Effect Of Microwave And Water-bath Post-polymerization Treatments On The Residual Monomer Content And Cytotoxicity Of Provisional Restoration Materials

Test Ⅰ Effect of post-polymerization treatments on the residual monomer content of chemically cured provisional restoration materialsObjective: To evaluate the effect of microwave and water-bath post-polymerization treatments on the residual monomer content of two kinds of provisional restoration materials.Methods: 9 blocks(50mm×30mm×2mm) for determining the amount of residual monomer were prepared with each material, following the manufacturers’ instructions and divided into three groups. Control group specimens were left untreated. Specimens of microwave group were treated with microwave irradiation for 3 minutes at 500 W. In water-bath group, specimens were submitted to immersion in water at 55°C for 30 minutes. The residual monomer was analyzed using high performance liquid chromatography. Data were analyzed by one-way ANOVA followed by SNK test(a= 0.05).Results: For polymethyl methacrylate material, the amount of residual monomer of microwave(0.21%±0.07%) and bath-water(0.99%±0.17%) groups were reduced significantlly compared with the control group(2.60%±0.61%). For bis-acryl composite resin, the residual monomer content of the three groups was less than 0.10%.Conclusions: The residual monomer content of polymethyl methacrylate material could be reduced significantly by microwave and water-bath post-polymerization treatments. For the bis-acryl composite resin, it was unnecessary to treat the material during clinical application.Test Ⅱ Effect of microwave and water-bath post-polymerization treatments on cytotoxicity of two kinds of provisional restoration materialsObjective: To evaluate the effect of microwave and water-bath post-polymerization treatments on the cytotoxicity of two kinds of provisional restoration materials.Methods:18 discs( 10mm×2mm) for assessing cytotoxicity were prepared with each material, following the manufacturers’ instructions and divided into three groups. Control group specimens were left untreated. Specimens of microwave group were treated with microwave irradiation for 3 min at 500 W. In water-bath group, specimens were submitted to immersion in water at 55°C for 30 min. The cytotoxicity was assessed by means of methyltetrazolium test. Data were analyzed by one-way ANOVA followed by SNK test(a= 0.05).Results: For polymethyl methacrylate material, the mean percentage viability of control group(47.6%±3.6%) was signi?cantly lower than those of microwave group(78.4%±4.3%) and bath-water group(54.4%±4.3%). For bis-acryl composite resin, there was no statistcally difference in the mean percentage viability among the three groups, and slight cytotoxic effect was observed.Conclusions: Microwave and water-bath post-polymerization treatments could reduce the cytotoxicity of polymethyl methacrylate material significantly,while had little effect on the bis-acryl composite resin.