The effect of nonvital bleaching on the shear bond strength of composite resin using three adhesive systems.
OBJECTIVE
To evaluate the effect of nonvital bleaching on the shear bond strength of composite resin using three adhesive systems.


METHODS
Two hundred seventy bovine teeth were assigned to 3 groups (n = 90): SP, paste of sodium perborate and water; CP, 37% carbamide peroxide; CO, control group (no treatment). After the bleaching treatment, the teeth in each group were cut into enamel (E) and dentin (D) sections. The teeth were embedded in polyester resin and polished in order to obtain a flat E or D surface. Each group was divided into 6 subgroups (n = 15) according to substrate (E and D) and adhesive system: SB, Single Bond (solvent: water/alcohol); PB, Prime & Bond NT (solvent: acetone); CLF, Clearfil SE Bond (solvent: water). The adhesive system was applied on each flat surface according to the manufacturer's instructions and a cylinder of composite resin Z-250 was overlaid. The specimens were stored in distilled water for 7 days at 37 degrees C. The SBS test was performed in a universal testing machine with crosshead speed of 0.5 mm/min. The data obtained (in MPa) were statistically analyzed with two-way ANOVA and Tukey's test (p < or = 0.05).


RESULTS
The bleaching treatment influenced the SBS, regardless of the adhesive system used. On enamel, the SP and CP bleaching treatments reduced the SBS values. On dentin, the SP bleaching agent reduced the SBS values, but the CP bleaching did not.


CONCLUSIONS
Nonvital bleaching treatment with sodium perborate may adversely affect shear bond strength of composite resin for both enamel and dentin. Similar effects can be expected from 37% carbamide peroxide bleaching agent on enamel but not dentin bonding strength. The use of water/alcohol and acetone-based adhesive systems cannot reverse the effects of bleaching treatments on bond strengths.
Shinohara
Mirela Sanae
MS
Department of Restorative Dentistry, School of Dentistry of Piracicaba, University of Campinas, Piracicaba, São Paulo, Brazil.
Peris
Alessandra Rezende
AR
Rodrigues
José Augusto
JA
Pimenta
Luiz André Freire
LA
Ambrosano
Gláucia Maria Bovi
GM
D000704:Analysis of Variance; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate; D001881:Borates; D000077463:Carbamide Peroxide; D002417:Cattle; D003188:Composite Resins; D001840:Dental Bonding; D003799:Dental Stress Analysis; D004338:Drug Combinations; D008422:Materials Testing; D016877:Oxidants; D010545:Peroxides; D011109:Polymethacrylic Acids; D019279:Resin Cements; D033081:Shear Strength; D014073:Tooth Bleaching; D019553:Tooth, Nonvital; D014508:Urea / Q000031:analogs & derivatives*
D001881:Borates; C438313:Clearfil SE Bond; D003188:Composite Resins; D004338:Drug Combinations; C444701:Filtek Z250; D016877:Oxidants; D010545:Peroxides; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; C115612:single bond; D000077463:Carbamide Peroxide; D017438:Bisphenol A-Glycidyl Methacrylate; D014508:Urea; C027707:sodium perborate