Study On Status Of Dental Caries And Salivary Microorganisms Among Five-year-old Lisu Children In Yunnan Province

Objectives:(1)To investigate dental caries and oral hygiene status of 5-year-old Lisu children in Yunnan Province.(2)To investigate the difference of salivary microorganisms between 5-year-old Lisu and local Han children with high caries and non-canesMethods:(1)According to the basic method of oral health survey published by WHO,basing on Lisu population agglomeration and economic situation,Yunnan Province was divided into different areas.760 Five-year-old Lisu and local Han children were examined by multi-stage and cluster sampling.The data was entered by excel.The results were analyzed by SPSS24.0 software.The saliva status of Lisu children was counted and compared with the local Han children.One-way analysis of variance was used to analyze the related factors affecting rickets.(2)The total DNA of saliva samples was extracted and amplified by PCR.The V4 region of 16S rDNA gene of bacteria was sequenced by Illumina MiSeq second generation high-throughput sequencing platform.Qiime,Mothur,Megan,Megan were used SPSS and other software were used to analyze the diversity and structure of salivary microfloraResults:(1)Oral health status of 5-year-old Lisu children in Yunnan Province:?The caries rate of 5-year-old Lisu children was 76.70%,and that of Han children was 82.70%.There was significant difference between the two groups(P=0.04,P<0.05).dmft of Lisu children and Han children were 4.99 ±4.60 and 5.50±4.83 respectively,there was no significant difference in the saliva between the two groups(P=0.04,P<0.05).Decayed teeth were the main,the average number of missing teeth and filling teeth were less than 0.1,and the filling rate of Lisu children was only 0.45%.The average visual plaque index of Lisu children was 61.61%,while that of Han children was 61.57%.There were no significant difference between the two groups(P=0.32,P>0.05).?Analysis with one-way ANOVA,the prevalence of dental caries Lisu children in Yunnan Province are related to the education level of parents,parental occupation and family income,and the number of children brushing their teeth every day.(2)Salivary microorganisms of 5-year-old Lisu children in Yunnan Province:?Sequence quality and OTU clustering:A total of 7,903,515 valid sequences were obtained from 80 samples.After quality control filtering,7,903,515 high-quality sequences were generated.Each sample produced at least 57,436 high-quality sequences with a sequence length between 220 and 260 bp.According to 97%similarity,706 different OTUs,177 in A1 group,176 in A2 group,177 in E1 group,176 in E2 group and 176 in E2 group were obtained.?Alpha diversity:Simpson index and Shannon index of 80 samples were less than 0.3,Shannon index was greater than 2,Coverage value was greater than 0.99.Kruskal-Wallis rank sum test showed that Simpson index and Shannon index were similar among the four groups,with no significant difference(P>0.05).From the dilution curve and Shannon curve,can be seen that the diversity of bacterial species in all samples is rich,but there is no significant difference between them.It can be seen from the grade abundance curve that the distribution of bacteria in oral microbial community is not uniform,and there may be dominant bacteria.? Microflora composition:PCoA analysis map,UPGMA clustering tree and histogram combined with plotting and thermal map can be seen that there is little difference in species composition among groups.?Community abundance analysis:There were 78 identical bacterial genera in the four groups,of which 15 were more than 1%and the same in the four groups were Streptococcus,Rochella,Puccinia,Neisseria,Twins,Porphyromonas gingivalis,Haemophilus,Veillonella,Streptococcus granulosus,Ciliarium,Escherichia coli,Shigella and Radiation.Mitobacillus,Clostridium,Alloprevotella.Among them,Streptococcus was the highest in the four groups.?Compared with the abundance:the genus Scardovia and Mycoplasma in the A1 group were significantly higher than A2 group.There was no difference between E1 group and E2 group.The genus Pseudopropionibacterium and Johnsonella in the A1 group were significantly higher than the El group.In the innocent group,the genus Skardovi in the E2 group is higher than the A2 group.Conclusions:(1)The caries rate of 5-year-old Lisu children and Han children in Yunnan Province was 76.70%and 82.70%respectively.The caries rate of Lisu children was lower than that of Han children.The caries prevalence of 5-year-old Lisu children in Yunnan Province were related to the education level of parents,parental occupation and family income,and the number of children brushing their teeth every day.(2)The diversity and abundance of salivary microorganisms in Lisu,Han and non-caries groups were higher,and there were dominant microorganisms in each group.(3)There are 15 dominant bacterial genera in the four groups:Streptococcus,Rochella,Puccini a,Neisseria,Twins,Porphyromonas gingivalis,Haemophilus,Veillonella,Streptococcus granulosus,Ciliarium,Escherichia coli,Shigella,Actinomyces,Clostridium,Alloprevotella.These 15 species may be the core microorganisms in oral environment.(4)Streptococcus is the predominant bacteria in the four groups,which is consistent with many previous studies,suggesting that Streptococcus is not necessarily cariogenic bacteria,and conforms to the non-specific plaque hypothesis.(5)The Scardovia and Mycoplasma genus were significantly higher of Lisu sorghum group than in Lisu innocent group.There was no difference between the Han sorghum group and Han innocent group.The genus Pseudo propionib-acterium and Johnsonella in Lisu sorghum group were significantly higher than Han sorghum group.In the innocent group,the genus Skardovi in Han innocent group is higher than Lisu innocent group.