Impact of Downward Load and Rotational Kinematics on Root Canal Instrumentation with a Heat-Treated Nickel-Titanium Rotary Instrument.

ABSTRACT: This study analyzed how different downward loads and rotational kinematics influence NiTi rotary instrumentation outcomes. Heat-treated NiTi instruments were used to prepare extracted human single-rooted premolars with a moderate canal curvature. Instrumentation was performed using an automated endodontic instrumentation device with controlled downward loading and torque/force sensing, under different downward load settings (1, 2, and 3 N), employing either continuous rotation (CR) or optimum torque reverse (OTR) motion, which is a torque-sensitive reciprocation. Instrumentation was completed without instrument fracture or ledge formation in all six groups. OTR-3N specimens displayed a significantly lower upward force (i.e., screw-in force) than OTR-2N specimens (p < 0.05). OTR-1N s

SUBMITTER: Yamamoto R 

PROVIDER: S-EPMC12786967 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature