Salivary mutans streptococci and caries development in the primary and mixed dentitions of children

Objectives: For more than 25 years, both cross-sectional and longitudinal s tudies of dental caries have focused on the role of salivary mutans strepto cocci (SMS) as a predictor of caries risk. This study examined the relation ship between SMS and longitudinal caries development in the primary and mix ed dentitions. Methods: Eighty-five children, initial mean age 3.8 years, w ere examined for dental caries at baseline and once annually for 6 years. C hildren's SMS were sampled with a tongue blade, which was impressed onto pl ates containing a medium selective for SMS. After incubation, colony formin g units of SMS were determined semi-quantitatively and categorized as low m oderate or high. Results: Children classified as high caries risk at baseli ne had significantly greater (P<0.05) dmfs scores for all teeth, and in the primary molars, than children classified as moderate or low caries risk at every age but 9 (P<0.10). Children classified as high risk at age 3 had th e greatest DMFS increment through age 8. Based on annual examinations, ther e was a trend towards increasing mean dmfs/DMFS scores among children class ified as high risk in every year. Conclusions: The current study is among t he first to report on the ability of annual measurements of SMS to identify long-term caries risk in both the primary and the mixed dentitions. Despit e limitations in predicting caries risk using microbiological methods, this longitudinal study supports the overall benefits of this type of testing.