Translative and transformative growth of the rat mandible

The growth of the rat mandible was studied during a period from 14 to 30 days of age. Roentgencephalometric and alizarin vital staining techniques were employed. Growth in length doubles the growth in breadth; the angle between the mandibular halves decreases slightly. Bone remodeling patterns were revealed with the alizarin technique. Posteriorly facing surfaces and the anterior end of the incisal process show apposition. Lateral facing surfaces of the posterior part of the mandibles were resorptive. A medio-posterior growth direction of these parts were found. The intermandibular articulation plays no role in the translative growth movements, in contrast to other articulations between skull bones as sutures and synchondroses, but serves primarily during biting and chewing.