January 25, 2013
Dear Mayo Clinic:
Is it safe to have silver (amalgam) fillings, or should I have them replaced with composite? I have read that the silver fillings have mercury in them and can leak over time.
Amalgam fillings are safe. A great deal of research has examined these fillings and found them to be an effective, long-lasting treatment for dental decay.
Amalgam, or silver, fillings are made with mercury, silver, tin and copper. In some cases, other metals may be included in amalgam fillings, too. Amalgam has been used for many years to replace decayed areas within teeth. It is an excellent material for this purpose. Amalgam is a strong, stable substance that holds up well when placed in a moist environment. It is also a good choice because it can tolerate the dramatic changes in temperature within your mouth.
We use amalgam fillings regularly at Mayo Clinic. They are best suited for larger fillings, such as those in molar teeth, as amalgam is a much more durable material than the material used in composite fillings. Composite resin fillings are made from plastic mixed with powdered glass to make them stronger.
Some people prefer composite resin fillings because they are white. This enables them to blend in with your teeth and have a more natural look than the silver amalgam fillings. However, composite fillings tend not to last as long as amalgam fillings, particularly in children. They also are more expensive.
Concerns have been raised over the years about the mercury in amalgam fillings. Mercury is an important component in the fillings because it effectively binds the other metals together, forming a strong bond that contributes to the filling's durability. It is important to note that there are several kinds of mercury. The mercury found in water that can build up in fish and lead to health problems if you ingest too much is not the same type of mercury used in amalgam. The mercury in amalgam is contained, or sequestered, within the filling.
A variety of research studies have shown that the levels of mercury in people who have amalgam fillings are well below the point at which mercury may cause health problems. That was found to be true even in those who had multiple amalgam fillings, some with as many as 15 fillings. No evidence exists that shows amalgam fillings increase the risk for health problems. So unless you are having trouble with your fillings or experience an allergic reaction to the material in amalgam fillings, there is no need to have them replaced.
It is possible that over long periods of time, usually several decades or more, amalgam fillings may not hold their original shape. If the fillings become deformed, then they need to be replaced. They also should be replaced if they start to break down over time.
The bottom line is that there is no need for concern about the safety of amalgam fillings. There is no evidence that shows any correlation between having amalgam fillings and increased risks for illness or developmental problems. Amalgam is an excellent, long-lasting material for fillings. If you have concerns about your fillings, or if you experience problems with them, talk to your dentist about the need for replacement.
— Thomas Salinas, D.D.S., Dental Specialties, Mayo Clinic, Rochester, Minn.