Competition and Caries on Enamel of a Dual-Species Biofilm Model with Streptococcus mutans and Streptococcus sanguinis

Abstract

The concept of caries as an ecological disease implies the understanding of the intricate relationships among the populating microorganisms. Under frequent sugar exposure, some bacteria from the dental biofilm develop pathogenic traits that lead to imbalances (dysbiosis). Depending on which microorganism colonizes the dental surface first, different competition strategies may be developed. Studying the interactions in the entire dental biofilm is not an easy task. In this study, therefore, we modeled the interplay among these microorganisms using a caries-inducing species ( S. mutans ) and a health-associated species ( S. sanguinis ). Initial enamel adherence with S. sanguinis seems to induce more intense competition against typically caries-inducing species. Besides continuous exposure with sugars, early colonization of the enamel by highly cariogenic species like S. mutans appears to be needed to develop caries lesions as well. Promoting early colonization by health-associated bacteria such as S. sanguinis could help to maintain oral health, delaying dysbiosis.