Remodelling of collagen fibers in the periodontal ligament and the supra-alveolar region.

Although the rate of turnover of collagen in the periodontal ligament may be somewhat higher than in the gingiva, it is doubtful whether this is the only factor that may explain why rearrangement of collagen fibers in the ligament occurs much more rapidly than in the supra-alveolar region under certain experimental conditions. It may well be that there are other factors that determine the ability of the periodontal tissues to rearrange themselves. On the basis of the distribution pattern of collagen phagocytosis by fibroblasts and the pattern of incorporation of 3H-proline it seems that turnover of collagen, at least in the periodontal ligament is evenly distributed across the width of the tissue. However, local variations in the presence of cells containing intracellular collagen fibrils may occur, as indicated by the observation that a relatively high concentration of ingested collagen fibrils is seen in fibroblasts in the direct vicinity of osteoclasts. It is suggested that coordinated action of fibroblasts and osteoclasts near the alveolar bone surface may represent part of a local mechanism through which rapid remodelling of certain areas in the periodontal ligament may be accomplished.