Fluoride Modulates Caries-Linked Oral Microbiome Dynamics In Children

This study aims to systematically analyze the dynamic shifts in oral microbial communities among children stratified by caries risk under fluoride intervention using 16S rRNA sequencing, thereby elucidating fluoride's regulatory mechanisms on oral microecology and providing scientific evidence to optimize its anticaries efficacy. In a 2-year longitudinal trial (approved by Guangxi Medical University Affiliated Stomatological Hospital Ethics Committee: NO.2022089), 48 children (3–8 years; 16/group: low/moderate/high caries risk) underwent biannual salivary microbiome profiling via 16S rRNA sequencing. Analyses included α-diversity metrics (Ace, Chao, Shannon), microbial co-occurrence networks, and PICRUSt-based functional annotation. At 12 months, α-diversity richness indices (Ace, Chao, Sobs) differed significantly among risk groups (p<0.05), with high-risk subjects enriched in Leptotrichia and Prevotella, while low-risk groups hosted Lautropia and Cardiobacterium. Longitudinal networks revealed simplified interactions in low-risk microbiomes but escalating complexity in moderate/high-risk groups. High-risk microbiomes exhibited suppressed metabolic pathways (starch/sucrose metabolism, TCA cycle; p<0.01). Over time, fluoride intervention led to enhanced antimicrobial and anti-metabolic traits in the oral microbiomes of moderate- and high-risk groups. Concurrently, cooperative and antagonistic interactions within microbial networks progressively increased in these groups, modulating ecological stability. These findings suggest that fluoride likely stabilizes oral microecology by inhibiting cariogenic bacterial growth, suppressing carbohydrate metabolic pathways, and restructuring microbial interactions, thus maintaining microecological equilibrium.