Evaluation of shear strength in metallic brackets bonded to ceramic surface

BACKGROUND: Brackets adhesion in ceramic surfaces has increasing relevance because adults, who usually have ceramic prostheses, are requiring orthodontic treatment. Evaluate the shear strength using different adhesive protocols in metal brackets bounded to ceramic surfaces and the remaining resin index (ARI) after its removal. METHODS: Sixty cylinders were manufactured in metal and ceramic and divided into: G1 - hydrofluoric acid + 10% Silane; G2 - blasting with aluminum oxide + Silane; G3 - hydrofluoric acid 10% + Single Bond Universal and G4 - blasting with aluminum oxide + Single Bond Universal. After thermal cycling, the samples were submitted to shear bond strength test. The ceramic surfaces were then classified by ARI. The data were analyzed with Kruskal-Wallis test. RESULTS: The average shear strengths were: G1 = 24.2 MPA; G2 = 21.3 MPA; G3 = G4 = 19.1 MPA to 14.2 MPA. There were differences between all groups (P<0.05) except for G3 (P>0.05). Regarding to ARI, there was no difference among groups (P>0.05). CONCLUSIONS: Single Bond universal treated with blasting aluminum oxide had the best performance, and promoted good shear strength, it caused less cohesive damage to the ceramic.