Coronal preflaring’s influence on the accuracy of root canal length determination by electronic apex locators

Objectives: To evaluate the influence of preflaring using LA Axxess and ProTaper Shaping files on the accuracy of Root ZX mini, Mini Apex Locator, and Propex II electronic apex locators (EALs). Methods: Thirty mandibular incisors were accessed, and their root canal length (RCL) was determined with the aid of a stereomicroscope. Then, the specimens were randomly assigned into two groups according to the preflaring instrument: G1- LA Axxess; G2- ProTaper Shaping files. The root canal length was determined in the alginate model by EALs before and after preflaring. Data were classified as accurate (≤ 0.5 mm) or inaccurate (> 0.5 mm or beyond the root canal length). McNemar's test was used to detect differences in the EALs’ accuracy before and after preflaring, and Cochran’s Q test was applied to detect differences in accuracy between the EALs. Results: McNemar's test identified differences in precision in the Propex II and Mini Apex Locator, with significantly increased accuracy after preflaring with ProTaper files. Cochrans’ Q test showed no differences between EALs’ accuracy (p>.05). Conclusions: Preflaring procedures increased accurate measurements for all the EALs, with statistical differences for Propex II and Mini Apex Locator when ProTaper instruments were used. All EALs showed similar accuracy.