A comparison of S. mutans prevalence in relation to caries experience in Norwegian and immigrant Vietnamese children.

Vietnamese immigrant and Norwegian children, matched according to caries experience, age, and sex, were compared with respect to S. mutans in dental plaque and in saliva. Regardless of ethnic group, S. mutans prevalence was highest in plaque over caries lesions and from fissures, and lowest in plaque from smooth surfaces. The S. mutans distribution appeared very similar in the two groups. Only in untreated Vietnamese children were the S. mutans saliva levels higher, probably reflecting the numerous untreated caries lesions present in this group. After caries treatment, we observed significant reduction in S. mutans levels in both saliva and smooth surface plaque.