Effect of different torques on dentinal crack formation following canal preparation using neoniti rotary system

Introduction: The aim of this study was to determine the incidence of dentinal cracks in the&nbsp; mesial root of maxillary molar during canal preparation using Neoniti system in different torque settings. Materials &Methods: In this in-vitro study, 60 maxillary molars extracted for various reasons were selected. The teeth were divided into 4 groups: one group(n=15) without preparation was considered as a control group (unprepared control group), the other 3 groups prepared with rotary neoniti system: group with standard torque (1.5 N/CM2)(n=15), group with high torque (2N/CM2)(n=15), and group with low torque (1N /CM2)(n=15). After a canal preparation procedure, the teeth were horizontally sectioned at 3, 6 and 9 mm from the apex. All sections were examined for determining the presence of cracks using a stereomicroscope. Data were analyzed using chi-square test. Results: There was no crack in the control group. The number of cracks was significantly higher in the high-torque group (80%) than standard- and low-torque groups (20%, 26.7%, respectively) (p<0.001). However, no significant difference was found between the standard-torque group and low-torque group (p<0.001). Conclusion: According to this study result, to avoid crack formation in higher torques using motors with torque control option is suggested.