Accuracy of wireless electronic apex locators in teeth with different types of root resorption: a 3D-printed tooth model study

This in vitro study aimed to evaluate the accuracy of wireless electronic apex locators (EALs) in determining the working length (WL) across seven distinct types of root resorption (RR) using three-dimensionally (3D) printed tooth models. 32 transparent resin tooth models representing one non-resorptive control and seven RR types (n = 4 per group), including internal resorption (IRR; 0.5- and 1-mm perforations), external resorption (ERR; 0.5- and 1-mm perforations), external apical resorption (EARR; grades 2 and 3), and external cervical resorption (ECR), were fabricated with precise geometric parameters. WL was measured using four EALs (Woodpex III Gold Plus, iRoot, Wirele-X, and AirPex). Data were analyzed using appropriate parametric and non-parametric tests with intraclass correlation coefficients (ICC) (p < 0.05). Significant differences among devices were observed in the control, IRR-0.5 mm, ERR-0.5 mm, ERR-1 mm, and EARR grade 3 (p < 0.05) groups, whereas IRR-1 mm, EARR grade 2, and ECR groups showed no significant differences (p > 0.05). The ICC values (0.00-0.55) indicated low-to-moderate consistency, with no calculable ICC in the uniform groups. ERR-1 mm represented the most challenging condition, with all devices showing high rates of mistaken measurements (75-100%). The accuracy of wireless EALs was influenced by both the device type and specific resorption morphology. All devices were fully accurate in the EARR grade 3 and IRR-1 mm models, whereas ERR-1 mm, ECR, and EARR grade 2 groups exhibited reduced accuracy. Resorptive defects that disrupt dentin continuity, particularly in the apical or cervical regions, compromise measurement precision, supporting the need for radiographic confirmation in such cases.