Ameloblastic odontoma in rats induced by N-butylnitrosourea

Four cases of ameloblastic odontomas were found in the Long-Evans rats treated with multiple oral administration of a heavy dose of N-butylnitrosourea. The tumor was found as an expansive enlargement over the mandible and was roentgen-opaque. The tumor was histologically characterized by various elements such as odontogenic epithelium, stellated reticulum tissue, enamel, and/or dentine, and was classified as ameloblastic odontoma.