Objective: This study aimed to evaluate the cleaning efficacy of different rotary systems during root canal treatment. Methods: Forty-five extracted mandibular molars were randomly divided into three groups according to the rotary system applied: Group 1, EDMax; Group 2, EdgeFile X1; and Group 3, Neoniti. The samples were irrigated with 5.25% NaOCl and normal saline as the final rinse. Roots were sectioned longitudinally and examined under scanning electron microscopy (SEM). The debris and smear that remained in the root canals were assessed using a five-score index and compared between groups and root sections. The statistical analysis was performed by Kruskal-Wallis, Friedman, Wilcoxon Signed Ranks, and Mann-Whitney U tests at P < 0.05. Results: There was a statistically significant difference in debris scores between groups at the apical third (P=0.003), but no significant difference was found in other root sections (P>0.05). The sequential rotary EDMax group had more apical debris compared to the single-file reciprocating EdgeFile X1 and single-file rotary Neoniti groups (P< 0.05). No significant difference was observed between the study groups in smear layer scores (P>0.05). However, the smear layer score was significantly greater in the apical than in other root sections in all groups (P<0.05). Conclusions: The single-file systems, Neoniti and EdgeFile X1, demonstrated superior cleaning efficacy compared to the sequential EDMax system in the apical third, whereas the efficacy of all systems was equivalent in other root areas. Single-file systems may be more effective for root canal cleaning, especially in areas that are more difficult to access.

Introduction: This study aims to evaluate the cyclic and torsional fatigue resistance of seven rotary systems. Methods and Materials: A total of 140 instruments were tested, 20 of each system including Genius (GN) 25/0. 04, TruShape (TS) 25/0. 06, Logic (LOG) 25/0. 06 taper, Vortex Blue (VB) 25/0. 06, ProTaper Gold (PTG) 25/0. 08, Hyflex CM (HCM) 25/0. 06 and Hyflex EDM (EDM) 25/0. 08 taper. Cyclic fatigue resistance testing was performed using an artificial stainless steel canal with a curvature (60° angle and 5-mm radius) located at 5 mm from the tip. The files (n=10) rotated until fracture, and time was recorded in seconds. The torsional test was evaluated according to ISO 3630-1. Data were analysed with one-way ANOVA and Tukey’ s tests (α =5%). The fractured surface of the instruments were assessed using scanning electron microscopy to confirm the type of fracture. Results: The cyclic fatigue resistance value of EDM was significantly higher than those of all tested instruments (P<0. 05). LOG showed a higher cyclic fatigue resistance than GN or TS (P<0. 05). There was no difference among the other groups (P>0. 05). The torsional test showed that PTG 25/0. 08 had the highest torsional strength value of all instruments tested followed by VB and EDM (P<0. 05). The LOG showed significant difference only with GN (P<0. 05). No difference was found among the other groups (P>0. 05). In relation to angular deflection, the GN; TS; HCM, and EDM showed significantly higher values until fracture than the other groups (P<0. 05). No difference was found among PTG, LOG, and VB (P>0. 05). Conclusion: Our in vitro study EDM group had the highest cyclic fatigue resistance among all the tested instruments. For the torsional test, the PTG showed highest torsional strength and lowest angular deflection values.

Introduction: All instrumentation techniques have been reported to be associated with extrusion of infected debris. The aim of this study was to evaluate the number of bacteria extruded apically from extracted teeth ex vivo after canal instrumentation using the two engine-driven techniques utilizing nickel-titanium instruments (Flex Master and M two).Materials and Methods: Seventy extracted maxillary central incisor teeth were used. Access cavities were prepared and root canals were then contaminated with a suspension of Enterococcus faecalis and dried. The contaminated roots were divided into two experimental groups of 30 teeth each and one control group of 10 teeth. Group I, Flex Master; Group2, M two; Group 3, control group: no instrumentation was attempted. Bacteria extruded from the apical foramen during instrumentation were collected in to vials. The microbiological samples from the vials were incubated in culture media for 24 h. Colonies of bacteria were counted and the results were given as number of colony-forming units. The obtained data were analyzed using the Kruskal-Wallis one-way analysis of variance and Mann-Whitney V-tests, with a = 0.05 as the level for statistical significance.Results: Findings showed that there was no significant difference as to the number of extruded bacteria between two engine-driven systems (P>0.05).Conclusion: Both engine-driven Nickel-Titanium systems extruded bacteria through the apical foramen.

Background and Aim: Effective cleaning and shaping of the root canal system is an essential part of a successful root canal treatment and is considered as one of the basic features of rotary instruments. The present study aimed to compare the efficacy of two types of nickel-titanium rotary files namely BioRaCe and Mtwo, in reduction of Enterococcus faecalis (E. faecalis) count in the root canal system. Materials and Methods: In this in vitro study, 50 extracted human single-rooted teeth were assigned to two groups plus a positive and a negative control group (20 samples in each group). First, the root canals were sterilized and were then inoculated with E. faecalis (ATCC: 11700). Subsequently, all the root canals were instrumented with BioRaCe and Mtwo nickel-titanium rotary instruments. Then, samples were collected from inside the root canals and cultured in a special medium to evaluate the remaining colonies. The Chi-square goodness of fit test was used to assess the difference in bacterial colony count after root canal preparation with the two rotary systems (alpha=0.05).  Results: Complete bacterial growth was observed in both the BioRaCe and Mtwo groups. There was no statistically significant difference between the two groups regarding bacterial elimination from the root canal system (P>0.05). Conclusion: Under the limitations of the current study, the two rotary systems exhibited no superiority over each other in terms of their ability to eliminate microorganisms from the root canal system.

Introduction: The aim of this study was to compare centering ability and dentin removal of three rotary systems in curved root canals of extracted teeth.Materials and Methods: Sixty root canals of mandibular first molars with curvatures ranging between 25-35o were divided into three groups of 20 teeth each. Based on pre-instrumentation radiographs that assessed the angle and the radius of canal curvatures, teeth with curvatures were equally spread between the three groups. The root canals were sectioned horizontally at two levels before preparation and then remounted onto the muffle. All root canals were prepared using a low-torque control motor with Mtwo or Medin or Race instruments. Cross sectional images were obtained before and after instrumentation. Cross-sectional area and centering ability were evaluated. The data were analyzed using the one-way ANOVA and Tukey tests.Results: Neither instrument fracture nor permanent deformation occurred during preparations. The best centering ability was obtained by Mtwo instruments compare to Race and Medin instruments. In the coronal and middle sections, Mtwo removed less dentin than Race and Medin; while the difference in the apical section was not significant.Conclusion: Under the conditions of this study, the debridement of root canals was more conservative with Mtwo. The canals prepared with these instruments were better centered in all three regions of the root.