title: Color stability of resin cements after accelerated aging.
abstract: OBJECTIVE
  To study the color stability of different resin cements after accelerated aging.
  
  
  METHODS
  The color stability of a self-adhesive resin cement (Unicem), one resin-based composite cement (Variolink II), one compomer cement (Principle) and one hybrid ionomer cement (FujiCEM) was studied. Two curing modes of Unicem (self-cured and dual-cured) and Variolink II (light-cured and dual-cured) were also tested. Specimen disks (n = 5) were prepared with a polytetrafluoroethylene split mold and subjected to accelerated aging for 150, 300 and 450 kJ/m2. Color (CIELAB system) was measured before and after each of the three aging cycles on a reflection spectrophotometer. deltaE*, deltaL*, deltaC* and deltaH* were calculated and analyzed by ANOVA.
  
  
  RESULTS
  The largest color change occurred during the first 150 kJ/m2 aging cycle, where deltaE* values ranged from 5.6 to 20.5 with Principle showing the least color change and FujiCEM the most. The color changes of all the tested materials were perceptible. The greatest changes were recorded for deltaL* and/or deltaC*. All specimens became significantly rougher and showed evidence of cracking and degradation after aging except Variolink II.
authors.affiliation: Houston Biomaterials Research Center, Department of Restorative Dentistry and Biomaterials, University of Texas Dental Branch at Houston, 6516 M.D. Anderson Blvd., DBB 467, Houston, TX 77030-3402, USA. huan.lu@uth.tmc.edu
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; D003124:Colorimetry; D020770:Compomers; D005899:Glass Ionomer Cements; D044367:Phase Transition; D017797:Prosthesis Coloring; D019279:Resin Cements; D013997:Time Factors
chemical_list: D020770:Compomers; C494890:FugiCEM; D005899:Glass Ionomer Cements; C483701:Rely X Unicem; D019279:Resin Cements; C465382:principle compomer; C103502:Variolink