Epithelial cell kinetics with atelocollagen membranes: a study in rats.

A recent development in guided tissue regeneration procedures is the use of resorbable membranes, which eliminate the need for subsequent surgical removal. In this study we performed flap surgery in rats with (experimental) or without (control) implantation of one of the newer materials, atelocollagen. We observed the gingival epithelial cell kinetics using 3H-thymidine and examined the extent of gingival epithelium migration. Histological observations at day 1 on the experimental side demonstrated regenerated epithelium apposed to the collagen membrane with an intervening layer of necrotic tissues and/or fibrinous exudate. There was no observable proliferation of regenerated epithelium toward the root apex. On day 14, the regenerated epithelium migrated apically along the treated root surface in the control group. By contrast, on day 14 in the experimental group, the regenerated epithelium contacted the root surface at the cemento-enamel junction (CEJ). Apical to the CEJ, there was new cementum formation with inserting connective tissue fibers. Autoradiographs from day 1 experimental sides demonstrated labeled cells in the basal cell layers from oral, crevicular, and junctional epithelium. From day 1 to day 5, labeling indices of oral epithelium and regenerating crevicular epithelium on experimental sides were lower than on control sides. These histological and autoradiographic findings suggest that atelocollagen membrane inhibits apical migration of regenerating epithelium and accelerates connective tissue reattachment in part by inhibiting the mitotic function of basal epithelial cells in early stages of wound healing.