Abstract: A dental handpiece for forming root canals comprising a motor, a cutting tool driven by said motor, and control means for automatically and periodically reversing the motor according to preset rotation periods of the tool in one direction and in the opposite one, respectively. Preferably, the preset rotation periods are each and independently selected in the range of 0.05 to 2.50 sec. Means for detecting the load torque applied to the tool may also be enabled, so that the control means reverse said motor when the torque detected by the load torque detection means reaches a preset reference value, the control means also triggering an acoustic signal when the detected load torque enters a neighborhood of the preset reference torque.