PREPARATION AND EVALUATION OF VISIBLE-LIGHT-CURED MULTI-METHACRYLATESFOR DENTAL COMPOSITES

To explore new VLC oligomers exhibiting low shrinkage, low water sorpt ion, and improved mechanical properties, a family of multi-methacrylat es, based on poly(isopropylidenediphenol) resin (BPA), was synthesized , characterized, and evaluated. The BPA resin, having an average of ei ght phenolic hydroxyl groups per molecule, was treated with ethylene c arbonate and the resultant product esterified at four different grafte d levels, using methacryloyl chloride. Structures of these EEBPA oligo mers, were confirmed by FT-SR and C-13 NMR. The EEBPA oligomer/TEGDMA (50/50, w/w) blends were combined with 0.5 wt% camphoroquinone(CQ) and 1.0 wt% N,N-dimethylaminoethyl methacrylate (DMAEM). The control was BisGMA/TEGDMA (50/50, w/w) blends having the same levels of CQ/DMAEM. Differential photocalorimetry (DPC) and differential scanning calorime try (DSC) showed the multi-methacrylate/TEGDMA (neat resin) blends hav e polymerization characteristics comparable to the BisGMA/TEGDMA contr ol. These multi-functional oligomers have lower polymerization shrinka ge and lower uptake of water and other liquids. In addition, two exper imental oligomers EEBPA #2 and #3 have higher compressive strength tha n the BisGMA and comparable diametral tensile strength to the BisGMA c ontrol. These results suggest that the new type of multi-functional me thacrylate oligomers (EEBPA) have potential application in formulating dental composites with improved properties.