Abstract
The purpose of this study was to evaluate, in vitro, the bond strength of brackets bonded to premolars previously subjected to bleaching with a 35% hydrogen peroxide. Twenty one healthy premolars were selected and randomly divided into three groups (n = 7). Group I (G1) included teeth that were not submitted to bleaching. The enamel surfaces of Groups II (G2) and III (G3) were submitted to a bleaching process with 35% hydrogen peroxide (Whiteness HP Maxx). On Group II (G2), after bleaching, the teeth were stored for 24 hours in distilled water at 98.6 °F, and then, premolar metallic brackets were bonded using Transbond XT (3M) resin. Group III (G3) was submitted to the same procedure seven days after bleaching. After bonding, all teeth were stored in distilled water at 98.6 °F for 24 hours. All groups were submitted to a traction test using an EMIC DL2000 universal testing machine at a speed of 0.5 mm/min. The bracket resistance to debonding was compared between the groups by the Kruskal-Wallis nonparametric test (p < 0.05) and it was verified that the bleaching agent significantly reduced bracket adhesion when bonded 24 hours after bleaching. However, seven days after bleaching, there was no significant difference on the resistance to debonding among groups G1 (19,52 kgf) and G3 (18,44 kgf), meaning that it is necessary to wait longer after bleaching to bond brackets.
Highlights
ObjectiveThe purpose of this study was to evaluate, in vitro, the bond strength of brackets bonded to premolars previously subjected to bleaching with a 35% hydrogen peroxide
Prietsch[14] concluded that dental bleaching with a 35% hydrogen peroxide reduces bond strength after 24 hours, suggesting that a period of seven days should be waited after bleaching
When the bracket debonding strength was confronted with the Control group and the group where bonding was performed seven days after bleaching (18.44 kgf), it was noticed that there was no statistically significant differences
Summary
The purpose of this study was to evaluate, in vitro, the bond strength of brackets bonded to premolars previously subjected to bleaching with a 35% hydrogen peroxide. Resultados e Conclusão: a resistência à descolagem dos braquetes foi comparada entre os grupos por meio da utilização do teste não paramétrico Kruskall Wallis (p < 0,05), verificando-se que o agente clareador reduziu significativamente a adesão dos braquetes quando colados 24 horas após o clareamento. Evaluation of the influence of dental bleaching with 35% hydrogen peroxide in orthodontic bracket shear bond strength. Prietsch[14] concluded that dental bleaching with a 35% hydrogen peroxide reduces bond strength after 24 hours, suggesting that a period of seven days should be waited after bleaching. Due to the increasing demand of adult patients for orthodontic treatment, associated to increasing care for dental esthetic, it is relevant to perform an evaluation of the influence of bleaching with a 35% hydrogen peroxide on the bond strength of orthodontic brackets. The teeth were, randomly divided into three groups (n=7), according to waiting period post-bleaching (24 hours and 7 days) (Table 1)
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