# What are the three noble metals used in dentistry?

Feb 28, 2016

The three noble metals used in dentistry are gold, platinum, and palladium.

#### Explanation:

The pure metals are never used in dentistry, because their alloys have superior properties.

There are three basic categories of dental alloys.

High noble alloys

These must contain over 60 % noble metal ($\text{Au, Pd, Pt}$) and more than 40 % must be gold.

A typical alloy contains 77% $\text{Au}$, 13% $\text{Ag}$, 8.5% $\text{Cu}$, 1.0% $\text{Pd}$, and less than 1% $\text{In, Ir}$, and $\text{Zn}$.

Noble alloys

These must have at least 25 % noble metal content.

A common alloy contains 40 % $\text{Ag}$, 20 % $\text{Au}$, 20 % $\text{Pd}$, 18 % $\text{In}$, 2 % $\text{Zn}$, and less than 1 % $\text{Ir}$.

Non-noble alloys

These alloys have a noble metal content less than 25 % (it may even be 0 %).

They often contain large percentages of $\text{Ni, Co, Cr}$, and $\text{Be}$.

A typical alloy contains 61 % $\text{Co}$, 27 % $\text{Cr}$, 6 % $\text{Mo}$, 5 % $\text{W}$, 1 %$\text{Si}$, and less than 1 % $\text{Mn, Fe}$, and $\text{C}$.