title: Composite resin bond strength after enamel bleaching.
abstract: This study evaluated the effect of enamel bleaching with a commercial product on the sheer bond strength of a composite resin. A total of 45 human extracted permanent molars were used. A flat enamel surface was obtained with 600-grit SiC paper. The teeth were then randomly distributed into three groups of 15 teeth each: Group 1: Enamel etching with 37% phosphoric acid gel (Coe) for 60 seconds, placement of an unfilled resin (Coe) thinly applied with a brush and a composite resin (Occlusin); Group 2: Enamel bleaching (Rembrandt Lighten Bleaching Gel, Den-Mat) for one hour, etching for 60 seconds and placement of unfilled and composite resins. Group 3: Enamel bleaching for 24 hours, etching for 60 seconds, and placement of unfilled and composite resins. A nylon ring over the etched enamel retained the composite resin. The teeth were thermocycled (X100) and sheared with a knife-edged blade in an Instron machine running at a cross-head speed of 1 mm/min. The results in MPa were: Group 1: 12.86 +/- 4.83, Group 2: 12.33 +/- 2.95, and Group 3: 7.67 +/- 1.98. An ANOVA revealed that Groups 1 and 2 were significantly different from Group 3 (P < 0.001). Fracture within the enamel occurred in 53% in Group 1, 33% in Group 2, and 0% in Group 3. The study reveals that the shear bond strength of composite resins is significantly reduced after enamel bleaching for 24 hours.
authors.affiliation: Department of Restorative Dentistry, University of Texas, Health Science Center at San Antonio 78284-7888.
authors.forename: F
authors.initials: F
authors.lastname: García-Godoy
authors.forename: W W
authors.initials: WW
authors.lastname: Dodge
authors.forename: M
authors.initials: M
authors.lastname: Donohue
authors.forename: J A
authors.initials: JA
authors.lastname: O'Quinn
mesh_terms: D000704:Analysis of Variance; D000077463:Carbamide Peroxide; D003188:Composite Resins; D001840:Dental Bonding; D003743:Dental Enamel / Q000737:chemistry / Q000187:drug effects*; D004338:Drug Combinations; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates; D010545:Peroxides / Q000009:adverse effects*; D011140:Polyurethanes; D013718:Tensile Strength; D014073:Tooth Bleaching / Q000009:adverse effects*; D014508:Urea / Q000009:adverse effects / Q000031:analogs & derivatives*; D014520:Urethane
chemical_list: D003188:Composite Resins; D004338:Drug Combinations; D008689:Methacrylates; D010545:Peroxides; D011140:Polyurethanes; C056413:Occlusin; C081715:Coe Bond; D000077463:Carbamide Peroxide; D014520:Urethane; D014508:Urea