Is Polymethly Methacrylate Stain Friendly when used in Extra-Oral Maxillofacial Prosthesis…?

Abstract

Background & Objectives: The present study was conducted to find out a stain material that can retain its color in acrylic for a long period, by assessing its chemical interaction with the parent material and to evaluate the color stability of commonly used acrylic resin-stain combinations after exposure to weathering. Method: This experiment was carried out on PMMA-stain combination specimens. The acrylic blocks were divided into two categories. Scrapings from first category were subjected to spectroscopy to determine the interaction of the four PMMA-stain combinations at molecular level. And scrapings from second category were tested with spectrophotometer after being subjected to weathering. The comparison between the graphs obtained was made using absorbance variance. Results: Glass paint, acrylic emulsion, and organic dye produce changes which are evident in the spectrograph. Fabric paint does not produce much change in the spectrograph. Before and after subjecting the acrylic resin-fabric paint combination to natural weathering, suggest that the colorant is most stable. On the contrary organic dye and glass paint are least stable of all the four stains. Conclusion: The addition of colors to PMMA for staining definitely produces changes in the structure of the PMMA at the molecular level. The addition of inorganic group stains produce change but which are insignificant, whereas the addition of organic group stains produce changes at the molecular level which are significant. Inorganic coloring agent (fabric paint) was the most color stable over time whereas the organic colorants (glass paint, acrylic emulsion, organic dye) were the least color stable. Keywords: Chemical interaction, color stability, PMMA-stain combination, weathering