Gold dental crowns have been a reliable restorative option for many decades, valued for their durability and long lifespan. While they are commonly referred to as “gold crowns,” they are actually made from specialized metal mixtures, or alloys, where the gold content can vary significantly. The actual amount of gold within a single crown depends on factors like the crown’s size and the specific alloy composition chosen by the dentist and lab.
The Role of Gold in Dentistry
Gold remains a preferred material in dentistry because of its unique combination of physical and biological characteristics. The metal is highly biocompatible, meaning it rarely causes allergic reactions or irritation to the surrounding oral tissues. This inertness ensures a stable and well-tolerated restoration within the mouth over many years.
Gold’s malleability and ductility allow dental technicians to cast incredibly precise margins. This precision enables the crown to form a tight seal against the tooth structure, minimizing the risk of recurrent decay beneath the restoration. Gold alloys also exhibit wear characteristics similar to natural tooth enamel, which is a major benefit for the opposing tooth. This property helps prevent excessive wear on the natural teeth that bite against the gold crown, especially for individuals who grind their teeth.
Understanding Dental Gold Alloys
The metal used in dental crowns is not pure, 24-karat gold, because pure gold is too soft to withstand the heavy forces of biting and chewing. Instead, gold is mixed with other metals like palladium, silver, and copper to create a stronger, more durable alloy. These alloys are categorized based on their noble metal content, which includes gold, platinum, and palladium, metals that resist corrosion and tarnish.
The highest quality category is the High Noble alloy, which must contain at least 60% noble metals, with a minimum of 40% being gold by weight. These alloys typically correspond to gold purities between 16 and 22 karats.
Noble alloys represent the second category, requiring a minimum of 25% noble metal content, while Predominantly Base Metal alloys contain less than 25% noble metals. The karat system indicates the proportion of gold: a 16-karat alloy is 16 parts gold out of 24 total parts, equating to approximately 66.7% pure gold content.
Determining the Actual Gold Content
The total weight of a gold crown can vary substantially depending on the size and location of the tooth being restored. A full gold crown for a smaller front tooth (incisor) will weigh less than one for a large back molar. The average weight for a typical full gold crown ranges from approximately 1.5 grams to 4.5 grams.
Even within this weight range, the pure gold content depends entirely on the alloy’s purity. For instance, a 3-gram crown made from a High Noble 75% gold alloy contains 2.25 grams of pure gold.
Conversely, a 3-gram crown made from a Noble alloy with 40% gold content contains only 1.2 grams of pure gold. The specific density of the metals mixed into the alloy also plays a role, creating variability even among crowns of the same size.
Valuation and Scrap Potential
When a gold crown is removed, its monetary value is determined by its scrap potential, which is based on the current market price of gold. The value is calculated from the crown’s total weight and its precise gold purity percentage, not its original cost as a dental device.
Since the crown is an alloy, the non-gold metals, such as copper and silver, must be separated during a refining process. Reputable refiners will melt and assay the material to accurately determine the exact percentage of all precious metals present, including gold, palladium, and platinum. The final payout is not the full market value of the gold contained but is instead the melt value minus the refining and processing fees.