Pd-Ag-Ga DENTAL ALLOYS WITH INTERNAL OXIDATION CHARACTERISTICS

Abstract

A Pd—Ag alloy system that utilizes internal oxidation by including a base metal addition of only Ga is provided. The Pd—Ag—Ga alloy is particularly well-suited for use in porcelain-fused-to-metal (PFM) applications because the alloy does not form a dark oxide upon heating. The high oxygen potential of the material ensures the development of a tenacious chemical bond with the porcelain when used in PFM applications. Moreover, the addition of gallium lowers the liquidus temperature of the alloy to improve castability and strengthens the alloy significantly.

Description

FIELD OF THE INVENTION[0001]This invention relates generally to improved palladium-silver alloys; and more particularly to a palladium-silver-gallium dental alloy with internal oxidation characteristics.BACKGROUND OF THE INVENTION[0002]Compositional analyses of palladium-silver dental alloys intended for porcelain-fused-to-metal (PFM) applications reveal that all commercial alloys currently available utilize various combinations of base metals, such as, In, Sn, Ga, Zn and Mn to create materials which are easily cast, have high mechanical strengths, have suitable coefficients of thermal expansion (CTE) and can create a proper bond with porcelains. However, all of these conventional alloys suffer from a serious limitation, namely, that they tend to develop dark oxides during porcelain firing. These dark oxides are difficult to mask and can negatively effect the overall esthetics of the porcelain, particularly in the thin sections of the porcelain.[0003]One method of addressing this ae...

AI Technical Summary

Benefits of technology

[0005]The present invention provides a palladium-silver alloy suitable for PFM dental applications that prevents the formation of dark oxides through a process of internal oxidation of the a

Problems solved by technology

However, all of these conventional alloys suffer from a serious limitation, namely, that they tend to develop dark oxides during porcelain firing.

These dark oxides are difficult to mask and can negatively effect the overall esthetics of the porcelain, particularly in the thin sections of the porcelain.

While using such compositions resolves the problem of dark oxide formation, it introduces new limitations.

Specifically, these palladium-silver alloys possess inferior mechanical properties, are potentially prone to distortion during fabrication and in service, have higher liquidus temperatures, and require an additional step in their processing (the application of a bonding agent prior to the porcelain bakes) in order to develop a bond with the porcelain.

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