Comparative Study of Working Length Determination in Teeth with External Root Resorption Using Clinical and Radiographic Techniques: In Vitro Study

Objectives The aim of this study is to compare the accuracy of CBCT, IOPA, and various electronic apex locators against the control group (Actual Working Length determination through visualization method using K-file size #15 under Microscope) in teeth with external root resorption. Materials and methods In this in vitro study, the sample consisted of 13 extracted permanent human teeth. External Root Resorption was induced at the 3 mm apical root. The control group will represent the actual working length (WL) that’s measured with a K-file #15 until the file tip can be seen visually at the apical foramen by using the CJ-Optic Flexion microscope. Then the teeth were placed in alginate, and the WL for each tooth was measured using two brands of electronic apex locators (APEX-S and RAYPEX 6) with a K-file #15. Measurements of WL from the file tip to the base of the rubber stopper at the reference point were done using a digital calliper (Mitutoyo 550-331-20 digital calliper, Japan). The teeth were then fixed with wax into a gypsum model, and radiographic techniques, including periapical technique & CBCT, were used to record the WL. The WL of each method was statistically compared with the actual WL (control group) using one-way ANOVA with p < 0.01. Result One-way ANOVA test showed statistically significant differences (P < 0.05) between all groups compared to the control group (actual WL). Whereas the Independent T-Test showed no statistically significant differences between APEX-S EAL and RAYPEX 6. Conclusion This study showed that there was a significant difference between the actual WL and the digital periapical radiography, CBCT, and two types of EAL. Thus, the combination of EAL and CBCT could be a reliable method for determining WL in the presence of ERR.