Accuracy of the Nouvag torque control motor for nickel-titanium rotary instruments

Objectives. To determine the torque output and examine the accuracy of 5 Nouvag torque control motors. Study design. A handpiece was attached to the motor and gripped with a vise. A size 50 Orifice Shaper, with a 0.07 mm/mm taper 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 done 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 the Student t test. Results. The actual torque values were significantly higher than the torque preset on the motor (P<.0001) and did not differ significantly among the motors (P > .05). Conclusions. The actual torque deviated from the preset torque. The usefulness of these motors is questionable.