title: Outdoor weathering of facial prosthetic elastomers differing in Durometer hardness.
abstract: BACKGROUND
  Facial prosthetic elastomers with wide ranges in hardness are available, yet material weatherability is unknown.
  
  
  OBJECTIVE
  The purpose of this study was to assess color, Durometer hardness, and tensile property changes after 3000 hours of outdoor weathering.
  
  
  METHODS
  Unpigmented elastomers with Durometer hardness 5, 30, 50, 70, and A-2186 were polymerized into dumbbells (ASTM D412) and disks, 34 mm in diameter by 6 mm thick. Materials were subjected to outdoor or time passage environments for 3000 hours. CIELab color (n=5), Durometer hardness (n=5), and tensile mechanical properties (n=10) were measured at 0 and 3000 hours, and group differences were assessed by material and weathering condition (ANOVA/Tukey, α=.05).
  
  
  RESULTS
  Except for A-2186, the mean Durometer changes for all materials were 1 unit or less, with no significant differences observed between time passage and weathered groups (P≥.05). Three-thousand-hour tensile mechanical property results demonstrated nonsignificant differences between time passage and weathered materials but significantly changed properties from immediately tested materials (P<.001). Outdoor weathering induced perceptible but acceptable color changes (1.7≤ΔE*≤2.6) for elastomers with Durometer hardness 5 and 30 and A-2186.
  
  
  CONCLUSIONS
  With a few exceptions, outdoor weathering produced relatively small changes in color, Durometer hardness, or tensile properties compared with time passage.
authors.affiliation: Graduate student, College of Dentistry, University of Nebraska Medical Center, Lincoln, Neb.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Willett
authors.affiliation: Researcher, Veteran Affairs Nebraska-Western Iowa Healthcare System, Omaha, Neb; Professor and Director of Biomaterials, Department of Adult Restorative Dentistry, College of Dentistry, University of Nebraska Medical Center, Omaha, Neb. Electronic address: mbeatty@unmc.edu.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Beatty
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D003116:Color; D003624:Darkness; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D055119:Elastic Modulus; D004777:Environment; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D058105:Polymerization; D019736:Prostheses and Implants; D012826:Silicone Elastomers / Q000737:chemistry*; D013053:Spectrophotometry / Q000295:instrumentation; D013472:Sunlight; D013718:Tensile Strength; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D004129:Dimethylpolysiloxanes; D012826:Silicone Elastomers; C013830:baysilon