Synthesis and photopolymerization of novel ALKYL-a- hydroxymethyl acrylate based dental crosslinking monomers

Abstract

The most commonly used dental restorative filling composites are composed ofBisphenol A glycolate dimethacrylate (Bis-GMA) monomer, an inorganic filler, and apolymerization initiator system. A comonomer such as triethyleneglycol dimethacrylate (TEGDMA) is added to adjust the viscosity of the dental resin.In this study, five new dental crosslinking monomers with improved adhesion totooth tissue, volume shrinkage and stability were synthesized. Four are based on t-butyl-?-hydroxymethyl acrylate (TBHMA): (i) via reaction of t-butyl-?-bromomethyl acrylate (TBBr) and Bisphenol A, (ii) by hydrolysis of t-butyl groups of the first monomer to give adiacid derivative, (iii) by conversion to amide derivative using benzyl amine, (iv) byconversion to amide derivative using (3-aminopropyl)-triethoxy silane (APTES). TheAHM based monomer (v) was synthesized from the Michael addition of APTES to 3-acryloyloxy-2-hydroxypropyl methacrylate (AHM).The photopolymerization behavior of the synthesized monomers with mixtures ofcommercial monomers Bisphenol A glycolate dimethacrylate (BisGMA)/triethyleneglycoldimethacrylate (TEGDMA) and BisGMA/2-hydroxyethyl methacrylate HEMA widelyused in dentistry was investigated using photodifferential scanning calorimetry. The rate of polymerizations and conversions were found to be similar to the commercial materials,although adhesion and stability properties were improved.