The effect of green tea on the shear strength of brackets after home whitening treatment

This study, we evaluated the effect of green tea on the shear bond strength of metal orthodontic brackets to human enamel after home whitening treatment. Ninety premolars were selected and divided into six experimental groups: G1, no treatment (positive control); G2, whitening (negative control); G3, no whitening?+?10?% sodium ascorbate (SA) gel; G4, no whitening?+?10?% green tea (GT) gel; G5, whitening?+?SA; and G6, whitening?+?GT. The samples of G2, G5, and G6 were whitened with 10?% carbamide peroxide for 8?h daily, during 14?days at 37?°C. G3, G4, G5, and G6 were treated with the respective antioxidants (GT or SA) for 1?h at 37?°C. After the treatments, the brackets were bonded with Transbond XT. Then, the samples were tested in a universal testing machine and the adhesive remnant index (ARI) was examined under 40× magnification. Data were submitted to analysis of variance, Tukey’s and Dunnett’s tests (α?=?5?%). The averages (standard deviations) obtained were: G1, 17.6 (4.1); G2, 9.8 (3.6); G3, 18.1 (4.1); G4, 18.2 (4.7); G5, 14.9 (2.5); and G6, 14.8 (5.4). G2 had statistically lower values than the other groups. Concerning the ARI, all groups had a higher number of flaws type score 0 (no material adhered to the tooth). We conclude that the use of GT can be an alternative method to allow bracket bonding immediately after home whitening treatment.