Influence of root canal curvature on the accuracy of an electronic apex locator: An in vitro study

OBJECTIVE: This study investigated whether the canal curvature has an influence on the accuracy of Electronic Apex Locator. MATERIALS AND METHODS: Sixty mandibular posterior teeth were decoronated. A number (No.) 10 file was inserted into the mesiobuccal canal and radiographs were taken to determine the degree of curvature by Schneider's method. Samples were divided into three groups of mild (<20°), moderate (20-36°) and severe curvature (>36°). After enlarging the orifice, the actual canal length was determined by introducing a file until the tip emerged through the major foramen when observed under 20X magnification. The teeth were embedded in an alginate model and the Root ZX was used to determine the electronic length. The data was analyzed by Kruskal-Wallis test followed by Mann-Whitney test. RESULTS: The difference in measurement of Actual and Electronic working length was statistically significant between group 1 and 2 (P < 0.05) as well as between group 1 and group 3 (P < 0.05) with group 1 showing the lowest difference. CONCLUSION: Considering ± 0.5 mm as tolerance limit for accuracy, the device was 95% accurate for the mild curvature group and 80% accurate for moderate and severe groups.