Molecular and cellular biology of alveolar bone.

Abstract

Alveolar bone is a specialized part of the mandibular and maxillary bones that forms the primary support structure for teeth. Although fundamentally comparable to other bone tissues in the body, alveolar bone is subjected to continual and rapid remodeling associated with tooth eruption and subsequently the functional demands of mastication. The ability of alveolar bone to undergo rapid remodeling is also important for positional adaptation of the teeth but may be detrimental to the progression of periodontal disease. The anatomical structure of alveolar bone, which is quite complex, has recently been described in detail (200). Alveolar bone is composed of bundle bone (209), which is formed in layers in a parallel orientation to the coronal-apical direction of the tooth. Sharpey’s fibers extend obliquely from the thin lamella of bone that lines the socket wall and are continuous with fibers of the periodontal ligament. A thicker outer layer of bone formed of cortical plates extends from the jaw bone and forms the lingual and labial surfaces of the alveolar process and is largely made up of spongy cancellous bone. Within the cancellous bone are numerous marrow spaces, with smaller endosteal spaces present in the cortical bone. Some of the small endosteal spaces extend into, and are contiguous with, the periodontal ligament. Because of the small size and anatomical complexity of alveolar bone, relatively few studies on the cellular, and particularly the molecular, aspects of alveolar bone structure and metabolism have been performed using alveolar bone itself. However, the ability of bone cells derived from adult rabbit alveolar bone to form mineralized tissue nodules with the characteristics of bone has been described (142, 224). A procedure has also recently been developed for the isolation of adult human alveolar bone cells, from 2-week-old osteogenic tissue recovered from dental implant surgery, that form bone tissue in culture (174). While these systems provide a means of investigating specialized aspects of the molecular