ABSTRACT
A cystic compound odontoma in the maxillary sinus occured in a 13-years-old boy, who had missing right upper third molar without having the hostory of extraction of the wisdom tooth. He complained nasal stuffimess, headache, and pain on the affected face, resembling any sign and symptoms of the maxillary sinus problems. The cysitc compound, sized 2 x 1.5 cm in diameter was pedunculated and attached on the posterior wall of the right maxillary sinus and above the antral floor. The location of the compound odontoma in the maxillary sinus was confirmed after panoramic, waters, spiral tomographic, CT examinations and surgical exploration. Irs location was on the medical, posterior, superior to the normal position of the maxillary third molar or the maxiilary dental arch. The cystic odontoma in the maxillary sinus made the patient have the sings and symptoms of mazillary sinustis. The cystic compound dodntoma might be originated from the dental lamina of the missing upper right thred molar. The "V principle" of the upper jaw growth and the pneumatization process fo the maxillary sinus could explain why the compound odontoma had peduncular shape and the location of odontoma was on the demial, superior to the normal position of the maxillary dental arch.