Histological and ultrastructural characteristics of the periodontal syndrome in the rice rat

Abstract

In this paper on the periodontal syndrome in the rice rat, the effects of dietary penicillin and tetracycline on the progressive inflammatory and degenerative changes (as seen in rice rats fed diet 700 alone) were noted at the light and electron microscopic level. Throughout the observation period (0–14 weeks postweaning), animals fed diet 700 with penicillin or diet 700 with tetracycline showed no evidence of bacterial colonization, a minimal PMN infiltrate restricted to the gingival epithelium and subjacent lamina propria, and no marked degenerative changes within cells that normally inhabited the periodontium (viz. epithelial cells, fibroblasts, osteoblasts). Marked osteoblastic or osteoclastic activity was rarely noted along the alveolar crest in this group of animals. These results give added support to the concept of a single microbial agent or group of microbial agents, as the primary etiology of this disease.

Gingivitis*

“…Studies on germ-free rats and dogs and on animals whose teeth have been kept meticulously clean provided new insights into the functioning of the normal host defense system around the teeth (Attstrom & Egelberg 1970, 1971, Attstrom 1971, Listgarten & Heneghan 1971, Garant 1976a, b, c, Schroeder 1977. Under normal conditions there is a constant stream of neutrophils migrating from the vessels of the gingival plexus through the junctional epithelium to the gingival margin, into the gingival sulcus and oral cavity (Ryder 1979(Ryder , 1980a. Most bacteria produce substances that chemotactically attract neutrophils (Lareau et al 1984), and chemotactic substances are also present in saliva.…”

“…These bursts were characterized by ulceration of the junctional epithelium and infiltration of large numbers of neutrophils. The discontinuities in the junctional epithelium were considered to result from uninterrupted chain-like streams of emigrating leukocytes through the junctional epithelium (Ryder 1979, 1980a, b, c. Page & Schroeder 1982. Osteoclast activity too was discontinuous, manifesting short periods of vigorous resorptive activity followed by longer periods of inactivity (Garant 1976a, b).…”