| OBJECTIVE:Dental caries is one of the most prevalent chronic infectious diseases in the children. Streptococcus mutans and Streptococcus sobrinus have been implicated as a major etiological agent of dental caries. Early dental caries is one of the most common diseases, but little is known about the dynamic characteristics of oral microbiota and the genetic patterns of microbial community composition while caries is developing. The first part of this study was to investigate the ratio of the major four bacteria to total bacteria in the dental plaque of different caries-susceptible children. The purposes of this second part of study were two fold:(â…°) to use molecular methods to detect all bacterial species, cultivable as well as not yet cultivable, that are associated with early childhood caries and severe early childhood caries; and (â…±) to describe the changes in bacterial profiles associated with the different states of this disease, that would provide alternative targets for biological intervention.METHODS:Dental plaques and oral examinations were obtained from 60 children 3 years old. Quantitatively detect 4 targeted cariogenic bacteria by real-time PCR and the mean dmft score were calculated. All tests were two-sided with a significance level of 0.05. All analyses were conducted with SPSS 17.0 software package. We sought to describe the bacterial profile shifting in different caries states by pyrosequencing analysis based on 16S rRNA gene V4 hyper variable regions. Apply Illumina MiSeq pyrosequencing for analysis random drawing for the ECC and S-ECC in the first part of this study.RESULTS:1. The dmfs score and the percentages of the four cariogenic bacterica among one-year increased were statistical significance (P<0.01). Yet the caries prevalence of the baseline time and the ending time were 66.7%å'Œ81.7%. There were distinct difference in the sum of the percentages of S.mutans and S.sobrinus in ECC and SECC group between the two examinations(P<0.01).2. In the clonal analysis, a total of 1669057 high-quality sequences were produced, accounting for 89.16% of valid sequences, according to the quality filtering. On average,57554 reads per sample were analyzed with an average length of 249 bp per read. There were 27 phyla and 525 genera were found. The results show that the plaque microbiota present in ECC was much more variable than S-ECC.10 phyla such as Parascardovia, Streptococcus, Leptotrichia, Neisseria, Prevotella, Veillonella, Corynebacterium, Fusobacterium, Capnocytophaga were found to be associated with ECC and S-ECC, and the bacterial profile didn’t differed significantly depending on these two caries status. Seven genera including Parascardovia, Streptococcus, Leptotrichi, Neisseria, Prevotella, Veillonella, Corynebacterium were highly increased in these two caries status.CONCLUSION:1. The ratios of cariogenic bacterica to total bacteria in plaque are closely associated with the prevalence of dental caries in children, the higher proportion of total bacteria, the caries’ susceptibility of subjects would continue.2. Our results indicate that the structure and microbial composition of oral bacterial communities are of great enrichment in different stages of caries progression and support the hypothesis of ecological plaque.3. These data may facilitate improvements in the prevention of dental caries. A comprehensive understanding of the breadth of diversity in this longitudinal study of plaque is necessary to fully evaluated the role of bacteria in diseases of the oral cavity. In conclusion, our results provide a framework for further studies of genetic profile of early childhood caries. |
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