The treatment modalities for odontomas are generally depend on the tumors size. Small and medium lesions can usually be removed easily allowing preservation of surrounding anatomical structures. In our study, we reported a conservative surgical treatment of a large complex odontoma. A 19-year-old woman was referred to our clinic after an incidentally observed lesion on her right mandibular angle. The patient was symptom-free at the time of visit. Computed tomography (CT) images showed a mass with a size of 3.5 cm x 3 cm x 2 cm. CT sections and tridimensional images showed partially eroded buccal and lingual cortex. Surgical treatment was indicated with an initial diagnosis of compound odontoma. The lesion removed after sectioning with bur and maxillo-mandibular fixation (MMF) were not thought to be necessary while the buccal and lingual cortexes were mostly reliable for preventing a fracture. In our case, the size of the odontoma was suitable for a conservative treatment method and with this modality we managed to prevent a possible fracture and eliminate the disadvantages of MMF.