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Abstract

Introduction: Dental caries is a common chronic oral disease, posing an important health impact and economic burden on the society. Photothermal therapy (PTT) is an innovative approach being used in cancer therapy, and gold nanoparticles (AuNPs) may be used as a photothermal agent (PTTA). This work explored the antibacterial potential of an experimental methacrylate-based dental resin loaded with AuNPs via PTT. Methods: A hydrophobic dental resin consisting of 70wt% Bisphenol-A-Dimethacrylate (BisEMA), 26wt% Tetraethylene-glycol-dimethacrylate (TEEGDMA), 2wt% photo-initiators, and 2wt% ethanol was prepared. Then, 120 nm gold nanoshells were added to the blend at loading concentrations: 0%, 1×10¹⁰ particles/mL (i.e., 0.01wt%) and 2×10¹⁰ particles/mL (i.e., 0.02wt%). Fourier-transform infrared (FTIR) spectroscopy was first used to assess the degree of conversion of the experimental blends following photopolymerization (740-760mW/cm²). A 20-hr Minimum Inhibitory Concentration (MIC) test was performed on irradiated solutions of AuNPs (200 to 0µg /mL) with planktonic Streptococcus mutans (S. mutans) in brain heart infusion media. Light treatments were: 1) Dark; 2) 15minute LED (660 nm, 11.1 J/cm²); 3) 30minute LED (660 nm, 22.2 J/cm²); and 4) 30second laser+2mm distance (95.5 J/cm²). Colony Forming Unit (CFU) count assay was then performed on 6mm-diameter resin disks following 24hr growth of a S. mutans biofilm. Light treatment for the CFU assay were: 1) Dark; 2) 30minute LED (22.2 J/cm²); 3) 60minute LED (44.4 J/cm²); 4) 30second laser+2mm distance (95.5 J/cm²); and 5) 30second laser+4mm distance (23.9 J/cm²). Data was analyzed by ANOVA (SPSS, α=0.05) followed by a post-hoc Tukey comparison. Results: The MIC results showed a reduction in planktonic S. mutans at 0.78µg/mL (P=0.009), 1.56 µg/mL (P