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Introduction: The purpose of this study was to investigate the shear bond strength (SBS) of a self-adhering flowable composite (Vertise Flow; Kerr, Orange, CA) and a flowable composite (X-tra base; Voco GmbH, Cuxhaven, Germany) to mineral trioxide aggregate (MTA), Biodentine (Septodent, Saint-Maur-des-Fosses Cedex, France), and calcium-enriched mixture (CEM; Yektazist Dandan, Tehran, Iran)., Methods: Sixty cylindric acrylic blocks with a hole (3 mm in diameter and 1.5 mm in height) were prepared. The acrylic blocks were filled with MTA, Biodentine, and CEM (n = 20) and accordingly allocated into 3 groups. The specimens were stored for 72 hours at 37°C and 100% humidity. Then, each group was divided into 2 subgroups according to the composite resin type used (n = 10). Vertise Flow and X-tra base were applied over MTA, Biodentine, and CEM and then polymerized. SBS was tested in a universal testing machine with a crosshead speed of 1 mm/min. Data were analyzed using 2-way analysis of variance and the Tukey test., Results: The Vertise Flow-CEM and X-tra base-MTA groups showed significantly higher SBS values than the group made of Vertise flow-Biodentine (P < .05). There were no statistically significant differences among the other groups (P > .05)., Conclusions: MTA and CEM exhibited higher SBS than Biodentine; therefore, they could be preferred under flowable composites., (Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The purpose of this study was to investigate the incidence of apical crack initiation and propagation in root dentin after several endodontic procedures., Methods: Sixty intact mandibular premolars were sectioned perpendicular to the long axis at 1 mm from the apex, and the apical surface was polished. Thirty teeth were left unprepared and served as a control, and the remaining 30 teeth were instrumented with ProTaper Universal instruments (Dentsply Maillefer, Ballaigues, Switzerland) up to size F5. The root canals were filled with the single-cone technique. Gutta-percha was removed with drills of the Rebilda post system (VOCO, Cuxhaven, Germany). Glass fiber-reinforced composite fiber posts were cemented using a dual-cure resin cement. The fiber posts were removed with a drill of the post system. Retreatment was completed after the removal of the gutta-percha. Crack initiation and propagation in the apical surfaces of the samples were examined with a stereomicroscope after each procedure. The absence/presence of cracks was recorded. Logistic regression was performed to analyze statistically the incidence of crack initiation and propagation with each procedure., Results: The initiation of the first crack and crack propagation was associated with F2 and F4 instruments, respectively. The logistic regression analysis revealed that instrumentation and F2 instrument significantly affected apical crack initiation (P < .001). Post space preparation had a significant effect on crack propagation (P = .0004). The other procedures had no significant effects on crack initiation and propagation (P > .05)., Conclusions: Rotary nickel-titanium instrumentation had a significant effect on apical crack initiation, and post space preparation with drills had a significant impact on crack propagation., (Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Photon-induced photoacoustic streaming (PIPS) is a novel technique used for the removal of material on root canal walls, such as bacteria and the smear layer. This study evaluated the efficacy of needle irrigation, the EndoActivator System (Dentsply Tulsa Dental Specialties, Tulsa, OK), and PIPS on the removal of antibiotic pastes from an artificial groove created in a root canal., Methods: Root canal preparation was performed up to size #40 on 84 extracted single-rooted teeth using ProTaper rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland). The specimens were then split longitudinally, and 2 standardized grooves were prepared in the coronal and apical part of each segment. Double (DAP) and triple antibiotic pastes (TAP) were placed in the grooves for 4 weeks, and the root halves were reassembled. Needle irrigation, the EndoActivator System, and PIPS were used for the removal of DAP and TAP. The root segments were disassembled, and the amount of remaining antibiotic pastes was evaluated under a stereomicroscope at 20× magnification using a 4-grade scoring system. The data were evaluated statistically using Mann-Whitney U tests with a 95% confidence level (P = .05)., Results: PIPS removed significantly more antibiotic pastes than the EndoActivator and needle irrigation (P < .001). The EndoActivator was superior to needle irrigation in removing antibiotic pastes (P < .001). There were no statistically significant differences between DAP and TAP and between coronal and apical thirds in their removing from artificially created grooves (P > .05)., Conclusions: PIPS was more effective in removing both DAP and TAP from artificial grooves in root canals than the EndoActivator System and needle irrigation. The EndoActivator was also more effective than needle irrigation. It is difficult to completely remove antibiotic pastes from root canals., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: We compared the effects of 6 different rotary systems on transportation, canal curvature, centering ratio, surface area, and volumetric changes of curved mesial root canals of mandibular molar via cone-beam computed tomographic (CBCT) imaging., Methods: Mesiobuccal root canals of 120 mandibular first molars with an angle of curvature ranging from 20°-40° were divided into 6 groups of 20 canals. Based on CBCT images taken before instrumentation, the groups were balanced with respect to the angle and radius of canal curvature. Root canals were shaped with the following systems with an apical size of 25: OneShape (OS) (MicroMega, Besancon, France), ProTaper Universal (PU) F2 (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next X2 (Dentsply Maillefer), Reciproc (R) R25 (VDW, Munich, Germany), Twisted File Adaptive (TFA) SM2 (SybronEndo, Orange, CA), and WaveOne primary (Dentsply Tulsa Dental Specialties, Tulsa, OK). After root canal preparation, changes were assessed with CBCT imaging. The significance level was set at P = .05., Results: The R system removed a significantly higher amount of dentin than the OS, PU, and TFA systems (P < .05). There was no significant difference among the 6 groups in transportation, canal curvature, changes of surface area, and centering ratio after instrumentation., Conclusions: The 6 different file systems straightened root canal curvature similarly and produced similar canal transportation in the preparation of mesial canals of mandibular molars. R instrumentation exhibited superior performance compared with the OS, TFA, and PU systems with respect to volumetric change., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of this in vitro study was to assess and compare the effect of photoactivated disinfection (PAD) on the bond strength of root canal sealers to human root canal dentin using the push-out test., Methods: Fifteen extracted human mandibular premolar teeth with single and straight roots were used. After the clinical crowns were removed from the cementoenamel junction, root canals were prepared with the ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) rotary system to the size of the F3 file. The smear layer of the roots was removed using 17% EDTA followed by 5.25% sodium hypochlorite (NaOCl) and distillate water. The roots were then randomly divided into 3 groups (n = 5) according to the final irrigation regimen. In group 1, PAD (FotoSan; CMS Dental, Copenhagen, Denmark) was applied to the root canals and light cured for 20 seconds. Group 2 was finally irrigated with a 2% solution of chlorhexidine gluconate, and group 3 served as the control group (NaOCl + EDTA). All the canals were then obturated with the lateral condensation technique using gutta-percha and AH Plus sealer (Dentsply Maillefer) sealer. One-millimeter-thick horizontal sections from the coronal and midthirds of each root (n: 5 × 4 = 20) were sliced for the push-out bond strength measurement. The data were converted to megapascals and statistically analyzed using 1-way analysis of variance and the post hoc Tukey test., Results: There was no significant difference among the bond strength of PAD, chlorhexidine gluconate, and NaOCl (P > .05)., Conclusions: We conclude that PAD does not adversely affect the bond strength of the AH Plus sealer to root canal dentin and that it can be used for the final disinfection of root canals., (Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)