Amalgam fillings are considered safe for most adults by major regulatory agencies, including the FDA. They contain about 50% mercury mixed with silver, tin, and copper, which understandably raises concern. But the mercury in a hardened amalgam filling behaves differently from liquid mercury: it’s bound within a stable alloy that releases only trace amounts of vapor during daily activities like chewing. That said, specific groups of people face higher risk and are advised to choose alternatives.
What Amalgam Fillings Actually Contain
Dental amalgam is a mixture of metals. Roughly half is elemental mercury, with the rest made up of silver, tin, copper, and sometimes zinc. When these metals are combined, they form a hard, stable compound. The mercury binds chemically with the other metals rather than sitting in its liquid form, which is why an amalgam filling doesn’t behave like a broken thermometer in your mouth.
That said, the filling does release small amounts of mercury vapor over time, particularly when you chew, grind your teeth, or drink hot liquids. Research measuring vapor during dental procedures found that even the highest-exposure moments, like dry polishing an amalgam surface (around 44 micrograms of mercury released), fell well below the daily occupational exposure thresholds set by regulatory agencies. Normal daily exposure from simply having fillings in place is far lower than that.
Who Should Avoid Amalgam
The FDA identifies several groups who may be more susceptible to the low-level mercury exposure amalgam produces:
- Pregnant women and their developing fetuses
- Women planning to become pregnant
- Nursing mothers and their newborns
- Children under six
- People with neurological disease
- People with impaired kidney function
- Anyone allergic to mercury, silver, copper, or tin
If you fall into any of these categories, mercury-free alternatives like composite resin are the better choice. For everyone else, the current evidence does not show amalgam fillings causing measurable harm.
What the Research Shows About Health Risks
The biggest concern people have is whether chronic, low-level mercury exposure from fillings can cause neurological problems, kidney damage, or other systemic disease. A systematic review comparing health outcomes in people with amalgam fillings versus those with composite resin fillings found no difference in systemic effects between the two groups. The review concluded that amalgam restorations, like modern resin-based materials, were not linked to an increased risk of systemic diseases.
The question of harm during pregnancy has also been studied directly. Mercury vapor does cross the placenta, but accumulation of mercury in the fetal brain from maternal fillings appears to be significantly less than in the mother’s brain. This is likely because the fetal liver converts mercury vapor into a form that doesn’t cross the blood-brain barrier as easily. A large study tracking children in the Seychelles whose mothers had amalgam fillings during pregnancy found no evidence of neurodevelopmental consequences in the children.
Some people do experience genuine allergic reactions to amalgam components. Symptoms can include oral ulcers, localized inflammation, and occasionally more generalized reactions after a filling is placed. If you’ve had allergic reactions to metals like nickel or silver in jewelry, mention this to your dentist before getting any metal-based restoration.
Amalgam vs. Composite: Durability Trade-Offs
One reason amalgam remains in use despite the availability of tooth-colored composites is longevity. A systematic review of long-term outcomes found that amalgam restorations last a median of 16-plus years, compared to about 11 years for composite resin. That five-year gap matters most for large fillings on back teeth, where chewing forces are strongest. Composite technology has improved considerably, but amalgam still holds an edge in durability for heavy-load restorations.
Composite fillings bond directly to tooth structure and require less removal of healthy tooth material during placement. They also look like natural teeth. For small to moderate cavities, composites perform well and avoid the mercury question entirely. For large cavities on molars, especially in patients who grind their teeth, the durability advantage of amalgam can be clinically meaningful.
Should You Have Existing Fillings Removed?
If you already have amalgam fillings that are intact and not causing problems, removing them purely over mercury concerns can be counterproductive. The removal process itself generates a burst of mercury vapor, with studies measuring 15 to 20 micrograms released when drilling out a single filling under water spray. That’s a significantly higher exposure than you’d get from years of the filling simply sitting in your tooth.
Removal makes sense when a filling is cracked, decayed around the edges, or causing an allergic reaction. It doesn’t make sense as a detox strategy. The FDA does not recommend removing intact amalgam fillings in people who are not in a high-risk group, and the temporary spike in mercury exposure during removal is the main reason why.
The Global Shift Away From Amalgam
Regardless of the safety data, the world is moving away from amalgam, primarily for environmental reasons. The European Union voted to ban dental amalgam starting in 2025, with provisions requiring member states to ensure adequate insurance coverage for mercury-free alternatives. The concern driving this decision is less about patient safety and more about mercury entering water systems through dental office wastewater.
In the United States, the EPA has required dental offices that place or remove amalgam to use amalgam separators since 2017. These devices capture mercury and other metals before they reach public sewage systems. The EPA estimates this rule prevents 5.1 tons of mercury from being discharged into water treatment facilities each year. As composite materials continue to improve and environmental regulations tighten, amalgam use will likely continue declining even in countries that haven’t imposed outright bans.