Methods: 2-Dimethyl-2-dodecyl-1-methacryloxyethyl ammonium iodine (DDMAI) (15wt.%, 20wt.%, and 25wt.%) was added into 2,2-bis[4-(2-hydroxy-3- methacryloyloxypropyl)-phenyl]propane (Bis-GMA)/methyl methacrylate (MMA) (80/20, wt/wt) dental resin system with camphoroquinone (0.7wt.%) and N,N’-dimethyl aminoethylmethacrylate (0.7wt%) as a photoinitiation system. DC was determined by FT-IR analysis. FS and FM of the polymer were measured using a three-point bending set up. WS and WSL were obtained until the mass variation of polymer in distilled water kept stable. Biofilm inhibition method was used to evaluate the antibacterial activity of the polymer, and the SEM was used to observe the formed biofilm on the polymer surface. Radiographs were taken to determine the radiopacity of the polymer.
Results: ANOVA analysis revealed that polymer with 20wt.% and 25wt.% DDMAI had higher DC than that of polymer without DDMAI (p<0.05), and polymer with 15wt.% DDMAI had nearly the same DC as polymer without DDMAI (p>0.05). All of DDMAI containing polymers had lower FS and FM than polymer without DDMAI (p<0.05). Polymer with DDMAI had higher WS (p<0.05), WSL (p<0.05) and radiopacity than that of polymer without DDMAI, and the values increased with the increase of DDMAI concentration. The amount of bacteria recovered from the surface of DDMAI containing polymer was less than that recovered from the surface of control polymer (p<0.05), and the result was consistent with the result of SEM.
Conclusions: DDMAI could endow Bis-GMA/MMA resin system with good antibacterial and radiopaque function without influencing the DC. However, incorporating DDMAI into Bis-GMA/MMA resin could decrease mechanical properties and increase water solubility, thus, further work need to be taken to optimize the resin formulation.