Determination of location of root perforations by electronic apex locators

This study was conducted to evaluate the accuracy of two electronic apex locators, the Sono Explorer Mark 2 Junior (Hakusui, Osaka, Japan) and Apit 2 (Osada, Tokyo, Japan) in detecting root perforations. The adequacy of radiographs for identifying root perforations was also assessed.

Thirty-two extracted human teeth were perforated in the middle third of the root and embedded in alginate. Determination of all perforations were carried out with K-files no. 25 attached to the apex locators tested. Two radiographs were taken at two angulations after each electronic measurement. The actual location of the file tip in relation to the perforation was determined with a stereomicroscope. A total of 512 radiographs were evaluated to attempt to identify root perforations.

The mean distance of the file tip from the external outline of the root surface was short for both instruments. A statistical difference (p < 0.05) was found between the two apex locators in dry canals or if saline solution was present. There was no significant difference between the two instruments in the presence of sodium hypochlorite. Evaluators radiographically identified 45% of the root perforations when located in buccal-lingual directions.

Under the in vitro conditions of this study, both devices determined the location of the perforations in an acceptable clinical range short of the root surface. Radiographs were found to be less reliable in identification of perforation locations.