Incidence of Dentinal Cracks after Root Canal Preparation with Twisted File Adaptive Instruments Using Different Kinematics

Abstract Introduction The purpose of the present study was to assess the effect of root canal instrumentation using Twisted File Adaptive instruments (Axis/SybronEndo, Orange, CA) with different kinematics (adaptive motion, 90° clockwise [CW]–30° counterclockwise [CCW], 150° CW–30° CCW, 210° CW–30° CCW, and continuous rotation) on crack formation. Methods One hundred five mandibular central incisor teeth were selected. Fifteen teeth were left unprepared (control group), and the remaining 90 teeth were assigned to the 5 root canal shaping groups as follows ( n  = 15): adaptive motion, 90° CW–30° CCW, 150° CW–30° CCW, 210° CW–30° CCW, continuous rotation, and hand file. All the roots were sectioned horizontally at 3, 6, and 9 mm from the apex with a low-speed saw under water cooling, and the slices were then viewed through a stereomicroscope at 25× magnification. Digital images of each slice were captured using a camera to determine the presence of dentinal cracks. Results No cracks were observed in the control group, and the continuous rotation group had more cracks than the reciprocation groups (90° CW–30° CCW, 150° CW–30° CCW, and 210° CW–30° CCW) ( P P P Conclusions The incidence of dentinal cracks is less with TF Adaptive instruments working in 210° CW–30° CCW reciprocating motion compared with working in continuous rotation and adaptive motion.