Endodontic management on a C-shaped mandibular molar fused with a supernumerary tooth: a report of a rare case

Aim: Fusions involving mandibular molars and supernumerary teeth are rarely reported. The complex internal anatomy makes the endodontic treatment of these teeth a challenge for the clinician. This report describes the endodontic management of a rare case of a C-shaped mandibular molar fused with a supernumerary tooth.

Summary: A 29-year-old male was referred for endodontic treatment of the right mandibular second molar. The initial clinical examination indicated atypical anatomy of this tooth, with the presence of a “supernumerary cusp”. Cone-beam computed tomography (CBCT) images showed that the cusp was a supernumerary tooth, with its canal separated in the cervical third, but fused in the apical third to the second molar canals, forming a single C-shaped canal. After clinical and radiographic examination, the diagnosis was irreversible pulpitis. The endodontic treatment was performed with the aid of a dental operating microscope. The root canals were instrumented using the crown-down technique and irrigation using 2.5% sodium hypochlorite (NaOCl). Passive ultrasonic irrigation was performed (2.5% NaOCl and 17% EDTA solutions) followed by obturation using the thermoplasticization technique. No clinical or radiographic changes were noted at the 12- and 24-month follow-up visits. 

Key-learning points:

• The analysis of CBCT images and the use of magnifying tools are essential for the diagnosis and treatment of teeth with complex root canal anatomy. 

• For teeth with complex anatomies, in addition to the traditional methods of root canal shaping and filling, it is necessary to associate methods that enhance the cleaning and disinfection of the root canal system.