Color stability and colorant effect on maxillofacial elastomers. Part III: weathering effect on color.

STATEMENT OF PROBLEM Maxillofacial prostheses are serviceable for approximately 6 months, after which they need to be refabricated because of the deterioration of color and physical properties. PURPOSE This third article in a 3-part series evaluated the color stability of commonly used colorant-elastomer combinations as a result of exposure to weathering. METHODS AND MATERIAL Fifteen specimens were fabricated for each of the 3 elastomers (Silastic medical adhesive type A, Silastic 4-4210, and Silicone A-2186) and 6 colorants (dry earth pigments, rayon fiber flocking, artist's oil paints, kaolin, liquid cosmetics, and no colorant) for a total of 270 specimens (18 groups of 15 specimens). The 15 specimens of each elastomer-colorant combination were separated into 3 test condition groups (control, time passage, and natural weathering) of 5 specimens per test condition group. Control specimens were evaluated within 1 month of fabrication. The time passage group was sealed in glass containers and kept in the dark for 6 months before testing. The natural weathering groups were placed on the roof of the dental school for 6 months and exposed to sunlight and weathering. Color and optical density data for each elastomer-colorant combination were subjected to a 1-way analysis of variance to examine effects among test conditions (control, time passage, and weathering). When significant differences were observed, the Student-Newman-Keuls multiple range test was performed to identify differences in elastomer-colorant combinations among each test condition at a significance level of .05. RESULTS Changes in color, as a result of weathering, were noted in many of the colorant-elastomer combinations. Also, color change occurred not only to the colored, but also to uncolored materials over time without exposure to weathering. CONCLUSION Clinically, the addition of colorants could have a stabilizing effect on the elastomer color when it is exposed to weathering.