The acidogenic microbial composition of dental plaque from caries-free and caries-prone people

Plaque samples collected from caries-free and caries-prone subjects were analysed for total bacteria, the ratio of acidogenic to total organisms and the proportions of streptococci, Streptococcus mutans and Actinomyces. The acidogenic composition of plaque reflected the dietary habits and caries status of an individual. A high acidogenic ratio was found in individuals with active lesions or recent restorations; individuals who were caries-free or had no recent lesions had a lower ratio although total organisms were similar. The ratio remained constant in sequential samples from caries-prone subjects but was increased by frequent exposure to sugar. Streptococci, Actinomyces and Strep. mutans were isolated from all samples but no consistent relationship was found between either their isolation frequency or proportions and caries status.