Host sweet preference modulates the salivary microbiome and its divergent associations with plaque-associated and non-plaque-related oral diseases

No significant differences in α- and β-diversity were observed among the three groups. However, distinct microbial structures at the genus and species levels were evident under different sweet consumption conditions. Under high sweet consumption, the caries group exhibited enrichment of microbiota closely associated with sugar metabolism and acid production (e.g., <i>Streptococcus, Rothia</i>), while <i>Ralstonia</i> was significantly enriched in the caries group, suggesting its potential role in high-sweet-induced caries development. Under low sweet consumption, the healthy control group showed enrichment of taxa such as <i>Stenotrophomonas</i>, potentially linked to ecological stability, whereas the dental fluorosis group demonstrated significant enrichment of <i>Fastidiosipila</i>, reflecting specific fluoride-induced selective pressure on the microbiome. This study indicates that although sweet consumption frequency did not significantly alter overall microbial diversity, it reshaped the oral microbiota structure in a disease-specific context. The caries group was more prone to developing a cariogenic microbial profile under high-sugar conditions, while the fluorosis group exhibited unique ecological adaptive characteristics.