- Oral bacteria play an important role in both health and disease. The oral cavity contains over 700 bacterial species that form complex biofilm communities on teeth and in other areas. - Certain bacteria like Streptococcus mutans and lactobacilli are associated with dental caries due to their ability to produce acid from carbohydrates, tolerate low pH environments, and form biofilms. These cariogenic bacteria were first isolated in the early 1900s. - While many people harbor cariogenic bacteria, not everyone develops caries. The ecological plaque hypothesis suggests that caries results from an environmental shift, like frequent sugar intake, that upsets the balance between pathogenic and commensal oral bacteria.