METHODS: The dental plaque samples derived from the permanent teeth of the children from 6 to 9 years old before and after the caries initiation were analyzed the bacteria organization in the biofilms by 16SrRNA microarray assay which allows the simultaneous detection of about 300 of the most prevalent or bacterial species including those that cannot yet be grown in vitro. A total of 60 plaque samples derived from 30 subjects (For 1 subject collected 2 samples respectively at caries-free stage and caries-onset stage) were used for analysis. We compared the bacteria found in biofilms at the two stages regarding the same individuals. Although Streptococcus mutans (S.mutans) has been considered as a major pathogen of dental caries, our longitudinal study exhibited that 50% subjects in caries state did not have detectable levels of S. mutans. Furthermore in the remaining 50% subjects the quantities of S.mutans detected from biofilms were outnumbered by some other microbial communities eg. Actinomyces spps., Veillonella spp., Neisseiria spp., Oral streptococci., and Prevotella.
RESULTS: Our results suggested that global patterns of microbial abundance in these populations are very distinctive. Meanwhile from caries-free state to caries state the detective difference of S.mutans had no statistic significance.
CONCLUSION: It indicated that dental caries may involve more complex communities of bacterial species, and S.mutans is not necessary for the caries initiation.