Cytotoxic effects of soluble plaque extract on cells in vitro

The accumulation of bacterial plaque on teeth is now generally accepted to be the prime etiologic factor in chronic inflammatory periodontal disease. Various plaque fractions were shown to affect in vitro cell growth and to produce degenerative changes within the cells. In the present work, the effects of a water soluble plaque extract (PE) on cell growth and morphology were studied. Plaque from several patients was pooled and a soluble extract prepared. Various concentrations of PE were added to BHK₂₁ cell cultures at different phases of the normal growth curve. The results indicate that cells grown in the presence of PE show marked cellular damage and inhibition of cell growth. Similar effects were observed when PE was added at different phases of the normal growth curve, even though earlier treatment resulted in increased inhibition. The results support the hypothesis that soluble plaque components may damage crevicular and attachment epithelia, thereby initiating an inflammatory reaction and pocket formation in vivo.