Synthesis and characterization of photo-curable bis-quaternary ammonium dimethacrylate with antimicrobial activity for dental restoration materials

• We synthesized a new quaternary ammonium dimethacrylate monomer QABGMA.
• QABGMA can endow significant improvement in antibacterial activity of dental resin.
• Increase new monomer will decrease DC of polymerization negligibly.
• Resin with 5–15 wt.% QABGMA monomer had higher water absorption.
• Resin with 5% QABGMA showed high percentage of cell viability.

In this study, new quaternary ammonium bis-phenol A glycerolate dimethacrylate (QABGMA) was synthesized and proposed as a possible antimicrobial dental monomer. Such monomer has the potential to copolymerize with other methacrylate monomers and impart antimicrobial activity in dental resins and other systems. QABGMA monomer was synthesized and incorporated (at 0–15 wt.%) into a 1/1 (wt./wt.) mixture of bisphenol A glycerolate dimethacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA). The mixture was cured by visible light irradiation and degree of conversion (DC) was measured by Fourier Transform Infrared Spectrophotometer (FT-IR). Weight increase and solubility of the cured specimens were measured by immersion in water and ethanol/water solution (75/25, v/v) at 37 ± 1 °C for 30 days. The antimicrobial activity of QABGMA monomer was investigated against Gram-positive bacteria (Streptococcus mutans, Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and a fungus Candida albicans. Finally, cytotoxicity and viability of resin on L929 fibroblast cells were quantified. The incorporated difunctional QABGMA reduced degree of conversion slightly and increased water absorption of the cured polymer. The dental materials obtained from the QABGMA polymerization system showed good antimicrobial activity against tested microorganisms. Also, resin with ⩾10 wt.% QABGMA showed significantly reduced viability.

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