title: Accelerated aging affects color stability of provisional restorative materials.
abstract: OBJECTIVE
  The color stability of two shades each of five acrylic resin and seven resin composite provisional restorative materials was evaluated by reflection spectrophotometry following in vitro accelerated aging.
  
  
  METHODS
  Specimens of provisional restorative materials were polymerized according to manufacturers' instructions and aged in an artificial aging chamber with exposure to a total ultraviolet irradiation of 60 kJ/m2. Color was measured by CIE L*a*b* on a reflection spectrophotometer before and after aging. Color change (delta E*) was calculated and analyzed statistically.
  
  
  RESULTS
  Statistically significant changes in color were observed after accelerated aging. Nine of the 12 provisional materials tested showed perceptible color change of at least one of the shades tested. The most color-stable materials were the acrylic, Alike, and the resin composites, Luxatemp and Protemp Garant, which had no perceptible color changes under these conditions.
  
  
  CONCLUSIONS
  Some acrylic resin and composite provisional materials change color significantly and perceptibly when exposed to in vitro accelerated aging conditions.
authors.affiliation: Department of Restorative Dentistry, University of Pennsylvania, School of Dental Medicine, Philadelphia, USA.
authors.forename: P G
authors.initials: PG
authors.lastname: Doray
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: J M
authors.initials: JM
authors.lastname: Powers
authors.forename: J O
authors.initials: JO
authors.lastname: Burgess
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D019554:Dental Restoration Wear; D003794:Dental Restoration, Temporary; D006801:Humans; D008422:Materials Testing / Q000379:methods / Q000706:statistics & numerical data; D017797:Prosthesis Coloring; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D003188:Composite Resins