The use of micro-computed tomography to determine the accuracy of electronic working length with two apex locators

Purpose: This study evaluated the precision of electronic working length by microcomputed tomography using two electronic apex locators (EALs). Methods: Twenty single-rooted permanent teeth without caries or restorations were selected as the subject teeth. The positions of the minor apical constriction (AC) and major apical foramen (AF) were measured by electronic root canal length, and microcomputed tomography was performed with the file inserted and fixed in the root canal. All teeth were measured individually and independently by two operators. The Mann-Whitney U-test was used to statistically test the AC and AF values using two EALs; P < 0.05 was defined as statistically significant. Results: This was 65.0% within 1.5 mm in the case of two EALs on AC. This was more than 90.0% within 1.0 mm in the case of two EALs on AF. Comparison of the differences between the respective AC and AF of the measurements obtained using the two EALs revealed no significant difference. Conclusion: The two EALs are devices that can greatly improve the accuracy of WL control.