Differential microbiome response to sucrose in caries-free and caries-affected individuals.

This study investigated the early salivary microbiome response to a sucrose challenge in caries-free and caries-active individuals. Eighteen healthy adults aged 24-40 years were recruited, including eight caries-free and ten caries-active participants. Saliva samples were collected at baseline and at 30 min and 2 h after a 20% sucrose rinse. Microbial diversity and composition were assessed using 16 S rRNA gene sequencing to compare dynamic changes between the two groups. The salivary microbiome of caries-active individuals showed a greater and more rapid increase in amplicon sequence variants (ASVs) and more complex microbial interaction networks following sucrose exposure. After 2 h, Actinomyces graevenitzii increased considerably in both groups, while Schaalia odontolytica was enriched only in caries-active individuals, suggesting a microbial signature associated with caries susceptibility. Although global diversity metrics (Shannon and Chao1 indices) did not change significantly after rinsing, caries-active individuals exhibited more pronounced ecological shifts, indicating heightened responsiveness to sucrose. These findings highlight the potential of the salivary microbiome as an early indicator of caries risk and underscore the importance of microbial dynamics in caries pathogenesis. The study provides new ecological insights into how dietary sugars influence oral microbiota and may inform microbiome-based strategies for caries prevention and early diagnosis.