Influence of resin modified glass ionomer cement incorporating protein-repellent and antimicrobial agents on supragingival microbiome around brackets

Objective: To explore the influence of RMGIC adhesives containing protein-repellent and quaternary ammonium salt agents on supragingival microbiome, enamel and gingival health around brackets.Materials and methods: Ten patients about to receive fixed orthodontics were enrolled in this study. Unilateral upper teeth bonded with RMGIC incorporating 2-Methacryloyloxyethyl phosphorylcholine (MPC) and Dimethylaminohexadecyl methacrylate (DMAHDM) were regarded as experimental group (RMD), while contralateral upper teeth bonded with RMGIC were control group (RMGIC), using a split-mouth design. Supragingival plaque was collected from both groups before treatment (T0), and at 1 month (T1) and 3 months (T2) of treatment. High-throughput sequencing was performed targeting v3-v4 of 16S rRNA gene. S. mutans and F. nucleatum quantification was done by qPCR analysis. Bracket failures, enamel decalcification index (EDI), DIAGNODent scores (Dd), plaque index (PI) and gingival index (GI) were monitored at indicated time points.Results: Within 3 months, alpha and beta diversity of supragingival plaque had no difference between RMGIC and RMD groups. From T0 to T2, the relative abundance of Streptococcus depleted in RMD but remained steady in RMGIC group. Streptococcus, Prevotella, and Fusobacterium became depleted in RMD, Haemophilus and Capnocytophaga became depleted in RMGIC group but Prevotella enriched. Quantification of F. nucleatum and S.mutans showed significant difference between RMGIC and RMD groups at T2. Teeth bonded with RMD had significant lower PI and Dd score at T2, compared with teeth bonded with RMGIC (p 0.05).Conclusion: By incorporating MPC and DMAHDM into RMGIC, the material could affect the supragingival microbial composition, inhibit the key pathogens, as well as the progress of plaque accumulation in the early stage of orthodontic treatment.