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.

1 . A dental alloy capable of undergoing internal oxidation upon heating, consisting essentially of Pd, Ag and Ga, wherein the alloy is substantially free of any additional base metal. 
     
     
         2 . The dental alloy of  claim 1 , having a composition of:
   Pd 45-90 Ag 10-55 Ga 0.1-3      
     
     
         3 . The dental alloy of  claim 1 , wherein the alloy further includes one or more additional base metals at a concentration no greater than 1 wt %. 
     
     
         4 . The dental alloy of  claim 1 , wherein the alloy further includes at least one grain refiner. 
     
     
         5 . The dental alloy of  claim 4 , wherein the at least one grain refiner is selected from the group consisting of Ru, Ir and Re. 
     
     
         6 . The dental alloy of  claim 4 , wherein the at least one grain refiner has a concentration of from about 0 to 3 wt %. 
     
     
         7 . The dental alloy of  claim 1 , wherein the alloy further includes at least one additional noble metal selected from the group consisting of Au and Pt. 
     
     
         8 . The dental alloy of  claim 7 , wherein the additional noble metal has a concentration of up to 10 wt %. 
     
     
         9 . The dental alloy of  claim 5 , wherein the composition has a molecular formulation of Pd 51.2 Ag 46.5 Ga 1.5 Ir 0.4 RU 0.4 . 
     
     
         10 . A dental appliance comprising a dental body formed at least partially from an alloy material capable of undergoing internal oxidation upon heating, the alloy consisting essentially of Pd, Ag and Ga, wherein the alloy is substantially free of any additional base metal. 
     
     
         11 . The dental appliance of  claim 10 , wherein the alloy further includes one or more base metals at a concentration no greater than 1 wt %. 
     
     
         12 . The dental appliance of  claim 10 , wherein the alloy has the following composition:
   Pd 45-90 Ag 10-55 Ga 0.1-3      
     
     
         13 . The dental appliance of  claim 10 , wherein the alloy further includes at least one grain refiner. 
     
     
         14 . The dental appliance of  claim 13 , wherein the at least one grain refiner is selected from the group consisting of Ru, Ir and Re. 
     
     
         15 . The dental appliance of  claim 13 , wherein the at least one grain refiner has a concentration of from about 0 to 3 wt %. 
     
     
         16 . The dental appliance of  claim 14 , wherein the alloy has a molecular formulation of Pd 51.2 Ag 46.5 Ga 1.5 Ir 0.4 Ru 0.4 . 
     
     
         17 . The dental appliance of  claim 10 , wherein the alloy further includes at least one additional noble metal selected from the group consisting of Au and Pt. 
     
     
         18 . The dental appliance of  claim 17 , wherein the additional noble metal has a concentration of up to about 10 wt %. 
     
     
         19 . The dental appliance of  claim 10 , wherein the appliance is a formed by fusing porcelain to the alloy. 
     
     
         20 . The dental applicant of  claim 19 , wherein the porcelain fusing occurs in an oxygen containing environment, and where the fusing conditions are controlled such that the rate of diffusion of the oxygen into the alloy is greater than the rate of diffusion of a solute out of the alloy.