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Introduction: To evaluate the impact of root canal preparation in teeth with ultraconservative access cavities (UltraAC) on the development of dentinal microcracks using a nondestructive longitudinal micro-computed tomography (micro-CT) imaging experimental model. Root canal preparation in teeth with traditional access cavities (TradAC) was used as control., Methods: Forty mandibular molars were scanned in a micro-CT device, anatomically matched, and distributed into 4 groups according to the type of access cavity and instrumentation system: traditional/Reciproc (TradAC/RC), traditional/XP-endo Shaper (TradAC/XP), ultraconservative/Reciproc (UltraAC/RC), and ultraconservative/XP-endo Shaper (UltraAC/XP). After root canal preparation, the teeth were rescanned. After reconstruction and co-registration procedures, the images were screened from the furcation level to the apex to identify the presence of dentinal microcracks., Results: From a total of 15,340 cross-section images, 19.65% (3014 slices) had some dentinal microcracks. The qualitative analysis demonstrated the presence of some dentinal microcracks in 11%, 33%, 19%, and 15% of the images of cross-sections in TradAC/RC, TradAC/XP, UltraAC/RC, and UltraAC/XP groups, respectively. All dentinal microcracks observed after root canal preparation were already present in the corresponding images before canal instrumentation. Therefore, no new microcracks were detected, regardless of the access cavity and root canal instrumentation system., Conclusions: Root canal preparation with Reciproc or XP-endo Shaper under traditional or ultraconservative access cavities did not create dentinal microcracks in extracted mandibular molars., (Copyright © 2022 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The purpose of this study was to perform a quality assessment and provide a scientific-based checklist for prevalence studies on root and root canal anatomy by appraising the methodological quality of in vivo studies using cone-beam computed tomographic (CBCT) imaging as the assessment tool., Methods: A systematic assessment of the literature was conducted, and 211 studies were selected and submitted to a methodological evaluation. Data were grouped into categories such as journal impact factor, open access availability, language, study origin, journal publisher, sample size, and CBCT settings. Interrater agreement was calculated by applying the Holsti method and Cohen kappa. The Kruskal-Wallis test and Pearson correlation coefficient were undertaken to assess the different variables (α = 0.05)., Results: The included studies (N = 211) reported data on 247,616 teeth from 41 countries. The maxillary first molar was the most studied tooth (n = 69) and the second mesiobuccal canal the most investigated anatomic feature. The highest scores were associated with high-impact journals (r = 0.482, P < .05), large sample sizes (r = 0.374, P < .05), non-open access availability (P < .05), and English-based language (P < .05), but geographic region and journal publisher also had an impact on quality scores. The identified methodological gaps were used to formulate a scientific-based checklist for this type of study., Conclusions: Although a small improvement in the global quality of the studies was observed over the years, only less than half of the studies correctly addressed the participant recruitment and frame and had an adequate sample size or provided sufficient CBCT imaging settings. The proposed checklist highlights the most pertinent points to guide researchers throughout the experimental design and the implementation of epidemiological cross-sectional studies of this nature., (Copyright © 2020 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Glide path preparation has been recommended as a mandatory clinical step to ensure the safe usage of nickel-titanium (NiTi) rotary instruments. This study aimed to evaluate the effectiveness and fracture rate of 4 pathfinding NiTi rotary instruments in mechanically negotiating moderately curved molar canals., Methods: Moderately curved maxillary (n = 120) and mandibular (n = 120) molars were randomly distributed into 4 experimental groups (n = 60, 30 maxillary and 30 mandibular molars) according to the instrument used for glide path preparation: ScoutRace 10/.02 (FKG Dentaire, La Chaux-de-Fonds, Switzerland) (800 rpm and 1-Ncm torque), ProDesign 25/.01 (Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) (350 rpm and 1-Ncm torque), Mtwo 10/.04 (VDW, Munich, Germany) (280 rpm and 1.2 Ncm torque), or ProGlider 16/.02 (Dentsply Maillefer, Ballaigues, Switzerland) (300 rpm and 5-Ncm torque). The instrument fracture rate and the absolute and percentage frequencies of molars in which the pathfinding instruments reached the full working length in all root canals according to tooth and canal types were recorded and statistically compared using the Pearson's chi-square test (α = 5%)., Results: The highest and lowest frequency of reached the full working length canals were observed in the ScoutRace (68.3%) and ProDesign (38.3%) groups (P < .05), respectively, whereas the Mtwo (58.3%) and ProGlider (51.6%) groups showed intermediate results (P > .05). The ProGlider group showed the highest percentage frequency of instrument separation (11.6%) followed by the Mtwo (8.3%), ScoutRace (3.3%), and ProDesign (3.3%) groups (P < .05)., Conclusions: ScoutRace performed more efficiently and with less instrument breakage than the other systems. ProDesign was the least efficient, and ProGlider exhibited the highest rate of instrument breakage among the systems tested., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

The purpose of this study was to assess the ability of an off-centered rectangular design system [ProTaper Next (PTN)] to maintain the original profile of the root canal anatomy. To this end, ProTaper Universal (PTU), Reciproc (R) and WaveOne (WO) systems were used as reference techniques for comparison. Forty clear resin blocks with simulated curved root canals were randomly assigned to 4 groups (n = 10) according to the instrumentation system used: PTN, PTU, R and WO. Color stereomicroscopic images of each block were taken before and after instrumentation. All image processing and data analysis were performed with an open source program (Fiji v.1.47n). Evaluation of canal transportation was obtained for two independent regions: straight and curved portions. Univariate analysis of variance and Tukey's Honestly Significant Difference test were performed, and a cut-off for significance was set at α = 5%. Instrumentation systems significantly influenced canal transportation (p = 0.000). Overall, R induced significantly lower canal transportation compared with WO, PTN and PTU (p = 0.000). The curved portion displayed superior canal transportation compared to the straight one (p = 0.000). The significance of the difference among instrumentation systems varied according to the canal level evaluated (p = 0.000). In its straight portion, R and WO exhibited significantly lower transportation than PTN; whereas in the curved portion, R produced the lowest deviation. PTU exhibited the highest canal transportation at both levels. It can be concluded that PTN produced less canal transportation than PTU and WO; however, R exhibited better centering ability than PTN.

Objective: Several studies demonstrate variability of root canal morphology of anterior teeth. This in-vivo study was designed to analyze and characterize root canal morphology of maxillary and mandibular anterior teeth using three-dimensional imaging., Method and Materials: Patients who required CBCT radiographic examinations as part of their routine examination, diagnosis, and treatment planning were enrolled on the study. A total of 1,200 healthy, untreated, fully developed maxillary and mandibular incisors and canines were included. The following observations were recorded: (i) number of roots and their morphology; (ii) number of canals per root; and (iii) primary variations in the morphology of the root canal systems., Results: Root canal morphology of maxillary teeth was consistent with a single canal extending from the pulp chamber to the apex in 98% of the cases. In contrast, in mandibular central and lateral incisors, the presence of a single canal represented 64.5% and 60.5% respectively. The second most common morphology was the presence of one canal leaving the pulp chamber, which divided into two within the root, and then merged to exit as one canal in 18% and 25.5% respectively. The presence of one canal leaving the pulp chamber and dividing short of the apex into two separate and distinct canals with separate apical foramina (variant 5) was recorded in 14.5% and 12% respectively., Conclusion: There was a low incidence of anatomical variation in maxillary anterior teeth. In contrast, mandibular anterior teeth presented with a high prevalence of two canals, especially central and lateral incisors. The reported data may help clinicians understand the variations in root canal morphology of anterior teeth in order to overcome problems associated with shaping and cleaning procedures.

The aim of this study was to analyze the antimicrobial activity and substantivity of Uncaria tomentosa Willd DC (cat's claw, CC) in root dentin contaminated with Enterococcus faecalis. Forty-eight human premolars were contaminated with E. faecalis (ATCC 29212) and randomly divided into four groups according to the irrigant used during chemomechanical preparation (CMP): CC group: 2% CC gel; CHX group: 2% chlorhexidine digluconate gel (CHX); NaOCl group: 5.25% sodium hypochlorite (NaOCl); and SS group: sterile saline (SS). Microbiological samples were collected before (S1) and after (S2) CMP and after 7 days (S3). Colony-forming units (CFU/mL) at the different sampling times and comparisons among the groups were statistically analyzed by Wilcoxon and Kruskal-Wallis tests (p < 0.05). Significant bacterial reduction was achieved in all groups after CMP (p < 0.05). Results show no significant difference between S3 and S2 (p > 0.05) in the CC and CHX groups. Bacterial load was higher in S3 than in S2 samples (p < 0.05) in the NaOCl and SS groups. Our results suggest antibacterial effect of 2% CC gel against E. faecalis in infected dentin, in addition to antibacterial substantivity of 2% CC and 2% CHX up to 7 days.

Aim: To investigate endotoxin levels from primary endodontic infections before and after chemomechanical preparation (CMP) and to determine their antigenicity against 3T3 fibroblasts through gelatinolytic activity of matrix metalloproteinases (MMPs)., Methodology: Twenty-four root canals with primary endodontic infection and apical periodontitis were selected. Samples were collected using paper points before (S1) and after chemomechanical preparation (CMP) (S2). The limulus amebocyte lysate assay was used for endotoxin measurement. Fibroblasts were stimulated with root canal contents for 24 h. Supernatants of cell cultures stimulated with root canal contents were collected after 24 h to determine the levels of MMP-2 and MMP-9 gelatinolytic activity using the zymography technique. Friedman and Wilcoxon tests were used to compare the amount of endotoxin before (S1) and after CMP (S2) (P < 0.05). Data obtained from gelatinolytic activity were analysed using anova and Tukey's tests (P < 0.05)., Results: Endotoxin was recovered in 100% of the samples. There was a significant reduction in endotoxin levels after CMP (P < 0.05). A correlation was found between the levels of endotoxins and MMP-2 expression (P < 0.05). Root canal contents of initial samples (S1) induced significantly greater MMP-2 expression by fibroblasts when compared to S2 and the nonstimulated group (P < 0.05). No gelatinolytic activity of MMP-9 was observed in S1, S2 and control group., Conclusions: Root canal contents from primary endodontic infections had gelatinolytic activity for MMP-2. Moreover, CMP was effective in reducing endotoxin levels and their antigenicity against fibroblasts on gelatinolytic activity., (© 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Introduction: The aim of this study was to evaluate the ability of the Twisted File Adaptive (TF Adaptive; SybronEndo, Orange, CA) system in maintaining the original profile of root canal anatomy. The ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) and Twisted File (TF) (SybronEndo) systems were used as reference techniques for comparison., Methods: Thirty simulated curved root canals manufactured in clear resin blocks were randomly assigned to 3 groups (n = 10) according to the instrumentation system: TF in rotary motion, TF in TF Adaptive motion, and ProTaper Universal. Color stereomicroscopic images from each block were taken exactly at the same position before and after instrumentation. All image processing and data analysis were performed with an open-source program (Fiji). Evaluation of canal transportation was obtained for 2 independent canal regions: straight and curved levels. Univariate analysis of variance and Tukey Honestly Significant Difference were used, and a cutoff for significance was set at alpha = 5%., Results: Instrumentation systems significantly influenced canal transportation (P = .000). A significant interaction between instrumentation system and root canal level (P = .000) was also found as follows: at the straight part, TF and TF Adaptive systems produced similar canal transportation, which was significantly lower than for the ProTaper Universal system; at the curved part, TF resulted in the lowest canal transportation followed by TF Adaptive and ProTaper Universal systems. Canal transportation was higher at the curved canal parts (P = .00)., Conclusions: The TF in rotary motion produced overall less canal transportation in the curved portion when compared with the others tested systems. The ProTaper Universal system showed the highest canal transportation., (Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Aim: To evaluate the influence of reciprocating single-file instrumentation with different working lengths (WL) and apical preparation sizes on apical bacterial extrusion., Methodology: Sixty-eight human single-rooted pre-molars were used. Conventional access cavities were prepared, and the root canals were contaminated with an Enterococcus faecalis suspension and incubated at 37°C for 30 days. Teeth were then divided into four groups of 15 specimens each (Reciproc size 25, .08 taper and Reciproc size 40, .06 taper instruments were used at the foramen; Reciproc size 25, .08 taper and Reciproc size 40, .06 taper instruments were used 1 mm short of the foramen). Positive and negative controls consisted of four infected and four uninfected pre-molars that were instrumented according to each experimental group. Bacteria extruded from the apical foramen during instrumentation were collected into vials containing 0.9% NaCl. The microbiological samples were then incubated in a brain-heart agar medium for 24 h. The resulting bacterial titre, in colony-forming units (CFU) per mL, was determined, and these data were analysed using a Wilcoxon matched-pairs signed rank test and a Kruskal-Wallis H-test. The level of significance was set at α = 0.05., Results: No growth was observed in the negative control group. All positive controls demonstrated bacterial growth after the experimental time interval. No significant difference was found in the number of CFU amongst all experimental groups (P = 0.95)., Conclusions: This study showed that the WL and the apical preparation size did not have a significant effect on bacterial extrusion when performing reciprocating instrumentation., (© 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Unlabelled: The search for new instruments to promote an appropriate cervical preparation has led to the development of new rotary instruments such as TripleGates. However, to the best of the authors' knowledge, there is no study evaluating TripleGates effect on the "risk zone" of mandibular molars., Objectives: The aim of this study was to evaluate the effects of a crown-down sequence of Gates-Glidden and TripleGates burs on the remaining cervical dentin thickness and the total amount of dentin removed from the root canals during the instrumentation by using cone beam computed tomography. The number of separated instruments was also evaluated., Material and Methods: Mesial roots of 40 mandibular first molars were divided into 2 equal groups: crown-down sequence of Gates-Glidden (#3, #2, #1) and TripleGates burs. Cervical dentin thickness and canal area were measured before and after instrumentation by using cone beam computed tomography and image analysis software. Student's t-test was used to determine significant differences at p < 0.05., Results: No significant differences (p > 0.05) were observed between the instruments, regarding the root canal area and dentin wall thickness., Conclusion: Both tested instruments used for cervical preparation were safe to be used in the mesial root canal of mandibular molars.

Introduction: The aim of this study was to evaluate the quality and bond strength of three root filling techniques (lateral compaction, continuous wave of condensation and Tagger's Hybrid technique [THT]) using micro-computed tomography (CT) images and push-out tests, respectively., Materials and Methods: Thirty mandibular incisors were prepared using the same protocol and randomly divided into three groups (n=10): Lateral condensation technique (LCT), continuous wave of condensation technique (CWCT), and THT. All specimens were filled with Gutta-percha (GP) cones and AH Plus sealer. Five specimens of each group were randomly chosen for micro-CT analysis and all of them were sectioned into 1 mm slices and subjected to push-out tests., Results: Micro-CT analysis revealed less empty spaces when GP was heated within the root canals in CWCT and THT when compared to LCT. Push-out tests showed that LCT and THT had a significantly higher displacement resistance (P<0.05) when compared to the CWCT. Bond strength was lower in apical and middle thirds than in the coronal thirds., Conclusions: It can be concluded that LCT and THT were associated with higher bond strengths to intraradicular dentine than CWCT. However, LCT was associated with more empty voids than the other techniques.

Introduction: This study aimed to evaluate the frequency of dentinal microcracks observed after root canal preparation with 2 reciprocating and a conventional full-sequence rotary system using micro-computed tomographic analysis., Methods: Thirty mesial roots of mandibular molars presenting a type II Vertucci canal configuration were scanned at an isotropic resolution of 14.16 μm. The sample was randomly assigned to 3 experimental groups (n = 10) according to the system used for the root canal preparation: group A-Reciproc (VDW, Munich, Germany), group B-WaveOne (Dentsply Maillefer, Baillagues, Switzerland), and group C-BioRaCe (FKG Dentaire, La-Chaux-de-Fonds, Switzerland). Second and third scans were taken after the root canals were prepared with instruments sizes 25 and 40, respectively. Then, pre- and postoperative cross-section images of the roots (N = 65,340) were screened to identify the presence of dentinal defects., Results: Dentinal microcracks were observed in 8.72% (n = 5697), 11.01% (n = 7197), and 7.91% (n = 5169) of the cross-sections from groups A (Reciproc), B (WaveOne), and C (BioRaCe), respectively. All dentinal defects identified in the postoperative cross-sections were also observed in the corresponding preoperative images., Conclusions: No causal relationship between dentinal microcrack formation and canal preparation procedures with Reciproc, WaveOne, and BioRaCe systems was observed., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Recognition of anatomic variations is a challenge for clinicians regardless of which tooth is treated. Maxillary premolars usually have 2 root canals, but the presence of 3 distinct root canals has been reported in 1%-6% of cases., Methods and Results: This report describes the case of a maxillary right second premolar with 4 separate canals: 1 mesial, 1 palatal, and 2 distal canals. This was confirmed by using cone-beam computed tomography and was successfully treated with rotary files and obturated by using a warm vertical compaction technique., Conclusions: The clinical significance of the present case is that this is the first report of 3 roots and 4 separate canals in a maxillary premolar. Precise knowledge of root canal morphology and its variation is also underlined. Cone-beam computed tomography examination and the operating microscope are excellent tools for identifying and managing these complex root canal systems., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: This study was designed to quantitatively evaluate the amount of apically extruded debris by the Self-Adjusting-File system (SAF; ReDent-Nova, Ra'anana, Israel). Hand and rotary instruments were used as references for comparison., Methods: Sixty mesial roots of mandibular molars were randomly assigned to 3 groups (n = 20). The root canals were instrumented with hand files using a crown-down technique. The ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) and SAF systems were used according to the manufacturers' instructions. Sodium hypochlorite was used as an irrigant, and the apically extruded debris was collected in preweighted glass vials and dried afterward. The mean weight of debris was assessed with a microbalance and statistically analyzed using 1-way analysis of variance and the post hoc Tukey multiple comparison test., Results: Hand file instrumentation produced significantly more debris compared with the ProTaper and SAF systems (P < .05). The ProTaper system produced significantly more debris compared with the SAF system (P < .05)., Conclusions: Under the conditions of this study, all systems caused apical debris extrusion. SAF instrumentation was associated with less debris extrusion compared with the use of hand and rotary files., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of this study was to analyze and characterize root canal morphology of maxillary molars of the Brazilian population using cone-beam computed tomographic (CBCT) imaging., Methods: Patients referred for a CBCT radiographic examination for accurate diagnosis and treatment planning were enrolled in the study. A total of 620 healthy, untreated, fully developed maxillary first and second molars were included (314 first molars and 306 second molars). The following observations were recorded: (1) number of roots and their morphology, (2) number of canals per root, (3) fused roots, and (4) primary variations in the morphology of the root canal systems., Results: First and second molars showed a higher prevalence of 3 separate roots, mesiobuccal, distobuccal, and palatal, with 1 canal in each root (52.87% and 45.09%, respectively). Two canals in the mesiobuccal roots represented 42.63% of teeth, whereas mesiobuccal roots of second molars presented 2 canals in 34.32%. The most common anatomic variation in the maxillary first molar was related to the root canal configuration of the mesiobuccal root, whereas the root canal system of the maxillary second molar teeth showed more anatomic variables., Conclusions: Mesiobuccal roots of maxillary molar teeth had more variation in their canal system than the distobuccal or palatal roots. The root canal configuration of the maxillary second molars was more variable than the first molars in a Brazilian population. CBCT imaging is a clinically useful tool for endodontic diagnosis and treatment planning., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Aim: To evaluate ex vivo the accuracy of the multifrequency electronic apex locator (EAL) Joypex 5 in primary molars., Methods: Fourteen primary molars were selected for a total of 25 root canals. Working length measurements were performed by direct observation (DO), using a 15 K-file into the root canal until its tip was visible at the apical foramen and electronically using the EALs Joypex 5. Data were analysed statistically using the intraclass correlation coefficient (ICC). To assess whether a significant difference in accuracy of the electronic apex locator existed, the Student's t test was performed at 5% significance., Results: No statistical difference was observed between the direct observation and the EAL measurement (p < 0.05). The ICC confirmed the agreement of different methods to measure canal length. The R(2) coefficient was close to 1, denoting a strong agreement between measures obtained with Joypex 5 and DO., Conclusion: The multifrequency EALs Joypex 5 showed adequate accuracy in the root length determination of primary teeth.

The aim of this study was to evaluate age-related morphological canal changes in mesial root canals of mandibular first molars of known ages. Fifty-six specimens were selected for this study and distributed into the following four age groups (n. 14): a) Group of children under 13 years, b) Group of adolescents (from 14 to 19 years), c) Group of young adults (from 20 to 39 years) and d) Group of older adults (over 40 years). The specimens were in perfect condition because after extraction they were carefully cleaned, sterilized, identified and stored in water. In order to improve the cleaning, they were placed in 1% sodium hypochlorite solution for four hours and rinsed in 10 vol. hydrogen peroxide for 8 hours. After that, a clearing technique was performed to illustrate root canal anatomy. Digitalized images of all samples were obtained by use of a stereomicroscope. Canals were noticeably simpler in older adults: they were sharply defined and narrow, sometimes too narrow. Calcification nuclei were not found and there were only a few remains of internuclear spaces. The canal system appeared cleaner, clearer and more sharply defined than in the other age groups. It may be concluded that there is a correlation between aging and morphological changes in the mesial root canals of mandibular first molars.

Introduction: The aim of this study was to analyze and characterize root canal morphology of mandibular molars of the Brazilian population by using cone-beam computed tomography (CBCT)., Methods: Patients who required CBCT radiographic examinations as part of their routine examination, diagnosis, and treatment planning were enrolled in the study. A total of 460 healthy, untreated, fully developed mandibular first and second molars were included (234 first molars and 226 second molars). The following observations were recorded: (1) number of roots and their morphology, (2) number of canals per root, (3) C-shaped canals, and (4) primary variations in the morphology of the root canal systems., Results: First molars showed a higher prevalence of 2 canals in the mesial root and 1 in the distal root with 2 separate roots (74%). In the mandibular second molars, the presence of 2 separate roots with 2 canals in the mesial root and 1 canal in the distal root represented 54% of the total. In 32% of the cases, 2 separate roots with 1 canal each in the mesial and distal roots were presented. The incidence of C-shaped canals was 1.7% of first molars and 3.5% of second molars., Conclusions: A higher prevalence of 2 separate roots with 2 canals in the mesial root and 1 canal in the distal root was observed in mandibular first and second molars (74% and 54%, respectively). Also, a lower incidence of C-shaped canals and 3-rooted teeth was observed in a Brazilian population. CBCT is a clinically useful tool for endodontic diagnosis and treatment., (Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of this randomized, controlled, prospective clinical study was to determine if foraminal enlargement instrumentation during endodontic treatment is associated with more postoperative pain compared with standard nonenlargement instrumentation., Methods: Forty volunteers with a single root canal were diagnosed with asymptomatic necrosis with apical periodontitis and randomized into 2 experimental groups (ie, the control group and the foraminal enlargement group). Endodontic treatment was performed in a single visit, and volunteers were instructed to record pain intensity (ie, none, slight, moderate, and severe). Scores from 1 to 4 were attributed to each kind of pain after 12, 24, and 48 hours. The Kolmogorov-Smirnov and Student's t tests were used to determine significant differences at P < .05., Results: No statistically significant age difference was found between the groups (P > .05, Student's t test). Postoperative pain showed no statistically significant difference between the groups at any observation period (P > .05). Also, no significant difference was observed in the mean number of analgesic tablets used between the groups (P > .05)., Conclusions: The foraminal enlargement and nonenlargement techniques resulted in the same postoperative pain and necessity for analgesic medication. This may suggest that the use of foraminal enlargement should be performed for endodontic treatment previsibility without increasing postoperative pain., (Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Dens invaginatus is a critical condition for endodontic treatment. It frequently presents a complex internal anatomy and might be associated with incomplete root and apical development. This article presents one of the few reported cases of endodontic retreatment of Type III dens invaginatus. First, the internal anatomy was modified using burs under an operating microscope. Next, conventional chemical and mechanical preparation with hand files and 2.5% sodium hypochlorite was performed. Finally, an intracanal dressing with calcium hydroxide was used for nine months, at which point the anatomical features in the root canal system could be accessed. Adequate periradicular healing was observed and regression of the lesion was noted at the two-year follow-up. This case reinforces the idea that knowledge about the biologic aspects of endodontics, combined with adherence to technical standards, is helpful in resolving complex cases.