| 摘要 |
An improved ultrasonic handpiece adapter for use in root canal procedures is provided in which a fire well is formed in the body of the device. The lower surface of the file well is frusto-conical in shape and receives a file wherein an enlarged file head has a frusto-conical shape at its bottom which seats against the lower surface of the file well when downward pressure is exerted on the file and which floats with respect to the lower surface of the file well when upward pressure is exerted on the file. A clutch mechanism is thereby provided wherein the file blade is in its engaged position during a cutting stroke and wherein the file blade floats during the motion of positioning the blade for the next cutting stroke. A cutting file has the tip of its shank flared so that the shank is prevented from being pulled through the file head. The apparatus may be connected to a conventional source of sub-sonic or ultrasonic power.
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