An Autoclave Effect on the Powder of Poly Methylmethacrylate

Abstract

Background: Although most of the physical and mechanical properties of denture base resin polymerized by the conventional heat polymerization have been studied, the effect of autoclave processing on these properties has not been fully determined. The effect of autoclave on acrylic powder has not studied before. Materials and methods: Vertex was the heat – cured acrylic denture base material included in this study. A total of 90 specimens were prepared, the specimens were grouped into three control groups of Vertex acrylic resin which(group A) as curing by conventional water- bath technique (74oC for 90 minutes, then boil for 30 minutes, (group B) which curing by water- bath (100°C for 30 minutes), and (group C)which curing by autoclave (120 °C under 1.4 bar for 45 minutes). The other three groups of Vertex acrylic resin after treatment of powder by autoclave in 132 °C for 4 hours, and then grouped into (A1,B1 andC1) which curing as previously. To study the effect of treatment of powder of acrylic resin byautoclave and the effect of autoclave processing. Three tests were conducted surface roughness (profilometer tester), transverse strength (Instron universal testing machine), and surface hardness (Shore D). The results were analyzed to Descriptive Statistics and ANOVA test. Results: There were no significant differences in surface roughness in all studying groups. There was a highly significant difference in transverse strength test results between studying groups. There was a significant difference in surface hardness test results between studying groups. Conclusions: The treatment of powder of acrylic resin by autoclave had no significant differences in surface roughness, but had a highly significant Difference in transverse strength in all test results, and a significant difference in hardness surface test in group B1. The autoclave processing technique might also be a good alternative to the conventional water- bath processing technique.