Resin infiltrant with antibacterial activity: effects of incorporation of DMAHDM monomer and NACP on physical and antimicrobial properties.

Objectives: Considering the fact that resin infiltrants lack antibacterial activity, this study assessed the influence of the quaternary ammonium monomer dimethylaminohexadecyl methacrylate (DMAHDM) and amorphous calcium phosphate nanoparticles (NACP) on the physical and antibacterial properties of an experimental resin infiltrant (ERI).

Methodology: The following groups were established: ERI (75/25 wt.% TEGDMA/BISEMA), ERI + 2.5% DMAHDM (2.5DM), ERI + 5% DMAHDM (5DM), ERI + 2% NACP (NACP), ERI + 2.5% DMAHDM + 2% NACP (2.5DM_NACP), ERI + 5% DMAHDM + 2% NACP (5DM_NACP), and Icon® (IC), a commercial resin infiltrant. Degree of conversion (DC; n=4), sorption and solubility (SO/SOL; n=8), and contact angle (CA; n=10) tests were conducted. Biofilm biomass (BB; n=6) and bacterial metabolism (BM; n=8) were evaluated after Streptococcus mutans (UA159) cultivation for 48 h on material samples. Data were evaluated by one-way ANOVA and Tukey or Games-Howell post hoc tests (α=0.05).

Results: IC exhibited the highest DC, with no difference from 2.5DM and 5DM. IC showed the lowest CA. IC had the lowest SO, followed by ERI, which had the lowest SOL, with no difference from IC. 5DM_NACP showed the lowest biofilm biomass, similar to 2.5DM and 5DM. Resin infiltrants containing DMAHDM showed reduced bacterial metabolism.

Conclusions: DMAHDM, with or without NACP, demonstrated significant antibacterial activity, while NACP impaired DC. Both DMAHDM and NACP increased the contact angle, sorption, and solubility of the resin infiltrant, which may affect the material's clinical performance.