title: Effects of five carbamide peroxide bleaching gels on composite resin microhardness.
abstract: The purpose of this study was to evaluate the effects of five home bleaching products containing 15-16% carbamide peroxide on the microhardness of microhybrid composite resin Z-250 (3M/Espe). A total of 72 specimens were fabricated in cylindrical acrylic matrices (4 x 2 mm), filled with composite resin and photo-activated for 40 seconds. They were divided in 6 study groups (n = 12), according to the bleaching product: Review (SS White), Magic Bleaching (Vigodent), Opalescence (Ultradent), Whiteness Perfect (FGM), Claridex (Biodinâmica), and a control group (not bleached). Specimens were exposed to 1 cc of bleaching gel for 6 hours daily for 2 weeks. The control group specimens were kept in artificial saliva throughout this time. All the specimens were then analyzed in a microhardness tester. Knoop hardness measurements were performed, and the results were submitted to parametric statistical analysis (analysis of variance and Tukey's test). Mean Knoop values and standard deviation were: baseline, 68.52a (4.28); control, 63.42b (7.16); Whiteness Perfect, 57.57c (1.81); Magic Bleaching, 57.22c (3.84); Opalescence, 57.03cd (4.00); Claridex, 53.64de (3.33); Review 51.45e (2.82). Identical letters mean statistical equality according to Tukey's test at the 5% significance level. The products significantly decreased Z-250 (3M/Espe) microhardness.
authors.affiliation: Department of Restorative Dentistry, Araçatuba Dental School-UNESP, Araçatuba, São Paulo, Brazil. alfbriso@foa.unesp.br
authors.forename: André L F
authors.initials: AL
authors.lastname: Briso
authors.forename: Inger T C
authors.initials: IT
authors.lastname: Tuñas
authors.forename: Letícia C A G
authors.initials: LC
authors.lastname: de Almeida
authors.forename: Vanessa
authors.initials: V
authors.lastname: Rahal
authors.forename: Glaucia M B
authors.initials: GM
authors.lastname: Ambrosano
mesh_terms: D000077463:Carbamide Peroxide; D003188:Composite Resins; D005782:Gels; D006245:Hardness Tests; D010545:Peroxides / Q000494:pharmacology*; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D003188:Composite Resins; D005782:Gels; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea