Dentures and alloys for use in same

The present invention relates to the use of palladium alloys for producing 
fixed and removable dentures. 
BACKGROUND OF THE INVENTION 
German Patent Specification DE-PS 33 16 595 (corresponding to U.S. Pat. No. 
4,551,302) discloses palladium alloys for producing fixed and removable 
dentures. The disclosure of this patent specification is incorporated 
herein by reference. The alloys described in that specification contain 65 
to 85% palladium, 0 to 10% gold and/or 0 to 5% platinum, 0.1 to 10% tin, 1 
to 10% gallium, 1 to 12% copper as well as 0.05 to 1.5% ruthenium and/or 
0.05 to 0.7% rhenium. Thus, the base metal content can be up to 32% by 
weight. 
When palladium alloys with such high base metal contents are melted in an 
oxidizing atmosphere, they occasionally tend to form a stable oxide film 
which floats on the liquid melt. The formation of such an oxide film 
brings about the accumulation and combustion of oxidizable alloy 
constituents. If the alloy is remelted several times, it can result in an 
undesired change of the alloy composition. Moreover, when a dental 
technician melts such alloy in an oxidizing atmosphere, he may not be able 
to see through the surface oxide layer and this is not able to perceive 
whether the alloy located under the oxide layer is sufficiently liquefied 
to be cast. 
Another undesired phenomenon associated with the formation of an oxide film 
is the fact that the melting crucible occasionally does not discharge 
completely, so that slag residues remain on the crucible bottom. These 
oxide films occur in particular in the case of alloys which contain more 
than 10% base metals, depending on the type of base metals added. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide a palladium alloy for 
producing fired and removable dentures, which do not form oxide films in 
an oxidizing atmosphere during melting even at rather high base metal 
contents. 
This object is achieved by a palladium alloy consisting of (a) 65 to 85% 
palladium, (b) 0 to 10% gold and/or 0 to 5% platinum, (c) 0.1 to 10% tin, 
(d) 1 to 10% gallium, (e) 1 to 12% copper, (f) 0.05 to 1.5% ruthenium 
and/or 0.05 to 0.7% rhenium as well as (g) 0.01 to 4% tungsten and/or 0.01 
to 4% aluminum and/or 0.01 to 4% zinc, the combined percentages of these 
metals and unavoidable impurities being 100%.