Influence of various types of surface modifications on the shear bond strength of orthodontic brackets on Y-TZP zirconia ceramics

Abstract

The aim of this study was to investigate the bonding properties of metal orthodontic brackets and surface modifications applied to the surface of zirconia samples. Zirconia samples were divided into 4 groups according to surface modifications: group I, Er:YAG laser; group II, Nd:YAG laser, group III, air abrasion with silica-coated aluminum oxide; and group IV, hydrofluoric acid. After the application of surface modifications, central incisor brackets were bonded to zirconia surface and then subjected to thermocycling 2000× between 5 and 55 °C. The bonding properties of each sample were evaluated using a universal testing machine. The nonparametric Kruskal–Wallis and Mann–Whitney U statistical tests were applied to analyze the significant differences among and between the groups. The results showed that surface modifications significantly affected shear bond strength. Shear bond strength of group III (7.42 MPa) was significantly higher than those of other groups. Group IV (3.58 MPa) was significantly lower than those of other groups. Group III seems to be the most suitable surface treatment to be applied to zirconium surfaces in terms of high bond strength and safety. Group II and group III can be considered as more suitable alternatives group IV.