Effect of Dry Pressure Heat Curing Technique on Water Sorption and Color of Heat Cured Acrylic Resin

Abstract

Aims: The purpose of this study was to evaluate the effect of dry pressure curing technique after immersion in distilled water for 1 ,4 and 12 weeks on the water sorption, solubility, and color change of heat cured acrylic resin as compared with conventional curing technique, also to evaluate the effect of immersion period on these properties. Materials and methods: Sixty specimens of vertex regular heat cured acrylic resin denture base material were used in this study, curing by two different technique, conventional curing technique and dry pressure curing technique, then immersed in distilled water for 1,4, and 12 week . The water sorption and solubility test were measured by means of mass change in the materials after water saturation and dehydration. While the color change test was measured by the samples converted to digital images on computer by using digital scanner, then the digital images were prepared with dimension 760 pixels*960 pixels for each samples by software program Adob Photoshop 9.0, by MATLAB 2010 program the image was analyzed to the basic primary colors RGB, then converted to (CIE L*a*b*) system by Photoshop 9.0 program, the CIE L*a*b* color difference metric were used to perform color change test. Mean values were compared statistically with T-test, one way analysis of variance and by Duncan's multiple range test to determined the significant different among the groups at p 0.05 in different times immersion (1,4,and 12 weeks). In comparisons between immersion time that there was significant difference at p≤ 0.05 in water sorption, solubility, and color change test for both curing techniques. Conclusion: The dry pressure curing technique has an effect on the water sorption and solubility ratios but no effect on color change of heat cured acrylic resin, while the immersion period have an effect on the water sorption, solubility, and color change.