Accuracy of the Justy II apex locator in determining working length in simulated horizontal and vertical fractures

Abstract

Aim: to study the effectiveness of an electronic apex locator (Justy II) in locating simulated horizontal and vertical fractures in single roots. Methods: an electronic apex locator (EAL) (Justy II, Yoshida Dentcraft, Tokyo, Japan) was used to measure the distance within the canal of horizontal (n=31) and vertical (n=31) fractures, created with a disk in single-rooted teeth. Accuracy of the EAL was evaluated by comparing the measurements with those made using a size 10 file. Data were analyzed with the non-parametric Passing and Bablok method. Results: for simulated horizontal fractures the EAL measured exactly the same length as a size 10 file, without constant or proportional errors. In vertical simulated fractures the EAL measured (on average) with a constant error of 7.5 mm shorter than the size 10 file; the difference had a wide confidence interval (–72.3 to 2.6 mm). Conclusion: in this laboratory study, the Justy II EAL was able to determine accurately the position of simulated horizontal fractures but was unreliable when measuring simulated vertical fractures.