Characteristics of Dental Restorative Composite Resins Prepared from 2,2-bis-[4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane Derivatives and Spiro Orthocarbonate

To reduce volumetric shrinkage of the commercially available polymeric dental composite during curing reaction, (2,2-bis [4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane) (bis-GMA) derivatives, i.e., (2,2-bis[3-methyl, 4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propan) (DMBis-GMA) and (2,2bis[3,5-dimethyl, 4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane) (TMBis-GMA) were synthesized and then new dental composite resin composed of Bis-GMA derivatives, diluent, spiro orthocarbonate (SOC), and inorganic filler was produced. Among the Bis-GMA derivative/Bis-GMA derivative/diluent mixtures, BisGMA/ TMBis-GMA/TEGDMA mixture exhibited the lowest volumetric shrinkage. Volumetric shrinkage of this mixture was further reduced by adding SOC. Volumtric shrinkage of dental composite prepared from commercially available resin monomer mixture was 2.5%, while that prepared from resin monomer mixture having minimum volumetric shrinkage was reduced to 0.7%. Mechanical strength of this dental composite was nearly the same with that of commercial products but the time required for the curing reaction was retarded.