A new method and apparatus for measuring root canal length.

For endodontics, it is necessary to determine the working length of the root canal accurately. Recently, the electronic method for measuring root canal length developed by SUNADA has become widely used in Japan. However, when an electro-conductive substance such as blood is present in the root canal, measuring errors tend to occur, causing clinical problems.We examined the present electronic method for measuring root canal length, and, from basic experiments, found that the measuring principle of this method depended on a simple electronic phenomenon.We were then successful in developing the Endotape method, which made it possible to measure the root canal length accurately even when electro-conductive substances such as blood and pus were present in the root canal. Also, the Endo-cater, an apparatus for measuring the root canal length, using applied high frequency, was shown to be greatly improved in its manipulability and measuring accuracy. These modalities were then applied clinically and good results were obtained.