Histological Studies on Long Junctional Epithelium: Ultrastructure of the Border Zone between Regenerated. - Epithelium and Connective Tissue Attachment

The purpose of this study was to examine ultrastructure of the border zone between long junctional epithelium (LJE) and the connective tissue attachment regenerated on a denuded dentin surface. Two One-year-old beagle dogs were used. After a mucoperiosteal flap had been made, dentin surfaces were exposed with removal of buccal alveolar bone and permolar cementum. The root surfaces were divided into 2 groups. One group (M) was produced by covering the exposed bone surface adjacent to the roots with polycarbonate membrane while the other group (N) was not covered. Animals were sacrificed by perfusion of 1% glutaraldehyde 4 and 8 weeks after surgery, and periodontal tissue were decalcified, postfixed, and embedded in epon. Ultrathin sections were observed by transmission electron microscopy. In the N group it was observed that 8 weeks after surgery the internal basal lamina of superficial LJE cells remained on the dentin surface beneath the apical LJE, and new cementum matrix had forme on the dentin surface. On the other hand, LJE cells of the M group were attached to all dentin surfaces, such that connective tissue reattachment had no yet occurred. The results suggest that coronal migration of may be closely connected with new cenentum formation LJE cells.