Clinical aspects of C-shaped canals in maxillary and mandibular second molars: a case report series and literature review

Introduction: The success of root canal treatment depends on the proper cleaning, shaping, and obturation of the root canal system, along with an adequate understanding of root canal morphology. One of the most important anatomical variations in maxillary and mandibular second molars is the C-shaped root canal system. The purpose of this study was to describe cases of upper and lower second molars with C-shaped canals, their treatment course, and their configurations according to a new classification using cone-beam computed tomography (CBCT) scans.Materials and methods: Ten teeth with C-shaped canals in 4 female patients were analyzed using CBCT scans. After instrumentation with an ultrasonic tip BUC #1 and ProTaper Next rotary files using the circumferential brushing technique, 5.25% NaOCl was agitated with passive ultrasonic irrigation. The C-shaped canals were filled using thermoplastic techniques with gutta-percha and AH Plus sealer.Results: All reported cases with C-shaped canals were bilateral. In mandibular second molars, the C1 configuration was more common at the coronal level, C1 and C2 were more frequent in the middle, and C3 and C4 were equally prevalent at the apical level. In maxillary second molars, C1 and C3 configurations were equally prevalent in the coronal and middle regions, with C4 more common in the apical section. Types I and VI root fusion were observed in upper second molars. Clinical and radiographic follow-up examinations revealed asymptomatic teeth with no pathological signs or symptoms. All presented cases were successfully treated.Conclusions: In the endodontic treatment of C-shaped canals, dental practitioners should utilize CBCT examination, an operating microscope, and ultrasonic tips to effectively clean and agitate the irrigants.