Effect of flask position and number in microwave oven on roughness and porosity of the onda-cryl resin

Abstract

This paper studied the effect of flask position and number in the microwave oven, on roughness and porosity of the Onda-Cryl re- sin. The wax patterns were embed- ded in fiberglass flasks. The power- liquid proportion, manipulation, and acrylic resin pressing were made according to manufacturers’ instructions. The specimens, three for each group were polymerized by microwave energy at 500 W with one flask centrally placed on the turning plate; one flask marginally placed on the turning plate; two flasks, one placed in the center and other in the margin, considering the values of the central flask, or margin flask. The time of polymerization process varied from 3 to 10 minutes for each specimen. The specimens were removed from flasks after cooling at room temperature and submitted to polishing by conventional procedure. After, they were submitted to rough- ness test with a Surfcorder SE 1700 perfilometer and porosity analysis with a stereoscopic microscopy. The data submitted to ANOVA and Tukey’s test showed that: 1- there was no significant statistical difference on the values of rough- ness in relation to flask positions, regarding polymerization time, as well as in relation to flask number; however when the interaction of position factor and flask number was verified, there was significant statistical difference. 2- There was significant statistical difference on the values of porosity when it was considered one flask in the center and two in relation to the one po- sitioned in the extremity. However, in relation to flask position and number; there was no significant statistical difference in the factor position. Key words: acrylic resin, rough- ness, porosity.