title: [Analysis of the color difference between discolored teeth and corresponding shade tabs in Vitapan Classical shade guide].
abstract: OBJECTIVE
  To analyze whether Vitapan Classical shade guide could be used to evaluate effectively the effect of tooth whitening.
  
  
  METHODS
  A total of 67 patients underwent Beyond cold light tooth whitening between February 2009 and July 2014. The effect of treatment was evaluated by Vitapan Classical shade guide. The percentage of discolored teeth that could not be matched by the aforementioned shade guide was calculated. By contrast, the color difference between discolored teeth and corresponding shade tabs was calculated for discolored teeth that could be matched by the shade guide.
  
  
  RESULTS
  Approximately 64% (16/25) of tetracycline teeth and 28% (17/61) of mottled-enamel teeth could not be matched using the Vitapan Classical shade guide, but yellow teeth were all matched, and the difference between any pair of teeth was statistically significant (P=0.000). For discolored teeth that could be matched, statistically significant difference was found in the ΔL*, Δb*, and ΔE between tetracycline and yellow teeth, as well as between tetracycline and mottled-enamel teeth. However, no statistically significant difference was found between mottled-enamel and yellow teeth. Moreover, no statistically significant difference was found in the Δa* among the three groups.
  
  
  CONCLUSIONS
  Vitapan Classical shade guide could not be used to evaluate effectively the effect of tooth whitening, especially for tetracycline and mottled-enamel teeth. The evaluating method should be improved.
authors.forename: Yingxin
authors.initials: Y
authors.lastname: Xu
mesh_terms: D003116:Color; D006801:Humans; D008027:Light; D014070:Tooth; D014073:Tooth Bleaching