Evaluation of Bond Strength of Pressed and Layered Veneering Ceramics to Nickel-Chromium Alloy

STATEMENT OF THE PROBLEM: The success of metal- ceramic- restorations (MCR) depends on the presence of strong bond between porcelain and metal substructure. PURPOSE: The purpose of this study was to evaluate the effect of hot pressing technique on the bond strength of a metal-porcelain composite in comparison to layering technique. MATERIALS AND METHOD: Thirty Nickel-Chromium specimens were produced by two methods; conventional porcelain layering on metal and hot pressing (n=15). Bond strengths of all specimens were assessed by the means of three–point bending test according to ISO 9693: 1999 (E) instructions. The data were analyzed using Students t-test (p< 0.001). RESULTS: The mean ± SD bond strength of conventional and hot pressing technique was 48.29 ± 6.02 and 56.52 ± 4.97, respectively. Therefore, the conventional layering technique yielded significantly lower mean bond strength values than hot pressing technique (p< 0.001). CONCLUSION: This study showed that it is possible to improve metal–porcelain bond strength significantly by applying an overpressure during porcelain firing.