PFM High Noble
Posted on 08/31/2011
The High Noble PFM, also known as "precious metals", is defined by the ADA as metals that include 60% or more gold + platinum group metals (palladium, platinum, rhodium, iridium, osmium or ruthenium) and at least 40% gold. This means, for example, that an 80% palladium, 20% gold alloy would NOT be a high noble alloy, since it does not contain 40% gold. Additionally, a 40% gold, 15% palladium, 45% other base metals would also not be a high noble metal since it does not have 60% of gold and palladium.
So, essentially, the High Noble PFM is a gold based alloy. However, not all high noble alloys look the same. 40% gold alloys most often look like silver and are typically called: white gold. Even a 75% gold alloy will often have a very dullish gold appearance - looking more like a semi-precious alloy than a gold alloy. It requires about 85 - 90% gold to give the PFM alloy a goldish hue. This is important especially when the patient has asked for gold and wants the golden look.
The above qualifications, however, do not apply to full cast alloys. Many high noble full cast alloys, even with a very low gold content of 40% can look very golden if copper or indium as added to the alloy. Copper is itself a golden metal and indium, when combined with palladium, can give a goldish hue. Copper is not often used in PFM alloys because it has potential to cause porcelain to discolor.
So, essentially, the High Noble PFM is a gold based alloy. However, not all high noble alloys look the same. 40% gold alloys most often look like silver and are typically called: white gold. Even a 75% gold alloy will often have a very dullish gold appearance - looking more like a semi-precious alloy than a gold alloy. It requires about 85 - 90% gold to give the PFM alloy a goldish hue. This is important especially when the patient has asked for gold and wants the golden look.
The above qualifications, however, do not apply to full cast alloys. Many high noble full cast alloys, even with a very low gold content of 40% can look very golden if copper or indium as added to the alloy. Copper is itself a golden metal and indium, when combined with palladium, can give a goldish hue. Copper is not often used in PFM alloys because it has potential to cause porcelain to discolor.