Abstract
The patient was a six-year old female. Her right cheek, having been hit hard four months before her entering the hospital, showed a slight swelling. Afterward since there was toothache the extraction of the first milk molar tooth of the right upper jaw was done. Later a fistula formed on the same spot. At the first examination a slight stiffness was recognized on the swellen part, but the Gerbel tuberosity was not seen in the right nasal cavity. The X-ray photograph showed a cystoma-like diaphaneity which occupied the right maxillary sinus. This cyst which was as big as a dove's egg, was wholly extracted by the Luc-Caldwell's method. In the cyst tooth was not found, but one normal tooth and two impacted tooth were extracted. The fistula was well-closed on the tenth day after the operation. The root cyst growing on the milk tooth is rare, but the results of the operation and also a X-ray photograph showed this to be a case of the cyst growing on the location of the extracted tooth.
