A dental crown is a custom-fabricated cap placed over a damaged or weakened tooth, restoring its shape, size, strength, and appearance. While modern dentistry offers many tooth-colored options, adults are still candidates for metal crowns, though their application is highly specialized. These durable restorations are typically reserved for teeth in the back of the mouth where their color will not be noticeable. The choice of material depends entirely on the tooth’s location and the physical demands of a patient’s bite.
The Modern Use of Metal Crowns
The decision to use a metal crown today is based on its superior mechanical properties, making it the preferred choice for teeth under extreme pressure. Molars, the large teeth at the back of the mouth, withstand the heaviest occlusal forces from chewing and grinding, and a metal crown offers unmatched fracture resistance in these high-stress areas. Full-metal crowns are exceptionally thin yet robust, requiring the least amount of healthy tooth structure to be removed during preparation.
This minimal tooth reduction is a significant biological advantage, preserving more of the natural tooth core and supporting the tooth’s long-term health. Metal crowns are also the material of choice when space between the upper and lower teeth is limited, as their strength allows for a very slender design. The term “silver crown” in adult dentistry typically refers to a full-metal alloy, not pure silver, chosen when durability outweighs aesthetic concerns.
Understanding the Material Differences
Dental metal crowns are complex alloys blended to achieve specific characteristics like strength, corrosion resistance, and biocompatibility. These alloys are categorized based on their noble metal content, which refers to metals resistant to chemical degradation, such as gold, palladium, and platinum. High-noble alloys must contain at least 60% noble metal, with 40% of that being gold, offering excellent fit and superior tissue compatibility.
Noble alloys have a lower noble metal content, at least 25%, and are highly resistant to tarnish and wear. Base-metal alloys contain less than 25% noble metals and are primarily composed of nickel, chromium, or cobalt. Base-metal alloys are known for their extreme hardness, allowing for the thinnest crown walls, but they can be harder on opposing natural teeth and carry a risk of allergic reaction in sensitive patients.
Aesthetic Alternatives to Metal Crowns
The primary reason to avoid a metal crown is the desire for a restoration that blends seamlessly with natural teeth. Modern ceramic materials have advanced significantly, providing tooth-colored options with improved strength. Monolithic zirconia, a ceramic material, is a popular alternative for back teeth because of its high resistance to fracture, with some types reaching strength comparable to metal.
Another widely used option is lithium disilicate, often branded as e.max, which is favored for crowns on front teeth due to its excellent translucency that closely mimics natural tooth enamel. These all-ceramic restorations offer a superior appearance, eliminating the dark line near the gumline sometimes visible with porcelain-fused-to-metal crowns. Placing an aesthetic crown typically requires removing more original tooth structure to accommodate the material’s thickness and achieve the desired cosmetic result.