title: Color and contrast ratio of resin composites for whitened teeth.
abstract: OBJECTIVE
  The purpose of this study was to determine the optical properties, color and contrast ratio (CR) of commercially available resin composites marketed for the restoration of whitened teeth.
  
  
  METHODS
  Twenty-six resin composites designed for restoration of whitened teeth and four shade B1 (control) were evaluated. Five resin composite disks (d=12mm, h=1.54mm) were fabricated for each shade of composite and were stored in water at 37 degrees C for at least 24h. A colorimeter was used to measure specimen color over both white and black backgrounds. CIELAB and CIExyY color spaces were used. The CIELAB color notation system provides values for L*a*b*. The CIExyY system provides lightness and chromaticity values, where Y represents lightness and xy chromaticity. The contrast ratio (CR) was assessed using, CIE xyY, of the specimens against black (Yb) and white (Yw) backgrounds, with CR=Yb/Yw. The data for L*, a*, b* and CR were analyzed by one-way ANOVA, Tukey's test, and the correlation L* and CR was analyzed by Pearson correlation test (alpha=0.05).
  
  
  RESULTS
  Significantly different L*, a*, b* values and CR were observed. Premise XL2 had the highest L* and CR values and Vit-l-escence PS had the lowest. Vit-l-escence PS had the highest a* value and Point 4XL2 had the lowest, Premise XL1 had the highest b* value and Supreme WB the lowest. The L* and CR correlation was positive and statistically significant.
  
  
  CONCLUSIONS
  Composites designated for whitened teeth have different levels of color and contrast ratio. Awareness of the optical properties of the composites allows the operator to choose the appropriate materials to mimic the remaining tooth structure.
authors.affiliation: Department of Restorative Dentistry, Oregon Health and Sciences University, Portland, OR 97239-3097, USA. dacostaj@hsu.edu
authors.forename: Juliana
authors.initials: J
authors.lastname: da Costa
authors.forename: Marcos
authors.initials: M
authors.lastname: Vargas
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Swift
authors.forename: Eric
authors.initials: E
authors.lastname: Anderson
authors.forename: Stephanie
authors.initials: S
authors.lastname: Ritter
mesh_terms: D003124:Colorimetry / Q000592:standards; D003188:Composite Resins / Q000737:chemistry* / Q000145:classification / Q000592:standards; D017267:Dental Prosthesis Design; D003793:Dental Restoration, Permanent / Q000379:methods*; D004955:Esthetics, Dental; D006801:Humans; D017797:Prosthesis Coloring; D014073:Tooth Bleaching; D014075:Tooth Discoloration / Q000145:classification* / Q000628:therapy
chemical_list: D003188:Composite Resins