title: Accelerated color change in a maxillofacial elastomer with and without pigmentation.
abstract: BACKGROUND
  Maxillofacial prostheses require frequent replacement because the elastomer and its color additives undergo changes.
  
  
  OBJECTIVE
  This study attempted to determine whether predictable color changes occur when 3 pigments are individually incorporated into a specific silicone elastomer.
  
  
  METHODS
  The materials included an RTV elastomer; 1 natural inorganic pigment, burnt sienna; and 2 synthetic organic pigments, Hansa yellow and alizarin red. Eight test groups of 10 polymerized specimens were established. Groups 1 and 2, acting as the control, involved only the elastomer. Groups 3 and 4 were composed of elastomer and burnt sienna. Groups 5 and 6 consisted of elastomer and Hansa yellow. Groups 7 and 8 comprised elastomer and alizarin red. Odd-numbered groups were assigned to a test site in Miami, Fla., whereas the even numbered groups went to Phoenix, Ariz. Specimens weathered in Miami and Phoenix received sunlight exposures of 1305.7 MJ/m2 and 1310.2 MJ/m2, respectively, over time. Before and after weathering, the L* a* b* color parameter (DeltaE*) of each specimen was determined spectrophotometrically.
  
  
  RESULTS
  Mean color changes that occurred in Arizona were larger than those produced in Florida. Specifically, these differences ranged from 0.4 (alizarin red groups) to 2.36 units for the 2 unpigmented control groups. Other differences showed significance for the unpigmented (P=.001), burnt sienna (P=.006), and Hansa yellow groups (P=.001).
  
  
  CONCLUSIONS
  Outdoor weathering tests in which documented ASTM methods were used provided a valid baseline for future research on color changes in maxillofacial prostheses.
authors.affiliation: College of Dentistry, University of Tennessee, Memphis, Tenn 38163, USA. jgary@utmem.edu
authors.forename: J J
authors.initials: JJ
authors.lastname: Gary
authors.forename: E F
authors.initials: EF
authors.lastname: Huget
authors.forename: L D
authors.initials: LD
authors.lastname: Powell
mesh_terms: D000704:Analysis of Variance; D000880:Anthraquinones / Q000737:chemistry / Q000528:radiation effects; D003116:Color; D005544:Forecasting; D006801:Humans; D008422:Materials Testing; D008447:Maxillofacial Prosthesis; D010860:Pigments, Biological / Q000737:chemistry* / Q000528:radiation effects; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D017797:Prosthesis Coloring; D012826:Silicone Elastomers / Q000737:chemistry* / Q000528:radiation effects; D013053:Spectrophotometry; D013472:Sunlight
chemical_list: D000880:Anthraquinones; D010860:Pigments, Biological; D011108:Polymers; D012826:Silicone Elastomers; C010078:alizarin