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Contents of Silver Amalgam Fillings
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Have you ever wondered what an amalgam filling looks like inside?

Dental Amalgam CapsuleMany people question how a metal can be soft enough to be shaped into a tooth yet hard enough to endure the force of chewing and other abuse that occurs during its ten or more years in your mouth.

Other people are curious about the amount of mercury contained in an amalgam filling…so let’s get some answers!

I opened up an amalgam capsule (pictured to the left) and took a picture of what I found inside:

Amalgam Filling Contents

Aside from the capsule body, I found three main components:

1 – Mercury Disc – Amalgam fillings are made up of about 50% mercury, and 50% metal powder.  The mercury is sealed away in a plastic disc so that it doesn’t evaporate and contaminate the environment.  The mercury disc breaks open when the amalgam capsule gets mixed.

2 – Metal Powder – The metal powder is made up of varying metals.  In the Dispersalloy brand of dental amalgam (a widely used brand), the metal powder contains about:

  • 69% Silver
  • 18% Tin
  • 12% Copper and
  • 1% Zinc

3 – Pestle – The pestle is simply a plastic rod.  When the amalgam is mixed and vibrated quickly back and forth, the pestle breaks open the sealed mercury disc and helps to thoroughly mix the mercury with the metal powder to form a soft metallic mixture.  While the amalgam is still soft, the dentist uses it to fill your cavities.  The amalgam begins to harden after a few minutes and eventually hardens into a filling that can withstand lots of force.


As you can see, the formulation of amalgam is pretty simple: mercury and metal powder.  Fortunately, modern amalgam capsules come pre-measured so that dentists don’t have to worry about mixing up mercury with other metals by hand.

Do you have any questions about the contents of amalgam fillings?  I’d love to hear your thoughts int he comments section below.  Thanks for reading!