Purpose: To evaluate the effect of various porcelain surface preparations on the shear bond strength of orthodontic brackets bonded to feldspathic metal ceramic porcelains and to observe the porcelain surfaces after each preparation. Materials and Methods: Sixty-four porcelain-fused-to-nonprecious-metal specimens were divided into four groups as follows. Group 1: glazed porcelain without surface preparation as a control group; group 2: porcelain surface treated with intraoral sandblasting; group 3: porcelain surface treated with Nd:YAG laser etching; group 4: porcelain surface etched with 9.5% hydrofluoric acid. One representative specimen from each group was observed under SEM after surface preparation. Silane coupling agent and System 1+ adhesive resin were applied to the surface-treated porcelain specimens. All specimens were stored in distilled water at 37°C for 24 h. Shear bond strength was tested with an Instron testing machine. Results: The mean shear bond strength achieved on surface-treated porcelain specimens was significantly greater than in the control group (p < 0.05). No significant difference was observed among the mean shear bond strengths of three surface-treated groups. SEM demonstrated that all three surface preparations created micromechanical retention. Conclusion: This study indicates that preparing porcelain surfaces by the methods described here increases the shear bond strength of orthodontic brackets bonded to porcelain surfaces.
Keywords: porcelain surface preparation, shear bond strength, orthodontic bracket, Nd:YAG laser, sandblasting, hydrofluoric acid etching