Differential diagnosis between cyst and tumor. Dentigerous cyst and ameloblastoma containing teeth.

A study was conducted on 21 cases of ameloblastoma (a type of tumor containing an embedded tooth) and 87 cases of dentigerous cyst. The former cases were selected from among those which had been diagnosed histopathologically. Using radiographs of these lesions, the following parameters were measured: 1) the distance between the cement-enamel junction of the embedded tooth and its attachment to the cystic wall; 2) the area of the radiolucent image (similar to the area with a cystic appearance). From measurements of the former parameter, it appeared that the embedded tooth extends more toward the root apex in ameloblastoma than in dentigerous cyst, whereas the latter parameter indicated that the radiolucent area varies in size slightly in ameloblastoma, but tends to be smaller in dentigerous cyst. Moreover, with regard to clustering between ameloblastoma and dentigerous cyst, no definite tendency was detected on distance, whereas only ameloblastoma without dentigerous cyst was seen above 20 cm2 of area.