Although amalgam dental fillings contain mercury, dental crowns do not. While fillings are used to fill cavities, a crown is used to entirely cover or "cap" a damaged tooth. Besides strengthening a damaged tooth, a crown can be used to improve its appearance, shape or alignment. Porcelain, acrylic or ceramic crowns can be matched to the color of your natural teeth. Other materials include gold and metal alloys. While stainless steel crowns may appear silver in color, they are actually composed of chromium, nickel and iron.

Silver fillings contain mercury

Dental crowns, therefore, are not considered potentially toxic, while dental amalgam fillings are. Amalgam containing mercury has been used in dentistry for about 150 years. That’s because amalgam, which is a combination of mercury, tin, copper, zinc,and palladium, is durable enough to withstand the rigors of biting and chewing. It’s also reasonably priced, making it affordable to most people who require dental work. It’s estimated that dentists place about 1 billion amalgam fillings per year.

Usually, those fillings remain intact until there is a reason to remove or update them. When fillings are removed or worked on, dentists drill the tooth. By disturbing the filling, mercury vapors and fine particles are released from the amalgam and into the air. The mercury, which is toxic, then becomes a hazard that dental practices must take precautions against.

Risks in the dental office

What you may not realize is that dental crowns, although they do not contain mercury, might still be hazardous. Often, crowns are placed right over the already-existing amalgam filling. It may give you the impression that because the filling is covered, the mercury is somehow sealed off. In reality, though, the mercury can seep from your filling to the tooth’s nerves and blood vessels. From there it can spread to your body’s nerve tissue and bloodstream.

Teeth require crowns because of damage or decay. After a root canal, dentists insert a small post into the tooth where the root was.

About two thirds of the post’s length descends downward into the jaw. The top sticks out above the jaw and becomes an anchor for the crown. Amalgam isn’t just used to manufacture fillings. It’s also frequently used to manufacture the posts for crowns, which is another source of mercury.

Some other risks besides mercury exposure include:

• bacteria from exfoliated skin, which can lead to infection¹
• chemical disinfectants, which can release VOCs into the air²
• viruses, including HBV, HIV, and HCV, as well as respiratory viruses like Covid-19³

Steps you can take

Because dentists work so frequently with amalgam, they should take precautions against mercury toxicity in the office. Some dentists use high-powered suction devices to keep teeth dry and remove debris, such as amalgam particles, during procedures. Some also use specialized waste management systems help keep mercury out of the plumbing system.

Dental practitioners can go even further to control infectious aerosols by installing a high-performance air purification system like the IQAir Dental Series with the FlexVac attachment. The FlexVac is an extraoral suction and infection control device that can control potential air quality issues at the source, filtering pollutants like:

• mercury vapors
• airborne pathogens
• drill aerosols
• bacteria
• viruses
• disinfectant smells
• abrasion powder
• volatile organic compounds (VOCs)
  

These precautions bring dental office safety another step closer to making the industry healthier. As long as mercury continues to be in amalgam, the need for precautions will continue.