Trifunctional methacrylate monomers and their photocured composites with reduced curing shrinkage, water sorption, and water solubility

Novel trifunctional methacrylates, 1,1,1-tris[4-(2'-acetoxy-3'-methacryloyloxypropoxy)phenyl]ethane (Ac-THMPE) and 1,1,1-tris[4-(2'-acetoxy-3'-methacryloyloxypropoxy)phenyl]methane (Ac-THMPM), have been prepared by acetylation of the hydrophilic hydroxyl groups of 1,1,1-tris[4-(2'-hydroxy-3'-methacryloyloxypropoxy)phenyl]ethane (THMPE) and 1,1,1-tris[4-(2'-hydroxy-3'-methacryloyloxypropoxy)phenyl]methane (THMPM), respectively, for use as dental monomers. Decrease in monomer viscosity resulted from the acetylation. Unfilled resins and composites based on the four trimethacrylates were evaluated for photopolymerization conversion, water contact angle, and curing shrinkage. Water sorption, water solubility, and flexural strength of the composites prepared from the trimethacrylate were measured. Those data obtained for the trimethacrylate-containing materials were compared with control 2,2-bis[4-(2-hydroxy-3'-methacryloyloxypropoxy)phenyl]propane (bis-GMA)-based materials in order to evaluate the applicability of the trimethacrylates as dental monomers. The acetylation of hydroxyl groups appeared to be an effective method to decrease curing shrinkage, water sorption, and water solubility of the dental composites. When compared with the bis-GMA composite, the composites based on Ac-THMPM and Ac-THMPM showed much lower curing shrinkage, water sorption, and water solubility, along with approximately equal conversion and flexural strength. (C) 2003 Elsevier Science Ltd. All rights reserved.