In This Article

Definition and composition

Dental amalgam is a restorative material composed of an alloy of mercury (approximately 50%) combined with a powdered mix of silver, tin, copper, and sometimes zinc. The word "amalgam" means a mixture or blend, and in dentistry, it refers specifically to this metal alloy used to restore decayed or broken teeth.

Unlike many other dental materials, amalgam is notable for its combination of durability, ease of use, and low cost — properties that made it the dominant restorative material for most of the 20th century.

Types of amalgam alloys

Modern dental amalgam formulations have evolved significantly from early versions:

  • High-copper amalgam: The current standard, with higher copper content (12–30%) that reduces corrosion and improves marginal integrity
  • Low-copper (conventional) amalgam: Older formulation, less commonly used today
  • Dispersalloy and other brand formulations: Proprietary blends with slightly different alloy compositions

How amalgam is placed

During placement, the dentist (or dental assistant) mixes elemental mercury with the alloy powder in a mechanical capsule. This creates a plastic, workable material that is packed into the prepared tooth cavity. The amalgam then undergoes a setting reaction and hardens over several hours, though it achieves functional hardness within minutes.

📋 Note on Mercury During Placement
During mixing and placement, mercury vapor can be released in the dental office environment. SMART protocol focuses partly on managing this exposure for both patient and staff.

How long does amalgam last?

Well-placed amalgam fillings can last 10–15 years or longer. Some patients have had the same amalgam fillings for 20–30+ years. However, over time, amalgam can:

  • Crack or fracture, particularly in large fillings
  • Develop marginal leakage, allowing bacteria to re-enter
  • Corrode or tarnish, affecting appearance
  • Cause tooth fracture in larger restorations due to expansion

Common alternatives to dental amalgam

  • Composite resin: Tooth-colored plastic/glass material; bonds directly to the tooth; most common alternative
  • Ceramic (porcelain): Highly aesthetic; often used for larger restorations (inlays/onlays)
  • Glass ionomer: Releases fluoride; used for certain cavity types
  • Gold alloys: Extremely durable; less common due to aesthetics and cost

See our full Compare Hub for a detailed side-by-side comparison of all restoration materials.

Continue learning

Now that you understand what amalgam is, learn about safe removal options.

What Are Mercury Fillings? → The SMART Protocol →