Streptococcus mutans infection level and caries in a group of 5-year-old children.

The level of Streptococcus mutans in stimulated saliva and its association with caries experience was evaluated in 149 5-year-old children. In general, salivary S. mutans levels were low, and it was detected only in 46% of saliva samples. There was, however, a clear association between salivary levels of S. mutans and caries experience (chi 2 = 53.65, p less than 0.001). Salivary examination was supplemented with plaque samples in 47 children. The number of S. mutans positive surfaces increased with increasing salivary levels. S. mutans was most often isolated and comprised the highest proportion in the approximal samples. The number of children with high salivary S. mutans levels was very low (6%) when taken into account that 13% of the children were fairly caries active (dmfs greater than or equal to 5). This most probably means that in evaluation of caries risk, the salivary S. mutans screening level is different in preschool children and in older children. The level should be determined in longitudinal studies before applying to preschool children.