Histological and ultrastructural characteristics of the periodontal syndrome in the rice rat. II. Ultrastructural observations on changes in the gingival sulcus, gingival epithelium and lamina propria.

Abstract

The periodontal syndrome in the rice rat was studied in animals fed a high sucrose diet. Progressive degenerative and inflammatory changes within the coronal aspects of the rice rat psriodontium (viz. sulcus, epithelium and lamina propria) were noted. PMN's were seen to migrate from blood vessels within the lamina propria, through the basal lamina, and to either the cemental surface or to the bacterial plaque, where a minimal degree of PMN phagocytosis and degranulation was observed. The degree of PMN phagocytosis appeared to be inversely related to the density of bacterial plaque as viewed on the electron microscopic level.Progressive degenerative changes (viz. vacuolization, lipid accumulation, mitochondrial swelling, etc.) were seen in gingivai epithelial cells subjacent to the bacterial plaque, as well as at the basal layer. Similar changes were noted in fibroblasts in the underlying lamina propria. At later stages of observation (8–14 weeks post‐weaning) a prominent population of macrophages and mononuclear cells was seen within the lamina propria. “Clumping” of these cell types with degenerating fibroblasts was a common finding.