Dental Amalgam: Filling a Need or Foiling Health : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 2)

Alternatives

No single material can completely replace dental amalgam. Gold and ceramic inlays and crowns can replace amalgam in larger back cavities or in medium-sized cavities on other stress-bearing tooth surfaces. Smaller cavities in premolars and molars can now be restored with resin-based composite materials, glass ionomers, or compacted gold.

Alternatives to dental amalgam are not as durable, however, especially in larger cavities, and can cost significantly more. "A wholesale conversion to non-amalgam materials would drive up national dental health care costs by about $12 billion in the first year, a tremendous cost impact," says Robert C. Eccleston, assistant to the director at FDA's Center for Devices and Radiological Health. "The cost would also increase in the years following any across-the-board conversion."

Also, according to the PHS report, it is possible that alternative dental restorative materials could have long-term toxicity problems of their own that have not yet been discovered. Since no definitive data exists to show that mercury in dental amalgam is directly linked to illness, and since amalgam is less expensive, easier to place, and more durable than alternatives, dental amalgam should continue to be used.

Composites

Composites, made from synthetic resins, are used to make attractive restorations in the front teeth. Dentists use a combination of composites and sealants, technically known as preventive resin restorations, to treat small cavities and conserve tooth structure. But the use of composites as substitutes for restorations in stress- bearing areas may be inappropriate because composites can leave a tooth susceptible to recurrent decay.

Pit and Fissure Sealants

In its report, PHS recommends dental sealants to prevent caries. Sealants prevent cavities by sealing with thin plastic coating the natural pits (round holes) and fissures (grooves) in their molars. Pits and fissures in permanent first molars account for 91 percent of the surface cavities in children up to 11 years of age. "The best restoration that is ever placed cannot be as good as the sound tooth structure that was there in the beginning," Corbin says. "But some of the preventive materials [sealants] actually improve tooth structure."

Glass Ionomers

Glass ionomers, introduced to dentistry in the 1970s, chemically bond to the tooth structure and have the beneficial side effect of releasing fluoride.

Ionomer placement technique requires limited drilling, so the procedure is quick and the result fairly attractive. Because glass ionomers are generally not used in occlusal surfaces (biting surfaces), their use is limited to baby teeth and primarily root surfaces.

Gold Foil

Although not widely used today, gold foil restorations (compacted gold) date back many centuries. These fillings may last 20 years or longer, but are not used for large or very visible areas. Gold foil restorations require more skill and careful attention to detail during placement to prevent harm to the tooth pulp (nerve) and gums. Its high cost also makes gold foil a less popular choice.

Cast Metal and Metal-Ceramic

Cast metal and metal-ceramic restorations generally require two or more dental appointments and are typically used for inlays, onlays, crowns, and bridges. Use of metal and metal-ceramic materials depends on the degree of tooth destruction from decay, breakage, or amount of tooth removed by drilling. It is also determined by the number of missing teeth, how important looks are to the patient, and the patient's oral hygiene and financial situation. These restorations cost approximately eight times more than amalgam and are most often used:

• in teeth involved in the stress from chewing and biting when moderate to severe breakdown of the tooth requires replacement
• if the patient demands a more pleasing appearance than that produced by amalgam.

Cast metal or metal-ceramic restorations are generally not used if:

• there is a danger of exposing the tooth pulp while preparing the tooth for restoration — for example, in patients under 18 whose pulp is higher in the tooth
• the patient shows evidence of extensive teeth grinding or clenching
• the patient is known to be allergic to the metals used in casting alloys (gold and certain non-precious casting metals).

Regulation

The PHS report recommends that FDA require restorative material manufacturers to identify the ingredients used in their products, and FDA is considering such an action. Industry disclosure of product ingredients would provide dentists with information necessary to prevent sensitivity reactions in allergic patients. The PHS findings indicate that it is inappropriate to recommend restrictions on the use of dental amalgam unless more studies show a definite link between amalgam and illness.

"The science simply doesn't justify such an action," FDA's Eccleston points out. "There are several reasons for not restricting amalgam. First, current evidence does not show that exposure to mercury from amalgam restorations poses a serious health risk in humans, except for a very small number of allergic reactions. Second, there is insufficient evidence that alternative materials have fewer potential health effects than amalgam.

About the Author

www.fda.gov
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.