Hemorrhagic cyst of the mandible associated with a retained root apex of the lower third molar.

An unusual case of hemorrhagic cyst of the mandible, associated with a retained root of the lower right third molar, is reported. The cyst was revealed by routine radiologic examination as part of treatment of the lower right second molar. Radiologically, a faintly outlined cavity with radiopaque mass was found in the third molar region. A final diagnosis of this condition was made after surgical intervention and histologic examination. A nonepithelial lining cavity was found, and the radiopaque mass was identified as a root apex.