Dental amalgam, commonly referred to as “silver fillings,” is one of the oldest and most widely used materials to repair teeth damaged by decay. While its use is declining due to health and environmental concerns, amalgam remains available in dentistry today. This shift away from the traditional material is driven by patient preference for less noticeable fillings and global regulatory movements.
The Current Landscape of Amalgam Use
Amalgam is still used by dentists globally, but its prevalence varies significantly by location and practice type. The European Union, for instance, is implementing a general ban on dental amalgam by January 1, 2025, following earlier restrictions for children and pregnant women. This regulatory action stems from the Minamata Convention on Mercury, an international treaty aimed at phasing down global mercury use.
In the United States, the Food and Drug Administration (FDA) and the American Dental Association (ADA) maintain that amalgam is safe and effective for the general population. However, the FDA recommends that certain high-risk groups avoid amalgam when non-mercury alternatives are available. Despite this official stance, the overall use of amalgam has trended downward in the U.S., particularly in private clinics. Public health programs often rely more heavily on amalgam due to its lower cost and established durability, especially for use in posterior teeth.
The Composition and Historical Popularity
Dental amalgam is created by mixing liquid mercury with a powdered alloy primarily composed of silver, tin, and copper. Mercury makes up about 50% of the final product, binding the metal particles into a strong, pliable material that is packed into a prepared cavity. High-copper amalgam, the modern standard, contains copper, which provides increased strength and corrosion resistance compared to older formulations.
The material was the dominant restorative option for over 150 years due to its exceptional performance. It is inexpensive, easy to apply, and sets into a hard, durable filling that withstands significant chewing forces. Its longevity and reliability made it the material of choice, especially where maintaining a completely dry field—a requirement for many modern alternatives—is challenging.
The Safety Debate Driving Change
The controversy surrounding dental amalgam centers on its mercury content, which is a known neurotoxin. Although the mercury is chemically bound when the filling sets, the material releases small amounts of mercury vapor. This release occurs particularly during the placement or removal of the filling, and through the regular actions of chewing and grinding.
Major health organizations have different perspectives on the significance of this vapor release. The FDA acknowledges the release of vapor but has historically concluded that exposure levels from amalgam fillings are too low to cause adverse health effects in most people. However, the agency has issued specific warnings for vulnerable populations, including pregnant women, nursing women, children, and people with pre-existing neurological conditions or impaired kidney function.
This caution highlights the potential for greater risk in those with developing nervous systems or compromised detoxification pathways. Regulatory action abroad, such as the EU ban, reflects a broader concern about the cumulative effects of mercury on human health and the environment. Dental office waste is a notable source of mercury pollution, which has driven environmental regulations worldwide to mandate the use of amalgam separators to capture waste before it enters the public water supply.
Modern Options for Dental Fillings
The decline in amalgam use has been paralleled by the increased sophistication and popularity of mercury-free restorative materials. Composite resin is the most common alternative, often called a “white” or “tooth-colored” filling due to its aesthetic qualities. This material consists of plastic and fine ceramic or glass particles, which can be custom-matched to the natural tooth color.
Composite fillings are chemically bonded directly to the tooth structure, allowing for a more conservative preparation of the cavity. While durable, composite resin is generally not as long-lasting as amalgam in high-stress areas, and its placement requires a strict moisture-free environment for proper adhesion.
Other options include glass ionomer cements, a blend of acrylic and glass components that release fluoride to strengthen surrounding enamel. These are typically used for:
- Smaller restorations.
- Temporary fillings.
- Areas where moisture control is difficult.
- Near the gumline.
For larger defects, indirect restorations like porcelain or ceramic inlays and onlays are custom-made in a lab for exceptional strength, durability, and aesthetic results.