Comparative Evaluation of the Accuracy of an Electronic Apex Locator Using Two Different Canal Conditions: An In Vitro Study

Introduction: Accurate determination of the working length is critical for the success of root canal treatment, as it ensures effective cleaning, shaping, and obturation of the root canal system. Electronic apex locators are widely used for this purpose; however, their accuracy may be influenced by intracanal conditions, particularly the presence or absence of irrigation solutions. This study aimed to evaluate and compare the accuracy of a third-generation apex locator under dry, normal saline, and 3% sodium hypochlorite canal conditions. Materials and methods: This in vitro study was conducted on 45 extracted human single-rooted teeth randomly divided into three groups (n = 15 each) based on canal conditions: dry, normal saline, and 3% sodium hypochlorite. The actual working length (AWL) was determined visually and was used as the gold standard. The electronic working length (EWL) was measured using a Root ZX Mini. The difference between the EWL and AWL was calculated. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey’s post-hoc test, and categorical accuracy was assessed using the chi-square test, with significance set at p < 0.05. Results: The normal saline group demonstrated the lowest mean deviation (0.21 ± 0.14 mm; 95% CI: 0.13-0.29), followed by the sodium hypochlorite group (0.34 ± 0.19 mm; 95% CI: 0.23-0.45), while the dry canal group showed the highest deviation (0.58 ± 0.22 mm; 95% CI: 0.46-0.70). A one-way ANOVA revealed a statistically significant difference between the groups (F = 18.74, p < 0.001). Post hoc analysis revealed significant differences between all groups (p < 0.05). The proportion of accurate measurements (±0.5 mm) was highest in the normal saline group, followed by the sodium hypochlorite and dry canal groups, although the chi-square test was not statistically significant (p = 0.071). Conclusions: Intracanal conditions significantly influenced the apex locator accuracy. Normal saline provided the most accurate measurements, whereas the dry conditions showed greater variability. Maintaining a moist canal environment may enhance clinical reliability.