Effect of various surface treatment procedures on shear bond strength of stainless-steel orthodontic brackets to composite resin

Abstract Aims: The aim of this study was to evaluate the shear bond strength of brackets bonded to composite restorations using four types of surface conditioning procedure. Materials and Methods: Thirty two cylindrical cavities were made at the center of self-cured acrylic resin blocks. All cavities were then filled with composite resin. The specimens were randomly divided into four groups. Group one: Composite surface was acid etched with 37% phosphoric acid. Group two: After using 37% phosphoric acid, bonding agent was applied and cured. Group three: After using 37% phosphoric acid silane coupling agent was applied then bonding agent was applied. Group Four: The composite surface roughened with a diamond bur, and then 37% phosphoric acid was applied. Brackets were bonded onto the composite prepared samples with Transbond XT. Shear Bond Strength was measured by a universal testing machine. KruskalWallis test was utilized for data analysis. Results: There was a significant difference between the four groups. The highest bond strength was that of Group 3. Group 1 had the lowest bond strength. Conclusions: Roughening the composite surface before acid etching was effective to improve the bond strength of orthodontic brackets to composite restorations. Addition of silane before bonding agent application result in highest bond strength.