title: Optical properties of pigmented polydimethylsiloxane prosthetic elastomers: effect of "outdoor" and "indoor" accelerating aging.
abstract: OBJECTIVE
  Optical properties of facial prosthetic elastomers undergo significant changes mainly due to aging. The resulting changes in their appearance are the main reasons of facial prosthesis' replacement.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate changes in the translucency parameter (TP) and color (ΔE*) of polydimethylsiloxane (PDMS) maxillofacial elastomers after exposure to 3 different aging conditions (time passage, accelerated "outdoor" aging, and accelerated "indoor" aging).
  
  
  METHODS
  The PDMS prosthetic elastomers tested in this study were low- (LTV) and high-temperature vulcanized (Episil and Mollomed, respectively) in various shades. Color changes (ΔE*) and translucency parameter (TP) were determined in the CIE L*a*b* system using a tristimulus colorimeter. Data were subjected to 2-way analysis of variance followed by Tukey post hoc test. In addition, TP values were analyzed by paired t tests. The significance level of α = 0.05 was set for all tests.
  
  
  RESULTS
  Translucency parameter values for most samples were significantly changed after aging, and ΔE* values were characterized as unacceptable. Both aging procedure and material type affected the changes that occurred. Moreover, dark-shaded samples of both silicone materials revealed significant changes in TP values before and after aging. ΔE* was not significantly different among the same material samples but had significant differences between the 2 materials (Episil and Mollomed). Time passage did not significantly affect TP values contrary to the other 2 accelerated aging procedures. Between outdoor and indoor aging, no significant differences were detected.
  
  
  CONCLUSIONS
  Accelerated outdoor and indoor aging caused significant changes in ΔE* and TP values. Significant changes were also detected between material types.
authors.affiliation: Department of Prosthodontics, Division of Removable Prosthodontics, Dental School, University of Athens, Athens, Greece.
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Polyzois
authors.forename: Panagiota N
authors.initials: PN
authors.lastname: Eleni
authors.forename: Magdalini K
authors.initials: MK
authors.lastname: Krokida
mesh_terms: D000704:Analysis of Variance; D003124:Colorimetry; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D008422:Materials Testing; D008447:Maxillofacial Prosthesis; D055095:Optics and Photonics; D017797:Prosthesis Coloring; D012826:Silicone Elastomers / Q000737:chemistry*; D012828:Silicones / Q000737:chemistry; D013997:Time Factors
chemical_list: D004129:Dimethylpolysiloxanes; C027899:Mollomed; D012826:Silicone Elastomers; D012828:Silicones; C545984:episil