Accuracy of an electronic apex locator under controlled clinical conditions.

Abstract

Abstract Clinical guidelines essential for accurate use of the electronic apex locator were developed. Common causes for inaccurate readings are described as well as ways to minimize inaccuracies. While strictly adhering to the developed clinical routines, the apex locator was used in a controlled experiment. The lengths of 127 root canals in human teeth, irrespective of diagnosis, were measured. With the instrument placed at the apical foramen, as assessed by the apex locator, a radiograph was taken with a parallelling technique. In 90.6% of the canals the tip of the instrument was assessed to be within 0.5 mm of the radio‐graphic outline of the tooth. In 7% of the canals the instrument was 1 to 2 mm short. Only 2.4% of the instruments were up to 1 mm long. Under the strict clinical guidelines used, the apex locator was (bund to be a valuable aid both in routine endodontic treatment and in special clinical situations where the use of radiographs was not feasible.