Comparative evaluation of three electronic apex locators in determining working length: An in-vitro study

Objective: The purpose of this in-vitro study was to determine the precision of three electronic apex locators (AppleDent AL, Eighteeth AL, and Coxo AL) in determining the working length (WL) of root canals using extracted human teeth. Although several new apex locator models have recently become commercially available, independent evidence regarding their measurement accuracy remains limited, underscoring the need for objective evaluation. Methods: A total of 90 freshly extracted human permanent single-rooted teeth with mature apices were standardized. Access cavities were prepared and canal patency was controlled (with a 10 K file) and AWL (with size 15 K file at ×25 magnification) were detected by the stereomicroscope. After embedding them in alginate to recreate the periodontium, teeth were randomly divided into 3 groups (n = 30). The average of 3 repeated measurements was used for the calculation of the EWL in each group. The value of AWL and EWL have been calculated. The accuracy was measured under ±0.5 mm and ±1.0 mm. Data were statistically treated with Shapiro-Wilk test (to assess data normality), Levene´s test, one-way ANOVA and Tukey's post hoc testing (α = 0.05). Results: In comparison with Eighteeth AL (0.41 ± 0.27 mm), the mean deviations of AppleDent AL and Coxo AL from AWL were by a lower level (by 0.24 ± 0.58 mm and by 0.24 ± 0.33 mm, respectively). Precision within ±0.5 mm was 50.0%, 86.7%, and 73.3% for AppleDent, Coxo, and Eighteeth models, respectively. All devices achieved a 90% or greater accuracy within ±1.0 mm. The ANOVA analysis confirmed that Eighteeth was different from AppleDent and Coxo (p = 0.012), which the Tukey's test also confirmed. Conclusions: All 3 electronic foramen locators showed clinical accuracy. Coxo AL performed far better, while AppleDent AL showed similar mean scores, but had higher variability, and Eighteeth overestimated the working length.