Evaluation of heated sodium hypochlorite's effect on the accuracy of contemporary electronic apex locators: an in vitro study

Abstract

Background Accurate determination of the working length (WL) is essential for successful root canal therapy. Although electronic apex locators (EALs) are widely used for this purpose, the impact of irrigant temperature on their precision remains poorly understood. Therefore, in this study, we investigated the effect of variations in sodium hypochlorite (NaOCl) temperature on the performance of modern EALs, with particular emphasis on the recently introduced EAL, Ai-Pex. Methods Twenty extracted human teeth were embedded in alginate to simulate clinical conditions. WL was measured using four EALs (Root ZX Mini, Propex Pixi, Raypex 6, and Ai-Pex) under three NaOCl temperature conditions: 19.4 degrees C (+/- 1.5 degrees C), 36 degrees C, and 70 degrees C. A dental operating microscope was used to determine the actual working length (AWL). Deviations between electronic and AWLs were recorded, and statistical analyses were conducted using repeated-measures analysis of variance (ANOVA) and chi-square tests. Results All EALs exhibited high accuracy, with deviations within +/- 0.5 mm of AWL across all NaOCl temperature conditions (p > 0.05). Ai-Pex achieved 95% accuracy at room and body temperatures and 100% accuracy at 70 degrees C. Similarly, Root ZX Mini, Propex Pixi, and Raypex 6 demonstrated consistent performance, with no statistically significant differences in accuracy across temperature groups. Conclusions This study confirms that variations in NaOCl temperature do not significantly impact the accuracy of EALs in determining the WL for root canal therapy. These findings underscore the reliability of contemporary EALs under different clinical conditions, including the newly evaluated Ai-Pex. Further, in vivo studies are necessary to validate these results.