title: Changes in scattering and absorption properties of esthetic filling materials after aging.
abstract: OBJECTIVE
  Assuming that color changes after aging are related to changes in translucency of materials, the purpose of the present study was to determine the correlation between the changes in color and the changes in scattering and absorption properties after accelerated aging with representative dental esthetic restorative materials: glass ionomer, resin-modified glass ionomer, compomer, and resin composite.
  
  
  METHODS
  Color was measured according to the CIELAB color scale in the transmittance and reflectance modes and used to calculate changes in color (deltaE*(ab)), color coordinates (deltaL*, delta a*, and delta b*), translucency parameter (deltaTP), scattering coefficient (deltaS), absorption coefficient (deltaK), and light reflectivity (deltaRI) after accelerated aging. Simple correlations between each pair of the changes in optical values were calculated, and multiple regression analysis was used to determine the parameters influencing the changes in color and color coordinates (p = 0.05).
  
  
  RESULTS
  In the resin composite and compomer, deltaS, deltaK, and deltaRI values were approximately zero, whereas deltaS was as high as 8.9 in the glass ionomer. For most comparisons, correlation coefficient (r) was between 0.700 and 0.997. DeltaL* was found to have a major influence on color changes, and deltaS, deltaTP, and deltaRI influenced deltaL*. Therefore, changes in scattering and absorption properties, after aging, were closely correlated with changes in color and color coordinates, especially in glass ionomer-based filling materials.
authors: Department of Dental Biomaterials Science, Dental Research Institute, College of Dentistry, Seoul National University, Seoul, Korea. ykleedm@snu.ac.kr
authors: Yong-Keun
authors: YK
authors: Lee
authors: Bum-Soon
authors: BS
authors: Lim
authors: Sang-Hoon
authors: SH
authors: Rhee
authors: Hyeong-Cheol
authors: HC
authors: Yang
authors: Yong-Kyu
authors: YK
authors: Lim