title: Optical properties of four esthetic restorative materials after accelerated aging.
abstract: OBJECTIVE
  To determine the differences in CIE L*, a*, and b* values, translucency parameter (TP), opalescence parameter (deltaO*ab), and color difference caused by the fluorescence (deltaE*ab-FL) of resin composite, glass-ionomer, resin-modified glass-ionomer, and compomer of A2 shade before and after accelerated aging.
  
  
  METHODS
  Color and spectral distribution of the materials were measured according to the CIELAB color scale relative to the standard illuminant D65 in the transmittance and reflectance modes. Aging was performed in an accelerated aging chamber with an energy exposure of 150 kJ/m2. The translucency parameter (TP) was calculated as the color difference (deltaE*ab) of the specimen over white and black backgrounds. Opalescence parameter (deltaO*ab) was calculated as the difference in blue-yellow coordinate (deltab*) and red-green coordinate (deltaa*) between the transmitted and reflected colors of a 1 mm-thick specimen. Color difference by the fluorescence (deltaE*ab-FL) in reflectance mode was calculated as an index of fluorescence. Differences and changes in optical properties were analyzed by the repeated-measures ANOVA.
  
  
  RESULTS
  Type of material and the mode of measurement (transmittance and reflectance) influenced CIE L*, a* and b* values significantly (P< 0.05) before aging. Accelerated aging influenced CIE L*, a* and b* values. Aging and the type of material influenced TP, deltaO*ab and deltaE*ab-FL values significantly (P< 0.05).
authors.affiliation: Department of Dental Biomaterials Science, Dental Research Institute, College of Dentistry, Seoul National University, Korea. ykleedm@snu.ac.kr
authors.forename: Yong-Keun
authors.initials: YK
authors.lastname: Lee
authors.forename: Huan
authors.initials: H
authors.lastname: Lu
authors.forename: John M
authors.initials: JM
authors.lastname: Powers
mesh_terms: D000704:Analysis of Variance; D003116:Color; D020770:Compomers; D003188:Composite Resins; D003793:Dental Restoration, Permanent / Q000379:methods; D005899:Glass Ionomer Cements / Q000737:chemistry; D008422:Materials Testing; D055095:Optics and Photonics; D013053:Spectrophotometry; D013997:Time Factors
chemical_list: D020770:Compomers; D003188:Composite Resins; D005899:Glass Ionomer Cements