Dentigerous cyst associated with an ectopic third molar in the maxillary sinus: A case report and review of literature.

Dentigerous cysts are the most common type of developmental odontogenic cysts arising from the crowns of impacted, embedded, or unerupted teeth. They constitute about 20% of all epithelium-lined cysts of the jaws. The teeth involved most often are mandibular third molar and maxillary canines. About 70% of dentigerous cysts occur in the mandible and 30% in the maxilla. Dentigerous cysts associated with ectopic teeth within the maxillary sinus are fairly rare, and only 20 cases had been reported in Medline since 1980. In the present paper, we report an additional case of dentigerous cysts associated with ectopic third molar in the right maxillary sinus. Also, pathogenesis of ectopic tooth, role of advanced imaging, differential diagnosis, and management are discussed.