In-vitro study of the adhesive strengths of brackets on metals, ceramic and composite. Part 2: Bonding to porcelain and composite resin.

In addition to part 1 of the study, the present paper investigated more than 25 resin/conditioner combinations with respect to their bond strengths to porcelain and composite resin. For that purpose stainless steel lingual buttons were bonded with the various adhesives and their shear bond strengths and types of bond failure were determined after 24 hours. All specimens were air-abraded with 50 microns Al2O3 for 2 or 4 seconds by means of a Microetcher before bonding. Results show that, on the porcelain, and composite under investigation, several materials yield bond strengths which are similar to or higher than what is achieved with the conventional acid etch technique on enamel. Maximum adhesive strength is not always desirable, however, for bonding brackets. The type of bond failure and the risk of irreversible damage to the bonded material have also to be taken into consideration.