Improving shear bond strength of metallic brackets after whitening

Juan Fernando ARISTIZÁBAL, Angela Patricia Polanía GONZÁLEZ, James A. MCNAMARA

Objective: To evaluate a protocol for bonding metallic brackets after bleaching with hydrogen peroxide (HP). Methods: 60 extracted maxillary premolar were randomly divided into an unbleached control group and two groups bleached with a solution of 35% hydrogen peroxide prior to bonding. The teeth in one of the treated groups were bonded immediately after bleaching; while the other group was treated with 10% sodium ascorbate immediately after bleaching and before bonding. The teeth in all groups were stored in an artificial saliva solution for 7 days after bonding. The shear bond strength data was measured in megapascals (MPa) and the fail attempts were verified. The significance level was established at p<0.05. Results: The unbleached group, in which brackets were bonded to untreated enamel, had the highest bond strength values (11.0±5.7MPa) in comparison to the bleached group (7.14±40MPa), in which brackets were bonded to recently bleached enamel. Slightly improved bond strength was observed in the antioxidant group (8.13±5.4MPa), in which the teeth were bleached and then the antioxidant was applied to the teeth before bonding. Unbleached and bleached groups showed statistically significant difference for shear bond strength (p=0.03) and load strength (p=0.03); no significant differences were noted between unbleached and antioxidant groups (p=0.52). Conclusion: The antioxidant treatment applied immediately after bleaching was effective in reversing the reduction in shear bond strength of brackets after tooth bleaching.

Keywords: Orthodontics. Tooth bleaching. Shear bond strength. Hydrogen peroxide. Sodium ascorbate.

How to cite: Aristizábal JF, González APP, McNamara JA. Improving shear bond strength of metallic brackets after whitening. Dental Press J Orthod. 2020 Sept-Oct;25(5):38-43. DOI: https://doi.org/10.1590/2177-6709.25.5.038-043.oar

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