Comparing Working Length Determination Accuracy Among Radiography and Two Apexlocators

Objectives: Radiography is the most common technique to determine the working length during root canal therapy. However, due to its shortcomings and side effects, electronic root determination has been developed. Fourth and the last generations of apex locators have improved disadvantages of previous instruments. The present study has evaluated the accuracy of Raypex-4 and SybronEndo apex locators as well as radiography technique to determine the working length in vitro.

Materials and methods: In this experimental study, 40 first and second mandibular molars (120 canals) which were extracted due to periodontal diseases with no previous root canal therapy, extensive caries, fracture, and root resorption were selected. The teeth crowns were sectioned with diamond disk and canals were accessed. Canals' lengths and the working length were determined by file congruous to canal diameter and when it was observed in the apex. Canals' working lengths were determined by Raypex-4 apex locator-VDW,Germany-, SybronEndo–USA-, and compared with radiography technique. Measures within ±0.5 mm of apex were considered as acceptable. Statistical analyses were done by Friedman and Wilcoxon Signed Ranks.

Results: The accuracy rate of Raypex-4, SybronEndo apex locators and Radiography technique were respectively 89.2%, 91.7% and 81.7 in range of ±0.5 mm of radiographic apex. The differences between canals' working lengths as determined by two apex locators were not statistically significant. , but demonstrated root canal lengths between apex locators and radiography technique differed (P<0.05, P<0.008).

Conclusion: Two apex locators showed similar accuracies to determine working length, while they were more accurate than radiography technique. It is recommended to use apex locators together with radiography technique in working length determination as a secondary aid.