Evaluation of the accuracy of different apex locators in determiningthe working length during root canal retreatment

This study aimed to assess the accuracy of three electronic apex locators (EALs) (DentaportZX [J Morita, Tokyo, Japan], Propex Pixi [Dentsply Maillefer, Ballaigues, Switzerland], and iPex II [NSK,Tokyo, Japan]) during root canal retreatment.

 The root canal lengths of 90 extracted single-rooted human teeth were determined under adental operating microscope at ×10 magnification. The actual working length (AWL) was 0.5 mm lessthan the root length. Electronic measurements were performed with the three EALs. The root canalswere instrumented and filled to the actual working length using the lateral compaction technique. Afterseven days, the teeth were retreated until the retreatment file was applied to the root canal at the workinglength determined by EALs, and then, the three EALs were used for determining the retreatmentworking length. Data were analyzed using chi-squared and Kruskal–Wallis tests.

 In the retreatment, the accuracy of EALs was reported at %83.3 for Dentaport ZX, %83.4 forPropex Pixi, and %80 for iPex II within a tolerance of 0.5± mm of the AWL.

Under the limitations of this study, Dentaport ZX, Propex Pixi, and iPex II can be a usefuladjunct during retreatment. Clinicians should be aware that residual materials in the root canal duringretreatment can affect the accuracy of EALs.