Synthesis and photopolymerization of piperonylamine derivatives as a polymerizable cyclic acetals co-initiator for light-cured unfilled dental resins

The aim of this study was to synthesize and characterize N,N-di(methacryly-ethoxycarbonyl-ethyl)-N-(1,3-benzodioxole-5-methylene)(DMEBM) to replace both triethylene glycol dimethylacrylate(TEGDMA) as a dilute and the non-polymerizable amine, which is added as a co-initiator in dental resinmixtures. 2,2-bis[4-(2-Hydroxy-3-methacryloxypropoxy) phenyl]-propane (Bis-GMA) and camphorquinone (CQ) were used as monomer and photoinitiator in these model dental resin systems, in contrast to ethyl 4-dimethylaminobenzoate (EDMAB) which was usually used as a co-initiator. DMEBM was synthesized via Michael-Addition reaction and characterized using H-1 NMR spectroscopy. A mixture of Bis-GMA/DMEBM/CQ was found to reach the double bond conversion of 67.5%, slightly higher than that of Bis-GMA/TEGDMA/CQ/EDMAB (66.8%) and Bis-GMA/TEGDMA/CQ/DMEBM (64.8%). In addition, the glass transition temperature of Bis-GMA/TEGDMA/CQ/EDMAB (93.4 degrees C) were higher than that of Bis-GMA/TEGDMA/CQ/DMEBM (89.3 degrees C) and Bis-GMA/DMEBM/CQ (80.4 degrees C). The water sorption and solubility of Bis-GMA/TEGDMA/CQ/DMEBM were higher than that of Bis-GMA/TEGDMA/CQ/EDMAB and Bis-GMA/DMEBM/CQ. However, the values were still within the range of the ISO 4049 standards. DMEBM could be used as a potential co-initiator and diluent for dental composite. Copyright (C) 2009 John Wiley & Sons, Ltd.