Adherence as an ecological determinant for streptococci in the human mouth

The adherence of Streptococcus species to dental plaque and oral epithelial surfaces was studied in vivo by introducing mixtures of streptomycin-labelled strains into the mouths of volunteers. The proportions of labelled Strep. sanguis recovered from the cleaned teeth or preformed plaques were much higher than those of Strep. salivarius after a 45 and 30 min experimental period respectively. The adherent behaviour of in vivo -grown labelled organisms for cleaned teeth was similar to that of the same species present naturally in the mouth. The data provide additional support for the concept that the low proportion of Strep. salivarius in dental plaque is due to its inability to adhere to the tooth surface or developing plaque. The proportions of labelled Strep. salivarius were higher than those of Strep. sanguis on the dorsum of the tongue but lower on the vestibular mucosa. The proportions of labelled Strep. mutans in both sites were low as compared to those of Strep. salivarius and Strep. sanguis . The relative adherence of these Streptococcus species to the tongue and vestibular mucosa correlates with their proportions found naturally in these sites. Thus, adherence seems to be an important determinant for the colonization of Strep. salivarius, Strep. sanguis and Strep. mutans on the tongue and vestibular mucosa as well as on teeth.