title: Effect of four different opalescence tooth-whitening products on enamel microhardness.
abstract: OBJECTIVE
  The purpose was to evaluate the effect of various Opalescence tooth-whitening products on enamel.
  
  
  METHODS
  Enamel blocks were exposed to Opalescence PF 10% Carbamide Peroxide (n = 10), Opalescence PF 20% Carbamide Peroxide (n = 10), Opalescence Trèswhite Supreme 10% Hydrogen Peroxide (n = 10) and Opalescence Quick PF 45% Carbamide Peroxide (n = 10) according to the manufacturer's instructions. The control group was enamel blocks (n = 10) kept in artificial saliva. The values were obtained before exposure and after the 14-days treatment period. Enamel blocks were kept in saliva between treatments. Indent marks on enamel blocks were examined using the scanning electron microscope for treatment effects.
  
  
  RESULTS
  All four different Opalescence products damaged enamel. The most damage was done when treated for a long period (112 hours). SEM images also showed damage to enamel by all 4 products. Opalescence with 10% and with 20% Carbamide Peroxide showed the highest damage, which also differed significantly (p < 0.05) from the saliva control group (p < 0.05; Tukey-Kramer Multiple comparison test).
  
  
  CONCLUSIONS
  All 4 Opalescence products damaged enamel. Higher damage was done by the 10% carbamide peroxide and 20% carbamide peroxide products because of the much longer exposure period (112 hours in comparison to 7 hours).
authors.affiliation: Oral and Dental Research Institute, Faculty of Dentistry, University of the Western Cape, Tygerberg, South Africa.
authors.forename: A
authors.initials: A
authors.lastname: Majeed
authors.forename: S R
authors.initials: SR
authors.lastname: Grobler
authors.forename: M H
authors.initials: MH
authors.lastname: Moola
authors.forename: R J
authors.initials: RJ
authors.lastname: Rossouw
authors.forename: T J W
authors.initials: TJ
authors.lastname: van Kotze
mesh_terms: D000077463:Carbamide Peroxide; D003743:Dental Enamel / Q000187:drug effects* / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D006244:Hardness; D006801:Humans; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000494:pharmacology*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D016877:Oxidants / Q000008:administration & dosage / Q000494:pharmacology*; D010545:Peroxides / Q000008:administration & dosage / Q000494:pharmacology*; D012464:Saliva, Artificial / Q000737:chemistry; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D012464:Saliva, Artificial; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide