Dental amalgam—also known as “silver fillings”—has been used for nearly a hundred years to treat cavities. There are several reasons why this mixture of metals has been the go-to material among dentists: Malleable when first applied, dental amalgam sets up into a durable dental filling that can take years of biting forces. What’s more, it’s stable and compatible with living tissue.
But there’s been growing concern in recent years about the safety of dental amalgam, with even some wondering if they should have existing fillings replaced. The reason: liquid mercury.
Mercury makes up a good portion of dental amalgam’s base mixture, to which other metals like silver, tin or copper are added to it in powder form. This forms a putty that can be easily worked into a prepared cavity. And despite the heightened awareness of the metal’s toxicity to humans, it’s still used in dental amalgam.
The reason why is that there are various forms of mercury and not all are toxic. The form making headlines is known as methylmercury, a compound created when mercury from the environment fuses with organic molecules. The compound builds up in the living tissues of animals, particularly large ocean fish, which have accumulated high concentrations passed up through their food chain.
That’s not what’s used in dental amalgam. Dentists instead use a non-toxic, elemental form of mercury that when set up becomes locked within the amalgam and cannot leach out. Based on various studies, treating cavities with it poses no health risks to humans.
This also means there’s no medical reason for having an existing silver fillings removed. Doing so, though, could cause more harm than good because it could further weaken the remaining tooth structure.
The most viable reason for not getting a dental amalgam filling is cosmetic: The metallic appearance of amalgam could detract from your smile. There are newer, more life-like filling options available. Your dentist, though, may still recommend dental amalgam for its strength and compatibility, especially for back teeth. It’s entirely safe to accept this recommendation.