Performance of Electronic Apex Locators, Root ZX3, NovApex N31, and Apex-S, in Irrigant Solutions of Varying Conductivity.

Background: The success of root canal treatment depends on precise control of the working length (WL), as it directly influences periapical healing and long-term prognosis. Optimal outcomes are achieved when obturation ends short of the radiographic apex, which requires accurate WL determination. This study evaluated the performance of electronic apex locators (EALs) in irrigant solutions with different electrical conductivities. Materials and Methods: Twenty human mandibular central incisors were assessed using Root ZX3®, NovApex N31®, and Apex-S®. Standardized reference lengths were established from the incisal edge to the root apex with a digital micrometer (DM). A size 15 K-file attached to each EAL was inserted into the canals until the devices indicated the apical foramen. The silicone stoppers were adjusted to the incisal edge, and the files were removed to measure the length with the DM. The differences between the lengths measured by the EALs and the actual WL were calculated. Statistical analysis was performed using the Friedman test followed by Tukey's post-hoc test, and the Kruskal-Wallis test with the Student-Newman-Keuls post-hoc test. The significance level was set at = 0.05. Results: Root ZX3® showed the highest accuracy (p < 0.05), regardless of the irrigating solution tested. No significant differences were found between NovApex N31® and Apex-S® (p > 0.05). When deionized water was used, both NovApex N31® and Apex-S® demonstrated minimal interference, whereas significant differences were observed with 2.5% NaOCl and Triton®. Conclusions: Root ZX3® demonstrated consistent accuracy across all irrigating solutions. NovApex N31® and Apex-S® performed similarly in deionized water but showed differences when compared with 2.5% NaOCl and Triton®.