New Diluents for Dental Composites

Five new urethane groups containing monomers 1–5, acetylated glycerol dimethacrylate (AGDMA), and glycerol trimethacrylate (GTMA) are synthesized as alternative diluents to triethylene glycol dimethacrylate (TEGDMA) for dental resins or composites. The synthesized monomers are characterized by means of ¹H NMR, ¹³C NMR, and IR spectroscopy. The secondary acrylamide group containing hybrid monomers 1 and 2 are solids. However, the monomers 3–5, AGDMA and GTMA are colorless and relatively low-viscosity liquids. They are not mutagenic in the Ames test and show a lower cytotoxicity and a lower polymerization shrinkage compared to TEGDMA. The tertiary amide group containing crosslinker 3 shows a significantly higher photopolymerization rate compared to that of TEGDMA in the presence of the monomolecular Ge-based photoinitiator Ivocerin. The synthesized diluents are evaluated in experimental dental formulations for resins, cements, and direct filling composites using a conventional binary camphorquinone/amine photoinitiator.