| 摘要 |
Apparatus is disclosed for use in cleaning dental root canals using an endodontic file. The file is mounted in a drill head driven by an electric motor. The motor is normally driven in one, forward direction, but periodically, the motor rotation is reversed for a very short time. The duration of the motor reversal is so short that although the motor rotates in the reverse direction, the inertia and backlash in the transmission between the motor output shaft and the drill head is such that the direction of rotation of the file in the root canal is not changed. |
