What are the disadvantages of amalgam tooth fillings?

Silver amalgam fillings contain a neurotoxin -- mercury. About half of the dentists in the US use a filling material that contains mercury. Whether or not the mercury is released and absorbed by the body while in its hardened form as a filling is a highly controversial topic. The ADA forbids dentists from replacing fillings for this reason alone. Placing the filling and removing the filling can be a toxic event, potentially harming both patient and dentist. This topic is evolving rapidly, so it's important to stay informed so you can make a decision on how you want to deal with this potential health hazard. Your dentist should be able to help you with this decision too.

Silver amalgam fillings also shrink and expand at a different rate than teeth do, which can cause stress fractures and eventual breakage of the tooth. Teeth are weaker to compressive chewing forces when they are restored with these fillings. Sometimes people don't like the way a silver filling looks.
The main disadvantage of amalgam tooth fillings is the color. Most patients today prefer that the filling matches the tooth. However, amalgam fillings are still used by dentists. They are more economical, can be used in difficult to get to areas of the mouth, and are more resistant to decay around the filling edges than tooth colored fillings. See your dentist to see which filling materials would be best for your mouth. 
Besides the obvious aesthetic disadvantages of silver metal in teeth, and the controversial content of methyl mercury present in amalgam restorations, studies have shown that amalgam fillings weaken teeth. In a study at the University of Minnesota, with compressive force placed on the occlusal (top) surfaces of 3 bicuspids: one with an amalgam filling, one composite (tooth colored) bonded filling, and one with no filling, the first tooth to break was the amalgam, the second was the one without a filling, and the strongest was the tooth with the bonded composite filling (it increased what is known as 'intercuspal stiffness' of the tooth). 
One disadvantage of silver amalgam tooth fillings is that they don’t match the color of your teeth, so they may be more noticeable than composite resin fillings, which are tooth-colored. In addition, more of your natural tooth must be removed in order to place an amalgam filling than a composite resin filling. Composite resin fillings require less drilling because they bond directly to the tooth. By contrast, amalgam fillings sit in the pocket in the tooth that the dentist creates.
Amalgam fillings are silver-colored and do not look as natural as a tooth-colored filling, especially when the restoration is near the front of the mouth. Also, the dentist may need to remove a larger part of the tooth to place an amalgam filling compared to other kinds of fillings.
Jonathan B. Levine, DMD
There are several disadvantages of using silver amalgam tooth fillings:
  • Many patients don’t like the look of silver in their mouths.
  • Sometimes healthy parts of the tooth need to be removed to make room for the amalgam filling.
  • It has the potential to crack and fracture more than other filling materials.
  • A very small percentage of people (one percent) are allergic to the mercury present in amalgam restorations. The reaction is typically similar to a mild rash.
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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.