[Clinical study of electrical root canal length instruments]

In a clinical study on 100 root canals we measured the difference between the length, which can be received by a roentgenogramme, and the length, which can be received by an electrical device. In cases with vital exstirpation in 80% we got a good conincidence, but in cases of pulp gangraena there were great differences. Indication of electrical devices for measuring tooth length only can be seen together with an existing X-ray; it is very important, whether the canal is dry enough for exact measuring.