Inflammatory lesions and bone resorption induced in the rat periodontium by lipoteichoic acid of Streptococcus mutans

Severe inflammatory lesions were induced in the periodontal tissues of the rat following the intragingival injection of lipoteichoic acid (LTA) from Streptococcus mutans. There was no difference in the severity and distribution of the lesions between nonimmunized rats and animals immunized against LTA after antigenic challenge. The lesions are characterized by the occurrence of granulation tissue, massive infiltration of PMNs, abscess formation, bone resorption, and new bone formation. Deacylated LTA and saline caused relatively mild inflammation, and no significant bone resorption or new bone formation was evident. The peak response was reached after 3 intragingival injections. The mechanisms by which LTA caused the pathological alterations in the rat periodontium and the possible relations of this experimental model to periodontal disease in the human are discussed.