Radiographic outcome of root canal treatment in dogs: 281 teeth in 204 dogs (2001–2018)

Da Bin Lee Dentistry and Oral Surgery Service, William R. Pritchard Veterinary Medical Teaching Hospital, University of California-Davis, Davis, CA

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Boaz Arzi Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA

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Philip H. Kass Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, CA

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Frank J. M. Verstraete Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA

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Abstract

OBJECTIVE

To evaluate the radiographic outcome of root canal treatment (RCT) in dogs and compare outcomes with those reported for a previous study performed at the same institution in 2002.

ANIMALS

204 dogs representing 281 teeth that underwent RCT.

PROCEDURES

The medical record database of a veterinary teaching hospital was searched to identify dogs that underwent RCT between 2001 and 2018. Only dogs that had undergone at least 1 radiographic recheck appointment a minimum of 50 days after RCT were included in the study. Dental radiographs were reviewed. Treatment was considered successful if the periapical periodontal ligament space was within reference limits and preexisting external inflammatory root resorption (EIRR), if present, had stabilized. Treatment was considered to show no evidence of failure (NEF) if preoperative EIRR had stabilized and any preoperative periapical lucency (PAL) remained the same or had decreased in size but had not completely resolved. Treatment was considered to have failed if EIRR or a PAL developed after RCT, if a preoperative PAL increased in size, or if preexisting EIRR progressed.

RESULTS

Follow-up time ranged from 52 to 3,245 days (mean, 437 days). RCT was classified as successful for 199 (71%) teeth, NEF for 71 (25%) teeth, and failed for 11 (4%) teeth.

CONCLUSIONS AND CLINICAL RELEVANCE

Results showed that almost 2 decades after RCT outcome in dogs was first evaluated, during which time numerous advances in dental materials and techniques had been made, the success rate of RCT was virtually unchanged.

Abstract

OBJECTIVE

To evaluate the radiographic outcome of root canal treatment (RCT) in dogs and compare outcomes with those reported for a previous study performed at the same institution in 2002.

ANIMALS

204 dogs representing 281 teeth that underwent RCT.

PROCEDURES

The medical record database of a veterinary teaching hospital was searched to identify dogs that underwent RCT between 2001 and 2018. Only dogs that had undergone at least 1 radiographic recheck appointment a minimum of 50 days after RCT were included in the study. Dental radiographs were reviewed. Treatment was considered successful if the periapical periodontal ligament space was within reference limits and preexisting external inflammatory root resorption (EIRR), if present, had stabilized. Treatment was considered to show no evidence of failure (NEF) if preoperative EIRR had stabilized and any preoperative periapical lucency (PAL) remained the same or had decreased in size but had not completely resolved. Treatment was considered to have failed if EIRR or a PAL developed after RCT, if a preoperative PAL increased in size, or if preexisting EIRR progressed.

RESULTS

Follow-up time ranged from 52 to 3,245 days (mean, 437 days). RCT was classified as successful for 199 (71%) teeth, NEF for 71 (25%) teeth, and failed for 11 (4%) teeth.

CONCLUSIONS AND CLINICAL RELEVANCE

Results showed that almost 2 decades after RCT outcome in dogs was first evaluated, during which time numerous advances in dental materials and techniques had been made, the success rate of RCT was virtually unchanged.

Introduction

Pulpitis is a painful condition of the tooth that may develop secondary to irritation or trauma to the pulpal tissues resulting from such conditions as dental fractures, abrasions, and caries that lead to dentin or pulp exposure, luxation injuries, and concussive injuries manifesting as intrinsic discoloration.13 If the inflammatory process is not reversed, pulpitis eventually leads to pulp necrosis.13 Once the pulp loses its vitality, the pulp cavity may become colonized by bacteria, which extends the inflammatory and infectious processes to the periapical tissues. This extension to periapical tissues is known as apical periodontitis or a periapical lesion and is evidenced on radiographs as a periapical lucency (PAL).24

Root canal treatment (RCT) is a commonly performed endodontic technique in dogs with the aim of restoring or preserving the health of the periapical tissues as an alternative to dental extraction. It comprises mechanical instrumentation of the root canal system, chemical disinfection, and obturation with an inert material.5 In a retrospective study6 published in 2002 that evaluated the outcome of RCT in 127 tooth roots of dogs, treatment was determined to be successful in 69% of roots, to have no evidence of failure (NEF) in 26% of roots, and to have failed in 6% of roots. The study6 revealed that preexisting PAL and external inflammatory root resorption (EIRR) were significantly associated with an increased risk of failure. Also, preoperative pulp necrosis was associated with a lower success rate, although not significantly so. Mandibular fourth premolar and first molar teeth combined, as well as canine teeth, were significantly associated with lower success rates, compared with maxillary fourth premolar teeth. On the other hand, the method and quality of obturation were not associated with RCT outcome and performing the RCT in 2 stages, with intracanal administration of calcium hydroxide between stages, was not significantly associated with the success rate.

Given that almost 2 decades have passed since the publication of the success rate of RCT6 in dogs and that advances in RCT obturation materials and techniques have been implemented in practice during that time, an update on the success rate of RCT in dogs is warranted. Hence, the objectives of the study reported here were to evaluate the radiographic outcome of RCT in dogs and compare outcomes with those reported for a previous study6 performed at the same institution in 2002.

Materials and Methods

Case selection criteria

The medical record database of the University of California-Davis William R. Pritchard Veterinary Medical Teaching Hospital was searched to identify dogs that underwent RCT between 2001 and 2018. Only dogs that had undergone at least 1 radiographic recheck appointment a minimum of 50 days after RCT were included in the study. The study population was representative of healthy dogs that were deemed to be suitable candidates for multiple anesthetic events.

RCT procedure

All RCTs were performed by diplomates of the American Veterinary Dental College or by veterinary dental residents under the supervision of a diplomate in accordance with quality guidelines for endodontic treatment established by the European Society of Endodontology,7,8 modified to accommodate the dental anatomy of dogs. Pulp vitality was assessed visually, with bleeding on access to the pulp cavity denoting vitality and a lack of bleeding denoting a lack of vitality. Radiographic images of the affected teeth were obtained by use of the bisecting angle or parallel technique9 prior to, during, and on completion of RCT. Conventional and digital (photostimulable phosphor plates) radiography techniques were used with film sizes of 2 and 4. Access sites (occlusal access with or without mesial access depending on the tooth) were created, and the pulp cavity was cleaned and shaped with handheld endodontic files and rotary instruments. Uniquely formulated glycol, peroxide, and EDTA chelating gels were used for file lubrication. Sodium hypochlorite (2.5% to 5.25%) irrigation solution was used for disinfection of the canal, and EDTA was used as a chelator. For staged RCTs, calcium hydroxide was placed in the canal until definitive obturation could be performed. Final obturation was performed with heated or cold gutta percha (Dentsply Tulsa Dental Specialties) and resin-based (AH 26, AH Plus, ThermaSeal, or ThermaSeal Plus; Dentsply Tulsa Dental Specialties) or flowable gutta percha (GuttaFlow or GuttaFlow 2; Coltene/Whaledent) endodontic sealers. Methods of obturation included vertical compaction with thermoplastic gutta percha (Successfil or Ultrafil; Coltene/Whaledent), single-cone thermoplastic gutta percha (Thermafil or ThermaSystem Plus; Dentsply Tulsa Dental Specialties), lateral compaction, and single-cone gutta percha. The choice of endodontic shaping and obturation techniques was largely dependent on availability at the time and personal preference of the operator. Access sites were restored with a glass-ionomer intermediate layer and composite resin (Filtek Supreme Plus; 3M ESPE) final restorative layer.

Follow-up evaluations

All dogs were anesthetized for follow-up radiography, and radiographic images were obtained by use of the bisecting angle or parallel technique. Conventional and digital (photostimulable phosphor plates) radiography techniques were used with film sizes of 2 and 4. The standard recommended follow-up protocol was 3 months after RCT and annually thereafter.

Outcome evaluation

All conventional and digital dental radiographic images were evaluated by 3 observers (DBL, BA, and FJMV) until a consensus on outcome was reached. Digital images were viewed on a medical-grade computer screen (Asus PB278Q; AsusTeK Computer Inc); conventional images were evaluated on a radiographic viewing box with a calibrated magnifying loupe (Peak Scale Loupe 7x; GWJ Co).

The quality of obturation was assessed by dividing the pulp cavity into thirds (coronal, middle, and apical). Voids were considered small if they were narrower than half the width of the obturated pulp cavity; all other voids were considered large. Overfill was recorded if there was radiopaque material in the periapical region. The largest diameter of any periapical lesion was measured, and comparable radiographic images obtained at each follow-up visit were examined.

RCT outcome was classified as successful, NEF, or failure in accordance with guidelines for radiographic assessment of RCT established by the European Society of Endodontology.7,8 Treatment was considered successful if the periapical periodontal ligament space was within reference limits and preexisting EIRR, if present, had stabilized. Treatment was considered to show NEF if preoperative EIRR had stabilized, and any preoperative PAL remained the same or had decreased in size but had not completely resolved. Treatment was considered to have failed if EIRR or a PAL developed after RCT, if a preoperative PAL increased in size, or if preexisting EIRR progressed.

Statistical analysis

The outcome at the most recent follow-up examination was recorded for each tooth. Dependent variables assessed included age at the time of RCT, sex (male or female), reason for RCT, treatment staging (ie, 1-stage vs 2-stage RCT), preoperative pulp vitality, evidence of preoperative EIRR, evidence of a preoperative PAL, method and material of obturation, type of sealer used, quality of obturation (ie, presence of voids), periapical evidence of extruded sealant material (ie, overfill), and whether the tooth fractured after RCT.

By definition, if a tooth had no evidence of a preoperative PAL or EIRR, the only possible outcomes were success or failure; NEF was not a possible outcome. Therefore, teeth with no preoperative PAL or EIRR were evaluated separately (on the basis of possible outcomes of success or failure) from teeth with preoperative PAL, EIRR, or both (on the basis of possible outcomes of success, NEF, or failure). For the purposes of analysis, all teeth in a single dog were considered independent because it was deemed that inherent characteristics of the individual common to all their teeth (eg, systemic disease or generalized dentin or enamel defects), other than the variables analyzed (ie, age and sex), would be uncommon or would not have a significant effect on the outcome of RCT.

To estimate the cumulative incidence of failure while accounting for censoring, teeth were categorized into 3 groups, depending on when they were radiographically reevaluated and what the outcome was at that time. Group 1 included teeth followed up for < 12 months after RCT, teeth in which RCT was considered to have failed within the first 12 months after the procedure, and teeth known from later appointments to have not failed within the first 12 months after the procedure. Group 2 included teeth with last follow up ≥ 12 and < 24 months after RCT, teeth in which RCT was considered to have failed within the first 24 months after the procedure, and teeth known from later appointments to have not failed within the first 24 months after the procedure. Group 3 included teeth with last follow up occurring ≥ 24 months after RCT and teeth in which RCT was considered to have failed at any time after the procedure. For teeth for which RCT was considered to have failed at the time of their first recheck examination, failure was not assumed to have occurred during an earlier time period. However, for teeth for which RCT was considered to have not failed during a later time period, failure was assumed to not have occurred during earlier time periods.

Fisher's exact test was used to evaluate the association of all variables with RCT outcome, except that the Kruskal-Wallis test was used to test whether age was associated with RCT outcome. For variables significantly associated with RCT outcome, χ2 tests of independence were used to determine which combinations of variable levels and outcome categories contributed to significance. For all analyses, values of P < 0.05 were considered significant.

Results

Medical records of 204 dogs that underwent RCT between 2001 and 2018 and had a minimum radiographic follow up of 50 days were identified. Mean age at the time of RCT was 4.9 years (range, 1 to 13 years).

In 63 of the 204 (30.9%) dogs, RCT was performed on > 1 tooth. The total number of teeth that underwent RCT was 281, of which 140 (49.8%) were in dogs that underwent RCT on > 1 tooth. Of the 281 teeth that underwent RCT, 171 (60.9%) were in male dogs and 110 (39.1%) were in female dogs.

Fifteen of the 281 (5.3%) teeth the underwent RCT were incisor teeth, 232 (82.6%) were canine teeth, 28 (10.0%) were maxillary fourth premolar teeth, 5 (1.8%) were mandibular first molar teeth, and 1 (0.4%) was a maxillary third premolar tooth. The most common indications for RCT were complicated crown fracture (146 teeth [52%]), complicated crown-root fracture (26 [9%]), intrinsic discoloration (42 [15%]), severe abrasion leading to pulp exposure (25 [9%]), crown amputation due to malocclusion (20 [7%]), and luxation (5 [2%]). Follow-up time ranged from 52 to 3,245 days (mean, 437 days). Thirty (11%) teeth had follow-up times of ≤ 3 months, 152 (54%) had follow-up times of > 3 to ≤ 12 months, 50 (18%) had follow-up times of > 12 to ≤ 24 months, 16 (6%) had follow-up times of > 24 to ≤ 36 months, 14 (5%) had follow-up times of > 36 to ≤ 48 months, and 19 (7%) had follow-up times of > 48 months. Eleven (4%) teeth fractured following RCT.

RCT outcome was classified as successful for 199 (71%) teeth (Figure 1), NEF for 71 (25%) teeth (Figure 2) and failed for 11 (4%) teeth (Figure 3). One hundred ninety-nine (71%) teeth had no evidence of a preoperative PAL or EIRR. Seventy-five teeth had evidence of a preoperative PAL, and 38 teeth had evidence of a preoperative EIRR (Table 1). Neither preoperative EIRR nor a preoperative PAL were significantly associated with RCT outcome. Pulp vitality was recorded for 149 teeth, of which 67 (45%) teeth were vital and 82 (55%) were nonvital. Overall, pulp vitality was not significantly associated with RCT outcome.

Figure 1
Figure 1

Intraoral radiographic images of the right maxillary fourth premolar tooth of a 2-year-old male mixed-breed dog with a complicated crown fracture. Images were obtained with digital radiography by use of the bisecting angle technique before (A), immediately after (B), 4 months after (C), and 1 year after (D) root canal treatment (RCT). Notice the preoperative periapical lucency (arrows; A and B), which had resolved by 4 months after RCT (C). The outcome was classified as successful.

Citation: Journal of the American Veterinary Medical Association 260, 5; 10.2460/javma.21.03.0127

Figure 2
Figure 2

Intraoral radiographic images of the right maxillary canine tooth of a 4-year-old male mixed-breed dog with a complicated crown fracture. Images were obtained before (A), immediately after (B), and 3 months after (C) RCT. Notice the preoperative periapical lucency (arrows) and external inflammatory root resorption. The external inflammatory root resorption was static 3 months after RCT (C), and the outcome was classified as no evidence of failure.

Citation: Journal of the American Veterinary Medical Association 260, 5; 10.2460/javma.21.03.0127

Figure 3
Figure 3

Intraoral radiographic images of the left maxillary canine tooth of a 7-year-old castrated male Labrador Retriever with severe abrasion resulting in pulp exposure. Images were obtained before (A), immediately after (B), and 3 months after (C) RCT. A chevron sign artifact (arrowheads) was visible on images obtained before and immediately after RCT. A periapical lucency (arrows) was visible 3 months after RCT, and the outcome was classified as failed.

Citation: Journal of the American Veterinary Medical Association 260, 5; 10.2460/javma.21.03.0127

Table 1

Outcome of root canal treatment (RCT) for 281 teeth in 204 dogs.

Variable No. of teeth No. (%) with a successful outcome
Preexisting PAL
 Present 75 5 (7)
 Absent 206 194 (94)
Preexisting EIRR
 Present 38 1 (3)
 Absent 243 198 (81)
Preoperative pulp vitality
 Vital 67 60 (90)
 Nonvital 82 55 (67)
 Not recorded 132 84 (63)
Staged RCT
 Yes 36 29 (81)
 No 245 170 (69)
Sealer
 Resin-based 71 51 (72)
 Flowable gutta percha 190 134 (71)
 Not recorded 20 14 (70)
Obturation material and method
 Vertical compaction with thermoplastic gutta percha 13 10 (77)
 Single-cone thermoplastic gutta percha 20 12 (60)
 Lateral compaction 67 51 (76)
 Single-cone gutta percha with sealer 152 104 (68)
 Combination 17 14 (82)
 Not recorded 12 8 (67)
Voida
 None 116 83 (72)
 Small 149 104 (70)
 Large 64 47 (73)
Overfill
 Yes 30 13 (43)
 No 251 186 (74)
Tooth
 Incisor 15 13 (87)
 Canine 232 173 (75)
 Maxillary fourth premolar 28 11 (39)
 Mandibular first molar 5 1 (20)
 Maxillary third premolar 1 1 (100)
Reason for RCT
 Complicated crown fracture 146 104 (72)
 Complicated crown-root fracture 26 21 (81)
 Intrinsic discoloration 42 24 (57)
 Severe abrasion 25 16 (64)
 Crown amputation due to malocclusion 20 16 (80)
 Luxation 5 3 (60)
 Other 15 12 (80)
 Not recorded 2 2 (100)
Fracture after RCT
 Yes 11 10 (91)
 No 270 189 (70)
Sex
 Sexually intact male 93 74 (80)
 Castrated male 78 48 (62)
 Sexually intact female 6 6 (100)
 Spayed female 104 71 (68)

EIRR = External inflammatory root resorption. PAL = Periapical lucency.

Values do not sum to 281 because some teeth had > 1 void.

Of the 281 teeth, 36 (13%) were treated with a 2-stage procedure. Overall, treatment staging (ie, 1-stage vs 2-stage RCT) was not significantly associated with RCT outcome. A resin-based sealer was used in 71 (25%) teeth, and flowable gutta percha was used as a sealer in 190 (68%) teeth; sealer was not recorded for the remaining teeth. Obturation was performed via vertical compaction with thermoplastic gutta percha in 13 (5%) teeth, single-cone thermoplastic gutta percha in 20 (7%) teeth, lateral compaction in 67 (24%) teeth, and single-cone gutta percha in 152 (54%) teeth. A combination of these methods was used in 17 (6%) teeth; for 12 (4%) teeth, the obturation method was not recorded. Type of sealer and obturation material and method were not significantly associated with RCT outcome.

Overfill was observed in 30 (11%) teeth and was not significantly associated with outcome. Sixty-two teeth (51 with small voids and 11 with large voids) had voids in the apical third of the pulp cavity, 34 teeth (all with small voids) had voids in the middle third, and 117 teeth (64 with small voids and 53 with large voids) had voids in the coronal third. Overall, presence, size, and location of voids were not significantly associated with outcome.

For the group of teeth with no preoperative PAL or EIRR and follow-up times of < 12 months or ≥ 24 months, tooth type was significantly (P = 0.019 and 0.049, respectively) associated with RCT outcome. Mandibular first molar teeth had a higher failure incidence than did other tooth types. Sex, age, and the reason for RCT were not significantly associated with RCT outcome.

Discussion

Results of the present study demonstrated that the success rate of RCT in dogs has remained virtually unchanged over the past 2 decades. Specifically, in the present study, RCT outcome was classified as successful or NEF in 270 of 281 (96%) teeth, compared with 95% of 127 tooth roots in a previous study6 performed at the same institution in 2002. We also demonstrated that a preoperative PAL or EIRR, pulp vitality, voids, and overfill had no significant association with RCT outcome. Moreover, neither the type of sealer used nor the material and method of obturation was significantly associated with RCT outcome.

The present and previous6 studies have proven that the success rate of RCT in dogs is consistently high, at 69% to 71% when stricter criteria are used (ie, successful) and 95% to 96% when less strict criteria are used (ie, successful or NEF). The RCT outcome classification scheme used in both studies was guided by the European Society of Endodontology's quality guidelines for endodontic treatment7,8 and previous studies on assessment of radiographic outcome of RCT in dogs6 and cats.10 There is a lack of standardization in radiographic criteria of RCT success in human studies, with stricter criteria involving complete resolution of any preexisting PAL and looser definitions entailing reduction in the size of any PAL.11 In the present study, stricter definitions were used to assess radiographic outcome to contribute to consistency in the literature, and radiographs were evaluated by 3 observers to ensure reliability and validity of the radiographic interpretations.

Well-known factors have been identified as prognostic factors for RCT outcome in humans, including a preexisting PAL,5,1221 pulp vitality,12,18,19,2123 quality of root canal filling (voids),5,12,13,2429 and extrusion of sealer into the periapical tissues (overfill).19,20,24,27 In the previous study6 evaluating RCT outcome in dogs, a preoperative PAL and EIRR as well as nonvital pulp (although not statistically significant) were associated with lower success rates, whereas voids and overfill were not associated with outcome. In cats, preexisting EIRR has been shown to significantly increase the rate of RCT failure, and although not significant, obturation voids in the apical third of the pulp cavity were associated with a 5-fold increase in the likelihood of RCT failure.10 However, overfill was not associated with RCT failure.10 In the present study, a preoperative PAL, perioperative EIRR, pulp vitality, voids (presence, size, and location), and overfill were not significantly associated with RCT outcome.

In the present study, we found that the type of sealer used and the material and method of obturation were not significantly associated with RCT outcome. This is important because new root canal filling materials are constantly being developed, and with these advances, the techniques used to obturate the root canal system also evolve. During the time period of the present study, gradual shifts were observed in this aspect for RCTs performed at the study institution. For example, the use of thermoplastic gutta percha and resin-based sealers was more common in the earlier years of the study period, whereas obturation with single-cone gutta percha points with flowable gutta-percha sealers dominated the latter half of the study period. As mentioned earlier, despite this shift, neither the type of sealer used nor the obturation material and technique were significantly associated with RCT outcome. A study30 comparing a resin-based sealer to a flowable gutta percha sealer in the canine teeth of dogs revealed no significant difference in the prevalence or magnitude of apical microleakage between the 2 materials. A study31 comparing success rates of RCT performed in humans with classic techniques (ie, instrumentation with stainless steel hand files, multiple treatment visits, and lateral condensation obturation) versus contemporary techniques (ie, instrumentation with hand and rotary nickel-titanium files, single-visit treatments, and warm vertical or lateral condensation obturation) found no significant difference between the 2 groups. The present study also found that staged treatments had no significant association with RCT outcome, compared with single-visit treatments. This agreed with findings of the previous study6 by our group. It is acknowledged that the obturation methods and materials evaluated in the present study may not be representative of methods and materials used in the general canine population, because obturation technique is highly dependent on individual preference. Despite the variety of clinicians who performed RCTs during the study period, all procedures were performed at the same institution under the supervision of a limited number of board-certified veterinary dentists.

Tooth type has been implicated as a factor that influences RCT outcome in humans, with multirooted teeth having more complex root morphology being observed to have less favorable outcomes.19,25,28,32 This was consistent with findings of the present study, which revealed significantly higher incidences of failure for mandibular first molar teeth, and although not statistically significant, a high incidence of failure for maxillary fourth premolar teeth. However, this finding should be interpreted with caution owing to the small numbers of mandibular first molar and maxillary fourth premolar teeth analyzed.

A limitation of the present study was that there were no guidelines for assessment of teeth that did not have a preoperative PAL or EIRR. A NEF outcome was not a possible for these teeth, because the presence of a PAL or EIRR was inherent to the definition. Therefore, if teeth with no preoperative lesions had not developed any lesions by the time of the final follow-up visit, RCT was classified as successful, regardless of follow-up time. It is possible that the outcome may have changed if these teeth were followed up for a longer period of time. However, this could be said for any of the teeth in the study, and the distinction between a successful outcome and NEF does not become as important when looser criteria are used to classify outcome.

In conclusion, results of the present study revealed that almost 2 decades since RCT outcome in dogs was first evaluated, during which time numerous advances in dental materials and techniques have been made, the success rate of RCT was virtually unchanged. RCT remains a viable treatment option for salvage of teeth in dogs with a high success rate. Neither preexisting EIRR nor a PAL was significantly associated with outcome, and the quality of obturation, overfill, and obturation materials and techniques were also not significantly associated with outcome.

Acknowledgments

No third-party funding or support was received in connection with this study or the writing or publication of the manuscript. The authors declare that there were no conflicts of interest.

The authors thank William Tedjo of the Colorado State University Department of Computer Engineering and Harrison Jow for technical assistance. The authors also thank Chrisoula Toupadakis Skouritakis for assistance with the figures.

References

  • 1.

    Hale FA. Localized intrinsic staining of teeth due to pulpitis and pulp necrosis in dogs. J Vet Dent. 2001;18(1):1420. doi: 10.1177/089875640101800102

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2.

    Berman LH, Rotstein I. Diagnosis. In: Berman LH, Hargreaves KM, eds. Cohen's Pathways of the Pulp. 11th ed. Mosby; 2016:232.

  • 3.

    Menzies RA, Reiter AM, Lewis JR. Assessment of apical periodontitis in dogs and humans: a review. J Vet Dent. 2014;31(1):821. doi: 10.1177/089875641403100101

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4.

    Torabinejad M, Shabahang S. Pulp and periapical pathosis. In: Torabinejad M, Walton RE, eds. Endodontics: Principles and Practice. 4th ed. Saunders Elsevier; 2009:4666.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5.

    Ng YL, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: systematic review of the literature–part 2. Influence of clinical factors. Int Endod J. 2008;41(1):631. doi: 10.1111/j.1365-2591.2007.01323.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6.

    Kuntsi-Vaattovaara H, Verstraete FJM, Kass PH. Results of root canal treatment in dogs: 127 cases (1995–2000). J Am Vet Med Assoc. 2002;220(6):775780. doi: 10.2460/javma.2002.220.775

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7.

    Consensus report of the European Society of Endodontology on quality guidelines for endodontic treatment. Int Endod J. 1994;27(3):115124. doi: 10.1111/j.1365-2591.1994.tb00240.x

    • Search Google Scholar
    • Export Citation
  • 8.

    European Society of Endodontology. Quality guidelines for endodontic treatment: consensus report of the European Society of Endodontology. Int Endod J. 2006;39(12):921930. doi: 10.1111/j.1365-2591.2006.01180.x

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9.

    White SC, Pharoah MJ. Projection Geometry. In: White SC, Pharoah MJ, eds. Oral radiology: principles and interpretation. 6th ed. Mosby; 2009:4652.

  • 10.

    Strøm PC, Arzi B, Lommer MJ, et al. Radiographic outcome of root canal treatment of canine teeth in cats: 32 cases (1998–2016). J Am Vet Med Assoc. 2018;252(5):572580. doi: 10.2460/javma.252.5.572

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11.

    Ng YL, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: systematic review of the literature—part 1. Effects of study characteristics on probability of success. Int Endod J. 2007;40(12):921939. doi: 10.1111/j.1365-2591.2007.01322.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 12.

    Pirani C, Chersoni S, Montebugnoli L, Prati C. Long-term outcome of non-surgical root canal treatment: a retrospective analysis. Odontology. 2015;103(2):185193. doi: 10.1007/s10266-014-0159-0

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13.

    Stoll R, Betke K, Stachniss V. The influence of different factors on the survival of root canal fillings: a 10-year retrospective study. J Endod. 2005;31(11):783790. doi: 10.1097/01.don.0000158229.43298.a9

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14.

    Friedman S, Abitbol S, Lawrence HP. Treatment outcome in endodontics: the Toronto Study. Phase 1: initial treatment. J Endod. 2003;29(12):787793. doi: 10.1097/00004770-200312000-00001

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15.

    Chugal NM, Clive JM, Spångberg LS. A prognostic model for assessment of the outcome of endodontic treatment: effect of biologic and diagnostic variables. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2001;91(3):342352. doi: 10.1067/moe.2001.113106

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16.

    Basmadjian-Charles CL, Farge P, Bourgeois DM, Lebrun T. Factors influencing the long-term results of endodontic treatment: a review of the literature. Int Dent J. 2002;52(2):8186. doi: 10.1111/j.1875-595x.2002.tb00605.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17.

    Dammaschke T, Steven D, Kaup M, Reiner Ott KH. Long-term survival of root-canal-treated teeth: a retrospective study over 10 years. J Endod. 2003;29(10):638643. doi: 10.1097/00004770-200310000-00006

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18.

    Hoskinson SE, Ng YL, Hoskinson AE, Moles DR, Gulabivala K. A retrospective comparison of outcome of root canal treatment using two different protocols. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;93(6):705715. doi: 10.1067/moe.2001.122822

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19.

    Azim AA, Griggs JA, Huang GT. The Tennessee study: factors affecting treatment outcome and healing time following nonsurgical root canal treatment. Int Endod J. 2016;49(1):616. doi: 10.1111/iej.12429

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 20.

    Ng YL, Mann V, Gulabivala K. A prospective study of the factors affecting outcomes of nonsurgical root canal treatment: part 1: periapical health. Int Endod J. 2011;44(7):583609. doi: 10.1111/j.1365-2591.2011.01872.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 21.

    Sjogren U, Hagglund B, Sundqvist G, Wing K. Factors affecting the long-term results of endodontic treatment. J Endod. 1990;16(10):498504. doi: 10.1016/S0099-2399(07)80180-4

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 22.

    Kojima K, Inamoto K, Nagamatsu K, et al. Success rate of endodontic treatment of teeth with vital and nonvital pulps. A meta-analysis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004;97:9599. doi: 10.1016/j.tripleo.2003.07.006

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 23.

    Raedel M, Hartmann A, Bohm S, Walter MH. Three-year outcomes of root canal treatment: mining an insurance database. J Dent. 2015;43(4):412417. doi: 10.1016/j.jdent.2015.01.013

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 24.

    Tavares PB, Bonte E, Boukpessi T, Siqueira JF Jr, Lasfargues J-J. Prevalence of apical periodontitis in root canal-treated teeth from an urban French population: influence of the quality of root canal fillings and coronal restorations. J Endod. 2009;35(6):810813. doi: 10.1016/j.joen.2009.03.048

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 25.

    Cheung GS. Survival of first-time nonsurgical root canal treatment performed in a dental teaching hospital. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;93(5):596604. doi: 10.1067/moe.2002.120254

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 26.

    De Moor RJ, Hommez GM, De Boever JG, et al. Periapical health related to the quality of root canal treatment in a Belgian population. Int Endod J. 2000;33(2):113120. doi: 10.1046/j.1365-2591.2000.00295.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 27.

    Ridell K, Petersson A, Matsson L, Mejàre I. Periapical status and technical quality of root-filled teeth in Swedish adolescents and young adults. A retrospective study. Acta Odontol Scand. 2006;64(2):104110. doi: 10.1080/00016350500367637

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 28.

    Huumonen S, Suominen AL, Vehkalahti MM. Prevalence of apical periodontitis in root filled teeth: findings from a nationwide survey in Finland. Int Endod J. 2017;50(3):229236. doi: 10.1111/iej.12625

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 29.

    Kirkevang LL, Orstavik D, Horsted-Bindslev P, Wenzel A. Periapical status and quality of root fillings and coronal restorations in a Danish population. Int Endod J. 2000;33(6):509515. doi: 10.1046/j.1365-2591.2000.00381.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 30.

    Lothamer CW, Anderson A, Hetzel SJ, et al. Apical microleakage in root canals obturated with 2 different endodontic sealer systems in canine teeth of dogs. J Vet Dent. 2017;34(2):8691. doi: 10.1177/0898756417713978

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 31.

    Fleming CH, Litaken MS, Alley LW, Eleazer PD. Comparison of classic endodontic techniques versus contemporary techniques on endodontic treatment success. J Endod. 2010;36(3):414418. doi: 10.1016/j.joen.2009.11.013

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 32.

    de Paula-Silva FWG, Santamaria M Jr, Leonardo MR, Consolaro A, Bezerra da Silva LA. Cone-beam computerized tomographic, radiographic, and histologic evaluation of periapical repair in dogs’ post-endodontic treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;108(5):796805. doi: 10.1016/j.tripleo.2009.06.016

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Figure 1

    Intraoral radiographic images of the right maxillary fourth premolar tooth of a 2-year-old male mixed-breed dog with a complicated crown fracture. Images were obtained with digital radiography by use of the bisecting angle technique before (A), immediately after (B), 4 months after (C), and 1 year after (D) root canal treatment (RCT). Notice the preoperative periapical lucency (arrows; A and B), which had resolved by 4 months after RCT (C). The outcome was classified as successful.

  • Figure 2

    Intraoral radiographic images of the right maxillary canine tooth of a 4-year-old male mixed-breed dog with a complicated crown fracture. Images were obtained before (A), immediately after (B), and 3 months after (C) RCT. Notice the preoperative periapical lucency (arrows) and external inflammatory root resorption. The external inflammatory root resorption was static 3 months after RCT (C), and the outcome was classified as no evidence of failure.

  • Figure 3

    Intraoral radiographic images of the left maxillary canine tooth of a 7-year-old castrated male Labrador Retriever with severe abrasion resulting in pulp exposure. Images were obtained before (A), immediately after (B), and 3 months after (C) RCT. A chevron sign artifact (arrowheads) was visible on images obtained before and immediately after RCT. A periapical lucency (arrows) was visible 3 months after RCT, and the outcome was classified as failed.

  • 1.

    Hale FA. Localized intrinsic staining of teeth due to pulpitis and pulp necrosis in dogs. J Vet Dent. 2001;18(1):1420. doi: 10.1177/089875640101800102

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2.

    Berman LH, Rotstein I. Diagnosis. In: Berman LH, Hargreaves KM, eds. Cohen's Pathways of the Pulp. 11th ed. Mosby; 2016:232.

  • 3.

    Menzies RA, Reiter AM, Lewis JR. Assessment of apical periodontitis in dogs and humans: a review. J Vet Dent. 2014;31(1):821. doi: 10.1177/089875641403100101

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4.

    Torabinejad M, Shabahang S. Pulp and periapical pathosis. In: Torabinejad M, Walton RE, eds. Endodontics: Principles and Practice. 4th ed. Saunders Elsevier; 2009:4666.

    • Search Google Scholar
    • Export Citation
  • 5.

    Ng YL, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: systematic review of the literature–part 2. Influence of clinical factors. Int Endod J. 2008;41(1):631. doi: 10.1111/j.1365-2591.2007.01323.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6.

    Kuntsi-Vaattovaara H, Verstraete FJM, Kass PH. Results of root canal treatment in dogs: 127 cases (1995–2000). J Am Vet Med Assoc. 2002;220(6):775780. doi: 10.2460/javma.2002.220.775

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7.

    Consensus report of the European Society of Endodontology on quality guidelines for endodontic treatment. Int Endod J. 1994;27(3):115124. doi: 10.1111/j.1365-2591.1994.tb00240.x

    • Search Google Scholar
    • Export Citation
  • 8.

    European Society of Endodontology. Quality guidelines for endodontic treatment: consensus report of the European Society of Endodontology. Int Endod J. 2006;39(12):921930. doi: 10.1111/j.1365-2591.2006.01180.x

    • Search Google Scholar
    • Export Citation
  • 9.

    White SC, Pharoah MJ. Projection Geometry. In: White SC, Pharoah MJ, eds. Oral radiology: principles and interpretation. 6th ed. Mosby; 2009:4652.

    • Search Google Scholar
    • Export Citation
  • 10.

    Strøm PC, Arzi B, Lommer MJ, et al. Radiographic outcome of root canal treatment of canine teeth in cats: 32 cases (1998–2016). J Am Vet Med Assoc. 2018;252(5):572580. doi: 10.2460/javma.252.5.572

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11.

    Ng YL, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: systematic review of the literature—part 1. Effects of study characteristics on probability of success. Int Endod J. 2007;40(12):921939. doi: 10.1111/j.1365-2591.2007.01322.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 12.

    Pirani C, Chersoni S, Montebugnoli L, Prati C. Long-term outcome of non-surgical root canal treatment: a retrospective analysis. Odontology. 2015;103(2):185193. doi: 10.1007/s10266-014-0159-0

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13.

    Stoll R, Betke K, Stachniss V. The influence of different factors on the survival of root canal fillings: a 10-year retrospective study. J Endod. 2005;31(11):783790. doi: 10.1097/01.don.0000158229.43298.a9

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14.

    Friedman S, Abitbol S, Lawrence HP. Treatment outcome in endodontics: the Toronto Study. Phase 1: initial treatment. J Endod. 2003;29(12):787793. doi: 10.1097/00004770-200312000-00001

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15.

    Chugal NM, Clive JM, Spångberg LS. A prognostic model for assessment of the outcome of endodontic treatment: effect of biologic and diagnostic variables. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2001;91(3):342352. doi: 10.1067/moe.2001.113106

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16.

    Basmadjian-Charles CL, Farge P, Bourgeois DM, Lebrun T. Factors influencing the long-term results of endodontic treatment: a review of the literature. Int Dent J. 2002;52(2):8186. doi: 10.1111/j.1875-595x.2002.tb00605.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17.

    Dammaschke T, Steven D, Kaup M, Reiner Ott KH. Long-term survival of root-canal-treated teeth: a retrospective study over 10 years. J Endod. 2003;29(10):638643. doi: 10.1097/00004770-200310000-00006

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18.

    Hoskinson SE, Ng YL, Hoskinson AE, Moles DR, Gulabivala K. A retrospective comparison of outcome of root canal treatment using two different protocols. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;93(6):705715. doi: 10.1067/moe.2001.122822

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19.

    Azim AA, Griggs JA, Huang GT. The Tennessee study: factors affecting treatment outcome and healing time following nonsurgical root canal treatment. Int Endod J. 2016;49(1):616. doi: 10.1111/iej.12429

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 20.

    Ng YL, Mann V, Gulabivala K. A prospective study of the factors affecting outcomes of nonsurgical root canal treatment: part 1: periapical health. Int Endod J. 2011;44(7):583609. doi: 10.1111/j.1365-2591.2011.01872.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 21.

    Sjogren U, Hagglund B, Sundqvist G, Wing K. Factors affecting the long-term results of endodontic treatment. J Endod. 1990;16(10):498504. doi: 10.1016/S0099-2399(07)80180-4

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 22.

    Kojima K, Inamoto K, Nagamatsu K, et al. Success rate of endodontic treatment of teeth with vital and nonvital pulps. A meta-analysis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004;97:9599. doi: 10.1016/j.tripleo.2003.07.006

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 23.

    Raedel M, Hartmann A, Bohm S, Walter MH. Three-year outcomes of root canal treatment: mining an insurance database. J Dent. 2015;43(4):412417. doi: 10.1016/j.jdent.2015.01.013

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 24.

    Tavares PB, Bonte E, Boukpessi T, Siqueira JF Jr, Lasfargues J-J. Prevalence of apical periodontitis in root canal-treated teeth from an urban French population: influence of the quality of root canal fillings and coronal restorations. J Endod. 2009;35(6):810813. doi: 10.1016/j.joen.2009.03.048

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 25.

    Cheung GS. Survival of first-time nonsurgical root canal treatment performed in a dental teaching hospital. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;93(5):596604. doi: 10.1067/moe.2002.120254

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 26.

    De Moor RJ, Hommez GM, De Boever JG, et al. Periapical health related to the quality of root canal treatment in a Belgian population. Int Endod J. 2000;33(2):113120. doi: 10.1046/j.1365-2591.2000.00295.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 27.

    Ridell K, Petersson A, Matsson L, Mejàre I. Periapical status and technical quality of root-filled teeth in Swedish adolescents and young adults. A retrospective study. Acta Odontol Scand. 2006;64(2):104110. doi: 10.1080/00016350500367637

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 28.

    Huumonen S, Suominen AL, Vehkalahti MM. Prevalence of apical periodontitis in root filled teeth: findings from a nationwide survey in Finland. Int Endod J. 2017;50(3):229236. doi: 10.1111/iej.12625

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 29.

    Kirkevang LL, Orstavik D, Horsted-Bindslev P, Wenzel A. Periapical status and quality of root fillings and coronal restorations in a Danish population. Int Endod J. 2000;33(6):509515. doi: 10.1046/j.1365-2591.2000.00381.x

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 30.

    Lothamer CW, Anderson A, Hetzel SJ, et al. Apical microleakage in root canals obturated with 2 different endodontic sealer systems in canine teeth of dogs. J Vet Dent. 2017;34(2):8691. doi: 10.1177/0898756417713978

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 31.

    Fleming CH, Litaken MS, Alley LW, Eleazer PD. Comparison of classic endodontic techniques versus contemporary techniques on endodontic treatment success. J Endod. 2010;36(3):414418. doi: 10.1016/j.joen.2009.11.013

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 32.

    de Paula-Silva FWG, Santamaria M Jr, Leonardo MR, Consolaro A, Bezerra da Silva LA. Cone-beam computerized tomographic, radiographic, and histologic evaluation of periapical repair in dogs’ post-endodontic treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;108(5):796805. doi: 10.1016/j.tripleo.2009.06.016

    • Crossref
    • Search Google Scholar
    • Export Citation

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