Synthesis and characterization of novel dimethacrylates of different chain lengths as possible dental resins

Objective. In this study three novel dimethacrylates of different chain lengths having bulky bicycloaliphatic rings were synthesized and proposed as possible dental monomers for dental resin mixtures. Methods. The monomers were prepared by the reaction of glycidyl methacrylate with dicarboxylic acid esters obtained from nadic anhydride and ethylene, 1,4-butylene and 1,6-hexylene glycols. The addition reaction of glycidyl methacrylate and the acidic compound was carried out in the presence of basic catalyst-tetraethylammonium bromide. The monomers were photopolymerized in the presence of a photoinitiator which was 2,2-dimethoxy-2-phenyloacetophenone. Unfilled homopolymers were evaluated for photopolymerization conversion and volumetric curing shrinkage. Water sorption, water solubility, flexural strength and hardness were measured. The prepared polymers were also subjected to dynamic mechanical studies (DMA). Results. The proposed dimethacrylates exhibit low curing shrinkage (about 4-5%) and high degree of double bond conversion (up to 84%). Their water sorption and water solubility are comparable to those of Bis-GMA composite resin. Furthermore, their thermo-mechanical properties are better than those of the commonly known dimethacrylates. Significance. The new dimethacrylates are promising photocurable dental monomers owning to simple synthesis, high degree of conversion coupled with low curing shrinkage and good mechanical properties. (C) 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.