A QUANTITATIVE COMPARISON OF SELECTED BACTERIA IN HUMAN CARIOUS DENTIN BY MICROSCOPIC COUNTS

The levels of selected cariogenic and obligately anaerobic bacteria ha ve been compared in carious dentine taken from fissures, smooth surfac es, and root surfaces. The numbers of infected dentinal tubules were d etermined by immunohistological staining using species-specific antise ra against selected bacteria. Selective localization was observed; mut ans streptococci were the predominant bacteria in dentine from fissure s and smooth surface coronal caries, but not from root surface caries. The proportion of mutans streptococci was higher in the shallow and m iddle layers of dentine from fissures and smooth surface coronal cario us lesions than from the deep layers. In root surface caries, Actinomy ces spp. were the predominant bacteria, and were present at higher lev els in the deep layer of root lesions than in the shallow and middle l ayers. The proportion of lactobacillus spp. was relatively low despite its high detection frequency in all layers of the three types of cari ous lesion. Immunohistological staining with species-specific antisera was able to reveal the distribution and the localization of various b acteria in carious dentine.