Histological Study of Long Junctional Epithelium: Ultrastructural Findings of Epithelial Attachment after Plaque Accumulation

This study was designed to examine ultrastructural histopathological changes of the long junctional epithelium (LJE) after plaque accumulation. Experimental LJE was formed as follows. The materials were premolars and their buccal aspects of 2 beagle dogs. After mucoperiosteal flaps were split, the roots were exposed artificially by removing cortical bone. The denuded root surfaces were treated with 1mg/m/ laminin (EY. Laboratory, U. S. A.) to induce epithelial cells, and polycarbonate membrane was used in conjunction to block the invasion of granulous tissue of alveolar bone origin. Four weeks later, LJE had formed. In the plaque accumulation experiment, plaque were deposited by feeding a soft diet without brushing of either the experimental or the control sites, the latter of which did not form LJE. Animals were sacrificed 1, 2 and 4 weeks after plaque accumulation and the tissues were light and electron-microscopically observed. 1. Light microscopically, the gingival sulci in the experimental site were deepened up to 4 weeks after being caused by the intercellular crack which occurred in coronal LJE just as in the junctional epithelium (JE) in the control site. 2. Ultrastructurally, no change of epithelial attachment apparatus was recognized up to 4 weeks after the experimental procedure. The findings of desquamated cells, degenerated cells and widened intercellular spaces were observed in LJE near the sulcus bottom, as in the JE of the control site.