Factors influencing the outcome of nonsurgical root canal treatment and retreatment: A retrospective study.

This study assessed the influence of diverse variables on the outcome of nonsurgical root canal treatment/retreatment. In general, 304 teeth from 218 patients were treated/retreated and the outcome evaluated by the periapical index (PAI). Teeth with apical periodontitis lesions that have not completely healed were classified as success or failure based on lenient and rigid criteria, respectively. Findings were evaluated using a logistic regression analysis. The overall success rates were 74% and 82% using the PAI-rigid and lenient success criteria, respectively. Specifically for treatment, the success rates were 73% (rigid) and 82% (lenient), while for retreatment they were 78% (rigid) and 83% (lenient). The treatment outcome was negatively affected by overextension, presence of preoperative lesion, lesion size >10 mm, and higher number of treatment visits (with no intracanal medication). Regarding retreatment, the chance of success was greater for teeth with adequate coronal restorations.

Planned Apical Preparation Using Cone-Beam Computed Tomographic Measures: A Micro-Computed Tomographic Proof of Concept in Human Cadavers.

INTRODUCTION: This study assessed the amount of unprepared surface areas at the apical 4-mm segment of the root canal after a planned preparation based on cone-beam computed tomography (CBCT) measurements. METHODS: Eighteen posterior mandible segments were obtained from cadavers and scanned using CBCT and micro-computed tomographic (micro-CT) imaging. CBCT images were used to measure the largest initial canal diameter from 29 root canals of premolars at 1, 2, 3, and 4 mm short of the apical foramen. Each measurement was used to select a master apical instrument with size/taper that was 1 diameter larger to prepare the apical 4 mm of each particular root canal. A post-preparation micro-CT scan was obtained, and the unprepared canal areas were calculated. RESULTS: A very high amount of surface areas over the apical 4 mm of the root canal was included in the final preparation (mean >90%). The unprepared areas ranged from as low as 3.7% to a maximum of 14.6% (mean and median, 9.2% and 9.1%, respectively). CONCLUSIONS: The proposed planned apical root canal preparation resulted in optimized root canal shaping with a substantial amount of prepared surface areas. The protocol used also resulted in a conservative canal enlargement using final instruments that were 1 size larger than the initial largest canal diameter.

Disinfecting and Shaping Type I C-shaped Root Canals: A Correlative Micro-computed Tomographic and Molecular Microbiology Study.

INTRODUCTION: This ex vivo study compared the disinfection and shaping abilities of 2 preparation protocols in C-shaped canals. METHODS: Mandibular second molars with type I C-shaped canals were pair matched based on micro-computed tomographic (micro-CT) analysis and distributed into 2 groups. The canals were contaminated with a mixed bacterial culture and prepared using 2 protocols, both with 2.5% sodium hypochlorite irrigation: XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) supplemented with XP-endo Finisher (FKG Dentaire) (XP-E) and BioRaCe (FKG Dentaire) supplemented with a Hedström file (Dentsply/Sirona, Tulsa, OK) (BR-Hed). Micro-CT scans and intracanal bacteriologic samples were taken before (scan #1 and sample 1) and after preparation (scan #2 and sample 2) and after the supplementary step (scan #3 and sample 3). Canal shaping was evaluated by micro-CT imaging, and disinfection was assessed by quantitative polymerase chain reaction. RESULTS: Micro-CT data from the XP-E (n = 21) and BR-Hed (n = 23) protocols revealed no significant differences between groups regarding shaping parameters (canal volume, surface area, structure model index, and prepared walls) after preparation and after the supplementary step (P > .05). All these parameters significantly increased after each preparation step (P < .05), except for structure model index changes after the XP-endo Finisher (P > .05). Bacteriologic data from the XP-E (n = 21) and BR-Hed (n = 22) groups showed that 14 (66.7%) and 10 (45.5%) S2 samples still had detectable bacteria, respectively. The corresponding figures for supplementary steps with the XP-endo Finisher and Hedström file were 11 (52.4%) and 10 (45.5%), respectively. Bacterial counts in sample 1 significantly decreased in samples 2 and 3 in both groups (P < .01). Intragroup comparison between sample 2 and sample 3 showed a 66% reduction in counts after using the Hedström file and 18% after using the XP-endo Finisher (P > .05 for both groups). The quantitative bacterial reduction was not different between groups (P > .05). CONCLUSIONS: The XP-endo Shaper and BioRaCe systems have similar disinfecting and shaping abilities in C-shaped canals. Supplementary steps with the Hedström file and the XP-endo Finisher were similarly effective in improving shaping, but this was not sufficient to enhance disinfection. About half of the cases, in both groups, still harbored detectable amounts of bacteria.

Distribution of sodium hypochlorite throughout the mesial root canal system of mandibular molars after adjunctive irrigant activation procedures: a micro-computed tomographic study.

OBJECTIVES: To evaluate and compare irrigant distribution throughout the root canal system of mesial roots of mandibular molars after application of distinct adjunctive irrigant activation procedures. MATERIALS AND METHODS: Fifteen extracted mandibular molars presenting Fan's type II, III, or IV isthmus configurations were selected. The canals were initially enlarged and cleaned. The same specimens were subjected to conventional positive pressure irrigation (PPI) followed by adjunctive irrigation approaches: passive ultrasonic irrigation (PUI), mechanical activation with the XP-endo Finisher instrument, and a control group in which the irrigant remained in the canal with no activation. Retention time for the irrigant was the same for all groups. Sodium hypochlorite mixed with a contrast medium (Omnipaque 300) was used as the irrigant. Before and immediately after the adjunctive irrigation, micro-computed tomographic (micro-CT) scans were taken to evaluate the volume of the entire root canal system that was filled by the irrigant. An exclusive analysis was also done for the isthmus area. RESULTS: Analysis of the entire root canal system showed that the XP-endo Finisher instrument promoted better distribution of the irrigant than PUI and the control group (p < 0.01). PUI was not significantly different from the control group (p > 0.05). A separate analysis of the isthmus area showed no significant difference between the adjunctive irrigation methods and the control (p > 0.05). CONCLUSIONS: The XP-endo Finisher instrument promoted better distribution of irrigant throughout the root canal system, especially in the apical canal segment, when compared to PUI. However, the tested approaches did not differ as to the ability to drive irrigants into the isthmus area. CLINICAL RELEVANCE: This study highlighted that the XP-endo Finisher instrument presented a better performance to distribute irrigant throughout the root canal system, especially in the apical canal segment compared to positive pressure irrigation and PUI.

Transportation assessment in artificial curved canals after instrumentation with Reciproc, Reciproc Blue, and XP-endo Shaper Systems.

AIM: In the present study, we compared the transportation of three different instrumentation systems in different levels of standardized artificial curved canals. METHODS: Sixty epoxy resin blocks containing simulated canals were divided into three groups (n = 20) according to the instrument used for canal preparation: Reciproc (REC), Reciproc Blue (REC Blue), and XP-endo Shaper (XPS). Pre- and post-instrumentation digital images of each specimen were superimposed by Photoshop software to evaluate the different amount of transportation. The Kruskal-Wallis and Wilcoxon were the non-parametric tests applied for the intergroup and intragroup analyses, respectively. The significance level was set at 5%. RESULTS: The XPS showed significantly less canal transportation than REC Blue at five levels (P < 0.05) and significantly less canal transportation at seven evaluated levels when compared with the REC (P < 0.05). REC Blue showed significant less canal transportation than REC at four of the eight evaluated levels (P < 0.05). All evaluated instruments showed a significantly higher amount of resin removal toward the inner wall compared to the outer wall of the curvature (P < 0.001). CONCLUSION: Although the XPS showed significantly less canal transportation than REC and REC Blue, all systems produced transportation from the original canal anatomy.

Root Canal Disinfection by Single- and Multiple-instrument Systems: Effects of Sodium Hypochlorite Volume, Concentration, and Retention Time.

INTRODUCTION: This ex vivo study evaluated the intracanal bacterial reduction promoted by chemomechanical preparation using a single-file technique varying the volume, concentration, and retention time of sodium hypochlorite (NaOCl) irrigation in comparison with a multifile system. METHODS: Palatal roots from extracted maxillary first molars were selected and anatomically matched based on microcomputed tomographic analysis for group distribution. The canals were contaminated with a fresh mixed bacterial culture grown in anaerobiosis and recently obtained from a tooth with apical periodontitis. Specimens were divided into 4 groups of 24 each according to the following preparation protocols: REC-6LOW (Reciproc R50 instrument [VDW, Munich, Germany], 6% NaOCl, low irrigant volume), REC-2.5LOW (R50, 2.5% NaOCl, low irrigant volume), REC-2.5HI (R50, 2.5% NaOCl, high irrigant volume), and BR-2.5HI (BioRaCe [FKG Dentaire, LaChaux-de-Fonds, Switzerland], 2.5% NaOCl, high irrigant volume). The total time of preparation was recorded. Intracanal bacteriologic samples were taken before and after preparation; DNA was extracted and subjected to quantitative polymerase chain reaction. RESULTS: Bacteria were detected in 22 initial samples from the REC-2.5LOW group and in 23 from the other groups. Intragroup analysis showed that all tested preparation protocols were highly effective in significantly reducing the intracanal bacterial counts (P < .001). Intergroup comparison of bacterial reduction levels revealed a statistically significant difference between BR-2.5HI and REC-2.5LOW (P < .05). Counts of bacteria were 2.5 times significantly higher in REC-2.5LOW compared with BR-2.5HI. No other significant differences were found in quantitative findings (P > .05). CONCLUSIONS: The concerted effects of multiple instruments, the high volume of irrigation, and the long retention time of NaOCl irrigant had a positive influence on intracanal disinfection during chemomechanical preparation.

Distance and Bone Density between the Root Apex and the Mandibular Canal: A Cone-beam Study of 9202 Roots from a Brazilian Population.

INTRODUCTION: Accidental damage to the inferior alveolar nerve is of concern during endodontic treatment of the posterior mandible teeth, and a careful evaluation of the relationship between the apices and the mandibular canal (MC) is mandatory to prevent iatrogenic complications. This study aimed to assess the distance between the root apices of posterior teeth and the MC and the bone density in such areas. METHODS: One thousand retrospective cone-beam computed tomographic scans were randomly selected from a private oral radiologic clinic database. The images were acquired with a limited field of view and analyzed by 2 evaluators who measured the shortest distance between the root apices and the upper cortical bone of the MC using Dental Slice software (Bioparts Biomedical Prototyping, Brasília, DF, Brazil). In addition, bone density was estimated using the tool "profile line of Hounsfield" and expressed in Hounsfield units. RESULTS: The distal root of the right second molars was the closest to the MC (mean = 3.41 mm), and the right first premolar root was the farthest from the MC (mean = 5.87 mm), respectively. The root apices were closer to the MC in women than in men (P < .05). In 1.79% of the cases, the roots were in contact or invading the MC, whereas 8.35% of the root apices were close to the MC (<1.00 mm), and 89.85% were distant from the MC (>1.00 mm). In 85.55% of the cases, the bone was dense. CONCLUSIONS: The results suggest that the risk of damage to the inferior alveolar nerve is higher for second molars, especially in female patients. The higher density of the adjacent bone may act as a protective factor against nerve damage arising from endodontic procedures.