Effects of Surface Treatments on Bond Strength Between Porcelain and Electroformed Gold Substrates

Purpose: To assess the effects in vitro of sandblasting with 50-µm and 110-µm aluminum oxide grits and application of Goldbonder on bond strengths between porcelain and electroformed pure gold. Materials and Methods: Forty electroformed gold substrates and eight Ni-Cr alloy substrates were fabricated. All specimens were divided into 6 groups (8 specimens per group, the Ni-Cr alloy substrates were placed into group F), and exposed to various surface treatments: group A: No treatment; group B: sandblasted with 50-µm grit Al2O3; group C: sandblasted with 110-µm grit Al2O3; group D: sandblasted with 50-µm grit Al2O3 + Goldbonder; group E: sandblasted with 110-µm grit Al2O3 + Goldbonder; group F: sandblasted with 110-µm-grit Al2O3. Porcelain was built-up to form a cylindrical shape on the metal substrate surface and fired. All the metal-porcelain specimens were tested for shear bond strength. Results: The shear bond strength of group F was statistically higher than the other groups. Shear bond strengths of groups A to E were significantly affected by different surface treatments. Group A presented the lowest shear bond strength. In groups D and E, the mean bond strengths were statistically higher than groups A, B, and C. There were no differences between groups B and C, and groups D and E. Conclusion: Sandblasting with 50-µm or 100-µm grit aluminum oxide improved the bond strength between porcelain and electroformed pure gold. Goldbonder further improved the bond of the sandblasted gold substrate. Different grit sizes exerted the same effects on the gold-porcelain bond. Keywords: electroformed gold, porcelain, PFM, adhesion