ABSTRACT
Objective To measure the curvatures of the distolingual root canals of permanent mandibular first molars by cone-beam computed tomography (CBCT). Methods The CBCT was used to collect 230 cases of mandibular first molar distalingual root from 513 patients. The images were created by 3-D reconstruction based on the BECT data. Images were analyzed by NNT image analysis software. Each tooth was captured in clinical (CV) and proximal view (PV) image, and measured by the Schneider method. Results The average curvature of the distallingual canal was (13.27 ± 8.57)° in CV, and (30.96 ± 11.63)° in PV. Most of the distallingual root in the buccolingual view was mild bending or moderate bending , and the proximal view was severe bending. The distal lingual root bending was the most common in the crown third of the root , next in the apical third of the root, in the middle third of the root. Conclusion CBCT is an effective tool for the detection of additional distolingual roots and is a valuable aid for dentists in root canal treatment.