Antimicrobial, biocompatibility, and physicochemical properties of novel adhesive methacrylate dental monomers

For the advancement of Class V restoratives, our goal was to evaluate the physicochemical and mechanical properties, antimicrobial functionality, and cytotoxic potential of novel antimicrobial copolymers. 5-Carboxy-N-(2-(methacryloyloxy)ethyl)-N,N-dimethylpentan-1-aminium bromide (AM(adh1)) and 10-carboxy-N-(2-(methacryloyloxy)ethyl)-N,N-dimethyldecan-1-aminium bromide (AM(adh2)) were incorporated into light-curable urethane dimethacrylate, polyethylene glycol-extended urethane dimethacrylate, ethyl 2-(hydroxymethyl) acrylate resin (UPE resin). In the AM(adh)s-UPE resin, the hydrophobic/hydrophilic balance, degree of vinyl conversion, flexural strength, elastic modulus, and shear bond strength were assessed. Antimicrobial properties were measured using Streptococcus mutans (planktonic and biofilm). Cytotoxicity was tested using human gingival fibroblasts and mouse connective tissue fibroblasts (ATCC(R) CCL-1 (TM)) exposed to two-fold serial dilutions (<= 10.6 mmol/L AM(adh1) or <= 8.8 mmol/L AM(adh2)). At 10% mass of AM(adh), the attained degree of vinyl conversion values (AM(adh1) = 90.1% and AM(adh2) = 88.5%) were not statistically different from the UPE resin (88.1%). At both AM(adh) levels, the flexural strength was reduced in a dose-dependent manner. Elastic modulus and contact angle were not significantly affected by AM(adh1). Variations in elastic modulus and contact angle were observed with AM(adh2); however, this does not disqualify it in future design of Class V restoratives. Compared to UPE resin, AM(adh1)-UPE and AM(adh2)-UPE (10% mass) copolymers reduced S. mutans biofilm 4.2- and 1.6-fold, respectively (p <= 0.006). In direct contact with human gingival fibroblasts or ATCC CCL-1 cells, at biologically relevant concentrations, the AM(adh)s did not adversely affect cell viability or their metabolic activity. This effort addresses a significant oral health issue associated with elderly populations. Its successful completion is expected to yield dental restoratives with well-controlled biofunction.