Supragingival plaque microbiome features in allergic rhinitis and allergic asthma and their association with dental caries: a cross-sectional study.

BACKGROUND: Allergic rhinitis (AR) and allergic asthma (AS) are associated with increased risk of dental caries, potentially associated with alterations in the oral microbiome. OBJECTIVE: To characterize supragingival plaque microbiome features and their associations with caries severity in allergic adults. DESIGN: This cross-sectional study enrolled patients with cat dander-induced AR or AS, along with age- and sex-comparable normal controls (NC). Supragingival plaque was collected for 16S rRNA gene sequencing. Microbial diversity, ANCOM-BC2 with multiple-testing correction and pseudo-count sensitivity analysis and LEfSe exploratory analysis were performed. Factors of caries severity (DMFT/DMFS) were examined with a random forest model and multivariable negative binomial regression. RESULTS: A total of 89 participants (32 AR, 46 AS and 11 NC) were included. Allergic patients exhibited significantly higher α-diversity than NC. ANCOM-BC2 analysis identified 24 taxa with an omnibus FDR threshold; a family-resolved, genus-unclassified Prevotellaceae passed the pseudo-count sensitivity analysis. LEfSe analysis identified Treponema and Bacteroidota as AR-enriched taxa, and Actinobacteriota as AS-enriched taxa. Treponema was the top-ranked random forest feature. Among allergic patients, regular dental check-ups were associated with lower DMFT (IRR = 0.47, 95% CI: 0.30-0.75) and DMFS (IRR = 0.34, 95% CI: 0.17-0.69). Corynebacterium abundance was inversely associated with DMFT (IRR = 0.56, 95% CI: 0.31-0.98), and Actinomyces abundance was positively associated with DMFS (IRR = 2.96, 95% CI: 1.07-8.19). CONCLUSIONS: Plaque microbial communities differed across groups, and selected taxa were associated with caries severity among allergic adults. Future investigations are needed to evaluate temporality and mechanisms.