The effect of bleaching agents on the microhardness of dental aesthetic restorative materials

J Oral Rehabil. 2002 Jul;29(7):657-61. doi: 10.1046/j.1365-2842.2002.00896.x.


This study investigated the effects of three home bleaching agents on the microhardness of various dental aesthetic restorative materials. The restorative materials were: feldspatic porcelain, microfilled composite resin and light-cured modified glass-ionomer cement and the bleaching agents Nite-White (16% carbamide peroxide), Opalescence (10% carbamide peroxide and carbapol jel) and Rembrandt (10% carbamide peroxide jel). A total of 90 restorative material samples were prepared 1 cm diameter and 6 mm thick and kept in distilled water for 24 h before commencing bleaching which was carried out for 8 h day-1 for 4 weeks. Microhardness measurements were then made using a Tukon tester. Statistically significant differences with respect to unbleached controls were found only for the feldspatic porcelain and microfilled composite resins (P <0.05) for Nite-White and Opalescence. All the bleaching agents decreased the microhardness of the porcelain and increased that of the light cured modified glass-ionomer cement. For the composite resin, whereas Nite-White increased its microhardness, the other bleaching agents decreased it. There were no significant differences between the bleaching agents for any of the restorative materials.

MeSH terms

  • Aluminum Silicates / chemistry
  • Analysis of Variance
  • Bisphenol A-Glycidyl Methacrylate / chemistry
  • Carbamide Peroxide
  • Composite Resins / chemistry
  • Dental Materials / chemistry*
  • Dental Polishing
  • Dental Porcelain / chemistry
  • Dental Restoration, Permanent*
  • Drug Combinations
  • Esthetics, Dental
  • Gels
  • Glass Ionomer Cements / chemistry
  • Hardness
  • Humans
  • Oxidants / chemistry*
  • Peroxides / chemistry
  • Polyvinyls / chemistry
  • Potassium Compounds / chemistry
  • Resins, Synthetic / chemistry
  • Surface Properties
  • Tooth Bleaching*
  • Urea / analogs & derivatives*
  • Urea / chemistry


  • Aluminum Silicates
  • Composite Resins
  • Dental Materials
  • Drug Combinations
  • Fuji II LC cement
  • Gels
  • Glass Ionomer Cements
  • Oxidants
  • Peroxides
  • Polyvinyls
  • Potassium Compounds
  • Rembrandt Lighten
  • Resins, Synthetic
  • Dental Porcelain
  • feldspar
  • Carbamide Peroxide
  • Bisphenol A-Glycidyl Methacrylate
  • Urea