The objective of the proposed research project is to investigate the use of a novel, gradient composition, sputtered oxide film for improving the bonding between metal and ceramic in porcelain- fused-to-metal dental restorations. The present process utilizes a discrete oxide layer formed by diffusion and an accumulation of oxide-forming elements from the bulk of the metal casting to the porcelain interface. The alternate technique proposed here involves the magnetron sputter deposition of a layer with a gradient oxygen composition that should have superior bonding to both the ceramic and metal components. The gradient will be achieved by slowly varying the gas composition during sputtering from argon to oxygen. This will result in a smooth compositional transition and may provide a reduction in the undesirable residual tensile stresses occurring at some porcelain-metal interfaces due to the difference in the thermal contraction coefficients. The use of this procedure may significantly improve the porcelain-metal bond strength, particularly with base metal casting alloys, and it should be less technique-sensitive than current dental laboratory procedures.
