Enhanced Adhesion of S. Mutans to Hydroxyapatite after Inoculation in Saliva

Streptococcus mutans cells form robust biofilms on human teeth and are strongly related to caries incidents. Hence, understanding the adhesion of S. mutans in the human oral cavity is of major interest for preventive dentistry. In this study, we report on AFM-based single cell force spectroscopy measurements of S. mutans cells to hydroxyapatite surfaces. We observe a significant increase of adhesion strength if S. mutans cells were exposed to human saliva before adhesion. In contrast, Staphylococcus carnosus cells are almost unaffected by the pre-treatment. Our results demonstrate that S. mutans cells are well-adapted to their natural environment, the oral cavity. This ability promotes the biofilm-forming capability of that species and hence the production of caries-provoking acids. In consequence, understanding the fundamentals of this mechanism may pave a way towards more effective caries-reducing techniques.