الفهرس 
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Abstract
The aim of this study was to evaluate the shear bond strength (SBS) of ceramic brackets to glazed monolithic zirconia using three different bonding protocols, and subjected to thermocycling.
MATERIALS AND METHODS: Forty-five monolithic zirconia discs were sectioned, sintered and glazed, and subsequently embedded into acrylic resin. The specimens were randomly assigned to 3 groups (n = 15) to be treated by: (A) Air abrasion with 50 μm aluminum oxide particles + Assure Plus, (B) Air abrasion with 50 μm aluminum oxide particles + silane + Assure Plus (C) Air abrasion with 50 μm aluminum oxide particles + hydrofluoric acid etching + silane + Transbond XT Primer. Ceramic brackets were bonded to the zirconia discs using light cure-composite system. Following thermocycling of 500 cycles between 5° - 55° C, shear bond strength, failure mode and Adhesive Remnant Index were assessed.
RESULTS: group C showed the highest SBS (8.15 ± 2.40 MPa), most of the specimens presented adhesive failure between the adhesive and the bracket base. The second highest SBS was presented by group B (7.80 ± 2.80 MPa), with no statistical difference between group C and B. Failure mode in group B was mainly in form of mixed cohesive failure within the adhesive itself. The lowest shear bond strength was shown in group A (2.49 ± 0.74 MPa), using only Assure plus after sandblasting. All the specimens in group A showed adhesive failure between the zirconia and the adhesive, leaving all the adhesive on the bracket base.
CONCLUSIONS: Assure Plus + silane and the classical bonding protocol for porcelain achieved clinically acceptable SBS of ceramic brackets bonded to glazed zirconia. However Assure Plus + silane achieved better debonding characteristics.