All-metal crowns are exactly as their name implies. They are dental crowns whose entire thickness is made up of metal. The classic all-metal crown is the gold crown, although you will also see some metal crowns that are silver in color.

The metal that is used to create dental crowns is actually an alloy (a blend of metals). Your dentist and the dental laboratory that will fabricate your crown will have a number of different alloys from which they can choose, however in most cases they will have just a few favorites that they are familiar with and like to use.

No dental crown is made from 100% gold because as a pure metal it is physical characteristics are inappropriate. As a ballpark measure, the alloys used to make dental restorations can run as high as 15 to 20 karat.

Different dental alloys have different physical properties.

The physical characteristics of each dental alloy, including their color (either yellow or white), will vary due to its precise composition. And these varying properties make some alloys better suited for certain applications as opposed to others.

As an example, there are a number of different yellow gold alloys used in dentistry. In general terms, some of these alloys are comparatively softer than others. The softer alloys offer the benefit that they are more malleable. This gives the dentist some control over adapting the restoration to the tooth. Softer alloys are typically most suited for relatively small gold restoration such as inlays. Gold crowns are typically made from the relatively harder alloys because they need greater strength and wear resistance.

The classification system for dental alloys.

There is a formal classification system that is used to categorize the different grades of alloys that can be used to make dental crowns. And as we describe on the next page of this topic, you, the dental patient, may need to make a decision as to which of these types is selected for your crown.

High noble alloys
Historically this group of dental alloys was referred to as the "precious metals." These alloys are the "gold standard" of dental alloys. Their composition must include over 60% noble metals (gold, platinum, and/or palladium), of which over 40% is gold.

Noble alloys
The historic term for this group of alloys was the "semiprecious metals." They have a composition that is over 25% noble metal content.

Non-noble or base metal alloys
The previous terminology for this group was the "nonprecious metals." They contain less than 25% noble metal. Usually a large portion of their content is nickel, chromium or beryllium.