Abstract
Objectives: The clinical manifestations of radiation-related caries (RRC) differ considerably from those of common caries. This study aims to investigate potential differences in the microbial compositions of supragingival plaque between RRC and common caries. Methods: Supragingival plaque samples from 10 RRC and 10 patients with common caries were analyzed using Type IIB Restriction-site Associated DNA sequencing for Microbiome (2bRAD-M). Analyses of microbial diversity, relative abundance and composition were performed. LEfSe analysis was employed to identify differentially abundant species between the 2 groups. Additionally, 24 RRC and 33 common caries samples were examined using qRT-PCR. Species indicators of RRC were identified through random forest analysis. KEGG and COG functional prediction analyses were conducted to assess microbial functional pathways. Results: 2bRAD-M sequencing revealed a significant enrichment of Prevotella conceptionensis, Treponema vincentii, and 4 Nanoperiomorbus species in the RRC group. These findings were further validated by LEfSe and qRT-PCR analyses, which confirmed the dominance of P. conceptionensis in RRC. Random forest analysis identified P. conceptionensis as a potential biomarker for RRC. The bacterial abundance in RRC samples was higher than in common caries, particularly in pathways related to glucose metabolism, including 6-phosphofructokinase activity and sugar transferases involved in LPS biosynthesis. Conclusions: This study uniquely identifies distinct microbial signatures in supragingival plaque associated with RRC compared to common caries. Prevotella conceptionensis was identified as a specific pathogenic bacterium linked to RRC. The underlying mechanisms may involve enhanced microbial glucose metabolism and an inflammatory response mediated by ferroptosis.