Kinematics of "Adaptive Motion" under Constant Torque Values

Introduction: To demonstrate the unknown kinematics of complex adaptive motion with respect to disclosed values, the aim of this study was (1) to analyze the adaptive motion and (2) to compare the effects of constant torque values on kinematics. Methods: A new endodontic motor (Aseptico AEU-28SYB Elements; SybronEndo, Orange, CA) and 8:1 contra-angle handpiece were used for analysis. A pilot test was conducted for synchronizing the external experimental stress on the shaft of the target object and the built-in torque sensor of the motor source. A load setup was developed by attaching universal precision weights to the shaft of the of the target object. The groups were adaptive motion with no load (TFA-0), adaptive motion with a 100-gcm constant load (TFA-100), and adaptive motion with a 200gcm constant load (TFA-200). The peak-to-peak-based phase identification method was used to analyze the kinematics. Student t and Mann-Whitney U tests were used where applicable (a = 0.05). Results: A noteworthy observation was the inconsistent kinematics of TFA-100 compared with the kinematics of TFA-0 and TFA-200. TFA-100 presented mixed phased kinematics, which consisted of both a quaternary phase (n = 33) similar to that of TFA-200 and a dual phase (n = 17) similar to that of TFA-0. The sequence of these quaternary and dual phases of TFA-100 was arbitrarily changing. The kinematic parameters of dual phase intermittent motion of TFA-0 and TFA-100 and quaternary-phase reciprocating motion of TFA-100 and TFA-200 revealed significant differences (P , .05). Conclusions: The main conclusions of the present study are the kinematics of adaptive motion was demonstrated, and the 100-gcm load is not sufficient for predictable and constant operation in the reciprocating mode. (J Endod 2022;48:355-361.)