Effect of Ultraviolet Protective Agents and Plasma Applications on the Color Stability of Maxillofacial Silicones

Objective: The purpose of the present study was to evaluate the color stability of maxillofacial silicones after applying plasma and ultraviolet protectives. Methods: Six different color specimen groups (clear, white, yellow, red, blue, and mixed) from additional polymerized maxillofacial silicone elastomer were prepared. The surface of the polymerized silicone was modified with argon and oxygen plasma. Then, five UV protective agents (benzophenone-3, 2-ethylhexyl salicylate, titanium dioxide, Ethylhexyl methoxycinnamate, and TiO2-ZnO) were applied to the modified silicones. Specimens of each color and UV group were aged with an accelerated aging and thermocycling device. The color difference (ΔE) of maxillofacial silicones was statistically analyzed by 4-way ANOVA (α=0.05). Results: The silicone specimens coated with 2-ethylhexyl salicylate (UV-ES) showed the lowest ΔE values in all color groups and aging regimes. The red color generally showed the highest ΔE values, and the white color showed the lowest ΔE values. When the silicone surfaces were modified with oxygen and argon plasma, oxygen plasma exhibited significantly higher ΔE values than the argon plasma in red color groups, whereas in yellow color groups, argon plasma exhibited higher ΔE values than the oxygen plasma. Conclusions: Coating the silicone surface with UV-ES followed by oxygen or argon plasma revealed a positive impact on the color stability of silicone elastomer. Plasma treatment and UV-ES coating may be used to enhance the clinical lifetime of silicone facial prostheses.