Accuracy of Working Length Measurement Using Cone Beam Computed Tomography at Three Field of View Settings, Conventional Radiography, and Electronic Apex Locator: An Ex-vivo Study

Determining the working length (WL) in root canal treatment facilitates the treatment prognosis. The introduction of apex locators and new CBCT devices in dentistry influenced this consideration. This comparative study evaluated the accuracy of working length measurement by cone-beam computed tomography (CBCT) in three fields of view (FOVs), conventional radiography, and the apex locator Raypex 5. The descriptive-analytical study was performed on 40 lower premolar teeth that met the inclusion criteria. Direct observation under the microscope was considered the gold standard and compared with measurements by the electronic apex locator, CBCT, and periapical images. The results were analyzed by paired t-tests and Wilcoxon tests. A significance level of 0.05 was considered in this study. CBCT 5×5 FOV with a p-value of 0.733 and analog radiography with a p-value of 0.001 achieved the working lengths with the highest and lowest accuracy, respectively. In addition, the difference between actual and measured working length using analog radiography was significant (p-value