Resumo

SANCHEZ TITO, Marco Antonio  e  KUONG GOMEZ, Nelly. Effect of 40% hydrogen peroxide on the shear bond strength of metallic brackets. Rev. Estomatol. Herediana [online]. 2017, vol.27, n.2, pp.81-87. ISSN 1019-4355.  http://dx.doi.org/https://doi.org/10.20453/reh.v27i2.3138.

Objectives: To evaluate the effect of a 40% hydrogen peroxide bleaching agent upon the shear bond strength of metallic brackets, bonded at different time intervals. Materials and Methods: 60 upper premolars were randomly assigned to 4 groups, with 15 in each group. In group I the brackets were bonded 1 hour after the teeth were subjected to bleaching. In group II the brackets were bonded after 7 days, and in group III after 14 days. One group served as a control and did not receive the bleaching treatment. The shear bond strength was measured by a universal testing machine and the Adhesive Remnant Index (ARI) rate was used to assess the interface where the fault was produced. Results: The results show that bleaching significantly reduces the adhesive strength of the brackets (p<0.05). The strength necessary to debond the brackets in group III (17.95 ± 1.76 MPa) was similar to that which was required in the control group (18.03 ± 3.08 MPa). Groups I and II presented low values (13.37 ± 2.09 MPa and13.58 ±1.75 MPa respectively). Significant differences were found in the ARI scores (p<0.05).Conclusions:The use of40% hydrogen peroxide as a bleaching agent reduces the adhesive strength of the brackets when they were bonded before 14 days of bleaching procedure.

Palavras-chave : Shear bond strength; bleaching agents; metalic brackets; dental bonding.