Experimental Changes of the Mandible

Abstract

The growth pattern of the mandible was investigated in nine Hampshire pigs from 8 to 20 weeks of age by means of serial cephalometric roentgenographs in combination with metallic implants. Tracings of the lateral roentgenographs were superposed on the images of the metallic implants to determine sites, increments, and direction of bone growth. The longitudinal distance between the metallic implants remained stable and thus revealed no evidence of interstitial growth in the bone. Appositional growth occurred at the posterior, inferior, anterior, and alveolar borders and at the lateral surfaces of the mandible. The most prolific sites of growth were the condyle and the posterior border. At the anterior border of the ramus, there was resorption. The mandible increased 1) in total length by growth at the posterior and anterior borders, 2) in ramus height by growth at the condyle and inferior border, and 3) in body height by growth at the alveolar and inferior borders. With changes in proportion of the growing mandible, resorption of the anterior border of the ramus resulted in the creation of a new posterior portion of the body. Thus, in the growing mandible, what was ramus at one time eventually became body. In the growing mandible, the body is stable except for changes at its borders. However, the position of the alveolar bone and teeth are subject to continuous change.