Accuracy of the TCM Endo III torque-control motor for nickel-titanium rotary instruments

The purpose of this study was to determine the torque output and examine the accuracy of five TCM Endo III torque control motors. A handpiece was attached to the motor and gripped with a vise. A 0.07 taper Orifice Shaper, size 50, was inserted in the handpiece. The instrument tip was clamped in a chuck connected to a torque sensor. Four torque settings were evaluated at 350 rpm. Ten tests were performed at each torque setting. A new instrument was used for each test. The means of the torque values generated by the motors at the different torque levels were analyzed using analysis of variance and post-hoc pairwise comparisons with the Bonferroni test. The actual torque values were significantly higher than the torque preset on the motor (p < 0.0001) and did not differ significantly among the motors (p > 0.05). The actual torque deviated from the preset torque. The usefulness of these motors is questionable.