A Followed-up Study On The Effect Of Flouride Varnish In Preventing The First Permanent Molar Caries And The Microbial Community Structure Of Saliva Among The School Children In Linxia City Of Gansu Province

Objective To evaluate the effect of fluoride varnish in preventing the first permanent molar caries of 6-7-year-old school children and investigate the change of structure of microbiome after using fluoride vanish for providing the necessary information for dental caries prevention.Methods Totally,1684 of 6-7-year-old school children has been selected from 10 primary schools in Linxia district which were divided into intervention group and control group.The first permanent molar of intervention group were used with the fluoride varnishes every 6 months among 2 years.Both groups were given oral hygiene instruction and followed up two years on the first permanent molars.Among the children of participating the research,38 children were randomly selected.In the experimental group(20),the control group(18),non-irritating saliva was collected before the first non-fluoride treatment and before each fluorine treatment.A period of 2 years was subjected to high-throughput sequencing of saliva samples and the diversity and composition of their saliva will be researched.Results1.The Incidence Rate of caries in intervention group was 18.7%,the mean DMFS of the first molar which had erupted before the research was 0.13(0.72),the mean DMFS(decayed,missing,filled,surface)of the first molar which had erupted during the research was 0.04(0.19).The incidence rate of caries in control group was 27.0%,the mean DMFT(decayed,missing,filled,teeth)was 0.46(0.89);the new mean DMFS of the first molar which had erupted before the research was 0.22(0.69),the mean DMFS of the first molar which had erupted during the research was 0.06(0.31).The caries indexes had significantdifferences between the two groups(P<0.05),the intervention group was lower than the control group.2.There was significant different between the experimental group and the control group in the abundance of Firmicutes and Bacteroidetes at the level during 24 months.There is few of cariogenic bacteria changed on the level of genus.3.A two-year follow-up study among school-age children of 6-9 years showed that any bacteria were not affected by time,fluoride,and the situation of caries,such as:Rothi,Veillonella,Granulicatella,Actinomyces,Selenomonas,Campylobacter,Atopobium.Conclusion1.The application of fluoride varnish and oral hygiene instruction can effectively prevent caries in the first permanent molar of 6-7-year-old school children.2.The oral microflora structure of the oral saliva community of 6-7 year-old school children after the first permanent molars was treated with fluorine vanish had little significant changes,and only a few communities showed abundance changes.3.There was “core microbiomes” in the mouth of children which was free from outside interference and played a role in maintaining the stability and health...