title: Evaluation and comparison of bond strength to 10% carbamide peroxide bleached enamel following the application of 10% and 25% sodium ascorbate and alpha-tocopherol solutions: An in vitro study.
abstract: OBJECTIVE
  To evaluate and compare composite bond strength to carbamide peroxide bleached enamel following the application of 10% and 25% sodium ascorbate and alpha-tocopherol solutions.
  
  
  METHODS
  Sixty premolars were divided into six groups. Groups I and VI served as unbleached and bleached controls respectively. Groups II, III, IV and V served as the experimental groups and were subjected to 10% carbamide peroxide bleaching followed by 10 min application of 10% and 25% sodium ascorbate and 10% and 25% alpha-tocopherol solutions, respectively. Following composite bonding, shear bond strength was determined and the results were analyzed using ANOVA and Tukey highest significant difference test.
  
  
  RESULTS
  Only Group IV showed significantly lower bond strength when compared to Group I (unbleached control). When compared to Group VI (bleached control), except Group IV, groups II, III and V showed significantly higher bond strength. However, there was no statistically significant difference between the experimental groups corresponding to 10% and 25% and similar concentrations of sodium ascorbate and alpha-tocopherol solutions.
  
  
  CONCLUSIONS
  Following 10% carbamide peroxide bleaching, except 10% alpha tocopherol, 10 min application of 10% and 25% sodium ascorbate and 25% alpha-tocopherol solutions significantly improves the shear bond strength of composite resin to enamel.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Manipal University, Mangalore, Karnataka, India.
authors.forename: Asha
authors.initials: A
authors.lastname: Thapa
authors.forename: Pai Ar
authors.initials: PA
authors.lastname: Vivekananda
authors.forename: Manuel S
authors.initials: MS
authors.lastname: Thomas
keywords: Alpha-tocopherol solution; carbamide peroxide; shear bond strength; sodium ascorbate solution