Electronic determination of root canal length by newly developed measuring device. Influences of the diameter of apical foramen, the size of K-file and the root canal irrigants.

A new electronic root canal measuring device called "ENDEX" which is able to determine the root canal length under moistened conditions using a relative value of different alternative electric currents is discussed in this study. This study is designed to investigate the efficiencies of the new device, in vitro, with respect to change in the root canal environment; namely the influence of the size of K-file, the diameter of the apical foramen and the various root canal irrigants. According to the present study, it was confirmed that the location of the apical foramen was clearly detected under moistened root canal with saline solution using any size of K-file. The locations of the tip of K-files were 0.5 mm inside the apical foramen when the relative value displayed 0.3 Volt, so that the apical constriction could not disturb during root canal measurement. One of the big problem with prior electrical measurement devices was not being able to determine the canal length under moistened conditions. However with this improved device, intracanal irrigants, such as saline, 5% NaOC1, 14% EDTA and 3% H2O2 did not interfere in detecting apical foramen irregardless of the size of K-file and the size of the apical foramen.