Results with the caries activity test "Cariostat" compared to prevalence of mutans streptococci and lactobacilli

The colorimetric test, Cariostat (Sankin, Japan), for measuring the caries activity, based on the presence of acidogenic microorganisms, was evaluated. The results were compared with the prevalence of mutans streptococci and lactobacilli in the samples. Pure cultures of S. mutans and lactobacilli were inoculated into the test medium. A maximum color change from blue to yellow was not obtained not even when large numbers of bacteria were used. Samples of stimulated saliva and plaque samples from people with different salivary levels of mutans streptococci and lactobacilli were inoculated into the test medium. Samples with very low or very high numbers of cariogenic bacteria were found in all score groups indicating that the Cariostat test did not satisfactorily differentiate samples with low or high numbers of microorganisms associated with dental caries.