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Introduction The purpose of the present study was to evaluate the remaining root canal filling material, apical transportation, and crack formation after retreatment with M-Wire Reciproc (VDW GmbH, Munich, Germany) and Reciproc Blue (VDW GmbH) systems in curved root canals. Methods Twenty-six mandibular first and second molars with mesial roots that had 2 separate canals with angles between 20° and 40° were selected for this study. The root canals were prepared with M-Wire Reciproc size 25 instruments (VDW GmbH), and they were filled with gutta-percha and AH Plus sealer (Dentsply Sirona, Tulsa, OK). The samples were randomly divided into 2 groups (n = 13 each) according to the retreatment system used: an M-Wire Reciproc group and a Reciproc Blue group. The canals were retreated up to instrument size 25 and then to size 40 in both groups. After the retreatment procedures, the residual filling material volume, apical transportation, and crack formation were assessed using micro–computed tomographic imaging. Results There were no significant differences between the groups in the amount of residual filling material (P > .05). The apical canal transportation values were significantly higher in the M-Wire Reciproc group than in the Reciproc Blue group at 1 mm. No significant differences were observed between the groups at any of the other levels with regard to apical transportation (P > .05) The new uncompleted and completed cracks were observed in both groups. There were no statistically significant differences between the groups in terms of crack and fracture formation (P > .05). Conclusions The Reciproc Blue system is as effective as the M-Wire Reciproc system in terms of the retreatment of the curved mesial roots of mandibular molars. However, the formation of new uncompleted and completed cracks was found during the retreatment procedures.

Introduction The aim of the present study was to evaluate the effects of calcium hydroxide (Ca[OH]2), Ca(OH)2 + ibuprofen, and Ca(OH)2 + ciprofloxacin in terms of receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) levels in asymptomatic periapical lesions. Methods Sixty-six patients were randomly divided into 3 groups using a Web program according to the medication selected: Ca(OH)2, Ca(OH)2 + ibuprofen, and Ca(OH)2 + ciprofloxacin. After removing gutta-percha from the root canals, the RANKL and OPG samples were taken from the interstitial fluid of the apical tissues using 3 paper points. At the second appointment, medicaments were removed, and second sampling was performed using the same method. The RANKL and OPG levels were measured by the enzyme-linked immunosorbent assay, and the RANKL/OPG ratio was calculated. Results According to the intragroup analysis, there were no statistically significant differences between the preoperative and postoperative levels of the RANKL/OPG ratio in any of the groups. Intergroup analyses showed that there were no statistically significant differences among the Ca(OH)2, Ca(OH)2 + ibuprofen, Ca(OH)2 + ciprofloxacin groups in terms of the percentage change in RANKL/OPG levels before and after treatment. Conclusions Within the limitations of the present study, it can be concluded that addition of ibuprofen or ciprofloxacin to Ca(OH)2 paste does not provide any extra benefit in terms of lowering RANKL and OPG levels.

The purpose of the present study was to assess the effect of root canal instrumentation using Twisted File Adaptive instruments (Axis/SybronEndo, Orange, CA) with different kinematics (adaptive motion, 90° clockwise [CW]-30° counterclockwise [CCW], 150° CW-30° CCW, 210° CW-30° CCW, and continuous rotation) on crack formation.One hundred five mandibular central incisor teeth were selected. Fifteen teeth were left unprepared (control group), and the remaining 90 teeth were assigned to the 5 root canal shaping groups as follows (n = 15): adaptive motion, 90° CW-30° CCW, 150° CW-30° CCW, 210° CW-30° CCW, continuous rotation, and hand file. All the roots were sectioned horizontally at 3, 6, and 9 mm from the apex with a low-speed saw under water cooling, and the slices were then viewed through a stereomicroscope at 25× magnification. Digital images of each slice were captured using a camera to determine the presence of dentinal cracks.No cracks were observed in the control group, and the continuous rotation group had more cracks than the reciprocation groups (90° CW-30° CCW, 150° CW-30° CCW, and 210° CW-30° CCW) (P.05). Both the continuous rotation and adaptive motion groups had significantly more dentinal cracks than the hand file group (P.05). Regarding the different sections (3, 6, and 9 mm), there was a significant difference between the experimental groups at the 9-mm level (P.05).The incidence of dentinal cracks is less with TF Adaptive instruments working in 210° CW-30° CCW reciprocating motion compared with working in continuous rotation and adaptive motion.

The aim of this study was to compare the incidence of root cracks after root canal instrumentation with the TF Adaptive, WaveOne, ProTaper Next, and ProTaper Universal systems.Seventy-five extracted mandibular central incisors with mature apices and straight root canals (5°) were selected and kept in distilled water. The root canals were instrumented by using the ProTaper Universal, ProTaper Next, WaveOne, and TF Adaptive systems. All the roots were horizontally sectioned 3, 6, and 9 mm from the apex with a low-speed saw under water cooling. The slices were then viewed through a stereomicroscope at ×25 magnification. The samples were photographed with a camera to determine the presence of dentinal cracks.The control group had no cracks, and the difference between the control group and the experimental groups was statistically significant (P.001). The ProTaper Next and TF Adaptive systems produced significantly less cracks than the ProTaper Universal and WaveOne systems in the apical section (3 mm) (P.05).Under the study conditions and within the limitations of this study, it can be concluded that the ProTaper Universal, ProTaper Next, WaveOne, and TF Adaptive instruments can result in dentinal cracks.

Low-level laser therapy (LLLT) is a practical, nonpharmacologic technique for reducing pain. This study evaluated the effect of LLLT on postoperative pain after root canal retreatment (RCR).This study enrolled patients (N = 36) who required root canal retreatment (RCR) on mandibular molar teeth, presented with periapical lesions with periapical index scores of 2 or 3, and had a pain visual analog scale (VAS) 50 and a percussion pain VAS50. The participants were divided into 2 groups: (1) patients scheduled for RCR followed by LLLT (n = 18) and (2) patients scheduled for RCR followed by a mock LLLT (placebo) (n = 18). Postoperative pain was assessed using the VAS. Data were collected and statistically analyzed with the chi-square test, the independent sample t test, and the Mann-Whitney U test (P = .05).On the first 4 days, postoperative pain significantly reduced in the LLLT group compared with the placebo group (P .05). However, no statistically significant differences in postoperative pain were found between the 2 groups after 5 and 7 days (P .05). The number of patients who needed analgesics was lower in the LLLT group than in the placebo group (P .05). No patient reported pain during LLLT application.LLLT may reduce postoperative pain after RCR of mandibular molars.

The aim of this study was to evaluate the effect of simultaneous length control during root canal preparation on postoperative pain compared with separate working length determination and root canal preparation. The design was a parallel-group, randomized, controlled trial with 2 arms.Forty-four molar teeth were randomly divided into 2 groups (n = 22), a control group (separate length determination and root canal preparation) and a simultaneous length control during root canal preparation group. The following variables were recorded: age; gender; tooth number; preoperative pain on the visual analog scale; pain level on days 1, 3, 5, and 7; and analgesic intake after the procedure and initial/final percussion pain. The data were analyzed with the χThe simultaneous length control during root canal preparation group resulted in lower postoperative pain levels on day 1 than did the control group (P .05). Despite 2 patients' intake of postoperative analgesics in the control group, no patient needed to use postoperative analgesics in the simultaneous length control during root canal preparation group (P .05).Simultaneous length control during root canal preparation as a non-pharmacologic strategy for reducing postoperative pain is a beneficial technique for preventing postoperative pain.

Introduction: The aim of this study was to compare the incidence of dentinal defects after retreatment procedures with different nickel-titanium rotary retreatment files. Methods: One hundred-eighty mandibular premolars were randomly assigned to 6 groups (n = 30 teeth per group). One group was left unprepared, and the remaining 5 groups were prepared with K-files (Dentsply Maillefer, Ballaigues, Switzerland) and filled with gutta-percha and AH plus sealer (Dentsply Maillefer, Ballaigues, Switzerland). Of these 5 groups, 1 group was left filled and received no further treatments; in the other groups, removal of the filling material was performed with Mtwo R (VDW, Munich, Germany), D-RaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland), R-Endo instruments (Micro-Mega, Besancon, France), or Hedstrom files (Dentsply Maillefer). Roots were then sectioned 3, 6, and 9 mm from the apex and observed under a microscope. The presence of dentinal defects was noted. Chi-square tests were performed to compare the incidence of dentinal defects between the groups. A Pearson correlation test was performed to check the correlation between defects and root level or remaining dentin thickness. Results: No defects were observed in the unprepared group. Dentinal defects were detected in all retreatment groups. Retreatment, groups showed significantly more defects than the filled but no retreatment group (P < .05). There was no significant difference in the occurrence of defects between retreatment groups (P > .05). There was no correlation between the appearance of defects and level of the root or remaining dentin thickness. Conclusions: Under the experimental conditions, all retreatment techniques used in this' study created defects in the root dentin.

The aim of the present study was to evaluate crack formation after flaring root canals with Gates Glidden drills and ProTaper Universal (SX; Dentsply Maillefer, Ballaigues, Switzerland), Endoflare (MicroMega, Besançon, France), Revo-S (MicroMega), and HyFlex (Coltene-Whaledent, Allstetten, Switzerland) flaring instruments.One-hundred eight mandibular molars were selected. Eighteen teeth were left unprepared to serve as negative controls; the experimental groups consisted of the mesiobuccal and mesiolingual root canals of the remaining 90 teeth, which were instrumented with the following coronal flaring instruments: Gates Glidden drills and ProTaper Universal SX, Endoflare, Revo-S SC1, and HyFlex 25.08 instruments. All roots were then sectioned perpendicular to the long axis at 1, 2, 3, 4, 6, and 8 mm from the cementoenamel junction. The sections were inspected under a stereomicroscope, and any crack formations were recorded. The data were analyzed using the chi-square test (P = .05).The Gates Glidden drills resulted in a higher rate of crack formation than that noted in the control group (P.05). Flaring of the root canals using the ProTaper Universal, Endoflare, Revo-S, and HyFlex instruments resulted in crack formation similar to that of the control group (P.05).The use of the Gates Glidden drills resulted in the formation of the most cracks. However, the results for the ProTaper Universal, Endoflare, Revo-S, and HyFlex flaring instruments were similar to those of the control group in terms of crack formation.

Introduction: The aim of this study was to evaluate the fracture resistance of teeth filled with 3 different endodontic sealers. Methods: Seventy-five single-rooted extracted mandibular premolars were decoronated to a length of 13 mm. The teeth were randomly divided into 5 groups (n = 15 for each group). In group 1, the teeth were left unprepared and unfilled (negative control), and in group 2, the teeth were left unobturated (positive control). The rest of the roots were prepared by using the ProTaper System up to a master apical file size of F3: group 3, bioceramic sealer (Endosequence BC sealer) + gutta-percha; group 4, mineral trioxide aggregate based sealer (Tech Biosealer Endo) + guttapercha; and group 5, epoxy resin-based sealer (AH Plus Jet) + gutta-percha. All root specimens were stored for 2 weeks at 100% humidity to allow the complete setting of the sealers. Each specimen was then subjected to fracture testing by using a universal testing machine at a crosshead speed of 1.0 mm/min(-1) until the root fractured. The force required to fracture each specimen was recorded, and the data were analyzed statistically. Results: The fracture values of groups 3 and 5 were significantly higher than those of group 4 (P < .05). There was no significant difference between groups 3 and 5 (P > .05). Conclusions: In contrast to Tech Biosealer Endo, Endosequence BC and AH Plus Jet sealer increased the force to fracture in root-filled single-rooted premolar teeth.