Introduction: This study was conducted to compare three rotary files of Superfile III Denco, Sp1 Gold v Taper, and ProTaper in terms of debris extrusion to find the best treatment option. Methods: In total, 51 extracted mandibular premolars were randomly assigned to three groups (n=17). Rotary systems of Sp1 Gold v Taper, Superfile III Denco, and ProTaper Universal were used in the first, second, and third groups, respectively. Canals were prepared up to the F2 file, and this process was conducted only by one operator. Moreover, an Orifice shaper specific to each group was used first, and files were removed from canals and then cleaned by wet gauze. In the preparation procedure, canals were washed to extract all debris from the canal. Eppendorf tubes were used to collect debris. Results: Mean debris values extruded from canals in the Sp1 Gold, Superfile Denco, and ProTaper Universal files were 0. 0025, 0. 0008, and 0. 0014, respectively. There was no significant difference among debris extruded by Superfile Denco III, Sp1 Gold V Taper, and ProTaper Universal files (P<0. 05). Conclusions: All instrumentation systems cause the extrusion of debris to the apical area. According to the results of the present study, there was no significant difference among debris extruded by Superfile Denco, Sp1 Gold, and ProTaper Universal files. It should be mentioned that because of variations in the study designs, the direct comparison of different studies that addressed this problem is not possible, and in vivo studies should be performed to evaluate its clinical relevance.

Background: Prevention of dentinal crack formation is of utmost importance in endodontic treatment. This study aimed to evaluate the effect of RaCe, ProTaper, and V-Taper rotary systems on dentinal crack formation in three root regions during endodontic treatment. Methods: Seventy human mandibular first molars were selected randomly, and their distal roots were used. Ten samples were assigned to the control group, and sixty samples were assigned to three groups (n = 20). Each group was prepared with RaCe, ProTaper, or V-Taper rotary files according to the manufacturers’,instructions. A stereomicroscope was used to view cracks at ×40 magnification. Friedman’, s, chi-squared, and Kruskal-Wallis tests were used for statistical analysis of data (P < 0. 05). Results: A comparison of the three rotary systems did not reveal any significant differences in the number of cracks between the three root thirds evaluated (P > 0. 05). A comparison of the number of cracks in the coronal, middle, and apical thirds in each rotary system showed that the number of cracks in the middle third was fewer than that in the two other thirds only in the V-Taper group (P < 0. 05), with no significant differences in the ProTaper and RaCe groups between the different root regions (P > 0. 05). Conclusion: The application of RaCe, ProTaper, and V-Taper rotary files resulted in a similar rate of crack formation in endodontic treatment. V-Taper files created the minimum number of cracks in the middle third.

Background and Aim: Very little is known about the fracture resistance of endodontically treated teeth restored with different design of esthetic post systems. The aim of this study was to compare the fracture resistance and failure mode of endodontically treated teeth restored with two different types of quartz fiber post.Materials and Methods: In this experimental, in-vitro study, twenty mandibular premolars with similar size were chosen and randomly divided into 2 groups (n=10). After cutting the crowns and endodontic therapy, the teeth were restored with a quartz fiber single Taper light-posts in group A and quartz fiber D.T light-post in group B. All posts were cemented with a dual cure cement. Composite resin cores were built up using a pre-formed polyester matrix and every specimen was embedded in an acrylic resin block with a layer of elastic polyether Impergum surrounding the roots as PDL. Compressive load was applied at 135 degree angle to the long axis of the tooth at a crosshead speed of 1mm/min until fracture occurred. T-test was used to determine the significance of the failure load values between the two groups.Results: There was no significant statistical difference in fracture resistance among two groups. The fracture load in groups A and B were 366.7±102.7 (N) and 382.4 ±67.3 (N) respectively. (P<0.6).Conclusion: According to the findings of this study, two different designs of quartz fiber posts did not influence the fracture resistance of endodontically treated teeth.

Introduction: Although micro-computed tomography (MCT) evaluation of the shaping ability of ProTaper Next (PTN) and Hyflex CM (HCM) files has been reported, to our knowledge, no study has assessed the performance of V-Taper 2H (VT) files. The aim of this study was to evaluate and compare the shaping ability of PTN, HCM, and VT systems in the mesial canals of mandibular molars using MCT. Methods and Materials: Thirty extracted first and second mandibular molars were scanned using MCT and randomly assigned to HCM, PTN, and VT groups. Images obtained before and after preparation were evaluated for the increase in the root canal volume, untouched surface area, and amount of accumulated hard tissue debris. One-way analysis of variance (ANOVA) and Kruskal-Wallis test were used to compare the variables in the groups (α =5%). Results: There were no statistically significant between-group differences in the postoperative measurements (P>0. 05). The canal volume increased in all three groups: PTN (73. 84%), VT (73. 48%), and HCM (49. 29%). The largest and smallest untouched areas were observed in the PTN (41. 37%) and VT (30. 85%) groups, respectively (P>0. 05). The debris formed during canal preparation was 1. 84%, 2. 16%, and 2. 42% in the VT, PTN, and HCM groups, respectively (P>0. 05). Conclusions: Based on our in vitro study, the PTN, HCM, and VT systems showed similar shaping abilities. None of the tested canals were completely free from debris, while the untouched surface area was considerably large. The VT system had the most favorable results with the smallest untouched surface area and least debris were. We would recommend further trials to endorse these findings.

Background and Aims: According to the common application of non-metal prefabricated posts in dentistry and lack of enough information about the stress distribution in the root canal walls by these posts, this study was performed to compare the effect of two simple Taper and double Taper posts on the stress distribution on root canal walls by photo elastic method.Materials and Methods: The design of this study was experimental in photoelastic system. The posts, used in this investigation, were double Taper and simple Taper fiber posts with 0.9 mm diameter and 20 mm length and epoxy resin. First two photo elastic models with tooth dimensions were fabricated and the posts were placed inside the model. Then the core of the each post was fabricated on the model. Each models were loaded in polariscope and the formed fringe order colored ring were photographed.Results: In 100 N, 90 degree angle loading in cervical and apical fringe order showed 2.50 and 1.39 in simple Taper posts and 1.39 and 2.35 in double Taper post. In 150 N, 30 degree angle loading in cervical and apical fringe order showed 4 and 2.65 in simple Taper posts, and 4 and 2.5 in double Taper post.Conclusion: In the vertical and oblique loads, double Taper fiber post showed better stress distribution than that of simple Tapered posts.

Background: Successful root canal treatment depends on correct cleaning, widening, and shaping of the root canal system. Root canal preparation using rotary files can cause dentin cracks. This study aimed to evaluate the number of dentin cracks created after the preparation of the mesiobuccal root canal of the first maxillary molars by ProTaper Gold and Edge Taper platinum rotary files using a stereomicroscope. Methods: In this laboratory study, 72 maxillary first molars were collected and randomly divided into three groups (n=24): control group, ProTaper Gold group, and Edge Taper platinum group. Mesiobuccal canal preparation was performed in Edge Taper platinum and ProTaper Gold groups up to file size F2. All roots were cut horizontally at distances of 3, 6, and 9 mm from the apex with a disc. The sections were examined under a stereomicroscope at 40x magnification. Fisher’s exact test and Chi-square test were used in SPSS version 22.0 for analyzing data. A significant level of 5% was considered. Results: In the control group, no cracks were observed in any of the sections. At 3 and 9 mm from the apex, the ProTaper Gold group had the highest frequency of cracks and at 6 mm from the apex, the Edge Taper platinum group had the highest frequency of cracks. There was no significant difference in the frequency of dentin cracks between ProTaper Gold and Edge Taper platinum groups in any of the sections. Conclusion: Both ProTaper Gold and Edge Taper platinum systems caused the formation of dentin cracks. Preparation of root canals by Edge Taper platinum and ProTaper Gold rotary files causes the formation of dentin cracks to the same extent.