Accuracy of apex locator.

An evaluation of the accuracy of the "Root ZX" apex locator was conducted on 20 single-rooted teeth that had been extracted because of severe disease or orthodontic treatment. After the pulp chamber had been accessed and the tooth length determined using the Root ZX apparatus, the file was fixed to the tooth with light-cured composite resin. After extraction, the tooth was longitudinally ground with a diamond bur until the file was visible. The distance between the file tip and the apical foramen was measured under a microscope (x 100). The results showed that the tip of the instrument reached the apical foramen in all teeth.