OBJECTIVETo compare the salivary microbial profiles of healthy subjects and those with severe early childhood caries (S-ECC) by using high-throughput sequencing.

METHODSSalivary samples were obtained from children with S-ECC (group C, n=24) and healthy children (group H, n=24). Total metagenomic DNA was extracted, and DNA amplicons of the V1-V3 hypervariable region of the 16S rRNA gene were generated and subjected to 454 sequencing. The characteristics of oral microbial communities from the two groups were compared based on microbial diversity and taxonomy assignment.

RESULTSFirst, the microbial richness was significantly higher in group C than group H (P<0.05). Second, the microbial community structure was significantly different for the groups H and C (P<0.01). In addition, caries microbiota was significantly conserved in group C (P<0.001). High expression of suspected cariogenic microorganisms in group C (P<0.1) and health related microorganisms in group H (P<0.1) were identified. Finally, models of caries risk assessment were proposed to distinguish caries from healthy subjects with over 70% accuracy.

CONCLUSIONSSalivary microbiota and certain taxa, such as caries-associated taxa (Prevotella), may be useful to screen/assess the children's risk of developing caries.