title: [Metameric effect between natural teeth and resin teeth of A2 shade].
abstract: OBJECTIVE
  The aim of this study was to determine the metameric color differences between natural teeth and three brands of commercially available resin teeth.
  
  
  METHODS
  The spectral reflectance and color coordinates of natural teeth and three brands of commercially available resin teeth of A2 shade were measured with a spectrophotometer (PR-650) according to the CIE L*, a*, b* and CIE XYZ color scale relative to illuminant D65, A, cool white fluorescent (CWF) and ultraviolet (UV), and the metameric indices were calculated to determine the metameric color differences between natural teeth and resin teeth.
  
  
  RESULTS
  CIE L*, a*, b* values were influenced by the type of illuminants in both natural teeth and resin teeth. The pattern of spectral reflectance curves for natural teeth and resin teeth of A2 shade were different, while there were more than three crossing points among each curves, which meant the color of natural teeth and resin teeth of A2 shade might be the same under certain illuminant. The metameric indices between natural teeth and resin teeth of A2 shade were 3.48, 2.52 and 3.36 under illuminant A; 1.21, 1.90, and 2.79 under illuminant CWF; 1.59, 2.07, and 4.07 under illuminant UV. The metameric indices between resin teeth of different brand were 1.08, 0.10, and 1.01 under illuminant A; 1.46, 2.23, and 0.94 under illuminant CWF; and 2.55, 2.69, and 4.64 under UV.
  
  
  CONCLUSIONS
  Changes in optical properties of resin teeth of A2 shade relative to the different illuminants were different from those of natural teeth, the metameric effect between natural teeth and resin teeth of A2 shade were significant. Therefore, shade matching between natural teeth and resin teeth should be performed under more than one illuminant.
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, China.
authors.forename: Yan-ling
authors.initials: YL
authors.lastname: Duan
authors.forename: Xu
authors.initials: X
authors.lastname: Tong
authors.forename: Yu-kun
authors.initials: YK
authors.lastname: Meng
mesh_terms: D003116:Color; D003188:Composite Resins; D006801:Humans; D008029:Lighting; D009066:Mouth, Edentulous; D012117:Resins, Synthetic; D013053:Spectrophotometry
chemical_list: D003188:Composite Resins; D012117:Resins, Synthetic