title: Spectrophotometric and visual evaluation of vital tooth bleaching employing different carbamide peroxide concentrations.
abstract: OBJECTIVE
  The aim of the present study was to assess the hypothesis that the efficiency of vital tooth bleaching depends on the concentration of carbamide peroxide agents.
  
  
  METHODS
  The front teeth of 30 subjects were bleached at home with 10%, 17% or 0% (control) carbamide peroxide for 1 week in a double-blind study design. Tooth shades were determined in the LCH color space employing a visual shade matching system and a spectrophotometer. Differences in lightness (Deltal), chroma (Deltac) and hue (Deltah) were measured to assess the treatment process. After 2 weeks of no treatment, tooth shades were evaluated again to assess stability of the resultant shade.
  
  
  RESULTS
  First-time changes of shade values could be observed after 3 days in the 17% group and after 7 days in the 10% group. After 1 week, in both the 17% group (Deltal: 2.80, Deltac: -3.33, Deltah: 0.60) and the 10% group (Deltal: 2.61, Deltac: -2.54, Deltah: 0.09), values for lightness and chroma were significantly different from the control (Deltal: 0.13, Deltac: 0.14, Deltah: 0.21, p<0.05) with no difference between the test groups (p>0.05). Two weeks after treatment, a rebound of shade values could be observed in the test groups (p<0.05).
  
  
  CONCLUSIONS
  The study indicates that higher concentration bleaching agents might whiten teeth faster with major changes in lightness and chroma. However, by bleaching daily for 1 week, similar effects can be achieved with both a high and a low concentration agent. After treatment, a regression of the resultant shade has to be expected.
authors.affiliation: Department of Operative and Preventive Dentistry, University of Bonn, Welschnonnenstrasse 17, 53111 Bonn, Germany. andreas.braun@uni-bonn.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Braun
authors.forename: Søren
authors.initials: S
authors.lastname: Jepsen
authors.forename: Felix
authors.initials: F
authors.lastname: Krause
mesh_terms: D000077463:Carbamide Peroxide; D003116:Color; D003124:Colorimetry; D004311:Double-Blind Method; D004338:Drug Combinations; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D016877:Oxidants / Q000008:administration & dosage*; D010545:Peroxides / Q000008:administration & dosage*; D013053:Spectrophotometry; D014070:Tooth / Q000033:anatomy & histology / Q000187:drug effects*; D014073:Tooth Bleaching / Q000379:methods*; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives*
chemical_list: D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea