Decreasing caries prevalence in Japanese preschool children is accompanied with a reduction in mutans streptococci infection.

OBJECTIVE

To evaluate the association between decreasing caries prevalence in Japanese preschool children and mutans streptococci (MS) infection.

METHODS

The prevalence of caries and salivary MS was examined in 1- to 3-year-old preschool children in 1995 (n = 135) and 2000 (n = 118).

RESULTS

The caries prevalence for 3-year-old subjects significantly declined from 65.1% to 37.5% (p < 0.01), reflecting the data seen in Japanese national oral health surveys in 1993 and 1999. Salivary MS detection for 3-year-old subjects significantly declined from 68.3% to 37.5% (p < 0.05). On the other hand, the decrease in the prevalence of caries and salivary MS was not significant in 1- and 2-year-olds. The correlation between caries experience (dft) and the salivary MS score for 3-year-old subjects with low caries prevalence in the later examination (r(s) = 0.479, p < 0.001) was comparable with that in 1995 (r(s) = 0.462, p = 0.001).

CONCLUSIONS

The recent decrease in decay in Japan is accompanied with a reduction in MS infection in the deciduous dentition. MS levels are closely related to caries prevalence in preschool children regardless of the extent of caries.