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. (Rev Port Estomatol Med Dent Cir Maxilofac. 2023;65(3):115-120) (c) 2024 Sociedade Portuguesa de Estomatologia e Medicina Dentaria. Published by SPEMD. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).