Force-torque and motion analysis of asymmetrical reciprocating endodontic system during canal shaping procedure with the X-SmartPlus and 6:1 contra-angle handpiece

To investigate motion analysis of an asymmetrical reciprocating system at different regions of a simulated curved canal comparatively, and to measure force and torque values on various simulated root canals by a reciprocating system. A customized data acquisition unit and target object were designed. An expert’s hands-on performance was recorded on various types of simulated root canals. In-the-canal motion analysis was detailed on curved canal. Data on motion kinematics were statistically analyzed with Kruskal-Wallis, followed by the Dwass-Steel-Critchlow-Fligner or one-way ANOVA, followed by a Tukey test where applicable (p < 0.05). Remarkably, no reverse torque occurred in the apical third of simulated root canals, although the motor continued reciprocation. Torque and force plot pattern of the J-type ellipse cross-sectional simulated root canals differed from the other three types of curved simulated root canals. A significant difference was observed in the median net cycle angles and engaging speeds (p < 0.05). Mainly, in-the-canal kinematics were affected by operation, and the tip of file did not rotate in the reverse direction at apex when manufacturer’s instructions were followed.