title: Color changes of resin composites in the reflectance and transmittance modes.
abstract: OBJECTIVE
  The objective of this study was to evaluate the changes in color and color coordinates after accelerated aging of resin composites depending on the measuring modes of reflectance and transmittance.
  
  
  METHODS
  Color of seven resin composites (1-mm thick specimens) was measured in the reflectance mode and in the transmittance mode. After the baseline color measurement, the specimens were aged for total energy of 150 kJ/m2. Color change after aging was calculated in the reflectance mode and in the transmittance mode. Based on the data of A2 shade composites, the influence of measuring mode on the color change (DeltaEab*) and changes in three color coordinates (DeltaL*, Deltaa* and Deltab*) after aging was analyzed by ANOVA (p<0.01).
  
  
  RESULTS
  Measuring mode influenced DeltaEab*, DeltaL* and Deltaa* values. There were significant correlations between the color changes measured in the reflectance mode and in the transmittance mode (r=0.91).
  
  
  CONCLUSIONS
  The color changes in the transmittance mode can roughly be estimated based on the reflected color changes.
authors.affiliation: Department of Dental Biomaterials Science, Dental Research Institute, College of Dentistry, Seoul National University, 28 Yeongeon-dong, Jongro-gu, Seoul, Republic of Korea. ykleedm@snu.ac.kr
authors.forename: Yong-Keun
authors.initials: YK
authors.lastname: Lee
authors.forename: John M
authors.initials: JM
authors.lastname: Powers
mesh_terms: D000704:Analysis of Variance; D003116:Color; D003124:Colorimetry / Q000379:methods; D003188:Composite Resins; D008027:Light; D013499:Surface Properties; D013997:Time Factors
chemical_list: D003188:Composite Resins