Development of visible light-cured multi-methacrylates for dental restorative materials

This study focused on new visible light-curing (VLC) oligomers exhibiting l ow shrinkage, low sorption of water, and improved mechanical properties. A family of multi-methacrylates, based on poly(isopropylidenediphenol) resin (BPA), was synthesized, characterized, and evaluated. The commercial BPA re sin is prepared from enzymatic polymerization (oligomerization) of bispheno l A. The BPA resin, having an average of eight phenolic hydroxyl groups per molecule, was treated with propylene carbonate and the resultant product, i.e, propoxylated BPA (PBPA) oligomer, was confirmed by Fourier transform i nfrared spectroscopy (FT-IR) and C-13 nuclear magnetic resonance (NMR). The propaxylated BPA (PBPA) was subsequently treated with methacryloyl chlorid e to produce the multi-methacrylates (EPBPA), identified by FT-IR and NMR. The EPBPA oligomer multi-methacrylate: triethylene glycol dimethacrylate (T EGDMA) (50:50/wt:wt) blends were combined with 0.5 wt% camphorquinone (CQ) and 1.0 wt% N,N-dimethyl-aminoethyl methacrylate (DMAEMA). The control was 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl] propane (BisGMA): TEG DMA (50:50/wt:wt) blends having the same levels of CQ/DMAEMA. Differential photocalorimetry (DPC) and differential scanning calorimetry (DSC) showed t hese multimethacrylate/TEGDMA (neat resin) blends have polymerization chara cteristics comparable to the BisGMA/TEGDMA control. These multifunctional o ligomers (EPBPA) have lower polymerization shrinkage and lower uptake of wa ter and some common organic solvents. These results suggest that the new ty pe of polyfunctional methacrylate oligomers (EPBPA) have potential applicat ion in formulating dental composites as direct esthetic restorative materia ls with improved properties.