Color Stability of Aged Maxillofacial Elastomers With Different Pigment Systems

Objectives: Color stability of extraoral maxillofacial prostheses affects the longevity and patient’s quality of life. This study evaluated the color stability of 6 pigmented maxillofacial elastomer groups subjected to artificial aging.
Methods: Four different types of silicone elastomers (MDX4-4210/Adhesive Type A100 [MDX/A100], MDX4-4210/Adhesive Type A564 [MDX/A564], A-2000, and M-511) at 10% concentration of opacifier were combined with five colors (red, yellow, blue, mixed, and opacifier only). Four different pigment systems were used with the elastomers (Artist Oil, e-Skin, Reality, and Technovent). Control groups contained no pigment or opacifier. Five specimens per group were fabricated, and three specimens were randomly selected for artificial aging in the weatherometer (N = 108). CIEL*a*b* values were measured with a spectrophotometer before and after an energy exposure according to SAE J1960. CIELAB 50:50% perceptibility (DE*=1.1) and acceptability threshold (DE*=3.0) was used to interpret color changes. Color differences after aging were subjected to 3-way analysis of variance. Means were compared by the Fisher PLSD intervals at the 0.05 level of significance.
Results: For mixed pigment group, all elastomers color changes were within perceptibility threshold (M511/eSkin [DE*=0.53] > A2000/eSkin [DE*=0.56] > MDX/A100 [DE*=0.70] > M511/Technovent [DE*=0.74] > M511/Reality [DE*=0.89]) except MDX/A564 (DE*=2.12). For red group, all elastomers mixed with e-Skin pigment had significant color changes above clinically acceptable thresholds (DE*=3.76-4.05). For yellow, M511/e-Skin (DE*=3.13) and M511/Reality (DE*=2.27) showed the most changes. Blues were all within acceptable thresholds (DE*=0.74–2.42) with M511/Technovent having the highest perceptible color change.
Conclusions: Overall from the mixed group, A2000/e-Skin was the most color stable elastomer, followed by M511/e-Skin, MDX/A100, M511/Technovent, M511/Reality (all 4 groups, p≥0.05) and MDX/A564 (p<0.05, from other 4 groups), respectively. Opacifiers protected elastomers from color deterioration (decreased in DE* value after opacifiers added). Red e-Skin affected A2000 and M511, blue affected M511/Technovent, and yellow affected. M511/e-Skin the most.