Antibacterial Resin Infiltrant: Effects of DMAHDM and NACP Incorporation

Objectives: This study evaluated the effects of incorporating the antibacterial monomer dimethylaminohexadecyl methacrylate (DMAHDM at 0.75%, 1.5%, 2.5%, or 5%), with or without nanoparticulate amorphous calcium phosphate (NACP at 2%), on physical properties and antibacterial efficacy of experimental resin infiltrants.
Methods: The evaluated groups were the Experimental Resin Infiltrant (ERI) Control (75/25 wt.% TEGDMA/BisEMA, 0.5% camphorquinone (CQ), and 1% ethyl 4- dimethylaminobenzoate (EDMAB)), ERI + 0.75% DMAHDM (0.75DM), ERI + 1.5% DMAHDM (1.5DM), ERI + 2.5% DMAHDM (2.5DM), ERI + 5% DMAHDM (5DM), ERI + 2% NACP (NACP), groups with different concentrations of DMAHDM combined with 2% NACP (0.75DM_NA, 1.5DM_NA, 2.5DM_NA, and 5DM_NA), and the commercial control Icon (DMG, Germany). The Degree of Conversion was evaluated using FTIR-ATR (n=10). Water Sorption and Solubility (n=10) and Contact Angle (n=6) were assessed using specimens from each group. The antibacterial potential was analyzed through Bioluminescence assay (n=18) after 24 hours of Streptococcus mutans (UA159) growth on the specimens. Data were analyzed through ANOVA and Tukey-test, except for Bioluminescence (Kruskal–Wallis), with a significance level of 5%.
Results: For Degree of Conversion, ERI showed the highest mean value, differing from all other groups, and NACP the lowest mean value. For Water Sorption, Icon exhibited the lowest mean value, differing from all other means. Next, IRE showed the second lowest mean value, differing from all the others, except from NACP, and 5DM_NA showed the highest mean value. For Solubility, 0.75DM exhibited the lowest mean value, and 5DM_NA the highest value. For Contact Angle, NACP showed the highest mean value. Regarding antibacterial activity, ERI, NACP, and Icon showed significantly higher relative luminescence unit medians, differing from all groups containing DMAHDM, which indicates higher bacterial metabolic activity.
Conclusions: The addition of DMAHDM, with or without NACP, significantly reduced biofilm viability on the materials. However, both agents compromised the evaluated physical properties.