title: Effect of Accelerated Aging on Color Change of Direct and Indirect Fiber-Reinforced Composite Restorations.
abstract: OBJECTIVE
  The aim of this study was to assess the effect of artificial accelerated aging (AAA) on color change of direct and indirect fiber-reinforced composite (FRC) restorations.
  
  
  METHODS
  Direct (Z250) and indirect (Gradia) composite resins were reinforced with glass (GF) and polyethylene fibers (PF) based on the manufacturers' instructions. Forty samples were fabricated and divided into eight groups (n=5). Four groups served as experimental groups and the remaining four served as controls. Color change (ΔE) and color parameters (ΔL*, Δa*, Δb*) were read at baseline and after AAA based on the CIELAB system. Three-way ANOVA and Tukey's test were used for statistical analysis.
  
  
  RESULTS
  Significant differences were found in ΔE, ΔL*, Δa* and Δb* among the groups after AAA (P<0.05). Most of the studied samples demonstrated an increase in lightness and a red-yellow shift after AAA.
  
  
  CONCLUSIONS
  The obtained ΔE values were unacceptable after AAA (ΔE≥ 3.3). All indirect samples showed a green-blue shift with a reduction in lightness except for Gradia/PF+ NuliteF.
authors.affiliation: Associate Professor, Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran; Department of Operative Dentistry, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Masoumeh Hasani
authors.initials: MH
authors.lastname: Tabatabaei
authors.affiliation: Assistant Professor, Department of Operative Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Farnaz
authors.initials: F
authors.lastname: Farahat
authors.affiliation: Assistant Professor, Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran; Department of Operative Dentistry, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Elham
authors.initials: E
authors.lastname: Ahmadi
authors.affiliation: Dentist, Private Practice.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Hassani
keywords: Aging; Color; Composite Resins