Microbial screening tests have been used to identify children who are at risk for development of dental caries.  In older individuals, these tests usually involve quantitation of the cariogenic bacteria, i.e., mutans streptococci and lactobacilli in stimulated saliva samples; whereas, in young children, tongue specimens collected with wooden or plastic tongue blades or the backs of mouth mirrors which are subsequently inoculated on selective agar media are frequently employed.  Some investigators have sampled other oral sites, such as plaque or the buccal mucosa, or have utilized conventional dilution and plating methods. Microorganisms in addition to cariogenic bacteria such as yeasts or Veillonella species also have been examined as indicators of caries status.  The table to the right shows that there is a high correlation between the quantity of mutans streptococci and the presence of dental caries in infants and toddlers.  

The development of genetic methodologies has stimulated the search in children for oral species other than MS or LB which may serve as risk indicators of the caries process.  Although molecular may eventually replace culture based techniques, the latter may be more practical for microbial screening in the clinical setting at the present time.