title: Effect of carbamide peroxide bleaching gel concentration on the bond strength of dental substrates and resin composite.
abstract: OBJECTIVE
  This study evaluated the effect of bleaching gel containing 10%, 15% and 20% carbamide peroxide (CP) on the bond strength of dental enamel or dentin and resin composite restorations.
  
  
  METHODS
  The buccal surfaces of 12 bovine tooth crowns were conditioned with 37% phosphoric acid, and the adhesive resin Single Bond 2 and the resin composite Filtek Z350 were used to perform the restorations. The blocks were sectioned to obtain bar specimens. Each specimen group (enamel-E, dentin-D) was divided into four subgroups (n=15): S-artificial saliva; 10-10% CP bleaching; 15-15% CP bleaching; 20-20% CP bleaching. CP was applied for six hours daily for two weeks. The specimens were submitted to the sigma test in a universal testing machine. The data were analyzed by one-way ANOVA and the Tukey post-hoc test and a correlation analysis (r) was performed.
  
  
  RESULTS
  For Group E, the mean value (+/- standard-deviation) was 21.86 (+/- 6.03)a, 18.91 (+/- 8.31)ab, 15.43 (+/- 7.44)b and 10.6 (+/- 4.94)c for ES, E10, E15 and E20, respectively. For Group D, the a values were 34.73 (+/- 4.68)a, 35.12 (+/- 13.43)a, 29.67 (+/- 6.84)ab and 24.56 (+/- 6.54)b for DS, D10, D15 and D20, respectively. A negative correlation between the CP concentration and mean values was observed for both the enamel (r=-0.95) and dentin (r=-0.85) groups.
  
  
  CONCLUSIONS
  In the current study, the bond strength of the restoration to enamel and the restoration to dentin were influenced by the application of CP and was dependent on the CP concentration in the bleaching gel.
authors.affiliation: Department of Restorative Dentistry, São Paulo State University, SP, Brazil. daphnecbarcellos@hotmail.com
authors.forename: Daphne Camara
authors.initials: DC
authors.lastname: Barcellos
authors.forename: Paula
authors.initials: P
authors.lastname: Benetti
authors.forename: Virgílio Vilas Boas
authors.initials: VV
authors.lastname: Fernandes
authors.forename: Márcia Carneiro
authors.initials: MC
authors.lastname: Valera
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D000077463:Carbamide Peroxide; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D008422:Materials Testing; D016877:Oxidants / Q000008:administration & dosage / Q000737:chemistry*; D010545:Peroxides / Q000008:administration & dosage / Q000737:chemistry*; D010756:Phosphoric Acids / Q000737:chemistry; D011897:Random Allocation; D012464:Saliva, Artificial / Q000737:chemistry; D013314:Stress, Mechanical; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014073:Tooth Bleaching; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D016877:Oxidants; D010545:Peroxides; D010756:Phosphoric Acids; D012464:Saliva, Artificial; C533204:filtek Z350; C115612:single bond; D000077463:Carbamide Peroxide; D017438:Bisphenol A-Glycidyl Methacrylate; D014508:Urea; C030242:phosphoric acid