The metagenome and metabolome signatures of dental biofilms associated with severe dental fluorosis.

Objective: To explore the plaque biofilm microbiome associated with severe dental fluorosis (SF), and to describe its metagenome and metabolome.

Methods: Sixteen plaque biofilm samples were collected from eight 6- to 15-year-old Thai children with SF and eight age-matched, caries-free and controls. Biofilms were analyzed using shotgun metagenomic sequencing, followed by bioinformatics evaluation.

Results: Taxonomic profiling of biofilms from SF and controls identified a total of 12 phyla and 354 species. While alpha diversity was similar between the groups, beta diversity analysis (P = 0.0010) indicated distinct microbial community structures. LEfSe highlighted key discriminatory taxa: five health-associated species (Actinomyces dentalis, Tannerella sp. HOT 286, Candidatus Nanosynbacter sp, Selenomonas noxia and Treponema sp OMZ 804 ) were enriched in controls, while Neisseria sicca, known for fluoride-sensitive esterase production, was significantly elevated in SF. Functionally, eight metabolic pathways were altered; three of these (phosphatidylcholine acyl editing, anhydromuropeptides recycling II, ubiquinol-7 biosynthesis), hypothesized to support N. sicca activity, were upregulated in the SF group.

Conclusion: SF is associated with a significant shift in the biofilm microbiota, characterized by enrichment of N. sicca and a reduction in health-associated taxa. Altered metabolic pathways supporting N. sicca provide mechanistic insights into its role as a candidate biomarker for fluorosis, warranting further investigation.