Resistência à flexão de resina acrílica polimerizada pela energia de microondas

Fracture strength of denture base resins of great concern in complete denture rehabilitation. Many approaches have been used to strengthen acrylic resin dentures and new processing methods have been investigated. The aim of this study was to evaluate the effect of two microwave curing cycles on the transverse strength of a acrylic resin. Three groups were evaluated (A, B and C) and one type of conventional heat-cured acrylic resin was used for all specimens (Classico). Two groups were cured in microwave oven (Continental AW-30): Group A) 3 minutes at 500W and Group B) Pre-polymerization for 13 minutes at 90W (flask on vertical position) and final polymerization for 1.5 minute at 500W (flask on horizontal position). Group C consisted of specimens cured in hot water bath for 9 hours at 74oC and was control group. A three point loading test was used to determine the transverse strength of test specimens (n= 9 per group) using a mechanical testing machine (MTS-810). The means of flexural strength (Mpa) of groups A, B and C were 101.27 (±12.31), 90.66 (±7.56) and 85.06 (±17.50) respectively. One-way analysis of variance demonstrated significant differences between the groups, and the Tuckey’s test showed significant differences (p<0.05) between groups A and C. It was concluded the Classico conventional heat-cured acrylic resin could be polymerized by microwave energy without damage to mechanical property evaluated.