Effect of antioxidant on orthodontic bracket bond strength after vital bleaching.

OBJECTIVES:: The objective of this study is to compare the neutralization effect of various antioxidant agents on the bond strength of composite resins on stainless steel and ceramic brackets immediately bonded to previously bleached teeth. MATERIALS AND METHODS:One hundred and sixty human maxillary premolars were used for the study. Teeth were divided into four groups (n = 40): Group 1 (control), Group 2 (bleached), Group 3 (sodium ascorbate), and Group 4 (tocopherol acetate). Each group was divided into two subgroups, one was bonded with stainless steel and other with ceramic brackets using 3M Transbond XT. Universal testing machine was used to determine the shear bond strength (SBS). RESULTS:Among the metal brackets, Group 1A had the highest SBS (12.18 + 1.41 MPa) and Group 2A had the least SBS (6.18 + 1.49 MPa). Weibull analysis indicated that bond strength for a 90% probability of failure was highest for Group 1A (13.99 MPa) and lowest for Group 2A (8.49 MPa). For ceramic brackets, Group 1B had the highest SBS (13.80 + 1.69 MPa) and Group 2B had the least SBS (8.05 + 1.85 MPa). Weibull analysis indicated that bond strength for a 90% probability of failure was highest for Group 1B (14.61 MPa) and lowest for Group 2B (8.85MPa). CONCLUSION:The in vitro study showed that bleaching reduced the SBS significantly, and this could be effectively reversed by the application of antioxidants in both metal and ceramic brackets.