Synthesis of dimethacrylates monomers with low polymerization shrinkage and its application in dental composites materials

In this work, a new dimethacrylate monomer named alpha,alpha'-Bis(4-(2'-hydroxy-3'-methacryloyloxy-propoxy)-3,5-dimethylphenyl)-1,4-diisopropyl-benzene (alpha,alpha'-BHMPDDB) was synthesized to replace 2,2-bis[4-(2'-hydroxy-3'-methacryloyloxy-propoxy)-phenyl]propane (Bis-GMA) as one component of dental composite materials. The structures of alpha,alpha'-BHMPDDB and its intermediate product alpha,alpha'-Bis(4-oxiranylmethoxy-3,5-dimethylphenyl)-1,4-diisopropylbenzene (alpha,alpha'-BODDB) were confirmed by FT-IR, H-1-NMR, and elemental analysis. alpha,alpha'-BHMPDDB was mixed with TEGDMA to form a new dental resin, and double bond conversion, polymerization shrinkage, contact angle, water sorption and solubility, flexural strength and modulus before and after water immersion of this new dental resin were studied. Compared with the commonly used Bis-GMA/TEGDMA dental resin, alpha,alpha'-BHMPDDB/TEGDMA had higher double bond conversion (60.5 +/- 0.3 %), lower polymerization shrinkage (5.6 %), and comparable flexural strength before water immersion (94.1 +/- 3.9 MPa), which made alpha,alpha'-BHMPDDB/TEGDMA having potential to replace Bis-GMA/TEGDMA as matrix phase of dental composites materials. However, alpha,alpha'-BHMPDDB/TEGDMA also had drawbacks, such as higher water sorption (5.06 +/- 0.17 %), water solubility (2.37 +/- 0.1 %), and lower flexural strength after water immersion (71.4 +/- 14.6 MPa).