Interactions of pigments and opacifiers on color stability of MDX4-4210/type A maxillofacial elastomers subjected to artificial aging.
BACKGROUND
The color instability and degradation of maxillofacial elastomers limit the function and cosmetic quality of facial prostheses.


OBJECTIVE
The purpose of this study was to measure the interactions of oil pigments plus dry earth opacifiers at 5%, 10%, and 15% by volume in stabilizing the color of MDX4-4210/type A silicone elastomers before and after artificial aging.


METHODS
In the first part of the study, each of 5 opacifiers (Georgia kaolin powder neutral, kaolin powder calcined, Artskin white, dry pigment titanium (Ti) white, or Ti white artists' oil color) at 10% concentrations were combined with each of 5 oil pigment types (no pigment, cadmium-barium red deep, yellow ochre, burnt sienna, or a mixture of the 3 pigments), for a total of 25 experimental groups of elastomers. In the second part of the study, 50 experimental groups of elastomers were made by combining 1 of 5 opacifiers at 5% and 15% concentrations with 1 of 5 oil pigments as in Part 1. Five specimens of each elastomer were tested, for a total of 375 specimens. In each part of the study, all specimens were aged in an artificial aging chamber. CIE L*a*b* values were measured by a spectrophotometer. The color differences (DeltaE*) were subjected to repeated-measures analysis of variance. Mean values were compared by Tukey-Kramer intervals (alpha = .05).


RESULTS
In Part 1, when the opacifiers were tested at 10% concentration, Ti white oil color had the most color change, and dry pigment Ti white had the least; all other opacifiers were not significantly different from each other. In Part 2, at 5%, Ti white oil color had the most color change; all other opacifiers were not significantly different from the others. At 15%, Ti white oil color again had the most color change, followed by Artskin white, kaolin powder calcined, and Georgia kaolin; Ti white dry earth pigment had the least color change. Overall, 5% Artskin white had less color change than the 15%, whereas 15% dry pigment Ti white had less color change than the 5% (P < .001). The 5% and 15% of other opacifiers were not significantly different.


CONCLUSIONS
At all 3 concentrations, oil pigments mixed with opacifiers helped protect the MDX4-4210/type A silicone elastomer from color degradation over time. Dry pigment Ti white remained the most color stable over time, followed by the pigments mixed with kaolin powder calcined, Georgia kaolin, Artskin white, and Ti white artists' oil color.
Department of Restorative Dentistry and Biomaterials, University of Texas Dental Branch at Houston, 77030, USA. Sudarat.Kiat-amnuay@uth.tmc.edu
Sudarat
S
Kiat-Amnuay
Trakol
T
Mekayarajjananonth
John M
JM
Powers
Mark S
MS
Chambers
James C
JC
Lemon
D001466:Barium Sulfate / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry*; D019187:Cadmium Compounds / Q000737:chemistry; D003116:Color; D004396:Coloring Agents / Q000737:chemistry*; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D004954:Esthetics; D005290:Ferric Compounds / Q000737:chemistry; D006801:Humans; D007616:Kaolin / Q000737:chemistry; D008043:Linseed Oil / Q000737:chemistry; D008422:Materials Testing; D008447:Maxillofacial Prosthesis; D017797:Prosthesis Coloring; D018036:Selenium Compounds / Q000737:chemistry; D012826:Silicone Elastomers / Q000737:chemistry*; D013053:Spectrophotometry; D013440:Sulfides / Q000737:chemistry; D013997:Time Factors; D014025:Titanium / Q000737:chemistry
D001672:Biocompatible Materials; D019187:Cadmium Compounds; D004396:Coloring Agents; D004129:Dimethylpolysiloxanes; D005290:Ferric Compounds; C020964:MDX 4-4210; D018036:Selenium Compounds; D012826:Silicone Elastomers; D013440:Sulfides; C059755:selenotrisulfide; C009495:titanium dioxide; C000499:ferric oxide; D007616:Kaolin; D001466:Barium Sulfate; D008043:Linseed Oil; D014025:Titanium