Evaluation of 24-Hour Shear Bond Strength of Resin Composite to Porcelain According to Surface Treatment

Purpose: The purpose of the present in vitro study was to examine shear bond strengths of resin composite to porcelain according to surface treatment. Materials and Methods: One hundred eight feldspathic porcelain blocks were prepared. Specimens were divided into nine surface treatment groups: sandblasting with 50- or 110-µm Al₂O₃, acid etching with hydrofluoric acid, applying silane agent, and combinations of these treatments. Microhybrid resin composite was condensed and light cured for 40 seconds on the porcelain specimens, which were then stored in distilled water at 37°C for 24 hours before mechanical testing. Results: The bond strengths were significantly different according to one-way ANOVA. The lowest bond strength was observed in the silane group (4.09 MPa); the highest bond strengths were observed with acid etching + silane (11.97 MPa) and sandblasting with 50-µm Al₂O₃ + acid etching + silane (12.34 MPa) (no significant difference between groups). Conclusion: Acid etching with 9.6% hydrofluoric acid gel or sandblasting with 50- or 110-µm Al₂O₃ particles alone did not provide adequate bond strength. Silane agent was effective in increasing the shear bond strength of resin composite to porcelain after sandblasting or acid etching. Porcelain treatment with a combination of 50-µm Al₂O₃ air abrasion, 9.6% hydrofluoric acid, and silane agent provided higher bond strengths than treatment with any of these procedures alone.