Heterogeneity Of Salivary Flora In Children With Different Dentition Stages And Its Association With Host Caries

Background: Based on high-throughput pyrosequencing,salivary microbiome of the primary dentition,mixed dentition and permanent dentition from those healthy and high caries samples were displayed and compared on the species abundance,diversity and community structure,aiming to deepen our understanding on the microbial's role in the occurrence and development of dental caries,thus to guide the establishment of caries risk evaluation model on different dentition stages for individualized prevention and treatment measuresMethods: One hundred of fifty children at age of 4-16 years range in Guangzhou were selected for oral examination.Saliva samples of high caries and health individuals were randomly collected and followed by genomic DNA extraction and amplification of16 S r RNA fragment of hypervariable region.454 high-throughput pyrosequencing were applied to disclose its microbial component.Multiple statistical methods were utilized to analyze the divergency between different groups.Results:(1)Based on the diversity analysis of salivary microbiome,there were significant differences in the species richness and diversity indices between healthy and high caries group(p<0.001);The bacterial diversity in the high caries group was higher than that of the healthy group.There were significant differences in species richness and diversity among those three kinds of dentition.The bacterial diversity index in primary dentition group were significantly higher than that of mixed dentition.And the bacterial diversity index in primary dentition group were also higher than that of permanent dentition However there is not significant difference among the mixed dentition group and the permanent dentition group(p>0.05);(2)The community structure was more similar among healthy people,while the community structure was more dispersed among high caries people(p<0.01);The community structure of primary dentition is much more divergent,comparing with those from the mixed dentition and permanent dentition.And the community structure of permanent dentition was conservatismer than that of mixed dentition;(3)No specific bacteria types of caries were found in different dentition stages.But the bacteria relative abundance was significant diffrence between the healthy peopleand the high caries people,at the level of bacteria classification,such as Actinobacteria,Proteobacteria,TM7,Bacteroidetes,Fusobacteria,Spirochaetes.Conclusions:1.The oral health status and aging can affect the composition and structure of the salivary flora2.There is no specific bacteria in dental caries,but there were significant differences in bacteria relative abundance.we speculated that the occurence of dental caries may be due to the imbalance of community.