Oral microbiome analysis of the dual effects of fluoride application for caries prevention in children
Objective Tho systematically evaluate the effects of regular fluoride treatment on oral bacterial and fungal communities in children,explore the association between these microbiome changes and the effect of dental caries prevention,and reveal the role of fluoride treatment in regulating the balance of oral microorganisms in children.Methods This prospective,randomized controlled study selected 40 children aged 3 to 12 years and randomly divided them into an experimental group(n=20)and a control group(n=20)for a period of 2 years.The experimental group received regular fluoride treatment,while the control group did not.Samples were collected at baseline,6 months,12 months,18 months,and 24 months,including saliva and dental plaque samples.The bacterial and fungal communities of the samples were analyzed by 16S rRNA and ITS high-throughput sequencing technologies,and the data were processed using QIIME 2 software.The Shannon diversity index and Simpson diversity index were used to evaluate microbial diversity,and the association between microbial composition and dental caries incidence was evaluated using redundancy analysis(RDA)and linear mixed models(LMM).Results The Shannon diversity index of the experimental group at 6 months,12 months,18 months and 24 months(3.72±0.28,3.80±0.27,3.85±0.25,3.90±0.26,respectively)was significantly higher than that of the control group(3.50±0.29,3.55±0.31,3.60±0.28,3.62±0.29,respectively),with P values of 0.013,0.004,0.002 and 0.001,respectively.Similarly,the Simpson diversity index of the experimental group was also significantly higher than that of the control group at each time point,with P values less than 0.01.In the bacterial community,the abundance of Streptococcus mutans,Lactobacillus and Actinomyces was significantly reduced in the experimental group(Streptococcus mutans was 8.32％±1.45％in the experimental group and 12.05％±2.22％in the control group at 6 months,P=0.013).In the fungal community,the abundance of Candida albicans was significantly reduced in the experimental group(Candida albicans was 3.32％±0.85％in the experimental group and 5.05％±1.22％in the control group at 6 months,P=0.013).Redundancy analysis showed that the RDA1 and RDA2 values of the experimental group were significantly higher than those of the control group at each time point,indicating that fluoride treatment had a significant effect on the structure of the microbial community.The results of linear mixed model analysis showed that the time effect(parameter estimate=-0.032,P=0.004)and treatment effect(parameter estimate=-0.045,P=0.002)had a significant effect on the microbial composition and the incidence of dental caries.Conclusion Regular fluoride treatment not only significantly improved the diversity of children's oral microbiota,but also significantly reduced the incidence of dental caries by regulating the structure of microbial communities and inhibiting functional genes related to dental caries.
Childhood cariesfluoride treatmentoral microbiomebacterial communityfungal community
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NSTL
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