Oriented cell and fiber attachment systems in vivo.

This investigation was undertaken to evaluate whether an oriented cell and fiber attachment system would develop if demineralized dentin surfaces were approximated in vivo. The approximated surfaces consisted of the internal, parallel surfaces of dentin cylinders. The experimental group was demineralized on both the external and internal surfaces of the dentin cylinder with citric acid, pH 1.0, for 3 minutes, but only the external surface of the control dentin cylinder was demineralized. Specimens were implanted transcutaneously into the backs of rats with one end protruding through the surface of the skin. Three specimens in each group were available for analysis at 1 and 10 days after implantation. The groups were compared using histologic and histometric analysis and the following conclusions were made. There were marked differences in the initial cellular response between the groups, and demineralization with citric acid prior to implantation predisposed towards a greater cell attachment at 1 and 10 days. An oriented fiber attachment developed between the demineralized approximated surfaces by 10 days, but did not develop between nondemineralized approximated surfaces. The morphology of the fiber attachment system was structurally similar to a periodontal ligament, with inserting fibers perpendicular to the implant surface. The findings of this study suggest that spatial approximation of appropriate substrates facilitates development of cell and fiber orientation. Thus, to regenerate a functionally oriented attachment system in the clinical setting, it may be beneficial to provide substrates that are appropriately approximated.