Accuracy of different generations of apex locators in determining working length; a systematic review and meta-analysis

Background and objective: The accurate determination of working length has a major influence on the prognosis of root canal treatment. Electronic Apex Locators (EALs) appear to be excellent tools for the determination of working length (WL). This study aimed to assess the accuracy of four generations of EALs. Materials and methods: For the purpose of the present review study, articles on different generations of EALs were selected from the PubMed, Cochrane Library, Google Scholar, and ScienceDirect databases using the search term apex locators. In addition, eligibility criteria were set and used for the inclusion of articles. Results: Fifteen studies satisfied the eligibility criteria and were included in this study. According to the results of four meta-analyses, the Cochran's Q-values were 3.042, 4.569, 0.636, and 0.443. The I2 value of four heterogeneity tests was zero (I-2 = 0). In addition, the effect sizes (risk ratios) of the four meta-analyses were 1.040, 0.997, 0.935, and 0.959. Conclusion: Based on the findings of this study, all four generations of apex locators under review were found to be accurate in measuring working length. Hence, the generation of an apex locator does not play a significant role in how accurately electronic devices determine working length. In addition, the results suggest that more clinical and laboratory trials are required in order to evaluate the accuracy of different generations of EALs in measuring working length. (C) 2021 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-NDlicense (http://creativecommons.org/licenses/by-nc-nd/4.0/).