Effect of polymerisation techniques on residual monomer amount released from different acrylic resins

The purpose of this study was to investigate the influence of different polymerisation methods (heat, auto-, injection moulding and microwave) with curing processes (conventional, short- and long-term terminal boiled heat polymerisation and room temperature polymerisation) in combination with varied water storage periods (24 h, 7 and 30 days) on the residual methyl methacrylate (MMA) contents of different dental acrylic resins. Twelve discs were fabricated for each denture base material. Specimens were immersed immediately in separate light proof glass bottles containing 20 mL 75% ethanol and 25% deionised water. Residual monomer (MMA) which eluted from acrylic resins was analysed with high performance liquid chromatography. Data were analysed by two-way analysis of variance and Tukey honestly significant difference tests. The MMA monomer amount eluted from autopolymerised acrylic resin groups (p<0·01) was higher than that from the other groups. Microwave polymerised acrylic resin showed the lowest residual monomer amount compared to the other acrylic resins (p<.01).