EXPERIMENTAL PERIODONTITIS INDUCED IN RATS BY STREPTOCOCCAL CELL-WALL FRAGMENTS

Bacterial cell wall fragments, consisting of peptidoglycan and associated polysaccharide of teichoic acid polymers were prepared from a group A streptococcus, a group D streptococcus, two Streptococcus mitis strains and Strepococcus sanguis. Injection of cell walls into rat gingival tissues resulted in self‐limiting inflammatory lesions that reached a peak in 2 to 3 days and resolved by 4 to 7 days/ An early polymorphonuclear leukocyte response was replaced by a mononuclear infiltrate characterized by a predominance of macrophages. Lymphocytes and plasma cells were not a common feature, even in animals given repeated injection of cell walls into the same area. A wide range of changes was seen in the alveolar bone, including loss of the periosteum with disappearance of osteoblasts, osteoclastic bone resorption, hyperplasia of the periostum with apparent osteoblastic activity, and osteoid formation. Osteoclast‐associated bone resrption was commonly seen on the periodontal ligament aspect of the alveolar bone and less frequently on the periosteal surface. Neonatal thymectomy did not alter the response, and respeated injections did not increase the severity of the reactions. Copyright © 1979, Wiley Blackwell. All rights reserved