In vitro comparison of three electronic apex locators

The purpose of this study was to compare the accuracy of the Root ZX II Apex Locator (RZX), the Elements Apex Locator (ELE), and the Precision Apex Locator (PAL).

Forty single-rooted extracted teeth were decoronated and the root canals coronally flared. Actual canal lengths were determined by inserting a #10 file until the tip was visualized (12.8x magnification) just within the apical foramina. Teeth were mounted in gelatin conducting medium and randomly tested with each electronic apex locator (EAL) to determine the electronic canal length. Differences between the electronic and actual canal lengths were calculated.

The mean differences were -0.02 mm, 0.13 mm, and 0.15 mm for the RZX, PAL, and ELE, respectively. One-way analysis of variance showed a highly significant difference among EALs (p = 0.003). Student-Newman-Keuls post hoc analysis found significant differences between the RZX and the PAL and between the RZX and the ELE at p < 0.05. No significant difference was noted between the PAL and the ELE. The proportion of electronic canal length measurements falling within +/-0.5 mm of the actual canal lengths for the EALs was as follows: 97.5% for the RZX, 95% for the PAL, and 90% for the ELE.

The RZX was the most accurate at locating the apical foramen compared with the ELE and the PAL.