Impact of Apical Patency on Accuracy of Electronic Apex Locators: In Vitro Study.

INTRODUCTION

This study aimed to investigate the importance of apical patency and its influence on the accuracy of 2 apex locators (Root ZX and Raypex 6).

METHODS

We determined the actual working length under dental operating microscope at ×25 magnification in 43 extracted human mandibular molars with completely formed roots and patent apical foramen. Readings of the 2 apex locators were then compared with the actual microscopic working length. Thereafter, we established apical blockage at the apical foramen; files were introduced to the same previous length determined by each apex locator before blockage. Variation in the readings of apex locators after blockage was compared with original readings before blockage to determine the measurement error.

RESULTS

Friedman's test showed no statistically significant difference between the 2 apex locators before blockage (P > .05; effect size = 0.013). Within the margin of accuracy ±1, both Root ZX and Raypex 6 revealed the same percentage of accuracy, 96.7%. After blockage, both apex locators revealed a statistically significant difference in median measurement error compared with the measurements before blockage (P < .05; effect size = 0.305). Root ZX showed a higher median measurement error (>-1 mm and 0.01-0.5 mm) than Raypex 6.

CONCLUSIONS

Apical foramen blockage has a negative influence on the accuracy of apex locators that was more pronounced in Root ZX than Raypex 6.