Comparative Accuracy of Electronic Apex Locators and Conventional Radiography for Working Length Determination in Permanent Teeth: A Systematic Review.

Accurate working length determination is essential for the success of root canal treatment. While radiographs have traditionally been used for this purpose, electronic apex locators (EALs) have been introduced as an alternative diagnostic tool. This systematic review and meta-analysis compared the accuracy of EALs with conventional and digital radiographs for working length determination in vivo and ex vivo studies. A comprehensive search of PubMed, Cochrane Library, LILACS, EBSCO, and Google Scholar was conducted, and 16 eligible studies were included. Across randomized controlled trials, EALs consistently achieved higher proportions of acceptable working length determinations, ranging from 87.0% to 92.1%, compared with 74.0% to 83.1% for radiographs, while the incidence of overextended cases was markedly lower in EAL groups. In vivo and ex vivo investigations confirmed that EALs provided superior or comparable accuracy to radiographs within the accepted tolerance range of ±0.5-1.0 mm of the apical constriction. Risk-of-bias assessment using QUADAS-2 indicated concerns in patient selection and reference standard domains, although the index test domain was generally low risk. Overall, the evidence suggests that EALs are more accurate and reliable than radiographs in determining working length, supporting their integration into endodontic practice, although further standardized, multicenter studies are needed to reinforce clinical recommendations.