Streptococcus Mutans - Life in The Oral Cavity

Life in The Oral Cavity

Surviving in the oral cavity, S. Mutans is the primary causal agent and the pathogenic species responsible for dental caries (tooth decay or cavities) specifically in the initiation and development stages.

Dental plaque is typically the precursor to tooth decay and contains more than 600 different microorganisms, contributing to the oral cavity’s overall dynamic environment that frequently undergoes rapid changes in pH, nutrient availability, and oxygen tension. Dental plaque adheres to the teeth and consists of bacterial cells while plaque is the biofilm on the surfaces of the teeth. Dental plaque and S. mutans is frequently exposed to "toxic compounds" from oral healthcare products, food additives, and tobacco. Degradation by-products of dental composites resins (fillings) can be another source of toxic chemicals that can interfere with the bacterial growth of S. mutans.

While S. mutans grows in the biofilm, cells maintain a balance of metabolism that involves production and detoxification. Biofilm is an aggregate of microorganisms in which cells adhere to each other or a surface. Bacteria in the biofilm community can actually generate various toxic compounds that interfere with the growth of other competing bacteria. However, there have been very few studies on how S. mutans can tolerate such exposure to various toxic substances during its growth in the oral biofilm and is, thus, poorly understood.

S. mutans has over time developed strategies to successfully colonize and maintain a dominant presence in the oral cavity. The oral biofilm is continuously challenged by changes in the environmental conditions. In response to such changes, the bacterial community evolved with individual members and their specific functions to survive in the oral cavity. S. mutans has been able to evolve from nutrition-limiting conditions to protect itself in extreme conditions. Streptococci represents 20% of the oral bacteria and actually determines the development of the biofilms. Although S. mutans can be antagonized by pioneer colonizers, once they become dominant in oral biofilms, dental caries can develop and thrive.