Odontoma, a malformation of the mature dental hard tissue, is the most prevalent odontogenic tumor, accounting for almost 40％ of all such tumors.
We herein report a case of large complex odontoma arising at the maxilla which was enucleated via a trans-maxillary sinus approach. The patient was a 30-year-old Japanese man. The right posterior dento-alveolar region of the maxilla showed diffuse swelling. A radiopaque lesion was detected at the right posterior region of maxillary alveolar bone with a dome-like protrusion into the right maxillary sinus on computed tomographic images. The lesion was clinically diagnosed as odontoma. The tumor of 38×30×21mm in size was safely excised via the trans-maxillary sinus without abnormal bleeding or damage to residual teeth under general anesthesia. The histopathological diagnosis was complex odontoma. No recurrence has been observed for more than one year after surgery.