title: The effect of bleaching agents on the microhardness of dental aesthetic restorative materials.
abstract: 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.
authors.affiliation: Department of Prosthodontics, Marmara University, Dentistry Faculty, Istanbul, Turkey. begum.t@usa.net
authors.forename: S B
authors.initials: SB
authors.lastname: Türker
authors.forename: T
authors.initials: T
authors.lastname: Biskin
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D000077463:Carbamide Peroxide; D003188:Composite Resins / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing; D003776:Dental Porcelain / Q000737:chemistry; D003793:Dental Restoration, Permanent; D004338:Drug Combinations; D004955:Esthetics, Dental; D005782:Gels; D005899:Glass Ionomer Cements / Q000737:chemistry; D006244:Hardness; D006801:Humans; D016877:Oxidants / Q000737:chemistry*; D010545:Peroxides / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D013499:Surface Properties; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D003188:Composite Resins; D003764:Dental Materials; D004338:Drug Combinations; C079765:Fuji II LC cement; D005782:Gels; D005899:Glass Ionomer Cements; D016877:Oxidants; D010545:Peroxides; D011145:Polyvinyls; D017680:Potassium Compounds; C112939:Rembrandt Lighten; D012117:Resins, Synthetic; D003776:Dental Porcelain; C016447:feldspar; D000077463:Carbamide Peroxide; D017438:Bisphenol A-Glycidyl Methacrylate; D014508:Urea