The histology of bone and cementum with special reference to movement of teeth

Abstract

The histogenesis of bone is indeed complex. This is forcibly shown in the healing of fractures and repair following infection. In those bones produced by either one or the other process the healing reaction may not be so severe, but in those other instances where both forms of osteogenesis occur one is faced with a multitude of possibilities. An excellent example of this is seen in the maxilla, which is entirely an intramembranous bone with a fairly well-developed vascular system. In this bone, for instance, the osteomyelitic process is much rarer and when present usually much less diffuse. In the mandible, on the other hand, there are five centers of endochondral bone formation on either side (Fig. 5). Thus the process of bone repair is more complicated, particularly in fractures or infections of the mandible involving areas of both types of bone formation. One cannot separate the histologic action of bone that occurs physiologically from that seen in pathologic processes. Although the process may be altered to some degree by morphologic changes in the cells concerned, the reduplication of the various phases is fairly constant. Even the formation of bone in the bone sarcomas, while altered to some extent by the neoplasia, can still be recognized as either intramembranous or endochondral. This is a most important fact to the clinician, for whether he be an orthodontist, an oral surgeon, or a general practitioner, he must rationalize his treatment according to the biologic principles of the tissue concerned.