Evaluation of color stability of silicone elastomers used in facial prothesis

Evaluation of color stability of silicone elastomers used in facial prothesisMaxillofacial prostheses are used for reconstruction of congenital, developmental and acquired defects of the head and neck. Silicone elastomers are commonly used materials for maxillofacial prosthesis. Silicones are colored with the technics of intrinsic coloration, fiber coloration and extrinsic coloration by using a variety of pigment materials. However the color changes have been in silicones over time. The purposes of this study are to measure the color changes values after the ageing of three different silicone elastomers' coloured and non-coloured examples with several colorant agents used in maxillofacial prostheses and to compare them with each other in the different parameters.For this aim, Cosmesil M511, Cosmesil M522 and Multisil-Epithetic silicone elastomers which are often used in the clinics and their pigments were used. Each silicone elastomer were subjected to intrinsic coloration, fiber coloration and extrinsic coloration. White, yellow, red, brown and mixture of same quantity of these colors were used in each of coloration types. And also specimens with no pigment were prepared and compared with the other specimens. For each color, 5 disk shaped silicone specimens ( 2 mm in thickness) were prepared. Specimens were aged in the accelerated aging machine for 300, 450 and 600 hours. The value of L*,a*,b* were measured by the spectrophotometer and by using these values the ?? (color changes) were calculated. The statistical analyses of these values were evaluated according to repeated measurable four way analyses of variance and Bonferroni test which is a post- hoc multiple compare test method.As a result of the study, the most color changes were in Cosmesil M522 (RTV) silicone, the least color changes were in Multisil-Epithetic (HTV) silicone in the intrinsic and fiber coloration groups. The least color changes were in Cosmesil M522 (RTV) silicone in extrinsic coloration group. Yellow colour had the most colour changes and the brown colour had the least colour changes in intrinsic and extrinsic coloration groups. In fiber coloration groups the red had the most and the white had the least colour changes. There was no significant difference in the ?E values of the non coloured (transparent) 300 hours aged silicones, but during 450 and 600 hours ageing the Cosmesil M522 silicone had the least colour changes. Brown and white pigments used in intrinsic coloration, white pigments used in fiber coloration and brown pigment used in extrinsic coloration were stated that they are acceptable in clinical usage(??<3).