Effect of Different Speeds of Up-and-down Motion on Canal Centering Ability and Vertical Force and Torque Generation of Nickel-titanium Rotary Instruments

摘要

IntroductionThis study was performed to evaluate how the speed of up-and-down motion affects the canal centering ability and torque/force generation of ProTaper Next rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland). MethodsTwenty-one simulated resin canal blocks with a J-shaped canal were prepared with ProTaper Next X1, X2, and X3 instruments using an original automated root canal instrumentation and torque/force analyzing device with up-and-down speed settings of 10, 50, and 100?mm/min (low-, medium-, and high-speed groups, respectively). Pre- and postinstrumentation images were superimposed, and centering ratios were calculated at 0–3?mm from the apex. The maximum vertical force and torque were also recorded. The results were statistically analyzed using 1-way analysis of variance and the Tukey test. ResultsAt 0, 0.5, 1, and 2?mm from the apex, the high-speed group showed the lowest centering ratio (ie, least deviation) followed by the medium-speed and low-speed groups (P?