Antibacterial Properties of Dental Copolymer Modified with Monomers Possessing Quaternary Ammonium Groups

Dental caries are treated using dental composite restorative materials (DCRM). However, commercial DCRMs lack antibacterial activity. This research aimed to analyze the in vitro antibacterial activity of a series of copolymers consisting of a urethane–dimethacrylate monomer (UDMA), bisphenol A glycerolate dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA) and urethane–dimethacrylate monomer with two quaternary ammonium groups and a 1,3-bis(1-isocyanate-1-methylethyl)benzene core (QAn+TMXDI, where n = 8, 10, or 12 is the number of carbon atoms in the N-alkyl substituent). QAn+TMXDI contents in copolymers were 20 and 40 wt.%. The results of the Staphylococcus aureus and Escherichia coli adhesion test demonstrated that the logCFU/mL decreased as the length of the N-alkyl chain decreased and QAn+TMXDI content increased. The copolymers of QA8+TMXDI 40 wt.%, Bis-GMA 40 wt.%, and TEGDMA 20 wt.% showed the highest antibacterial activity, with a logCFU/mL of 2.39 for S. aureus and no viable E. coli cells.