What dental alloys can be used to make all-metal and porcelain-fused-to-metal dental crowns?
What types of metals are used in dental crowns?
There are a number of different dental alloys that can be used in the fabrication of dental crowns, either all-metal or porcelain-fused-to-metal. Notice that the term alloy was used in the preceeding sentence. No pure metals are used, not even gold. This is because the physical properties of dental alloys are superior, as related to those characteristics needed for a dental crown.
The classification of dental alloys.
There is a formal classifications system that is used to categorize dental alloys. It is as follows.
- High noble alloys (Historic terminoloy: Precious metal.)
- This group of dental alloys has a composition that must be over 60% noble metal (gold, palladium and/or platinum), of which more than 40% must be gold. These metals are the "gold standard" of dental alloys to which all others are compared. High noble alloys are those that are easiest for the dentist and dental laboratory to work with, provide for a very accurate fit of the crown on the tooth and create the most predictable bond with porcelain.
- Noble alloys (Historic terminology: Semiprecious metal)
- These alloys have a noble metal content that is, at minimum, over 25%.
- Non-noble (Historic terminology: Nonprecious)
- The alloys are also know as base metals. Their noble metal content is less than 25%. They often contain large percentages of nickel, chromium or beryllium.
Why should I care what metal is used to create my dental crown?
There are several reasons why the choice of the dental alloy that is used to create your dental crown should be important to you. Some of these reasons will affect you directly. Others will be more of a concern to your dentist and the dental laboratory that makes your crown.
Dental alloys can be white or yellow.
In those cases where an all-metal dental crown is being placed, you might have a preference as to whether it should have a yellow (like gold) or silver ("white") coloration. An alloy's composition determines its color.
High noble metal alloys cost more.
The noble dental metals are gold, platinum and palladium. These are pricey materials and the higher their content the greater the cost of the dental alloy. In some applications the overall cost between using a high noble or base metal alloy might be small. But in the case of an all-metal crown for a large molar it might be a consideration.
The coverage provided by a dental insurance policy might vary.
Some people have metal allergies.
Studies have reported that about 10% of the female population and 5% of the male have an allergic response to nickel, chrome and/or beryllium alloys (metals often found in nonprecious dental alloys).
Your dentist and their dental laboratory might have a strong opinion about which alloy should be used.
Dentists and dental laboratories often have a set opinion about which types of dental alloys they are interested in working with. Drawing from their knowledge and experience, they know that some types of metals are easier to work with than others. Some tend to create more predictable restorations. The dentist and lab are interested in getting the job done right the first time. They know that any difficulties and problems just end up costing them money. If choosing a certain type of alloy makes this more likely, that's the one they are going to want to work with.
In general, dentists and dental labs prefer to work with high noble alloys. These metals are easiest to cast, provide the most accurate fit to the tooth, can offer some malleability so the fit of the crown can be adjusted, and offer the most predictable bond with porcelain.
Which type of alloy should you choose for your dental crown?
Assuming that cost is not a factor, a high noble alloy is always the best choice.
