Abstract
Clinical isolates(1488 strains) of gram-positive streptococci were non selectively isolated from dental plaque of 16 Japanese children(age: 2-yr-olds-5-yr-olds), Streptococcus mutans and Streptococcus sobrinus in these isolates were detected and identified by the Southern hybridization technique using DNA probes specific to S. mutans and S. sobrinus. We also compared the detection ratios of the two species and caries prevalence in 16 children.
1) S. mutans was found in all 16 children (100%)
2) S. sobrinus was found in 13 out of 16 children (81.3%)
3) In 1488 clinical isolates, the detection rate of S. mutans was 10.9% and that of S. sobrinus was 5.2%. The detection rate of S. mutans was twice of that of S. sobrinus.4) Seven children who had both species of S. mutans and S. sobrinus showed a high caries prevalence. Although other children who had both species showed lower caries prevalence, they had several important factors that indicated they might shift to a high caries prevalence in the future.
These results suggest that existence of both S. mutans and S. sobrinus in the oral cavity may influence caries prevalence.
