An electron microscopic study of attachments between periodontal fibers and bone during alveolar remodeling.

Three types of periodontal membrane-to-bone attachments are described for remodeling surfaces of the bony alveolar wall. An adhesive type, which is the most widespread means for tooth anchorage on resorptive bone surfaces during active tooth movements, involves the following histogenic steps: A layer of ground substance is first deposited by fibroblast-like cells on the naked surface of recently resorbed bone. As this continues, new precollagen and the dissociated ends of collagenous fibrils become embedded in the accumulating ground substance, and these fibrils in turn become joined to intact collagenous fibrils, blending with the remainder of the periodontal stroma. Such adhesive attachments continuously form and re-form as the resorption front proceeds. A continuous type of attachment also occurs on resorptive bone surfaces in which some (not all) bone matrix fibrils survive the resorptive process. These former bone fibrils become incorporated into the periodontal membrane and are continuous between the bone matrix and the stroma of the contiguous periodontal membrane. An intermediate type of attachment also occurs and is primarily an adhesive attachment that also contains a scattering of fibrils which are continuous from the bone matrix across the resorptive bone surface into the fibrous matrix of the periodontal membrane.