[An in vitro study of two kinds of root apex locators to diagnose vertical root fracture].

OBJECTIVE: To evaluate the accuracy of Root ZX and Raypex5 root apex locators in detecting vertical root fractures. METHODS: A total of 20 extracted bi-canal, single-root premolars were extirpated of pulp and expanded to root foramen. The actual length of root canal was measured. The root canal filling amplifier in root canal was hammered and root vertical fractures occurred. The actual length of vertical fracture root canal was measured. Root ZX and Raypex5 were used to measure the canal length in incomplete and complete vertical root fracture respectively. The lengths measured by two kinds of root apex locators were compared with actual canal length. RESULTS: All of the simulated vertical root fractures were buccal-lingual fissure through the apical foramen. To incomplete vertical root fracture, Root ZX and Raypex5 couldn't detect the vertical root fracture. To complete vertical root fracture group, Root ZX and Raypex5 detected the vertical root fracture within +/- 1.0 mm in 97.5%, 100% respectively. CONCLUSION: The root apex locator lacks of diagnostic value for incomplete vertical root fracture, but provides with preferable veracity for complete vertical root fracture.