- What do amalgam fillings contain?
- What are the benefits of using amalgam to repair cavities?
- Are there health concerns about amalgam fillings?
- What other materials are used to treat dental cavities?
- Are there health concerns about these dental filling materials?
- Should pregnant women get amalgam fillings?
- How safe are amalgam fillings for children?
- How is amalgam waste from dental offices disposed of ?
For more than 150 years, dental fillings known as amalgams have been widely used to treat tooth decay.
Amalgam fillings are made of a mixture of metals. The ingredients include equal parts of elemental mercury (43 to 54 percent), and an alloy powder (46 to 57 percent) mainly composed of silver, tin, copper.
Dental amalgam is used to repair dental cavities in people of all ages. Because of amalgam’s durability, it is a good choice if a tooth is severely damaged or if a cavity is below the gum line. Teeth located in the back of the mouth (molars) have to bear great stresses from chewing and grinding, and an amalgam-filled molar will resist cracking or breaking.
Amalgam is very pliable when placed in a tooth, it is easy to use, and hardens to a very durable filling that lasts many years.
Other considerations for a dentist to choose amalgam include a patient’s poor dental hygiene; the need for moisture control during the tooth filling process; cost, when it is an overriding concern for a dental patient.
Generally amalgam is less expensive than other filling materials.
Concern has been raised about amalgam because it contains elemental mercury, and very small amounts of mercury vapor are emitted from dental fillings. The vapor is absorbed in the body mainly through inhalation or ingestion.
The U.S. Food and Drug Administration (FDA) is currently reviewing dental amalgam safety to determine if any special labeling or restrictions for certain populations (children and pregnant women, for example) will be required. The FDA will be issue a final rule classifying dental amalgam by July 28, 2009. See the FDA link below for more details.
Amalgam use has declined a great deal since the 1970’s due to:
- increased use of composite (plastic) tooth colored materials.
- better oral hygiene.
- preventative measures such as community water fluoridation, fluoride applied directly to teeth, and sealants.
1. Composite resin fillings – composite fillings are a mixture of powdered glass and plastic resin. It is used for fillings, inlays, veneers, crowns, or to repair portions of broken teeth.
- Advantages – strong and durable; tooth colored; resists breaking; does not corrode; generally holds up well to the forces of biting
- Disadvantages – costs more than dental amalgam; material shrinks when hardened and could lead to further decay and/or temperature sensitivity.
2. Resin-Ionomer cement – a mixture of glass, plastic resin and organic acid that hardens when exposed to blue light used in a dental office. Often used for small fillings, cementing metal and porcelain metal crowns and liners
- Advantages – tooth colored, looks good; minimal amount of tooth needs to be removed, and it bonds well to both enamel; good for non-biting surfaces.
- Disadvantages – cost similar to composite resin; not recommended to restore biting surfaces of adult teeth; wears faster.
3. Glass-Ionomer cement – self-hardening mixture of glass and organic acid; tooth-colored; used for small fillings, cementing metal and porcelain, temporary restorations.
- Advantages – reasonably good looking; minimal amount of tooth needs to be removed, and it bonds well to tooth enamel and dentin below.
- Disadvantages – cost is similar to composite resin; not recommended for biting surfaces in permanent teeth; tends to crack over time; can dislodge.
4. Nickel or Cobalt-Chrome alloys – mixture of nickel and chromium; dark silver colored, used for crowns, fixed bridges, and most partial denture frameworks.
- Advantages – good resistance to further decay if restoration fits well; excellent durability; does not corrode in the mouth; resists leakage.
- Disadvantages – dark silver color; conducts heat and cold and may cause sensitivity; can be abrasive to opposing teeth; high cost.
5. Porcelain (ceramic) – glass-like material formed into fillings or crowns using a model of the prepared tooth; tooth colored, veneers, crowns and fixed bridges.
- Advantages – good resistance to further decay if restoration fits well; resistant to surface wear on opposing teeth; no tooth sensitivity.
- Disadvantages – material is brittle and can break under biting forces; may not be recommended for molars; higher cost.
6. Gold alloy – gold-colored mixture of gold, copper and other metals, and is used mainly for crowns, fixed bridges and some partial denture framework.
- Advantages – good resistance to further decay if fits well; excellent durability-does not fracture under stress; does not corrode in the mouth.
- Disadvantages – is not tooth-colored; conducts heat and cold; high cost; cannot be used for partial fillings.
7. Porcelain fused to metal – glass-like material that is “enameled” on top of metal shells. It is tooth-colored and is used for crowns and fixed bridges.
- Advantages – good resistance to further decay if restoration fits well; very durable; does not cause tooth sensitivity.
- Disadvantages – more tooth must be removed; higher cost.
* The length of time a restoration (filling, crown, inlay, veneer, etc) will last depends upon a person’s dental hygiene, home care, diet and chewing habits.
Ingredients in dental fillings and materials may have side effects or cause allergic reactions, just like other materials we may come in contact with in our daily lives.
There are no documented cases of allergic reactions to composite resin, glass ionomer, resin ionomer or porcelain. There have been rare allergic responses to dental amalgam, porcelain fused to metal, gold alloys and nickel-cobalt-chrome alloys.
Women should have their dental work completed before becoming pregnant. However, the American Dental Association (ADA) Women’s Oral Health report recommends the following:
- Other than good plaque control, it is good to avoid non-emergency dental care if possible, during the first trimester and the last half of the third trimester, when a woman may be less comfortable sitting in a dental chair.
- Non-emergency dental care should take place in the second and first half of the third trimester.
- The second trimester is the safest period for providing routine dental care.
- Dental emergencies should be dealt with as they arise during pregnancy.
There are no studies that have identified health problems in infants born to women with amalgam fillings. Pregnant women seeking dental care should inform their dentist that they are pregnant and discuss treatment options.
Tooth decay among children and young adults has declined due to many preventative measures such as topical and systemic fluoride, sealants, and improved oral hygiene practices.
Recently, the National Institute of Dental and Crainialfacial Research (NIDCR) released the results of two long-term clinical trials which studied the health effects of amalgam in children. One of the studies was conducted in Europe, the other in the United States. Independently these studies reached the same conclusion: children whose cavities were filled with dental amalgam had no adverse health effects.
Vermont requires all dentists to collect amalgam waste before it goes down the drain, using amalgam separators. The Dental Best Management Practices (BMPs) require all dental practices to self-certify for compliance with the requirements by January 31, 2007.
Proper handling of dental amalgam waste and other hazardous wastes are also required under the BMPs, and will lead to a significant decrease in amalgam/mercury waste releases into wastewater treatment plants and systems.
For the past ten years, the Vermont Dental Society and Vermont’s dental community have advocated for and implemented BMPs to reduce the amount of mercury waste from amalgam released into the environment. Their efforts included educational materials, elemental mercury collection programs for dentists, collaboration with the Vermont Department of Environmental Conservation on dentist surveys, and development of the self-certification program for the dental BMPs.
- Questions and Answers on Dental Amalgam
US Food and Drug Administration
- Dental Amalgam Use and Benefits
Centers for Disease Control and Prevention
- Amalgam Information
American Dental Association