Factors Affecting the Electric Apical Locators in Widely-Enlarged Canals

―The Reamer Size and the Irrigating Solution Examined by 3 Apparatus―

Abstract

Abstract : The electric measurement of the canal length has established firm support among Japanese endodontists. Many types of devices are now commercially available. By this method, it is easy to determine the canal length without exposing patients to the X-ray. However, the results obtained are affected by various factors that modulate the electric conditions of the canal. Among these, we focused on the amount of 3% hydrogen peroxide in the canal and the size of the reamer used as the electrode.

 Widely-enlarged canals were investigated in this study using 3 kinds of apical locators, i. e. Endodontic Meter-SⅡ (EM), Root ZX (ZX) and Justy (JS). The EM uses 400Hz, while both ZX and JS adopt combinations of high and low frequencies. The experiment was conducted on 7 extracted human teeth. As the results, the indicated canal length was longer when the canal was filled with 3% hydrogen peroxide. When a #25 reamer was used, the impedance seemed to be higher than that with a #15 reamer, thus the size of the reamer affected the meter readings. The changes in meter readings brought by these factors were similar in all 3 apparatus.