Besides dental amalgam, there are many other restorative materials that are used in dentistry. These materials have not been as effective as dental amalgam in providing a durable and long-lasting restoration, especially in larger lesions. However, advances in technology have resulted in improvements that have expanded their use. The following presents a comparison of these materials. For a full discussion of the advantages and disadvantages of each of the alternative materials discussed in this section, refer to the Benefits Report in Appendix I and a series of summary tables provided in Appendix II.

The public is familiar with the use of composites as esthetic restorations in the anterior teeth. Recent improvements in the materials have resulted in increased uses in the nonstress-bearing areas of the posterior teeth. Currently, dentists are using a combination of composites and sealants (preventive resin restorations) to treat incipient (small) lesions and thereby conserve tooth structure. Some dentists may advocate composites for individuals who are concerned about dental amalgam. This use of composites as substitutes for restorations in stress-bearing areas may be inappropriate. Composites have other inherent limitations; specifically, their sensitivity to moisture requires precise techniques on the part of the dentist and their lack of resistance to chewing stress may compromise their durability.

Composites are used in:

• small to moderately sized lesions in the posterior teeth with no or little stress-bearing forces,
• small to moderately sized anterior restorations,
• repairs of porcelain crowns,
• situations where a preventive resin is needed, and
• foundations for metal, ceramic, and cast-metal restorations.

In contrast, dentists generally do not use composites when:

• restorations are required for stress-bearing posterior teeth, since the wear factor will be great, and
• moisture control is poor.

Sealants prevent dental caries by sealing the pits and fissures of posterior teeth. Since pits and fissures of permanent first molars account for 91 percent of the carious surfaces in children up to 11 yeas of age, sealants are an appropriate choice (see Appendix I for details). However, the use of sealants as a treatment strategy to preserve healthy tooth structure is still not widespread. The 1989 National Center for Health Statistics' Health Interview Survey found that 13 and 17 percent of 8 and 14 year olds, respectively, were reported to have received sealants.

Dentists use preventive resin restorations, a combination of composites and sealants, to treat early caries found in the pits and fissures. A dentist would use this combination when the carious lesion extends into and beyond the enamel so that the use of sealants alone will not suffice. These restorations should only be placed in the nonstress-bearing regions of the dentition. Use of preventive resin restorations is generally governed by the desire to treat small lesions conservatively.

Glass ionomers were introduced to the dental profession in the 1970s. Originally, their acceptance by the dental community was limited because of problems associated with manipulation of the material, setting sequence, moisture sensitivity, less than expected esthetic value and surface texture. Recently, dentists are increasing their use of glass ionomer because of the following characteristics:

• the material chemically bonds to the tooth structure and releases fluoride,
• the placement technique is conservative, requires minimal drilling and the patient response is excellent,
• the procedure is often quick, painless, and may not require local anesthesia, and
• the restoration is fairly esthetic.

The limitations of the material include low tensile strength, low impact and fracture resistance and degradation qualities.

The recommended uses of this material are:

• to restore small to moderately sized cavities in deciduous (baby) teeth,
• as a cavity liner,
• during caries control procedures, and
• for restorations around the gum line (root surface, caries, or abrasion).

Glass ionomers are generally not used in:

• the occlusal surfaces of adult teeth,
• stress-bearing restorations, and
• situations where moisture control is difficult.

The various uses of gold foil date back many centuries, although its use today is diminishing. Gold foil restorations are noted for their longevity, lasting up to 20 years if placed properly. Generally, this material is not used for large restorations because of its inability to withstand stress.

Gold foil restorations require great skill and stringent attention to detail by the dentist during placement. The trauma associated with placement may result in potential damage to the pulp and/or periodontal tissues. Because of the high cost associated with gold foil and the limited number of applications, this material is rarely used. In its place is an increased use of the other improved alternative materials.

Gold foil restorations are used for:

• incipient (small) cavities in nonstress-bearing areas when esthetics is not a major concern, and
• repair of endodontic (root canal) access openings in gold crowns or for gold crown margins, inlays, or onlays.

They are not used in:

• children and young adults, or
• stress-bearing areas of the dentition.

Cast metal and metal-ceramic restorations generally require two or more appointments and are typically used for inlays, onlays, crowns, and/or bridges. The dentist and the laboratory technician must pay close attention to detail in each step of the process when using these materials. The decision to use cast metal or metal-ceramic restorations is dependent on the degree of tooth destruction, the number of missing teeth, the esthetic needs of the patient, the oral hygiene of the patient, and the patient's financial capability, since these restorations cost approximately eight times more than amalgam

Data about the longevity of noble metal (gold, platinum, and palladium) inlays compared to amalgam vary. One study found that the longevity of cast metal restorations was almost 90 percent greater than that of amalgam. The reported lifetime average for full metal crowns was 10 years, with recurrent caries accounting for 58 percent of the failures. Failures with these types of restorations are a result of clinical deficiencies, laboratory deficiencies, inadequate communication between the dentist and laboratory technician, technique sensitivity of the materials, and patient factors, such as poor oral hygiene.

These restorations are typically used in instances when:

• high stress is expected in the targeted oral area,
• moderate to severe breakdown of the natural tooth requires cusp replacement, and
• the patient demands an esthetic appearance rather than conservative treatment (metal-ceramic).

They are generally not used when:

• there is a danger of pulp exposure during tooth preparation, for example, in patients under 18 years of age,
• patients exhibit evidence of extensive bruxing and/or clenching when opposing natural teeth, and
• there is documented allergy to the metals used in casting alloys.

The dental profession has embraced the use of this material in recent years. Improvements in its formulation resulted in a material with enhanced physical properties. Consequently, porcelain and the newer glass ceramics are increasingly used for constructing artificial denture teeth, full crowns, inlays, onlays, laminate veneers, and the veneers found over a metal substructure for crowns and bridges. Although the improvements in this material have led to the development of all-ceramic crowns, their most appropriate use is limited to low stress-bearing areas.

Ceramic restorations are used for

• anterior crowns when esthetics cannot be assured with the use of porcelain-fused-to-metal restorations,
• posterior teeth that are subjected to low biting forces, and
• patients for whom optimal esthetics is an overriding concern.

Ceramics are not typically used when:

• there is a danger of pulp exposure during tooth preparation, for example, in patients under 18 yeas of age,
• the posterior areas are subjected to high biting forces and in situations where porcelain-fused-to-metal crowns cannot be used,
• evidence exists of extensive bruxing and/or clenching, and
• the technician is inexperienced in using the processing technique.

Table 2 is a summary comparison of selected characteristics of posterior restorative materials.

For additional details about the characteristics and a complete discussion of all restorative materials, consult the Benefits Report in Appendix I. This report also contains a discussion of the biocompatibility of restorative materials. The Report notes that biocompatibility with local tissues is acceptable when restorative materials are properly handled and placed. Although there are reports of adverse systemic reactions, generally allergic skin reactions, the literature indicates that they are rare and self-limiting, and tend to be allergenic in nature. There are no reports of systemic toxic reactions. There are documented reports of local reactions to amalgam, composites, and other restorative materials in a small percentage of individuals. Additional details can be found in the Benefits Report.