Histological and ultrastructural characteristics of the periodontal syndrome in the rice rat. III. Ultrastructural observations on changes in the transseptal fiber area and alveolar crest.

Abstract

In this study on the periodontal syndrome in the rice rat, the progressive inflammatory and degenerative changes were noted in the transseptal fiber area and alveolar crest.The predominant inflammatory cell types within the transseptal fiber area were PMN's, monocytes and macrophages. Progressive degenerative changes were noted in fibroblasts and collagen fibers with replacement of these elements by the inflammatory infiltrate.At the alveolar crest, extensive osteoclastic activity was observed. Expressions of this activity included the presence of prominent osteoclast ruffled borders and osteoclastic phagocytosis of osteocytic cells. Degenerative changes within osteoblasts were noted at later stages.From these observations, the accelerated rate of destruction seen in this animal model can be explained in part by the increase in resorptive elements (macrophages, osteoclasts) with the simultaneous decrease in formative elements (epithelial cells, fibroblasts, osteoblasts).