Introduction: Cementoblastoma is a rare and benign odontogenic mesenchymal tumor, often characterized by the formation of cementum-like tissue produced by neoplastic cementoblasts attached to or around the roots of a tooth.
Case report: 22-year-old male patient was referred to the Federal University of Paraná after occasional finding on a routine panoramic radiograph. Clinical examination suggested no alterations. Medical and family history presented no alterations as well. Computed tomographic (CT) showed the presence of a radiopaque area associated with the roots of the impacted third molar measuring 15 mm × 10 mm inside the left maxillary sinus. The treatment plan suggested was to surgically remove it under general anesthesia. An intraoral approach was conducted, using the Newmann incision from the superior left first molar to the retromolar area with anterior and posterior relaxant incisions. Using a Caldwell-Luc access next to the maxillary tuberosity region, the maxillary sinus was exposed and the calcified mass attached to the roots of the tooth was reached. Pathological mass removed was sent for histopathological investigation. Examination revealed dense, mineralized, cementum-like material and vascular soft tissue areas that consisted of cementoblasts. One-year follow-up shows no recurrence and absence of symptoms.