Background: Odontoma is a benign mixed odontogenic tumor that affects the jaws, being the second most common odontogenic tumor. According to its clinical and radiographic characteristics, it is subdivided into compound, which simulates multiple small teeth, and complex, being a radiopaque mass of variable size. The indicated treatment is surgical excision of the lesion. Differential diagnoses include supernumerary tooth, ameloblastic fibro-odontoma, and osteoma, for which the specific characteristics of the lesion and the histopathological report are crucial for reaching a definitive diagnosis. Objective: to report the clinical case of a lesion with presumptive diagnosis of odontoma vs. supernumerary tooth, which caused the retention of tooth 13 is horizontally positioned for traction with orthodontic appliances. Therefore, it was necessary to extract the tooth along with the lesion and perform bone grafting and membrane placement for regeneration. Description of the case: Patient with no clinical presence of tooth 13, who presents an exophytic area on the vestibular bony plate, with no mucosal alterations. Panoramic radiography and computed tomography reveal tooth #13 impacted in a horizontal position and irregularly shaped radiopaque areas with multiple rounded hyperdense shadows around it. Tooth 13 extraction, underlying tissue biopsy, scraping, bone curettage performed. Simultaneous guided bone regeneration with allograft, collagen membrane. Flap repositioned, sutured after procedure. The histopathological examination shows dense sclerotic tissue with active young fibroblastic areas and incomplete fragmented adherences of sclerotic bone with calcification. Structures resembling dentin with a focal tendency to calcify were identified, consistent with a compound odontoma. Conclusion: The combination of oral clinical examinations with panoramic radiographs and 3D tomographies is essential for precise diagnoses. The patient's age, dental eruption, location, and symptoms are crucial for treatment. A case is illustrated where bone grafting and a membrane corrected a bone defect following the removal of a lesion and a tooth, proving to be pivotal for the success of the treatment.