Physicochemical, Mechanical, and Antimicrobial Evaluation of Novel Bioactive Resin
Objectives: We seek to develop bioactive composites that physicochemically and biologically outperform conventional Class V restoratives. This study synthesized/evaluated a novel methacrylate dental monomer, designed to have antimicrobial functionality.
Methods: 2-(methacryloyloxy)-N,N,N-trimethylethan-1-aminium dodecyl sulfate (MTADS) was synthesized and validated by 1H-nuclear magnetic resonance spectroscopy and mass spectrometry. Copolymers were formulated by adding MTADS (10% mass) to light-curable urethane dimethacrylate (UDMA) / polyethylene glycol-extended UDMA / ethyl 2-(hydroxymethyl) acrylate resin (hereafter UPE resin). MTADS-UPE copolymers were assessed for degree of vinyl conversion (DVC), flexural strength (FS), and elastic modulus (E). Antimicrobial properties were determined using planktonic Streptococcus mutans and Porphyromonas gingivalis biofilms. Controls included UPE resin (no MTADS) or a commercial antimicrobial dental restorative containing methacryloyloxydodecyl pyrimidinium bromide.
Results: MTADS was successfully synthesized and validated. The DVC value of MTADS-UPE copolymer (86.4%), was not statistically different from the UPE control (88.1%). Compared to the UPE resin, the mean FS and E of 10% MTADS-UPE copolymer resin was reduced 23.7% and 20.1% (P≤0.05), respectively. Planktonic S. mutans testing indicates that antimicrobial activity of 10% MTADS-UPE copolymer disks was 500-fold greater (P≤0.0001) than UPE resin. Although not statistically different, P. gingivalis biomass on MTADS-UPE disks was nearly 5.0 and 1.5-fold lower than that observed with a commercial antimicrobial dental material or the UPE resin, respectively.
Conclusions: Despite the reduction in mechanical properties of the MTADS-UPE copolymers, it is deemed as a suitable candidate for incorporation into multifunctional composites, due to the favorable DVC values. Moreover, antimicrobial functionality of MTADS is promising. Incorporated into composites simultaneously with amorphous calcium phosphate filler, new antimicrobial monomers are expected to yield a new class of restoratives with both antimicrobial and remineralizing capabilities.