Determination of Critical Size Defects in the Mandibles and Calvaria of Mongrel Dogs and Cynomolgus Monkeys

A variety of bone grafts and implants have found utility in oral and maxillofacial surgery. In reconstructive surgery, osteoinductive agents such as grafts and implants frequently are required either to repair maxillofacial defects or to augment the maxillofacial skeleton. Little consistency has been sustained among research investigators in choosing an appropriate animal model for maxillofacial bone research. In an attempt to describe a protocol for the development of maxillofacial nonunions, experiments were reviewed which used calvarial and mandibular defects as models. The creation of experimental nonunions in calvaria and mandible was found as size-dependent. Defects of a size which will not heal during the life-time of an animal may be termed critical size defects CSDs. A rationale was postulated for testing bone repair materials BRMs using CSDs in a hierarchy of animal models. This protocol suggests that testing would be initiated in the calvaria of the rat and rabbit followed by testing in the mandibles of dogs and monkeys. While calvarial CSDs have been established in the rat, rabbit, and dog, research is still needed to describe the CSD in the calvaria of the monkey and the mandibles of dogs and monkeys.