[Accuracy of 2 electronic canal length measuring instruments].

Two electronic root canal length measuring instruments were used to measure the working length to "the apex" in 88 teeth scheduled for extraction. After extraction, the canal length was measured using X-Ray and microscopic observation after section of the teeth. The accuracy of the RCM apex locator in determining canal measurement within +/- 0.5 mm from the apical foramen varied around 62%. The "NO'X" allows a success rate of 41% in the same conditions. The conditions of this experiment shows that electronic root-canal length measuring instruments do not work in case of hemorrhage or swelling.