The Effect of Surface Treatments and Bonding Agents on the Shear Bond Strengths of Orthodontic Brackets Bonded to Aged Composite Resin Restorations

To compare the mean bond strengths and mode of bond failure, in vitro, of five bonding systems (MIP 1, Plastic Conditioner2, Assure2, Scotchbond3, and Transbond XT 1), when bonding an orthodontic bracket to an artificially-aged composite resin restoration, with and without mechanical surface preparation with a diamond bur. Methods: Class V buccal composite resin restorations were prepared in 240 upper right central incisor dentoform teeth. The restorations were artificially aged for 35 days, bonded with metal brackets, stored in distilled water at 37°C for 30 days, thermocycled for 500 cycles, and subsequently debonded with an Instron universal testing machine. Results: The mean bond strengths for Transbond, MIP, Plastic Conditioner, Assure, and Scotchbond groups were 12.1, 12.3, 13.3, 17.2, and 17.7 MPa respectively. The mean bond strengths for Transbond+Diamond, MIP+Diamond, Plastic Conditioner+Diamond, Assure+Diamond, and Scotchbond+Diamond groups were 18.5, 16.4, 19.1, 19.5, and 20.7 MPa respectively. ANOVA revealed a statistically significant difference (P ≤0.05) among the groups. Conclusions: Mechanically roughening the surface of a composite resin restoration with a diamond bur, provided significantly greater bond strengths, regardless of the bonding resin used. However, Assure and Scotchbond, without diamond bur preparation, provided similar bond strengths to Transbond, MIP and Plastic Conditioner, with diamond bur preparation. 1 3M Unitek, Monrovia CA 2 Reliance Orthodontic Products, Itasca IL 3 3M ESPE, St. Paul MN i