PROBLEM TO BE SOLVED: To integrally provide a mechanism, which pushes down the stopper provided to a measuring needle in a freely slidable manner, to a clip holder and to make it possible to push down the stopper by one finger of the hand, which has the clip holder, not only to simplify the push-down operation of the stopper but also to facilitate root canal length measuring work.SOLUTION: A conductive root canal length measuring needle 1a is clipped to electrically detect that the tip of the root canal length measuring needle reaches the root apex and the push-in depth of the root canal length measuring needle into the root canal 3 at this time is replaced with the stopper 4 provided to the root canal length measuring needle in a freely slidable manner to measure the length of the root canal from the length from the tip of the measuring needle 1a to the stopper 4. A measuring electrode wire having a clip part 6a, which is brought into contact with the measuring needle 1a, provided to the tip part thereof and a measuring needle clip holder cylinder 11, through which the measuring electrode wire is inserted, are provided and the measuring needle clip holder cylinder 11 has the operation lever 30 piercing through the holder cylinder 11 in the up and down directions crossing the holder cylinder 11 at a right angle to move and a stopper push-down member 32 coming into contact with the upper surface of the stopper 4 to downward push down the stopper is provided to the lower end of the operation lever 30.COPYRIGHT: (C)2012,JPO&INPIT【課題】測定針に摺動自在に設けられたストッパを押し下げる機構をクリップホルダに一体的に設け、該クリップホルダを持っている手の指一本でストッパを押し下し得るようにし、もって、ストッパの押下操作を簡易にし、根管長測定作業を容易にする。【解決手段】導電性の根管長測定針1aをクリップして該根管長測定針の先端が根尖に達したことを電気的に検出し、その時の根管長測定針の根管3内への押入深さを該測定針に摺動自在に設けられたストッパ4に置き換え、該測定針1aの先端から該ストッパ4までの長さより根管長を測定する。先端部に測定針1aに接触されるクリップ部6aを有する測定電極線と、該測定電極線が挿通される測定針クリップホルダ筒11とから成り、該測定針クリップホルダ筒11は、該ホルダ筒11に直交する上下方向に該ホルダ筒11を貫通して移動する操作バー30を有し、該操作バー30の下端にはストッパ4の上面に当接して該ストッパを下方に押し下げるストッパ押し下げ部材32を有する。【選択図】図1
