal curvature orthograde removal will not be possible and attempts to do so could lead to a much higher rate of iatrogenic complication

Answer 151

nickel-titanium instruments often break up into fragments when subjected to the energy supplied by an ultrasonic instrument

Answer 152

Tube and H-file technique

Answer 153

Wire and loop technique

Answer 154

Used for removing separated instruments A,B: cancellier instrument. C,D: mounce instrument. cyanoacrylate used to bond the instrument to the separated file

Answer 155

* blunderbuss canal * thin/fragile dentinal walls

Answer 156

* Cessation of root development * leaving teeth prone to fracture continued root development following regenerative endodontics / apexification in immature teeth: * regenerative endodontics: increase in root width 28.2%, in root length 14.9% * apexification with MTA: increase in root width 0%, in root length 6.1% * apexification with calcium hydroxide: increase in root width 1.52%, in root length 0.4%

Answer 157

* Appropriate source of stem cell/progenitor cells * Growth factors that are capable of promoting stem cell differentiation * Appropriate scaffold for the regulation of cell differentiation

Answer 158

* morphogenetic protein * transforming growth factor β * fibroblastic growth factor

Answer 159

* The primary goal: elimination of symptoms and evidence of bony healing. * The secondary goal: increased root wall thickness and/or increased root length which is considered desirable yet perhaps not essential. * The tertiary goal: positive response to vitality testing.

Answer 160

* Bleach <3% (greater than 3% can be cytotoxic to PDL cells and stem cells) * Chlorhexidine 2% is antimicrobial but has serious cytotoxic effects on stem cells – may not be irrigant of choice * EDTA promotes survival of stem cells and can release growth factors from dentin

Answer 161

* Can eliminate bacteria residing in dentinal tubules * May be cytotoxic to stem cells at high concentrations * May cause tissue reactivity

Answer 162

No significant histologic difference. PRP/PRF may be useful when there is insufficient bleeding.

Answer 163

Tooth discoloration

Answer 164

Clinical success rates in published clinical cases exceed 90%

Answer 165

* fever * pain on chewing * irritability * diminished appetite * selective rejection of hard food * dropping food * unilateral chewing (more calculus on affected side) * sensitivity to hot/cold * pawing at mouth * rubbing head/chin on ground or furniture * head shy * ptyalism * tooth discoloration * drying tracts * facial swelling with abx responsiveness ## Footnote Lewis

Answer 166

* acute apical periodontitis of pulpal origin * chronic apical periodontitis * periapical abscess with sinus * periapical abscess w/o sinus * radicular cysts

Answer 167

* acute apical periodontitis– primary * acute apical periodontitis– secondary (exacerbation of chronic apical periodontitis), NON-epithelialized * acute apical periodontitis– secondary (acute exacerbation of chronic apical periodontitis), epithelialized * chronic apical peridontitis (periapical granuloma), NON-epithelialized * chronic apical periodontitis (periapical granuloma), epithelialized * periapical true cyst (originates from cell rests of Malassez) * periapical pocket cyst (epithelial cell-lined, sack-like extension of the root canal)

Answer 168

* sclerosing osteitis * chronic focal sclerosing osteomyelitis * chronic local sclerosing osteomyelitis * local chronic sclerosing osteomyelitis * chronic productive osteitis * periapical pulpo-osteosclerosis * pulpo-periapical osteosclerosis * reactive osteosclerosis * apical condensing osteitis * periapical osteosclerosis * periapical condensing osteitis * enostosis * bone whorl * periradicular bone condensation * osteitis condensans

Answer 169

infection of the root canal and its contents * through breaches in dental hard tissue (most common) * severed periodontal blood vessels * anachoresis

Answer 170

continued intraradicular microbial presence within the complex apical root canal system: * lack of aseptic control * poor access cavity design * missed apical and non-apical ramifications * inadequate instrumentation and debridement * marginal temporary or permanent restoration leakage

Answer 171

* pulp exposure * pulp becomes colonized by oral bacteria * inflammatory response (pulpitis) occurs * pulp becomes necrotic

Answer 172

in low grade pulpitis residual infection following endo tx leads to a net increase in bone production rather than destruction as a result of increased osteoblastic activity. dogs can, however typically it is seen as asymptomatic and the diagnosis needs to be supported with histopathology not just rads so underrepresented in dogs

Answer 173

intact teeth: 90% bacteria are obligate anaerobes pulp exposure teeth: almost 70% obligate anaerobes within their apical third

Answer 174

* histo 7d * rads 15d * CBCT 7d

Answer 175

* spontaneous resolution * further intensification * granuloma formation * abscess formation * sinus formation * spread into bone

Answer 176

Uncommon in dogs (mostly dentigerous cysts, no true cysts in dogs). true cysts originate from proliferation of the cell rests of Malassez (from Hertwig’s epithelial root sheath); molecular mechanisms stimulate epithelial cell proliferation and promote bone resorption. pocket cysts are an extension of the root canal cavity wall of neutrophils at apical foramina. forms in response to microbes in root canal. periapical cysts do NOT occur in same frequency or presentation as in humans. Periapical cysts in dogs are RARE in literature and frequently don’t have histo to support their origin

Answer 177

in order of increasing pathos’s: * zone of stimulation * zone of irritation * zone of contamination * zone of infection zone of stimulation (results in increased bone density and thicker trabeculae)

Answer 178

irreversible pulpitis 10x more likely to occur in mandible than maxilla, most often in premolar-molar region (anecdotally around 309/409)

Answer 179

idiopathic osteosclerosis pseudonyms: * dense bone island * bone scar * bone eburnation * bone whorl * exostosis * local bone sclerosis * focal periapical osteopetrosis

Answer 180

Difficult and still not 100% * teeth with large deep carious lesions or previous endodontic tx have condensing osteitis (inflammatory) * teeth with no evidence of endo dz or only superficial carious lesions are deemed idiopathic osteosclerosis (human differentiation)

Answer 181

apical periodontitis Tx goals: * maintain tooth * resolve pain/symptoms * regression or resolution of periapical radiolucencies on rads * wound healing (resolve inflammation at a tissue cellular or molecular level) repair because regeneration is not possible to restore original architecture post-natal; most post-natal healing is combo of regeneration and repair ## Footnote Lewis

Answer 182

Somatic cells have a limited life span and capability for division known as Hayflick limit

Answer 183

standard (orthograde) RCT (or ext not mentioned) with surgical (retrograde) RCT less common. No difference in long-term success between staged RCT vs 1 stage. Short-term studies in dogs showed superior healing with inter-appointment root canal dressing (2 stage). No difference in outcome based on whether rotary or manual instrumentation was used for shaping and debriding the root canal in dogs.

Answer 184

if asymptomatic: not treated if symptomatic: RCT or XSS

Answer 185

when no radiographic abnormalities were detected, histo analysis confirmed apical periodontitis in **40%** of cases when periapical disease was interpreted radiographically, **90%** of roots had apical periodontitis diagnosed histologically

Answer 186

many don’t even try * condensing osteitis: increase in periapical radiopacity, associated with endo dz * reactive bone: less well defined * osteosclerosis: typically not associated with endo dz or periapical region

Answer 187

* most common: **target lesions** where radiolucent border surrounded by radiopacity * less common: **focal lesions** which was homogenous and lacked the circumferential halo * **lucent lesions** which periapical radiolucency w fibre-osseous pattern on histo * **multi confluent lesions** w multiple confluent opacities * **resorptive lesion** involving external root resorption

Answer 188

same 5 radiographic patterns as for condensing osteitis: * ‘target’ lesion: a radiolucent border surrounding a radiopacity (most common for condensing osteitis) * ‘focal’ lesion: homogenous, lacks the circumferential halo (most common for idiopathic osteosclerosis) * ‘lucent’ lesion: a periapical radiolucency with a fibro-osseous pattern on histological analysis * ‘multiconfluent’ lesion: multiple confluent opacities * ‘resorptive’ lesion: any pattern involved with external root resorption

Answer 189

7.1% 30-50% (same # for dogs)

Answer 190

cortical bone (cancellous bone does not accurately reflect bone loss)

Answer 191

in dogs: recommended 3-6 mo recheck rads then annually for remainder of life (we say 5y). in humans: recheck rads 3, 6, 12, 24mo and as long as 4y to see resolution of chronic periodontitis radiographically within 1y.

Answer 192

* if affected tooth is asymptomatic despite rad changes * decrease in radiographic lucency * no change in size of periapical radiolucency * initial increase in size of periapical radiolucency but no further change * resolve in radiographic abnormalities

Answer 193

* viscosity to fill irregularities in the root canal * bond from the core obturation material to dentinal wall

Answer 194

to compare the use of a polymer epoxy resin sealer (AH Plus), to a silicone-based sealer (GuttaFlow 2), when using a cold injection technique with a single master cone of gutta-percha for obturation. an apical dye leakage test was utilized to compare the two endodontic sealer systems. * Following obturation and restoration, specimens were immersed in India ink for 48 hours. * A tooth mineral clearing technique was utilized to render the tooth samples transparent. * Subsequently, the apices were evaluated for prevalence and magnitude of apical dye penetration under magnification.

Answer 195

excessive demineralization affecting ability to perform apical dye leakage test

Answer 196

cold injection sealer with single GP cone

Answer 197

* preparation (includes access) * sterilization * obturation

Answer 198

* ZOE * CaOH * GI * bioglass * polymer resins * silicone based

Answer 199

epoxy-amide resin made of 2 pastes (1 catalyst, 1 base) that are mixed together and polymerize to form epoxide-amide addition polymer via thermal poly addition reaction. Both pastes contain radiopaque fillers and Aerosil. Come in double barreled syringe with self mixing tip. * polymerization is temperature dependent. * working time 4 hours, minimum setting time 8 hours. * slight shrinkage during polymerization: 1.76% decrease in volume. * Solubility 0.32%. * Tensile bond strength 4-7 MPa.

Answer 200

* easy to mix and place in canal * slightly thixotropic (decrease viscosity under slight pressure increasing flow capabilities). * carcinogenicity * allergenicity * Older formulations had higher release of formaldehyde during polymerization leading to cytotoxicity. Newer formulations have minimum amount of formaldehyde release (3.9ppm) and are nontoxic in mutagenicity and systemic toxicity tests. Cytotoxic for 4 hours corresponding to working time.

Answer 201

Guttaflow 2 is a silicone based sealer combining sealer RoekoSeal (polydimethysiloxane mixed with filler and radiopaque materials), ground GP powder, and silver nano particles (aka magic goo). * working time 10-15 minutes * curing time 25-30 minutes. * post polymerization expands volume by 0.2% * solubility 0%. * shear bone strength 1MPa (no data from manufacturer for this #) * Thixotropic with optimal flow. Guttaflow 2 FAST: * working time 4-5 minutes * curing time 8-10 minutes

Answer 202

GF 2 is easy to work with, provides optimal flow and easily placed in canal with speedy cure. Good bioavailability and nontoxic. In tissue can encapsulate in fibrous granulation bed (but minimal blushing doesn’t appear to be an issue)

Answer 203

AH plus had deeper penetration than GF but not significant if apical dye leakage is past apical delta thought is the apical seal is not sufficient

Answer 204

Microleakage of the restoration

Answer 205

in combination with thixotropic materials can have increased risk of extrusion of materials into periapical region (the ability to decrease viscosity under slight pressure, thus increasing the flow capabilities)

Answer 206

Tubules contain Tomes fibre, nerve ending, and fluid Tomes fibres are the odontoblast processes which perforate the dentin. N.B. Tomes process is something different - involved in enamel secretion by ameloblast

Answer 207

reversible pulpitis: * pulp can return to a non-inflamed state. * generally a symptom of pulpal inflammation caused by some form of short-term irritation such as caries, dental treatment, or trauma irreversible pulpitis: * tooth will progress to pulp necrosis

Answer 208

Anachoresis – infection of a tooth via bloodstream or regional lymphatics

Answer 209

Trauma causes inflammation within the pulp. Since it is in a confined space, as inflammation progresses rather than classical swelling (enlargement of tissue), pressure within the pulp chamber develops, leading to collapse of venules. This prevents blood from draining away and leads to pulp strangulation.

Answer 210

in the absence of bacterial contamination pulp necrosis does not cause periapical periodontitis

Answer 211

Pulp exposure caused by crown fracture of 108 has resulted in **hyperplastic pulpitis**

Answer 212

Histopathology

Answer 213

* acute apical periodontitis of pulpal origin * chronic apical periodontitis * periapical abscess with sinus * periapical abscess without sinus * radicular cysts

Answer 214

Rads: normal or slight widening of PDL at apex. Clinical signs: tenderness, pain on palpation/percussion (tough to see in vet patients).

Answer 215

produces the classical periapical lucency seen on radiographs

Answer 216

May be no signs if acute. May be chronic signs of endodontic disease if an acute flare of a chronic process.

Answer 217

A periapical abscess which has arisen from chronic apical periodontitis.

Answer 218

endodontic disease which has progressed and made a draining tract (sinus). sinus tracts may be seen * facially * suborbital * ventral‐mandibular * within the oral mucosa (gingival or at the mucogingival line)

Answer 219

proliferation of cell rests of Mallasez create an apical epithelium lined cyst cavity at the apex. two types of radicular cysts: * Pocket cyst: when it communicates with the pulp * True cyst: when cavity lining is complete and does not communicate with the pulp radiographically appears as a classic radiolucency.

Answer 220

a radicular cyst is differentiated from a periapical granuloma via histopathology. * cysts are sack-like structures with a complete epithelial lining. * granulomas only contain a mixed cell population including epithelial tissue. both appear as a lucency on rads

Answer 221

Reactive bone formation and increased radiodensity of periradicular alveolar bone. Pulp inflammation stimulates osteoblast activity.

Answer 222

Can’t be differentiated on rads

Answer 223

* Condensing osteitis * Radicular ankylosis * external root resorption occurs in some endodontic disease * Periradicular osteomyelitis (alveolar bone expansion) appears as osteopenia and expansion of the alveolus

Answer 224

* Condensing osteitis * Chronic focal sclerosing osteomyelitis Condensing osteitis and periapical osteosclerosis are indistinguishable radiographic signs seen as increased bone density involving periapical and periradicular alveolar bone.

Answer 225

Primary endo usually have a crown fracture. If it continues to a wide PDL can be called a J lesion. Primary perio usually have deep pockets and wedge shaped periodontal lesions.

Answer 226

* Class I - Primary endo * Class II - Primary Perio * Class III - Separate endo/perio component *Memory trick: alphabetical order - Endo, Perio, Separate*

Answer 227

* Group I - **hand instruments**. barbed broaches, K files, H files. for pulp removal and initial canal shaping. * Group II - **low-speed latch-type instruments**. Gates-Glidden drills, Peeso reamers. to enlarge the coronal part of the root canal. * Group III - **engine-driven NiTi rotary instruments** adapt to curved canals. LightSpeed etc. * Group IV - **engine-driven self-adjusting files (SAF)** a hollow NiTi. 3D adaptation to the shape of the root canal, both longitudinally and in cross-section. * Group V - **engine-driven reciprocating instruments**, move back and forth in a reciprocating motion rather than a full rotation. Think endo pulse, jack-hammer, woodpecker or… * Group VI - **ultrasonic instruments**.

Answer 228

Ledging, gouging, zipping, stripping, and translation are all caused by straight–stiff files working in curved canals and trying to regain their straight shape.

Answer 229

Barbed broach * for removing pulp tissue whole * Insert, twist 180 and remove * Will grab tooth walls and ruin everything/break - very fragile

Answer 230

Gates glidden drill * enlarge access and flare coronal portion of access * ISO sizes in increments of 20 starting at 50 (smallest is ISO 50, largest is ISO 150)

Answer 231

Reamers and files are both made the same way from a triangle, square, or rhomboid blank. Twisted to create a spiral Files: * twisted more than reamers (more flutes per mm) * have ¼ to >1/2 spirals per mm * Tend to carry better and give better tactile sense but don’t cut as aggressively * Used in a push-pull or in a ¼ turn and pull fashion Reamers: * have <1/10 - <1/4 spirals per mm. * They are more aggressive at cutting but poorer carrying * Used in a clockwise turning fashion

Answer 232

H-File. Made by machine cutting a round blank to remove a triangular spiral and thus leaving a continuous spiral with a thin core.

Answer 233

K file * Square makes a cutting circle in 1/4 turn (90 deg turn will bring a new cutting face the position where adjacent one started) * Triangle makes a cutting circle in 1/3 of a turn (need to rotate a triangle 120 deg to bring another cutting flute into position of the adjacent one) * Rhombus needs to turn 180 degrees because it’s asymmetrical need to go halfway around to bring a new flute to the position of the adjacent cutting flute (which is on the opposite side)

Answer 234

K file: stiffer, lower cutting ability, less prone to breakage H file: less stiff, more aggressive cutting, more prone to breakage

Answer 235

Will thread into dentin when rotated and dethreading it will stress or break the metal. Basically an H file is a long skinny screw.

Answer 236

Taper: the gradual increase in the diameter of an endodontic file from the tip to the handle. standard taper is 0.02, meaning that for every mm of length of the file the diameter increases in 0.02 mm.

Answer 237

White Yellow Red Blue Green Black Begins at 15, increases by 5’s until 60 then by 10’s for every colour. N.B. Lightspeed does have a 65 file, it is also blue like the 60. 70’s are green

Answer 238

it is the fraction of a mm in width at the tip of the file. tip diameter of 50 is 0.5 mm, of 15 is 0.15 mm, of 100 is 1 mm.

Answer 239

Blunt tips - will only follow a canal, won’t cut a new one. Radial lands - spaced between cutting edges that are at the periphery of the file but non cutting. Negative rake angle - promotes scraping rather than cutting.

Answer 240

For ribbon shaped canals and for making a good coronal flare (used in a push-pull manner only and more aggressive cutting).

Answer 241

lateral compaction have a pointy end

Answer 242

Vertical compaction have a flat end

Answer 243

made from the sap of the “palaquim” tree (Palaquim gutta)

Answer 244

* alpha phase - sticky, pliable, will flow under pressure. * beta phase - cones are beta phase. more rigid. Heat will transform from beta to alpha; Cooling and condensing will shift it back (VERY slow cooling will allow it to remain alpha, but this doesn’t usually happen with normal compacting and cooling)

Answer 245

* 18–22% gutta‐percha * 59–76% zinc oxide * remainder being a combination of radiodense materials and plasticizers Cohen’s lists: * Gutta-percha 19–22% * Zinc oxide 59–79% * Heavy metal salts 1–17% * Wax or resin 1–4%

Answer 246

Standard cones correspond to ISO sizes. Conventional cones manufactured to be similar in taper to spreaders for use as accessory cones.

Answer 247

* lubricate the root canal * dissolve organic pulp and necrotic debris * soften dentin * destroy bacteria * flush debris from the canal * remove the smear layer

Answer 248

* Lubricates * softens dentin * dissolves inorganic debris * bactericidal

Answer 249

not effective in removing the biofilm or dissolving necrotic organic tissue

Answer 250

* dissolve inorganic material * dissolve organic tissue * biocompatible * antibacterial * non‐toxic * penetrate dentinal tubules * easy to use Bleach (NaOCL) either full strength (6%) or half strength (3%)

Answer 251

Instruments are passively placed in the canal and rotated 90° clockwise to engage canal wall dentin and then rotated counterclockwise as axial force is applied to the instrument. Helps K-Files remain centred with fewer complications

Answer 252

Place fitted master cone in the canal with the sealant. Pre-fit a spreader and after master cone in place. Jam the spreader in to 1-2 mm short of apex. Don’t split the root and place an accessory cone. Repeat until 2/3 of canal is obturated

Answer 253

Heat and roll together 2-3 large GP cones and place while warm. May help in very large canals which are challenging to instrument. Can re-soften the tip for better adaptation with heat eucalyptol or chloroform dip for 3-5 seconds. Used in very large immature canals.

Answer 254

Usually used with warm compaction. Use a heated instrument (red-hot) to heat the GP core after in place with sealer. Withdraw the heated instrument and use a plugger to vertically compact the warm material. Repeat with additional pieces of GP until filled.

Answer 255

Measure plugger 5-7 mm short of the apex. Place a GP cone and sealer and then put a plugger that can be heated. Push it to 2-3 mm from the measured point and allow it to cool while maintaining the force. Heat it again prior to withdrawl. Fill remainder of canal with sealer and GP.

Answer 256

Plug made for use with lightspeed. Place to 2-3mm from the apex for a test fit. Apply sealer with a lentulo and spread with a paper point. Place the plug and check with a rad. Unthread the carrier. Place a GP cone and more sealer. Remove excess with a heated plugger and then vertically compact

Answer 257

Basically Guttaflow, polydimethylsiloxane containing small particles of gutta‐percha. No additional sealer. Fill canals by injection or lentulo Can use with a master GP cone or above techniques for large canals

Answer 258

Sealer applied Heated GP placed into canal and compacted while warm Will have shrinkage due to cooling. Compacting it while warm will compensate for the shrinkage

Answer 259

Use a slow-speed handpiece at 10,000RPM and a compacting instrument. Feed instrument in beside the GP. As it rotates heat is generated and blades force the GP apically and laterally. Feed in additional points as it’s withdrawn. Not usually used in vet endodontics

Answer 260

Refers to the vertical dimension of the fill. * filled beyond the apex is overextended * filled short of the apex is underextended

Answer 261

It refers to the fill in any dimension. overall quality of the obturation.

Answer 262

some sealers (eugenol) will inhibit the polymerization of composites

Answer 263

If struggling to find a canal expose the whole floor of the chamber in the region and then put a drop of bleach or hydrogen peroxide – will bubble over the canal

Answer 264

to establish an unrestricted passageway from the crown through the pulp cavity to the apical terminus of the endodontic canal

Answer 265

Chelating agents such as ethylene‐diamine‐tetra‐aceticacid (EDTA) can be used to aid in the dissolution of inorganic calcification within the canal

Answer 266

penetration of the pulp chamber floor but not completely through the root/crown wall, typically with burs or files during exploration for root canals. Canals can also be gouged, but this is more appropriately termed ledging or hedging. If gouging results in complete extension into the periradicular tissues or outside the crown, this is called a perforation.

Answer 267

ledging or transportation

Answer 268

prevention: * prebend stiff files * use flexible files * don’t use too much apical presssure management: * prebend a file at 45 deg and use with tip towards the trus canal, springiness should help direct it into place. * continue with bent files until filing complete

Answer 269

Zipping or elliptication

Answer 270

Enlarge the whole canal to remove the elbow adjacent to the apical vault

Answer 271

Stripping/lateral perforation

Answer 272

Stripping is caused by overzealous instrumentation in the mid root area. Prevent with judicious filing and anti-curvature pressure. Treat perforation with MTA. If it won’t stop bleeding use an intracanal medicament CaOH for 2-3 weeks.

Answer 273

Backup technique is used to create a new apical stop.

Answer 274

* apexogenesis (VPT in immature vital teeth with open apices) * apexification (for immature, non-vital permanent teeth with open roots, aiming to induce a calcified barrier at the root tip to allow for proper root canal obturation) * regenerative endodontics

Answer 275

The goal is to stimulate root end closure (or a hard tissue barrier to serve as a closed root end) soin an immature non-vital permanent tooth with an open apex so that eventually a standard endodontic procedure may be carried out.

Answer 276

6-24 months

Answer 277

* EDTA promotes the survival of apical papilla stem cells * EDTA can expose a reservoir of growth factors from dentin (bioactive molecules entrapped in the dentin matrix during dentin mineralization can be released by rinsing dentin with chelating agents)

Answer 278

Primary: * elimination of symptoms * evidence of bony healing Secondary: * increased root wall thickness and/or increased root length * desirable, not essential Tertiary: * positive response to vitality testing

Answer 279

* stem cells * growth/differentiation factors * scaffold

Answer 280

periapical cyst (those pesky rests of mallasez) apicoectomy, curettage, and histopathology indicated

Answer 281

The most common indications for surgical treatment is when standard endodontic therapy is not possible or has been ineffective in resolving periapical problems * internal root apex inaccessibility * external root end complications

Answer 282

The 4 categories of apical surgical intervention are: * periradicular drainage * periapical curettage * apical resection or apicoectomy * retrograde obturation or filling

Answer 283

* Removal of a diseased apex * Allow access for retrograde filling

Answer 284

A flat resection

Answer 285

Class I preparation

Answer 286

Slot of Matzuri

Answer 287

Zinc oxide cements or MTA

Answer 288

Dentigerous cysts are associated with an embedded/impacted adult tooth. have also been associated with deciduous teeth. Impacted teeth occur most frequently in the canine (maxillary) and premolar teeth of toy and small breed dogs as well as in brachycephalic breeds. clinical presentation: * large fluctuant swelling * missing tooth on oral exam * incidental finding on dental radiographs

Answer 289

* significant bone destruction w possible secondary pathologic fx * external root resorption * pulpitis of adjacent teeth due to lytic expansile nature of dz

Answer 290

* perio-endo lesion * blunt trauma * systemic bacterial infection * internal root resorption * hyperthermia (thermal injury)

Answer 291

* in human lit possibility of malignant transformation to ameloblastoma / SCC * histopathology is important since suspected dentigerous cysts have been found to actually be odontogenic keratocysts, unicystic ameloblastomas, and dental follicles

Answer 292

no evidence of cyst recurrence or RCT failure increased bony opacity at apex of 304 (RCT tooth): * condensing osteitis * cementoma * idiopathic osteosclerosis * possibly normal maturation and incorporation of bone graft material

Answer 293

* central cavity * epithelial lining * fibrous capsule

Answer 294

odontogenic cyst derived from odontogenic epithelium. cyst encapsulates the crown of the unerupted tooth and is attached to the CEJ. dentigerous cysts are typically asymptomatic but can become large expansile and destructive to surrounding bone

Answer 295

fluid accumulates between either the REE and enamel or in between layers of enamel organ. fluid accumulation occurs as a result of pressure exerted by an erupting tooth on an impacted follicle which obstructs venous outflow leading to rapid transudative mvmt across capillary wall. This increased hydrostatic pressure separates follicle from crown.

Answer 296

necrotic deciduous teeth; in vet med most dentigerous cysts are associated with uneruppted mandibular P1 which have no deciduous precursor

Answer 297

* MMPs (2 and 9) might be a growth mechanism of odontogenic cysts * PTHrP involved in many physiological processes including endochondral bone growth and tooth eruption associated with osteoclastogenesis * PTHrP induces RANKL production by osteoblasts * PTHrP noted in fibrous and cystic lining * OPN expression pattern in epithelial lining of dentigerous cysts might be an early indicator of neoplastic transformation of dentigerous cyst into a unicystic ameloblastoma * IHC association with RANK * RANKL * OPG

Answer 298

ameloblastoma and SCC

Answer 299

* Group 1: Manually operated instruments. barbed broaches, K-files, H-files * Group 2: Low-speed engine-driven instruments with a latch type attachment. Gates-Glidden drills, Peeso reamers Usually used in coronal portion (not curvature) * Group 3: Engine-driven Ni-Ti rotary instruments. They consist of a rotating blade that can safely be operated in curved root canals. * Group 4: Engine-driven, self-adjusting instruments, adapt 3D to the shape of the root canal. Self-adjusting files (SAF) * Group 5: Engine-driven reciprocating instruments. WaveOne, other reciprocating rotary Ni-Ti files * Group 6: Ultrasonic and sonic instruments. Used for cleaning, irrigation, and removing posts

Answer 300

Smaller. Larger files more prone to cyclic fatigue.
Smaller NiTi files are generally less prone to torsional failure because they have a lower metal mass and a smaller cross-sectional area, which means they are more flexible. While larger files have higher torsional strength, smaller files are preferred for narrow or curved canals to reduce the risk of fracture from torsional stress.

Answer 301

entire tooth discoloured tan ## Footnote purple or gray 71 dogs 84 teeth total
Gross signs of total or partial pulp necrosis in 92% of these teeth (based on no bleeding at all or no bleeding in coronal pulp but bleeding in radicular pulp)
57% of teeth had radiographic sign of endodontic disease
N.B. Only examined pulp on 64 teeth and had rads on 84 so % numbers based on different denominators
Concluded risk of unnecessary endodontic therapy is <10% in discoloured teeth even without radiographic changes indicative of endodontic disease.

Answer 302

Factors which affect results: * Effective disinfection and sealing of the coronal access * Diameter of the open apex: successful with as small as 0.5 mm, much more successful if >1mm * Patient’s age: in people 8-16 years; suggest age in pets of 5 months to 2 years

Answer 303

While nifty to read this is an old-school rehash of Cohens later chapters… skipperoo

Answer 304

Step by step to accompany the article where they did this in a cat.
Apexification: * a method of inducing formation of a calcified barrier in a root with an open apex or the continued apical development of an incompletely formed root in teeth with necrotic pulp * Involves cleaning and debriding the root canal, then putting 2-3mm of MTA at the level of the apical foramen within the canal to induce cementogenesis at the apex * Usually 2 stages – place MTA and fill with CaOH or other medicament, then finish obturation at another time * Can do a 1 visit technique by adding a barrier of self curing GI over the MTA and then obturating immediately

Answer 305

Retrospective analysis of success/failure of VPT for crown reductions and crown fractures used CaOH as medicament for all of them.
Paper is a bit wacky, numbers aren’t totally consistent, vary from one place to another… – they did owner surveys to ask if teeth were still vital (90% thought they were) and rechecked 32 of them.
Of the teeth that actually got rechecked 100% of the crown reductions were vital and 100% of the CCF >7days before VPT teeth were non vital
In the 4 immature teeth with CCF’s even though they became non vital 3/4 teeth had additional radicular development to permit RCT.

Answer 306

The dental pulp is richly innervated by both myelinated (A-fibers, mostly A delta-type) and unmyelinated (C-fibers) axons.
A-fibers * responsible for the sensitivity of dentin. * They respond to stimuli that induce sharp pain in human teeth for example drilling of dentin and drying of dentin with air blasts. C-fibers * activated only when the stimuli used reach the pulp proper. * They respond to intense heating. * In human teeth dull pain is induced at a temperature level corresponding to the heat thresholds of intradental C-fibers. * C-fibers may play a role in the mediation of the dull pain connected with pulpal inflammation

Answer 307

Triggered by mechanoreceptors. These are especially numerous in the apical 1/3 of the PDL. dull aching or throbbing pain should respond to local anesthesia

Answer 308

Lewis JR. Dental bulge restoration and gingival collar expansion after endodontic treatment of a complicated maxillary fourth premolar crown-root fracture in a dog. J Vet Dent. 2008;25(1):34-45. A
Biologic width is approximately 2 mm in the dog – 1 mm for gingival fibre attachment to the tooth ## Footnote 1 mm for junctional epithelium
This 2 mm distance must be maintained from the edge of any restorative placed to the crest of the alveolar bone (i.e. must recontour bone to preserve this 2mm when placing subgingival restorations)
The dental bulge is a protective feature of the tooth helping to direct food and debris away from the sulcus
Gingival collar expansion was accomplished by means of an oblique sliding flap

Answer 309

A

Coronal flaring

Uses gates gliddens and other NiTi instruments

Answer 310

A

Advice that the master apical rotary file (MAR) be determined when a file requires 12 packs to reach working length. (Senia & Wildey)

Answer 311

A

Safety, effectiveness and simplicity

Answer 312

A

Preparation, sterilization, obturation

Answer 313

A

standard root canal of extracted canine teeth in dogs, sealed with guttaflow or AH+ and evaluated for sealing ability with a dye leakage test.

Answer 314

A

No significant difference in the prevalence of microleakage or the magnitude of penetration

Answer 315

A
Clearing method is finnicky and needs to be watched carefully for complete dissolution of the sample
completely dissolved 6 AH+ teeth and 3 guttaflow teeth out of 20 in each group

Answer 316

A

Less fomaldehyde release on setting

Answer 317

A

Epoxy amide sealer

Answer 318

A

shrinkage of 1.7%

Answer 319

A

Silicone based sealer

Answer 320

A

Expansion by 0.2%

Answer 321

A

AH+ - solubility of 0.3%; guttaflow 2 has solubility of 0%

Answer 322

A

dye penetration

fluid filtration methodology

dye extraction methods

bacterial or toxin infiltration methods

Answer 323

A

Lubrication of files and chelation or softening of inorganic material of the canals
EDTA

Answer 324

A

5.25% either full or 1/2 strength

Answer 325

A

sterilization of the canal and to dissolve organic material.

Answer 326

A
standard or Type 1 as master cones - conventional or Type 2 with a tapered point similar of spreader and used as accessory points

Answer 327

* instrument fatigue from overuse: Ni-Ti files do not show visible signs of fatigue similar to stainless steel files, and should be discarded after 3 to 6 uses. * applying excessive apical pressure (rotary motion) * manufacturing defects are rare

Answer 328

at the shaft-shank junction under extreme force/torque, but it can occur anywhere along the file

Answer 329

* take a radiograph * use loupes or surgical microscope for visualization * attempts to remove (file braiding, magnetized instruments, ultrasonic endo tips) * enlarge access * owner informed * then consider switching to different option

Answer 330

* positioning the coronal access opening in a downward direction and then placing an ultrasonic scaler in contact with the tooth may vibrate the fragment out of the opening. * the access can be slightly enlarged and the scaler touched against the exposed portion of the fragment to loosen it with ultrasonic activation. * vibrating around the instrument in a counterclockwise fashion creates an unscrewing force to the fragment as it is being vibrated. This will assist removing an instrument fragment that has a clockwise cutting action. * Ni-Ti instruments often break into fragments when subjected to the energy supplied by an ultrasonic instrument. * for deeper fragments, a plugger or spreader can be placed in direct contact with the object, and the ultrasonic scaler touched to the spreader and vibrate the object indirectly with ultrasonic energy. Although ultrasonic methods may be helpful, the ultrasonic instrument itself may separate or push the separated file further into the canal.

Answer 331

* obturate around it as long as cleaning, shaping, and obturation of the apical 1/3 is possible * convert to surgical endodontic therapy (resect the apex, remove the fragmented instrument, and seal the remaining portion of the root) * hemisection with extraction of the involved root and its associated portion of the crown * tooth extraction

Answer 332

* NiTi files should be discarded after 3-6 uses * Small endodontic files (08 and 10) and path finders should be used only once

Answer 333

A

~Effective disinfection of the canal and sealing coronal access
~diameter of the open apex – the wider the better to let in more stem cells

~ Age of patient (8-16 years in humans is best)

Answer 334

* successful in 42/45 (93.3%) teeth * NEF in 3/45 (6.6%) teeth * failure 0% significance with NEF: preoperative PAL, postoperative PAL, postoperative EIRR. not associated with increased risk of failure: obturation voids, overfill. ## Footnote *"Endodontic Treatment Outcome of 45 Incisor Teeth in Dogs Determined by Intraoral Radiography". Magnolia M. Jucan, Curt Coffman, Glenna E. Mauldin, Lisa A. Fink. JVD 2023.*

Answer 335

Lubriction of files nd cheltion or softening of inorgnic mteril of the cnls
EDT

Answer 336

5.25% either full or 1/2 strength

Answer 337

steriliztion of the cnl nd to dissolve orgnic mteril.

Answer 338

* standard or Type 1 as master cones * conventional or Type 2 with a tapered point similar of spreader and used as accessory points

Answer 339

Propolis extracts can generally decrease inflammation within exposed pulp tissue and induce collagen synthesis resulting in reparative dentin formation with an organized tubular structure. Thai propolis extract has been developed as a storage medium for avulsed teeth and has been demonstrated to preserve the viability of human PDL cells from extracted premolars for up to 3 hours. It is not toxic to human dental pulp cells in vitro.

Answer 340

Calcium hydroxide has antibacterial activity after being dissociated into hydroxyl ions, and promotes reparative dentin formation. A major drawback for long-term use of calcium hydroxide as a pulp-capping agent is bacterial leakage into the pulp from poor sealing ability and solubility of calcium hydroxide, lack of adhesion, and tunnel defects from porous dentin bridges.

Answer 341

* Dentinal tubules of the dentin bridge were more orderly arranged in the Thai propolis group than in the calcium hydroxide group. * Type and extent of pulp inflammation, mineralization, necrosis and number of hyperemic blood vessels between the propolis and the calcium hydroxide groups were not statistically significantly different.

Answer 342

dogs weighing less than 10 kg * 22/84 (26.19%) CCRF maxillary PM4 underwent extraction after RCT. * 13/22 (59.1%) extracted PM4 teeth had a PPD of 4 mm or more. * 13/14 (92.85%) teeth with a PPD over 4 mm were extracted after RCT. dogs weighing more than 10 kg * 8/38 (21.05%) CCRF PM4 teeth were extracted after RCT. * 6/8 (75%) extracted PM4 teeth had a PPD of 5 mm or more. * all teeth were extracted when PPD exceeded 5 mm. ## Footnote *"Evaluating periodontal probing depth and furcation involvement on the endodontic treatment of maxillary fourth premolar complicated crown-root fractures in 122 teeth". Gyumin Kim, Youngung Kim, Kue Hwan Choe, Sangjun Oh, Su Young Heo, Namsoo Kim. AJVR 2025.*

Answer 343

CCRF with F0: * success/NEF 95.75% success 91.5% (43/47) NEF 4.25% (2/47) * failure 4.25% (2/47) CCRF with F1: * success/NEF 66.2% success 62% (44/71) NEF 4.2% (3/71) * failure 33.8% (24/71) CCRF with F2: * failure 100% (4/4) ## Footnote *"Evaluating periodontal probing depth and furcation involvement on the endodontic treatment of maxillary fourth premolar complicated crown-root fractures in 122 teeth". Gyumin Kim, Youngung Kim, Kue Hwan Choe, Sangjun Oh, Su Young Heo, Namsoo Kim. AJVR 2025.*

Answer 344

RCT outcomes were poor when PPD reached or exceeded: * 5.43 mm for F0 * 4.6 mm for F1 * 3.76 mm for F2 ## Footnote *"Evaluating periodontal probing depth and furcation involvement on the endodontic treatment of maxillary fourth premolar complicated crown-root fractures in 122 teeth". Gyumin Kim, Youngung Kim, Kue Hwan Choe, Sangjun Oh, Su Young Heo, Namsoo Kim. AJVR 2025.*

Answer 345

* success/NEF 80% (63/79) success 72% (57/79) NEF 8% (6/79) * failure 20% (16/79) ## Footnote *"Vital pulp therapy in dogs maintains an 80% success rate independent of patient age: a 25-year retrospective study". Ethan Elazegui, Elias Wolfs, Scott J. Hetzel, Jason W. Soukup. JAVMA 2025.*

Answer 346

No significant correlation between age and success. No significant correlation between time from pulp exposure to VPT and succcess (low sample size for the > 24-hour group): * immediate: 18.6% (11/59) failure * < 24 hours: 28.6% (4/14) failure * > 24 hours: 16.7% (1/6) failure Deep penetration of pulp dressing significantly increased failure odds: * 39.1% (9/23) failure with deep penetration * 13.2% (7/53) failure without indication for VPT significantly affected outcome * malocclusion 12.5% (7/56) failure * CCF 38.5% (5/13) failure ## Footnote *"Vital pulp therapy in dogs maintains an 80% success rate independent of patient age: a 25-year retrospective study". Ethan Elazegui, Elias Wolfs, Scott J. Hetzel, Jason W. Soukup. JAVMA 2025.*

Answer 347

* success/NEF 97.6% success 91.6% NEF 6% * failure 2.4% ## Footnote *"Filling material effects on root canal treatment outcomes of 83 canine teeth in cats using a taperless rotary file system". Daehyun Kwon, Chun-Geun Kim, Gyumin Kim, Youngjin Jang, Se Eun Kim, Hyun Min Jo. JFMS 2025.*

Answer 348

* bioceramic sealer (One-Fil): 97% success * bioceramic plug (OrthoMTA) & silicone-based sealer (GuttaFlow): 95% success * silicone-based sealer (GuttaFlow): 83.3% success statistically significant ## Footnote *"Filling material effects on root canal treatment outcomes of 83 canine teeth in cats using a taperless rotary file system". Daehyun Kwon, Chun-Geun Kim, Gyumin Kim, Youngjin Jang, Se Eun Kim, Hyun Min Jo. JFMS 2025.*

Answer 349

* excellent biocompatibility: prevents rejection from the surrounding tissues * contain calcium phosphate components: enhance their setting properties, facilitate the formation of a crystalline structure and chemical composition similar to apatite found in teeth and bone -> enhanced adhesion between the sealer and dentin * high pH (>11): elicits potent antibacterial effects; as such, they effectively eliminate microorganisms within the root canal system. * lower cytotoxicity responses than other sealers ## Footnote *"Filling material effects on root canal treatment outcomes of 83 canine teeth in cats using a taperless rotary file system". Daehyun Kwon, Chun-Geun Kim, Gyumin Kim, Youngjin Jang, Se Eun Kim, Hyun Min Jo. JFMS 2025.*

Answer 350

MAF was determined by enlarging the apical portion to least one and up to three ISO sizes larger than the initial apical file size but within a diameter range smaller than the access hole MAF = 69.64 − 2.40 × age + 3.63 × weight a significant positive correlation with body weight and a negative correlation with age ## Footnote *"Filling material effects on root canal treatment outcomes of 83 canine teeth in cats using a taperless rotary file system". Daehyun Kwon, Chun-Geun Kim, Gyumin Kim, Youngjin Jang, Se Eun Kim, Hyun Min Jo. JFMS 2025.*

Answer 351

significantly associated with reduced success: * pre-existing PAL: success 77.7%, failure 33.3% * overfill: success 75%, failure 25% not significantly associated with RCT outcome * preoperative EIRR: success 60%, failure 40% * voids: success 80%, failure 20% ## Footnote *"Filling material effects on root canal treatment outcomes of 83 canine teeth in cats using a taperless rotary file system". Daehyun Kwon, Chun-Geun Kim, Gyumin Kim, Youngjin Jang, Se Eun Kim, Hyun Min Jo. JFMS 2025.*

Answer 352

overfill rates were significantly associated with sealer type * bioceramic sealers (3/33, 9.1%) * bioceramic plugs (1/20, 5%) * silicone-based sealers (8/30, 26.7%) Pre-existing PALs, preoperative EIRR, and voids were not significantly correlated with the incidence of overfill. ## Footnote *"Filling material effects on root canal treatment outcomes of 83 canine teeth in cats using a taperless rotary file system". Daehyun Kwon, Chun-Geun Kim, Gyumin Kim, Youngjin Jang, Se Eun Kim, Hyun Min Jo. JFMS 2025.*

Answer 353

Gutta-percha cones soften at a temperature above 147° F (64° C). These cones can easily be dissolved in chloroform and halothane, and dissolve less in turpentine or xylene.

Answer 354

Force direction determines fracture pattern propagation in the same direction as the load direction

Answer 355

71.7-811 N (noted to be highly variable) Noted that canines optimised for disal-mesial force direction (biting) and no teeth in that category fractured <200N (and weakest was labial-lingual) *But when correcting for crown surface area this finding was non-significant (ie. the distal-mesial group happened to have big teeth in it). So crown surface area is key for force-fracture, rather than force direction

Answer 356

There was no statistical difference in the prevalence of microleakage between GuttaFlow2 and AH Plus

Answer 357

Thixotropic: Decreases viscosity under pressure, improving flowability. AH plus jet is thixotropic, so when you push down on it it flows more.

Answer 358

AH plus – Slight shrinkiage upon polymerisation (1.76%). Gutta flow – Expands 0.2%

Answer 359

9.4% of samples yielded no cultivable bacteria — all from teeth that were clinically vital and radiographically normal.

Answer 360

54% Gram negative, 46% Gram positive. 53% facultative anaerobes, 42% strict anaerobes, 5% aerobes. Predominantly opportunistic pathogens: Pasteurella, Bacteroides, Propionibacterium.

Answer 361

* endodontic samples: Bacteroides, Snowella, (Porphyromonas). * sulcal samples: Porphyromonas, Fusobacterium, (Moraxella). Relative abundance: * Bacteroides 24.7% in endodontic samples 2.77% in sulcal samples * Snowella 11.7% in endodontic samples 0.79% in sulcal samples * Porphyromonas 10.27% in endodontic samples 20.86% in sulcal samples * Fusobacterium 0.51% in endodontic samples 9.42% in sulcal samples The most abundant genera were Gram negative strict anaerobes (expected in the necrotic endodontic environment).

Answer 362

produces hypochlorous acid and chlorite ions (active species) This causes Chloramination (denaturation) of proteins. Also oxidation, hydrolysis and lipid destruction. loses its dissolving and antibacterial capacity within 2 minutes

Answer 363

There is also an argument that states that because NaOCl removes collagen fibrils when used as the final irrigant, it could interact and decrease the bonding strength of a resin-based canal sealer (eg. AH plus)

Answer 364

readily adsorbed onto the hydroxyapatite crystals of dentin and being released back into the environment

Answer 365

CHX + NaOCL = insoluble precipitate, parachloroaniline. Causes cyanosis, carcinogenic and penetrates dentinal tubules to interfere with obturation.

Answer 366

“mixture of tetracycline, acid and detergent”

Answer 367

Successful: 32/50 teeth (64%) NEF: 14/50 teeth (28%) Failure: 4/50 teeth (8%)

Answer 368

External inflammatory root resorption (EIRR): 28 teeth EIRR: not significantly associated with the risk of failure of RCT The reason for failure of the 4 canine teeth in this study was postoperative resorption. Only one of these canine teeth had evidence of preoperative EIRR.

Answer 369

Periapical lucency: 7 teeth Sealant extrusion: 18 teeth Sealer extrusion, pre-op periapical lesions and tooth resorption did not impact treatment success.

Answer 370

Crown reduction at the time of RCT Higher success with RCT alone vs. RCT + crown reduction for malocclusion (P = 0.038)

Answer 371

*"Fracture Limits of Maxillary Fourth Premolar Teeth in Domestic Dogs Under Applied Forces". Soltero-Rivera M et al. FVETS 2019.* a cadaver study on non-endodontically treated maxillary P4s: mean maximum force to fracture of intact teeth was 1,281 N. in the present study the mean maximum force to fracture was 831 N . = Endo access/treatment reduces fracture resistance# differences in angle of impact between studies

Answer 372

None of statistical significance* No correlation between crown height:diameter ratio, root canal volume, impact angle, and fracture resistance. There was a trend. "authors believe the lack of identified statistical significance was primarily due to the minimal variation in crown height to diameter ratio in the cohort, as was intentional in the study design, rather than the height to diameter ratio not being a significant contributor to overall fracture resistance"

Answer 373

The time from pulp exposure to treatment (evaluated in 10-hour increments) was not significantly (P = 0.346) associated with outcome. "In cases of CCF, the time from pulp exposure to treatment ranged from 3 to 250 hours (median, 24 hours). Of these, 6 were treated > 48 hours after pulp exposure because of extenuating circumstances"

Answer 374

Of the 13 teeth affected by local discoloration, 5/13 (38%) were vital. Three of these were vital without inflammation, and 2 were vital with inflammation. The remaining 8/13 (62%) were nonvital. Four were nonvital without inflammation, and 4 were nonvital with inflammation. =10/13 (77%) problematic if combining nonvital + inflamed.

Answer 375

Non vital: (87.6%, 85/97) Radiographically normal: 18.6% (19/102) Radiographic perio disease: 48% (49/102) Radiographic tooth resorption: 28% (29/102)

Answer 376

Periapical lucency: 24/86 (27.9%) Teeth with pulp necrosis are highly likely to transilluminate abnormally (92%) contralateral teeth demonstrated a higher prevalence of endodontic disease (65.8%) and periodontal disease (61%)

Answer 377

Successful for 199 (71%) teeth NEF for 71 (25%) teeth Failed for 11 (4%) teeth Success + NEF = 96%

Answer 378

Preoperative PAL and EIRR = 29% Neither preoperative EIRR nor a preoperative PAL were significantly associated with RCT outcome. Treatment staging was not significantly associated with RCT outcome.

Answer 379

Notably only one significant association in this whole paper: Mandibular first molars without PAL or EIRR had a higher failure rate at <12 months follow up and > 24 months follow up. Not associated: Preoperative PAL Preoperative EIRR Pulp vitality 1-stage vs 2-stage RCT Sealer type (resin vs GuttaFlow) Obturation method/material Overfill Voids (presence, size, location) Age Sex Reason for RCT

Answer 380

Successful for 51/55 (92.7%) teeth NEF for 3/55 (5.45%) teeth Failed for 1/55 (1.82%) teeth Success + NEF = 98.18%

Answer 381

PAL PAL + Obturation material* - Sig better outcomes with single cone technique than thermoplastic when PAL present PAL + Crown* - Sig better outcomes when crown placed on PAL tooth (the 1 case of EIRR and PAL preoperatively failed but too small sample to analyse) Not associated: EIRR Age Obturation material alone* Voids Overfill Crowns alone* File separation% % implies significant but doesn't actually specify.

Answer 382

File separation with intra-canal retention of the file segment occurred in 4/56 (7.14%)

Answer 383

Success 100% (29/29), NEF 0% (0/29), Failure 0% (0/29) 7/29 teeth had a preoperative periapical lucency and all 7 had resolved at follow up check 0/29 had preop EIRR (Follow up requirement was >2 years later for study inclusion)

Answer 384

8 teeth in 7 dogs

Answer 385

Significant CFU reductions in both groups (P<.0001) PDT with azulene and low-intensity laser is as effective as traditional NaOCl-based chemicalsurgical disinfection for intracanal microbial reduction No The sequence of application (PDT before or after standard prep) does not affect antimicrobial outcomes

Answer 386

**Maximum force prior to fracture in intact teeth (Group 4): 389N.** Not significantly different from: * Group 1 (RCT through a mesial access without treatment of the pulp chamber), 382N * Group 3 (RCT through a mesial access, instrumentation of the pulp chamber through an incisal access, without pulp chamber obturation or restoration of the incisal access), 404N Group 2 (RCT through a mesial access with instrumentation of the pulp chamber through an incisal access, obturation of the pulp chamber with resin-modified glass ionomer, and restoration of the incisal access with composite resin): **Obturated and restored group 2 teeth were significantly weaker than all other groups, with maximum force prior to fracture of 256N**.

Answer 387

* The maximum force prior to fracture in groups 1(A) 382N, 3(C) 404N, and 4(D) 389N were not statistically different -> restored mesial and incisal accesses with pulp chamber instrumentation did not affect fracture resistance * obturated and restored group 2(B) teeth demonstrated a median maximum force prior to fracture of 256N * This difference was statistically significant, with pair-wise comparisons demonstrating that **obturated and restored group 2 teeth were significantly weaker than all other groups**. ## Footnote *"Effect of pulp chamber access, instrumentation, obturation, and restoration on the fracture resistance of endodontically treated canine teeth in dogs". JVD 2024. Popovic et al.*

Answer 388

most teeth sustained an uncomplicated crown fracture. * group 1: 73.3% UCF, 26.7% CCF. * group 2: 100% UCF (teeth fractured within the obturation or restorative materials, preventing pulp exposure). * group 4: 93.3% UCF, 6.7% CCF. ## Footnote *"Effect of pulp chamber access, instrumentation, obturation, and restoration on the fracture resistance of endodontically treated canine teeth in dogs". JVD 2024. Popovic et al.*

Answer 389

* cultures: Pasteurella, Bacteroides, Propionibacterium * 16S rRNA: Bacteroides, Snowella, Porphyromonas ## Footnote *"Endodontic Microbiome of Fractured Non-vital Teeth in Dogs Determined by 16S rRNA Gene Sequencing". Marjory Xavier Rodrigues, Ana Nemec, Nadine Fiani, Rodrigo C. Bicalho, Santiago Peralta. FVETS 2019.* *"Microbiological Aspects of Naturally Occurring Primary Endodontic Infections in Dogs". Spela Srecnik, Irena Zdovc, Urska Javorsek, Tina Pirs, Zlatko Pavlica, Ana Nemec. JVD 2019.*

Answer 390

based on radiographic evaluation: * 10/15 (66.7%) success * 5/15 (33.3%) NEF * 0/15 (0%) failure Success: the periapical lesion (PAL) and bone defect created by surgery had completely healed and no new root resorption was detected. NEF: the PAL remained the same or had not completely resolved and root resorption was static.

Answer 391

Success: 42/45 teeth (93.3%) NEF : 3/45 (6.6%) Failure: 0/45 (0%)* Success + NEF = 100% *1 new EIRR case at postops that they "considered stable" Charlie is irritated by this.

Answer 392

Presence of preoperative periapical lucency (P=.018) Presence of postoperative periapical lucency (P=.003) Presence of postoperative external inflammatory root resorption (P=.012). =Were associated with assignment of cases to the NEF group, since no case was deemed a failure. *I've included this as they might ask about it but the fact that the paper tested this is ludicrous. Obviously EIRR postop will be associated with NEF/failure and similarly for the others. Take home message: Preoperative EIRR, type of sealer, presence of voids, overfill etc was not associated with NEF...

Answer 393

Retrograde passage of sodium hypochlorite (NaOCl) through the nasolacrimal duct, inducing chemical injury to the cornea. In domestic cats, the nasolacrimal duct is located dorsal or dorso-medial to the root of the maxillary canine tooth, with the two separated only by thin alveolar bone. Treatment: * immediate management of chemical corneal injuries should include copious flushing of the corneal surface, followed by swift referral for ophthalmic assessment * topical antibiotics * ophthalmic lubrication * systemic analgesia ## Footnote *"Complications of Intracanal Irrigation During Root Canal Therapy of a Maxillary Canine Tooth in a Cat". V. J. Jordan, N. Paik Koh. JVD 2025.*

Answer 394

Use of **Ca(OH)2** and **deep penetration of dressing material into the vital pulp** were each significantly associated with increased odds of treatment failure. Dressing material: * 92% success with MTA * 58% success with Ca(OH)2 Deep penetration of dressing material into the vital pulp: * 54.2% success * 45.8% failure Not significantly associated with outcome: * diagnosis (malocclusion or UCF vs CCF) * within the CCF group, the time from pulp exposure to treatment (evaluated in 10-hour increments) * formation of a tertiary dentin bridge * sex and weight of the dog * tooth type * open/closed apex prior to VPT * radiographic appearance of small voids in the restoration immediately after treatment or clinically evaluated as rough, damaged, or missing restoration at the last follow-up examination * occlusal contact of the treated tooth with another tooth or soft tissue ## Footnote *"Vital pulp therapy in dogs: 190 cases (2001–2011)". Niina Luotonen, Helena Kuntsi-Vaattovaara, Eva Sarkiala-Kessel, Jouni J. T. Junnila, Outi Laitinen-Vapaavuori, Frank J. M. Verstraete. JAVMA 2014.*

Answer 395

Dressing material: * 92% success with MTA * 58% success with Ca(OH)2 (significant) ## Footnote *"Vital pulp therapy in dogs: 190 cases (2001–2011)". Niina Luotonen, Helena Kuntsi-Vaattovaara, Eva Sarkiala-Kessel, Jouni J. T. Junnila, Outi Laitinen-Vapaavuori, Frank J. M. Verstraete. JAVMA 2014.*

Answer 396

* success/NEF 85% success 73% NEF 12% * failure 15% ## Footnote *"Vital pulp therapy in dogs: 190 cases (2001–2011)". Niina Luotonen, Helena Kuntsi-Vaattovaara, Eva Sarkiala-Kessel, Jouni J. T. Junnila, Outi Laitinen-Vapaavuori, Frank J. M. Verstraete. JAVMA 2014.*

Answer 397

Deep penetration of dressing material into the vital pulp in 24/190 (12.6%) teeth: * 54.2% success * 45.8% failure (significant) ## Footnote *"Vital pulp therapy in dogs: 190 cases (2001–2011)". Niina Luotonen, Helena Kuntsi-Vaattovaara, Eva Sarkiala-Kessel, Jouni J. T. Junnila, Outi Laitinen-Vapaavuori, Frank J. M. Verstraete. JAVMA 2014.*

Answer 398

* success/NEF 94% success 69% NEF 26% * failure 6% ## Footnote *"Results of root canal treatment in dogs: 127 cases (1995–2000)". Helena Kuntsi-Vaattovaara, Frank J. M. Verstraete, Philip H. Kass. JAVMA 2002.*

Answer 399

* tooth type: 43% success for mandibular P4/M1 56% success for canine teeth 78% for maxillary P4s (significant difference compared to maxillary P4) * preexisting PAL: 43% success * preexisting EIRR: 50% success use of intra-canal medication and the method and quality of obturation NOT associated with outcome. ## Footnote *"Results of root canal treatment in dogs: 127 cases (1995–2000)". Helena Kuntsi-Vaattovaara, Frank J. M. Verstraete, Philip H. Kass. JAVMA 2002.*

Answer 400

* success/NEF 96% success 71% NEF 25% * failure 4% ## Footnote *"Radiographic outcome of root canal treatment in dogs: 281 teeth in 204 dogs (2001–2018)". Da Bin Lee, Boaz Arzi, Philip H. Kass, Frank J. M. Verstraete. JAVMA 2022.*

Answer 401

Tooth type: * significantly higher failure for mandibular M1 teeth (20% succcess) * although not statistically significant, a high incidence of failure for maxillary P4 teeth (39% success). This finding should be interpreted with caution owing to the small numbers of mandibular M1 (5 teeth) and maxillary P4 (28 teeth) analyzed. preoperative PAL: * 5/75 (7%) success with * 194/206 (94%) success without preoperative EIRR: * 1/38 (3%) success with * 198/243 (81%) success without Neither preoperative EIRR nor a preoperative PAL significantly associated with outcome. preoperative PAL, EIRR, pulp vitality, voids (presence, size, and location), and overfill NOT significantly associated with RCT outcome. ## Footnote *"Radiographic outcome of root canal treatment in dogs: 281 teeth in 204 dogs (2001–2018)". Da Bin Lee, Boaz Arzi, Philip H. Kass, Frank J. M. Verstraete. JAVMA 2022.*

Answer 402

An apical delta was present in all 334 roots. The apical delta represented approximately 12-18% of the total root length for all roots.

Answer 403

Non-apical ramifications: all canals that emerge from the main root canal and are completely separated from the apical delta. * Secondary canals: exit the main canal in the apical third of the root. * Lateral canals: exit the main canal in the middle or cervical third of the root. * Accessory canals: branch from secondary canals. Secondary, lateral, and accessory canals communicate with the periodontal ligament.

Answer 404

Non-apical ramifications in 25.1% of roots. * Secondary canal(s) in 20.6% of roots * Lateral canal(s) in 6.9% of roots * Accessory canal(s) in 1.5% of roots For all roots, lateral canals were not observed in the cervical third of the root or at the furcation region.

Answer 405

Non-apical ramifications in: * 68% of maxillary P4 teeth * 20.4% of mandibular M1 teeth The distal root of the maxillary P4 had the highest incidence (47.2%) of non-apical ramifications.

Answer 406

103 mature feline carnassial teeth (54 maxillary P4, 49 mandibular M1 teeth) from 44 cats * 45.5% of cats had at least 1 furcation canal in one of their carnassial teeth * patent furcation canals in 27.2% of teeth No significant difference in prevalence between maxillary P4 (15/54, 27.8%) and mandibular M1 (13/49, 26.5%) teeth.

Answer 407

Ionic shift in the dentinal fluid affecting the a-delta fibres

Answer 408

* Rapid change in temp causes sudden fluid flow within tubules Stimulates A-delta fibre nociceptors * A gradual change will excite C fibres and elicit dull/delayed/diffused ache

Answer 409

cold pulp testing: Highly sensitive, IF there is a response to control tooth (47% excluded due to lack of response on control tooth) * Sensitivity 100% * Specificity 89% (occasional false positives)

Answer 410

Electric pulp testing: * Sensitivity 96% (very occasional false negative) * Specificity 100%

Answer 411

Transillumination: * Sensitivity 59% (lots of false negatives) * Specificity 95% (occasional false positives)

Answer 412

Superior P4s: * Lateral canals in 10% of roots * 86% of lateral canals in the apical third * 14% of lateral canals in the middle third Inferior M1s: * Lateral canals in 3% of roots * 2% of lateral canals in the apical third * 1% of lateral canals in the middle third

Answer 413

Due to the higher frequency of lateral canals in maxillary P4s (10% of roots) compared to mandibular M1s (3% of roots), it is imperative to perform more thorough cleaning and instrumentation while performing endodontic treatment on maxillary P4s compared to mandibular M1s.

Answer 414

At the time of eruption of the permanent tooth, only about 50% of the expected tooth root length has formed. * Depending on the tooth, apices close in dogs between 7-10 months of age, in cats between 7-11 months of age. * Even if the apex has closed, the dentin remains thin in young animals -> it is recommended to maintain pulp vitality in patients 18 months or younger.

Answer 415

Reversible pulpitis: a clinical diagnosis based on subjective and objective findings indicating that the inflammation should resolve and the pulp return to normal. Irreversible pulpitis: a clinical diagnosis based on subjective and objective findings indicating that the vital inflamed pulp is incapable of healing. Objective determinants of irreversible pulpitis: * excessive or deep purple hemorrhage from an exposed or amputated pulp * persistent hemorrhage for greater than 5 min following partial coronal pulpotomy

Answer 416

a tooth fracture is considered to have caused “near pulp exposure” when the remaining dentin thickness overlying the pulp is approximately 0.5 mm or less. * a pinkish hue is visible when ~0.5 mm of dentin remains. * In dogs, dentin is nearly twice as porous as in humans, therefore some consider near pulp exposure to be at a dentin thickness of less than 1-2 mm. If the UCF has near pulp exposure, then the pulp can have a negative reaction to etching and bonding, and indirect pulp capping should be performed. A protective layer of hard-setting calcium hydroxide or other base layer material is applied prior to restoration.

Answer 417

The treatment is achieved in 2 visits. The first visit prepares and fills the canal with calcium hydroxide or triple antibiotic paste (TAP) in a similar process to that for the first visit for calcium hydroxide apexification. TAP is traditionally made from a 1:1:1 ratio of ciprofloxacin:metronidazole:minocycline. The second visit (1-4 weeks later) involves removing the calcium hydroxide or antibiotic paste from the prepared canal and inducing apical bleeding into the canal by overinstrumenting the canal 2 mm past the root end. Alternatives to creating a blood clot include filling the canal with platelet-rich plasma (PRP), platelet-rich fibrin, or autologous fibrin matrix. Several studies in dogs found the best outcomes after using TAP for disinfection, followed by PRP as a scaffold. Finally, an MTA or other bioceramic material barrier is placed as a capping material over the blood clot followed by a glass ionomer, and the tooth is restored.

Answer 418

* success/NEF 30/37 (81%) success 18/37 (49%) NEF 12/37 (32%) * failure 7/37 (19%) ## Footnote *"Radiographic outcome of root canal treatment of canine teeth in cats: 32 cases (1998–2016)". Peter C. Strøm, Boaz Arzi, Milinda J. Lommer, Helena Kuntsi, Amy J. Fulton Scanlan, Philip H. Kass, Frank J. M. Verstraete. JAVMA 2018.*

Answer 419

preexisting EIRR (associated with preoperative pulpal necrosis): * success 1/7 (14%) * NEF 3/7 (43%) * failure 3/7 (43%) Preexisting EIRR and patient age ≥ 5 years significantly increased the rate of RCT failure. ## Footnote *"Radiographic outcome of root canal treatment of canine teeth in cats: 32 cases (1998–2016)". Peter C. Strøm, Boaz Arzi, Milinda J. Lommer, Helena Kuntsi, Amy J. Fulton Scanlan, Philip H. Kass, Frank J. M. Verstraete. JAVMA 2018.*

endodontics Flashcards

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