Color Stability of MDX4-4210/Type A Maxillofacial Elastomer with Opacifiers and Pigments

Objectives: Color instability often limits the service of facial prostheses and poses esthetic problems for patients. This study determined the effects of opacifiers used at different ratios on the color stability of pigmented MDX4-4210/Type A maxillofacial elastomer after artificial aging. Methods: Seventy-five groups (n=5) were made by variously combining 1 of 5 opacifiers [5%, 10% or 15% of Georgia kaolin [Gk], calcined kaolin [Ck], Artskin white [Aw], titanium white dry pigment [Td], or titanium white oil color [To]] with 1 of 5 dry earth pigments [no pigment [control], cosmetic red, cosmetic yellow ochre, cosmetic burnt sienna, or a mixture of all pigments]. Specimens were artificially aged in an aging chamber. CIE L* a* b* values were measured by spectrophotometer. Color differences ( delta E*) at 150, 300 and 450 kJ/m2 were subjected to 4-way analysis of variance with repeated-measures. Means were compared by Tukey-Kramer intervals at the 0.05 level of significance. Results: Adding dry earth pigments to any of the kaolin groups did not protect silicone MDX4-4210/Type A from color degradation over time. Mixing red pigment in all groups increased delta E* values from 0.2-3.1 up to 6.9-38.6. Additions of 15% of Td, Aw, To, Gk and 10% of Ck showed significantly better color stability compared to other concentrations (p<0.05). Td was the most color stable over time, followed by the pigments mixed with Ck, AW, To and Gk. Conclusions: Inorganic dry earth pigments mixed with opacifiers did not protect the MDX4-4210/Type A silicone elastomer from color degradation over time especially with cosmetic red.