Influence of pigments and opacifiers on color stability of silicone maxillofacial elastomer

Abstract

Objectives To determine the effects of opacifiers and silicone pigments on the color stability of silicone A-2000 maxillofacial prosthetic elastomers subjected to artificial aging. Methods Seventy-five groups ( n = 5) were made by various combinations (5%, 10%, and 15%) of four dry earth opacifiers (Georgia kaolin, Gk; calcined kaolin, Ck; Artskin white, Aw; titanium white dry pigment, Td); and 1 silicone pigment white (Sw) with one of 5 silicone pigments (no pigment (control), red (Pr), yellow (Py), burnt sienna (Po), and a mixture of Pr + Py + Po). A reflection spectrophotometer was used for color measurements. Color differences (Δ E*) between baseline and after an energy exposure of 450 kJ/m 2 in an artificial aging chamber were calculated. A Δ E* = 3.0 was used as 50:50% acceptability threshold in result interpretation, while Δ E* = 1.1 was used as 50:50% perceptibility threshold. Means were compared by Fisher's PLSD intervals at the 0.05 level of significance. Color differences after aging were subjected to three-way analysis of variance. Results Yellow ochre mixed with all opacifiers at all intervals had increased Δ E* values significantly from 0.7–2.1 up to 3.8–10.3. When mixed groups were considered, at 5%, Gk exhibited the smallest color changes, followed by Td < Aw = Sw < Ck, respectively. At 10%, Aw < Td < Gk < Sw = Ck. At 15%, Td < Aw < Gk = Sw < Ck (< indicates p < 0.0001 and = indicates p > 0.05). The smallest color differences, observed for opacifier groups, were recorded for Gk at 5%, and Td and Aw at 10% and 15%. Overall, 15% Td exhibited the smallest, whereas 5% Ck exhibited the most pronounced color change after artificial aging. All Δ E* values were below the 50:50% acceptability threshold, indicating acceptable color stability. Color differences for 10% and 15% of Aw and Td were below 50:50% perceptibility thresholds, indicating excellent color stability. Conclusion Silicone pigments mixed with 10% and 15% Artskin white and titanium white dry pigment opacifiers protected silicone A-2000 from color degradation over time. Yellow silicone pigment significantly affected color stability of all opacifiers especially silicone pigment white and calcined kaolin.