Accuracy of three different electronic apex locators in detecting simulated horizontal and vertical root fractures

The aim of this in vitro study was to evaluate the accuracy of three electronic apex locators (EALs): Root ZX, Foramatron D10 and Apex NRG, in the detection of fractures in teeth having simulated horizontal and vertical root fractures. A total of 90 extracted intact, straight, single-rooted teeth were divided into six groups of 15 teeth each. In Groups A, B and C, an incomplete horizontal fracture was simulated by preparing a horizontal incision in the coronal, middle or apical portion of the root until the circumferential half of the canal was exposed in the horizontal plane respectively. In Groups D, E and F, an incomplete vertical root fracture was simulated by preparing a vertical straight incision to expose the canal in the coronal, middle or apical portion of the root all the way in the longitudinal plane respectively. The simulated fractures were 0.25 mm in thickness in all groups. The teeth were embedded in 1% agar and the canals were irrigated with saline solution during electronic measurement. Detection of the simulated root fractures was established with a size 10 K-file when the meter value reached 'APEX' on each EAL. In Groups A, B and C, Kruskal-Wallis tests revealed that there were no statistically significant differences between the three EALs. However, statistically significant differences were found among the EALs in Groups D, E and F (P < 0.0001, one-way anova and Tukey's post-hoc test). In conclusion, the three EALs tested were accurate and acceptable clinical tools in the detection of horizontal root fractures. However, the three EALs were unreliable in detecting the position of vertical root fractures.