PROBLEM TO BE SOLVED: To eliminate the need of replacing the entire ultrasonic vibration source by preventing wear of a screw part connecting a vibration transmission member which transmits ultrasonic vibrations and the ultrasonic vibration source.SOLUTION: A relay joint member 9 is interposed between a vibration transmission member 2 for transmitting ultrasonic vibrations generated by the ultrasonic vibration source and a dental chip 8, and by making a screw diameter on the connection side of the vibration transmission member 2 of the relay joint member 9 larger than the screw diameter on the connection side of the dental chip 8 or making a lead angle of a screw on the connection side of the vibration transmission member 2 smaller than a lead angle of a screw on the connection side of the dental chip 8, fastening torque on the connection side of the vibration transmission member 2 is made larger than that on the connection side of the dental chip 8, return by the vibrations of the screw part on the connection side of the vibration transmission member 2 of the relay joint member 9 is prevented, and the wear of the screw part by the return is prevented.COPYRIGHT: (C)2013,JPO&INPIT【課題】超音波振動を伝達する振動伝達部材と超音波振動源とを接続するネジ部が磨耗しないようにして、超音波振動源全体を取り替えなくて済むようにする。【解決手段】超音波振動源が発生する超音波振動を伝達する振動伝達部材2と歯科用チップ8との間に中継ジョイント部材9を介在させ、中継ジョイント部材9の振動伝達部材2接続側のネジ径を歯科用チップ8接続側のネジ径より大きくし、または振動伝達部材2接続側におけるネジのリード角を歯科用チップ8接続側におけるねじのリード角より小さくすることで振動伝達部材2接続側の締め付けトルクを歯科用チップ8接続側より大きくして、中継ジョイント部材9の振動伝達部材2接続側ネジ部の振動による戻りを防止し、戻ることによるネジ部の磨耗を防止する。【選択図】図1
