Spontaneous Complex Odontoma in a Sprague-Dawley Rat.

Abstract

ABSTRACT. Complex odontoma from a female Sprague-Dawley rat is described histopathologically. Necropsy revealed a hard (bony), white mass (3.0 × 3.0 × 2.1 cm) on the left mandible. Microscopically, the mass consisted of islands or nests of epithelial and mesenchymal elements that formed abortive tooth structures. In other areas, tooth formation consisted of a pulp cavity lined by layers of odontoblasts, dentin, enamel, and ameloblasts. Concerning all features of normal tooth formation which was differentiated and mineralized yet completely disorganized, the diagnosis of complex odontoma was recommended.KEY WORDS: complex odontoma, odontogenic tumor, Sprague-Dawley rat.

Anatomy and Disorders of the Oral Cavity of Rat-like and Squirrel-like Rodents

“…28 Tumors of odontogenic epithelium with odontogenic mesenchyma have been initially reported as odontomas. 29 They have been reported in rats, 29 mice, 30 prairie dogs, 23,[31][32][33][34] and other non-rodent species. 28 Odontomas are further classified as compound odontomas and complex odontomas, according to their histologic features and degree of organization.…”

“…Elodontomas and pseudo-odontomas have been reported affecting elodont incisor teeth of several rodent species. Dental disease with histologic, clinical, and radiological elements consistent with elodontomas or former odontomas have been reported in the guinea pig, 38 degu, 39 pet tree squirrels (Paraxerus cepapi), 28 rats, 29,[40][41][42] and mice. 30,[43][44][45] Dental disease with histologic, clinical, and radiological elements consistent with pseudo-odontomas have been reported in the prairie dog 3,5,7,[31][32][33][34][35]46 (reported also as elodontomas), 47 eastern gray squirrel, 48 and anecdotally in a chinchilla, a chipmunk, 3 and a citellus.…”

“…Affected patients may suffer from altered tooth eruption and the formation of odontoma-like masses. 29,30,42,45 Repeated trauma or fractures (from chewing on cage bars, falls from a height, or improper trimming of maloccluded incisors) with resultant acquired dental disease, localized infection near the apical tissue of incisors with damage to the continuously developing odontogenic tissue, its follicle, and to the surrounding alveolar bone have also been suggested as a cause of odontomas, pseudoodontomas, and elodontomas in prairie dogs and other squirrels. 3,7,28,32 Traumatic damage to the odontogenic tissue may be so severe that it completely disrupts the epithelial cords creating daughter germ cells, each being capable of continuous development forming its own hard and soft tissue components but in a haphazard manner, leading to the formation of hamartomatous masses.…”

Pathology of the Exotic Companion Mammal Gastrointestinal System

“…A complex odontoma and an ameloblastic odontoma have both been recognized. 43,44 One gastric carcinoid tumor developed in the glandular stomach of an older rat. It appeared as a focal raised mass.…”