Amalgam Use and Benefits

Before one can enter into a discussion about the use of dental amalgam restorative materials, it is necessary to consider the conditions for use, the criteria for an optimal restorative material, and factors that would influence the success of the material.

Dental amalgam, in widespread use for over 150 years, is one of the oldest materials used in oral health care. Its use extends beyond that of most drugs, and is predated in dentistry only by the use of gold. Dental amalgam is the end result of mixing approximately equal parts of elemental liquid mercury (43 to 54 percent) and an alloy powder (57 to 46 percent) composed of silver, tin, copper, and sometimes smaller amounts of zinc, palladium or indium.

Because of a general decline of dental caries among school children and young adults, the use of dental amalgam began to decrease in the 1970's. There are also changes in patterns of dental caries, largely the result of topical and systemic fluoride, sealant use, improved oral hygiene practices and products, and possibly dietary modifications. In 1990, over 200 million restorative procedures were provided in the United States; of these, dental amalgam accounted for roughly 96 million, a 38 percent reduction since 1979. This trend is expected to continue.

There are also reports that carious lesions today are generally smaller, easier to treat, and managed by more conservative treatment that retains tooth structure. Because of this decrease in the frequency and size of dental caries, there has been a relative increase in the use of alternative dental restorative materials. The most commonly used and less expensive of the alternative materials, however, cannot be used for large lesions and need more frequent replacement. Also, there are currently many serviceable dental amalgam restorations that will need replacing in the future. Approximately 70 percent of the restorations placed annually are replacements. Most of these replacements will require amalgam or other metallic materials, because composite materials often lack sufficient strength or durability to be considered adequate substitutes.

Today, dental amalgam is used in the following situations:

It is not used when:

There are unique characteristics to dental amalgam that appear to enhance its use, just as there are characteristics that discourage its use (Table 1).

For additional information, see The Benefits of Dental Amalgam report in Appendix I.

The use and attributes of alternative dental restorative materials are discussed in the Alternatives.

Table 1.
Comparison of the Advantages and Disadvantages of
Dental Amalgam as a Restorative Material

Advantages

Disadvantages

  • Durable
  • Least technique sensitive of all restorative materials
  • Applicable to a broad range of clinical situations
  • Newer formulations have greater long-term resistance to surface corrosion
  • Good long-term clinical performance
  • Ease of manipulation by dentist
  • Minimal placement time compared to other materials
  • Initially, corrosion products seal the tooth-restoration interface and prevent bacterial leakage
  • One appointment placement (direct material)
  • Long lasting if placed under ideal conditions
  • Often can be repaired
  • Economical
  • Some destruction of sound tooth tissue
  • Poor esthetic qualities
  • Long-term corrosion at tooth-restoration interface may result in "ditching" leading to replacement
  • Galvanic response potential exists
  • Local allergic potential
  • Concern about possible mercury toxicity
  • Marginal breakdown

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