Dental Fillings, Prevention of Decay

by Food and Drug Administration (FDA)

(Page 2 of 3)

Fillings

Once decay is removed, a filling is placed inside the cut-out area to retain the tooth's shape and function, including chewing. Today, a variety of filling materials is available.

One of the oldest and now most commonly used is amalgam, a metal alloy of silver, tin, copper, and sometimes indium, palladium and zinc that is mixed with about an equal amount of mercury. FDA regulates amalgam alloy as a medical device.

According to a November 1998 article in the Journal of the American Dental Association, dentists continue to use amalgam primarily because it is inexpensive and durable and withstands the tremendous forces of chewing. A 1993 U.S. Public Health Service report on dental amalgam said that amalgam typically lasts from 8 to 12 years. Only gold alloy and metal-ceramic crowns last longer — up to 18 years.

Amalgam has drawn controversy in the past 10 years because its critics contend that the mercury emits minute amounts of vapor, causing a variety of health problems ranging from multiple sclerosis and arthritis to mental disorders. However, several investigations by the federal government and others have not borne this out, and the use of amalgam is supported by FDA, the National Institute on Dental and Craniofacial Research, the American Dental Association, and other professional organizations.

In a scientific literature review published in the November 1998 Journal of the American Dental Association, professors of dentistry in the United States and China found that research has not yet shown that mercury vapors escaping amalgams are "in concentrations high enough to produce any detectable effect on the body." The authors concluded that, contrary to some dentists' current practice, "dentists cannot ethically tell patients that amalgam is a health hazard and that removal of restorations will benefit their health."

While amalgam remains the most commonly used dental filling, its use does appear to be declining. According to the dental association's journal article, the use of amalgam for filling back teeth has dropped from 85 percent in 1988 to 58 percent in 1997. "The use of amalgam will likely continue to diminish, and it will eventually disappear from the scene," the journal article said.

One reason for the decline is the introduction of new materials that afford similar durability and strength as amalgam and, unlike the silver-colored fillings, can be made to match the color of a patient's teeth. "The aesthetics' side of it is very important to many patients," Runner says. However, using these materials — composites, glass ionomers, and metal-ceramic crowns — can cost a patient from 1.5 times to 8 times the cost of an amalgam restoration.

Prevention of Decay

Of course, much of the pain and expense of treating cavities can be eliminated through preventive measures.

Many of these measures, says Dennis Mangan, Ph.D., chief of the Infectious Diseases Branch of the extramural division of the National Institute on Dental and Craniofacial Research, are aimed at interrupting the decay process — for example, eliminating the sugars that serve as a source of food for bacteria in the mouth, eliminating the bacteria that feed on the sugars, strengthening the tooth's enamel to make it harder for acids to attack. Or, Mangan says, "It can be some combination of all of them."

Some of the most successful preventive measures involve fluoride, a mineral that occurs naturally in many foods and water. Fluoride helps prevent decay by making the tooth more resistant to acid attacks. It also has been found to reverse early decay where acid has broken through the enamel by remineralizing the affected area.

To function effectively as an anti-decay substance, fluoride should not only be applied to the teeth but ingested, as well. The most important way in which fluoride is ingested is through fluoridated public drinking water. Dental experts cite water fluoridation, which began 50 years ago, as the main reason for the decline in cavities in children since World War II.

In areas with inadequate or no water fluoridation, children between 6 months and 16 years may need fluoride supplements. A dentist can prescribe the correct dose.

Fluoride can be applied directly to teeth with the use of fluoridated toothpastes and mouth rinses. Less-concentrated rinses are available over-the-counter, while stronger concentrations require a dentist's prescription.

Consumers need to be sure that children don't use fluoride products without supervision because excess ingestion of fluoride can cause defects in the tooth's enamel that range from barely noticeable white specks or streaks to cosmetically objectionable brown discoloration. The defects, known as fluorosis, occur while the teeth are forming, usually in children under 6 years. Although tooth staining from fluorosis cannot be removed with normal hygiene, a dentist may be able to lighten or remove these stains with professional-strength abrasives or bleaches.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.