Accuracy of three electronic apex locators in determining the apical foramen in multi-rooted teeth: Randomised clinical and laboratory study.

This study aimed to compare the accuracy of three electronic apex locators (EALs), Raypex 5, Apex NRG and ProPex II, in locating the apical foramen (AF) in vivo. Thirty multi-rooted teeth were included in the study. Distances from the file tip to the radiographic apex from the buccal (R1) and mesial (R2) aspect were measured after extraction. The distance from the file tip to the AF (L) was measured microscopically. Raypex 5, Apex NRG and ProPex II were accurate to within ± 0.5 mm in 84.6%, 78.6% and 66.7% of cases, respectively. R1, R2 and L measurements between the EALs were not statistically different (P > 0.05). R1 and L correlated positively (r(2) = 0.817; P < 0.001). There were no significant differences in all measurements between vital and non-vital root canals (P > 0.05). There was no statistically significant difference between the EALs. There was a positive correlation between electronic and radiographic measurements when locating the AF.