A previous study (Lee et al., JDR 81:487, 2002) showed gold sputtering improved porcelain adherence to cast titanium using area fraction of adherent porcelain (AFAP) test by SEM/EDS.

Objective: To investigate the effect of gold-coating on the bond strength of porcelains to cast titanium using three point bending test. Methods: Cast titanium (grade 2 with 108 GPa of Elastic Modulus) plates (l=30, w=3.5, h=0.45-0.55 mm) were prepared using magnesia-based investment (Selevest CB) and centrifugal casting machine (Ticast Super R). The specimen porosity was radiographically determined and defective plates were discarded. SiC paper was used to standardize dimensions (except height) of 42 plates to l=25mm and w=3.0mm. Specimens were divided into 6 groups with two types of gold-coatings (Deck-Gold NF, Degussa and sputter gold-coating at 40 mA for 1,000 seconds) and control groups without coating for two low-fusing porcelains (Duceratin, Ducera and Titankeramik, Vita). The gold-coatings were applied after the surfaces were air-abraded with 50 μm Al₂O₃. The metal/ceramic specimens were prepared according to the ISO 9693 and manufacturers' direction for each porcelain. Three point bending test was conducted at a crosshead speed of 1.0mm/min. The results [n=7, MPa, mean (SD)] were statistically analyzed using ANOVA and Scheffe's test (α=0.05). Results:

	Control	Deck-Gold NF	Gold Sputter
Duceratin	32.2 (4.0)*	29.7 (2.8)*	20.6 (7.3)
Titankeramik	29.1 (2.6)**	33.1 (7.6)**	26.8 (2.7)**

*, ** indicate no statistical difference in the same row. In either porcelain, there were no statistical differences in bond strength among surface conditions except for Duceratin baked to the gold sputtered titanium which showed  significantly lower strength. Conclusion: There was no correlation between AFAP test and three point bending test to investigate the porcelain adherence to cast titanium. Partially supported by a NIH/NIDCR grant 11787.