Study On Low-shrinkage Resin-based Dental Restorative Materials With Antibacterial Function

Currently, methyl methacrylate resins play a role in dental restoration resin, and the most typical resin is bisphenol A-bisglycidylmethacrylate (Bis-GMA). However, this resin often is invalid because of the existence of polymerization shrinkage and oral bacteria. Recently, considerable research effort has focused on developing novel resin matrix with low shrinkage performances or antibacterial properties. In this study, dual functional dental restoration resins were firstly prepared by modified with expanding monomer and quaternary ammonium salts (QAS) antibacterial monomer.Frist, two spiroorthocarbonate expanding monomers,3,9-diethyl-3,9-dihydroxymethyl-1,5,7,11-tetraoxaspiro[5,5]undecane (DHOM) and3,9-diethyl-3,9-bis (allyloxymethyl)-1,5,7,11-tetraoxaspiro[5,5]undecane (BAOM), were synthesized and characterized by’H NMR and FTIR. Then the expanding monomers were mixed with epoxy3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (EE) and Bis-GMA to create a ternary hybrid system, respectively. Then the hybrid system was solidified via visible light-initiated polymerization. The best component ratio of the hybrid system was determined by testing the polymerization shrinkage and double bond conversion. The results showed that with the increase of DHOM or BAOM, the volumetric shrinkage of the system reduced to the least shrinkage of2.97%and2.73%, respectively.Second, two QAS antibacterial monomers, methacryloxylethyl cetyl dimethyl ammonium hexafluorophosphate (DMAE-CH) and2-methacryloxylethyl dodecyl methyl ammonium hexafluorophosphate (MAE-DH), were synthesized and characterized by1H NMR, FTIR and MS. The antibacterial activities of the two monomers were tested against oral bacteria (S.aureus and S.mutans) through measure the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The results indicated that the MIC value and the MBC value of DMAE-CH to the S.mutans were3.35μg/mL and6.7μg/mL and MAE-DH to S.aureus were5.04μg/mL and10.07μg/mL, both showed strong bactericidal activity against two strains of bacteria.Finally, the antibacterial monomers were respectively added to the low-shrinkage resin systems, and their bactericidal activities of the dual functional resin were evaluated. Then, the polymerization shrinkage, double bond conversion, hardness of the dual functional resin were also tested. The results showed that, compared to original resin system, the dual functional resin system performed higher polymerization conversion and better bactericidal activity, but the hardness declined slightly after being modified.