Alterations in the facial skeleton of the guinea pig following a lesion of the trigeminal motor nucleus.

In thirty-three of sixty-six guinea pigs of the Topeka strain small, unilateral, electrolytic lesions were produced in the motor nucleus of the trigeminal nerve. Unoperated animals and the side contralateral to the muscle paralysis served as controls. Lesions were created when animals were 15 days or 75 days of age, and the animals were killed 15, 30, 45, or 60 days postoperatively. Each animal was subjected to dry skull preparations or radiographic and histologic techniques. Alterations in craniofacial form were noted in both the growing animals and the animals with little growth remaining. Alterations in form and function included paralysis and atrophy of the muscles of mastication on the lesion side, hypereruption of teeth, and reduction in growth of facial bones on the lesion side. Remodeling changes were evident in the glenoid fossa, the condylar process, and the coronoid process on the operated side but were not apparent in the contralateral control or the unoperated control animal.