Changes in dental plaque microbial richness and oral behavioral habits during caries development in young Chinese children.

OBJECTIVE To detect changes in the microbial richness of dental plaque and oral behaviors during caries development in young Chinese children. METHODS Supragingival plaque samples and a survey of oral behaviors of 130 children aged 3 at baseline were analyzed at 6 months and 12 months. Total DNA was isolated from all samples and PCR-denaturing gradient gel electrophoresis analysis was conducted. RESULTS In the follow-up, 44 children had caries or cavity fillings at 6 months, a further 28 children had caries or cavity fillings at 12 months. The other 58 children remained caries-free at 12 months. According to the changes in caries status at the 12-month follow-up, all participants were divided into three groups: caries-free, caries at 6 months and caries at 12 months. The changes in oral behaviors during the 12-month follow-up were not significantly different in the three groups. The frequency of eating sweets and eating sweets before sleeping was significantly different among the three groups at baseline. At baseline, the average detectable bands of caries in the 12-month caries group were similar to those of the caries-free group; both of them were higher than that of the 6-month caries group. At 6 months, the average detectable bands of the 12-month caries group were significantly lower than that of the caries-free group although the children of the 12-month caries group were caries-free at that time. CONCLUSIONS For young Chinese children, the high frequency of eating sweets and eating sweets before sleeping are risk factors of caries onset, and the decrease in microbial richness could occur 6 months before the onset of caries.