title: Color and optical properties of resin-based composites for bleached teeth after polymerization and accelerated aging.
abstract: OBJECTIVE
  To determine changes in color and optical properties after polymerization and accelerated aging of white resin-based composites (RBCs) used to restore bleached teeth and compare them with those of conventional shades.
  
  
  METHODS
  Four white shades and two conventional shades (A2, A3) of two different brands of RBCs (Vitalescence, Synergy) were measured before and after polymerization and after accelerated aging for 150 kJ/m2. Color was measured according to CIE L*a*b* color scale on a reflection spectrophotometer, and scattering coefficient, absorption coefficient, contrast ratio and translucency parameter were calculated.
  
  
  RESULTS
  After curing, the color change ( E*) of white RBC was not significantly higher than that of conventional shade (P= 0.05). Color change after curing was positively influenced by the change of K (beta = 0.55), and negatively influenced by the changes of L*, b* and S (beta = -0.34, -0.95 and -0.70, respectively). After aging for 150 kJ/m2, the color changes of white RBCs were 2.4 and 5.8, and those of conventional shade were 1.7 and 2.9, respectively. Higher a* and b* values had a negative influence on the color change for both polymerization and aging.
authors.affiliation: Department of Dental Biomaterials, College of Dentistry, Seoul National University, Korea.
authors.forename: Y K
authors.initials: YK
authors.lastname: Lee
authors.forename: J M
authors.initials: JM
authors.lastname: Powers
mesh_terms: D003116:Color; D003188:Composite Resins / Q000737:chemistry; D003793:Dental Restoration, Permanent; D016014:Linear Models; D008422:Materials Testing; D055095:Optics and Photonics; D011108:Polymers / Q000737:chemistry; D019279:Resin Cements; D013053:Spectrophotometry; D018709:Statistics, Nonparametric; D013997:Time Factors; D014073:Tooth Bleaching
chemical_list: D003188:Composite Resins; D011108:Polymers; D019279:Resin Cements; C452441:Synergy composite resin; C452440:Vitalescence composite resin