Hello, I wanted to know if porcelain fused to high noble metals ARE THEY SAME AS FUSED TO METAL CROWNS? I also wanted to know how does it look? I’ve been reading about all porcelain crowns are the best but it doesn’t say if the fused to high noble are the same as all porcelain.
- Edna from California
A high noble metal is a metal, and a porcelain fused to high noble crown is a porcelain fused to metal crown. An all-porcelain crown has no metal in it.
Porcelain fused to metal is the general category, where you have a metal foundation and then the porcelain is fused over the metal. The metal strengthens the crown. But it also makes the crown opaque, and the dental lab has to use opaquers to block out the color of the metal. And it causes there to be a dark line at the gumline, if not right away, then over time.
There are basically three categories of metals used as a foundation for these crowns. There is a base metal, which has nickel and chromium in it, and less than 25% of the noble metals, which are gold, platinum, and palladium. This metal is strong and stiff, but it also is harder to work with and doesn’t fit the tooth as tightly. It also has metal sensitivity issues, since it is estimated that more than 5% of the population is allergic to nickel.
The second category is noble metal. This has between 25 and 60 percent noble metal. The third category is high noble, which must contain over 60 percent of any combination of gold, platinum and palladium. These alloys fit more precisely, are easier to work with, and cause no allergic reactions. They are also more expensive.
Which crown is the best? It depends on the clinical situation. For a tooth in the front of the mouth, the all-ceramic crown is what we prefer. It has natural translucency, and can be made to look exactly like a natural tooth. With excellent artistry, it can be exactly matched to other, adjacent natural teeth. Also, any porcelain fused to metal crown is going to tend to develop a dark line at the gumline – if not at first, then over time. But for a molar, the strength of the porcelain fused to metal becomes a more critical issue, and the lack of translucency will not be noticed, nor will the dark line at the gumline. So, in our office, we tend to prefer the porcelain fused to high noble metal (sometimes called porcelain fused to gold) as the best crown for most of those situations.
I hope this is helpful.