title: In vitro colorimetric evaluation of the efficacy of various bleaching methods and products.
abstract: OBJECTIVE
  Various bleaching modalities are now offered to patients, either monitored by the dental office or self-directed, for which relative efficacy is unknown. The aim of this in vitro study was to evaluate the ability of different bleaching products and protocols to lighten enamel and dentin.
  
  
  METHODS
  Bovine tooth samples of standardized thickness (2.5 +/- 0.025 mm with similar dentin and enamel thicknesses) were prepared and stained with whole blood and hemolysate before being submitted to 11 different bleaching regimens: home bleaching using 10%, 15%, 16%, or 20% carbamide peroxide, power bleaching using 15% hydrogen peroxide, 30% hydrogen peroxide, or 25% carbamide peroxide with or without light activation, and over-the-counter bleaching strips containing 5.3% hydrogen peroxide. Colorimetric measurements were performed on each sample side, according to the CIE L*a*b* system, before and after staining as well as after each series of 5 bleaching sessions (number of applications varied from 5 to 20 times, according to the bleaching protocol).
  
  
  RESULTS
  All products and protocols produced a similar bleaching effect on enamel, while the home bleaching regimen proved largely superior to lighten dentin.
  
  
  CONCLUSIONS
  In-office bleaching techniques proved less efficient than home bleaching for removing stains deposited in dentin.
authors.affiliation: Department of Cariology and Endodontics, School of Dentistry, University of Geneva, Switzerland. didier.dietschi@medecine.unige.ch
authors.forename: Didier
authors.initials: D
authors.lastname: Dietschi
authors.forename: Sandrine
authors.initials: S
authors.lastname: Rossier
authors.forename: Ivo
authors.initials: I
authors.lastname: Krejci
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000077463:Carbamide Peroxide; D002417:Cattle; D003124:Colorimetry; D003742:Dental Devices, Home Care; D003743:Dental Enamel / Q000187:drug effects; D003804:Dentin / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D006861:Hydrogen Peroxide / Q000008:administration & dosage*; D016877:Oxidants / Q000008:administration & dosage*; D010545:Peroxides / Q000008:administration & dosage*; D014073:Tooth Bleaching / Q000379:methods*; D014075:Tooth Discoloration / Q000188:drug therapy; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives*
chemical_list: D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide