Oral CBCT in the diagnosis of C-shaped canals of mandibular second molars

Objective To investigate the clinical efficiency of dental cone-beam computed tomography(CBCT) in the diagnosis and treatment of C-shaped canals of mandibular second molars in root canal therapy.Methods 62 mandibular second molars that failed in the first root canal therapy were included in this study.The periapical films could not indicate the anatomic forms of root canals and the suspicious missed canals.The teeth were scanned by CBCT.Results 52 canals(83.87%) were diagnosed as C-shaped canals,among which the numbers of C1 type,C2 type and C3 type were 28(53.84%),18(34.62%) and 6(11.54%),respectively.Among the 52 teeth with C-shaped canals,2 teeth failed to receive the root canal therapy due to root canal perforation,and 50 teeth received gutta-percha filling through warm gutta-percha obturation and vertical condensation to fill the irregular root canal system so as to fill the root canals thoroughly.After endodontic retreatment,50 teeth(96.15%) showed satisfactory outcome with no complications identified.CBCT functioned in positioning the lesioned root canals with a high accuracy.Conclusions CBCT can analyze the configuration of root canals in a three-dimensional view,which is of prime importance in the diagnosis and treatment of C-shaped canals of mandibular second molars.