Topic:
MEDICAL CARE; DENTISTS;
Location:
DENTISTRY;

OLR Research Report


January 5, 2005

 

2005-R-0038

DENTAL AMALGAM PREVALENCE AND ALTERNATIVES

By: Saul Spigel, Chief Analyst

You asked about the prevalence of dental amalgam use and the alternatives to its use.

We have attached OLR report 2002-R-0744, which provides background information on the use and composition of dental amalgam, views on its use, and legislative activity concerning it.

SUMMARY

The use of dental amalgam in the U.S. is declining according to the U.S. Public Health Service (USPHS) and the American Dental Association (ADA). In 1990 amalgam was used in slightly fewer than half of all dental restorations. This represented a 38% decline in its use over the previous decade. USPHS expected the decline to continue, and it confirmed this trend in a 1997 report. The ADA estimates that approximately 30 to 35% of fillings places today are amalgam. It believes amalgam use drops about three to five percent each year. We were unable to find data on the prevalence of dental amalgam use in Connecticut.

Several alternatives to dental amalgam are available. They include gold, porcelin, and composite resins. Dental organizations claim these alternatives are generally more costly; take longer to make, sometimes requiring two appointments; and, except for gold, are not as durable as amalgam.

PREVALENCE

The use of dental amalgam in the U.S. has declined over the past 25 years. A 1993 USPHS report stated that dental amalgam accounted for 96 million, or just under 50%, of the 200 million restorative procedures U.S. dentists conducted in 1990. This represented a 38% reduction in amalgam use since 1979. USPHS predicted this trend would continue.

In 1997, USPHS stated that its prediction appeared to be holding true, based on limited survey and anecdotal information. Most of the reasons it cited for the decline appeared to be attributable to a decrease in cavities. The USPHS noted that (1) many dentists were relying on dental sealants to prevent cavities (thus reducing the need for amalgam fillings), (2) community flouridation programs and increased use of flouride-containing dental products continued to reduce cavities, and (3) pediatric dentists were moving away from using amalgam in favor of resin (plastic), mercury-free, tooth-colored materials that are bonded to the tooth.

USPHS cited an ADA membership survey indicating that between 1990 and 1995 general practice dentists performed about 15% fewer “posterior restorations” (filling back teeth) each week. It also cited a 1997 survey of Michigan residents that reported “…profound improvements in oral health” in all age groups, which had led to decreased need for restorative care.

ALTERNATIVES TO AMALGAM

Several alternatives to dental amalgam are available. They include gold, porcelin, and composite resins. According to dentists, they are generally more costly; can take longer to make, sometimes requiring two appointments; and, except for gold, are not as durable as amalgam.

The following tables compare restorative materials. Direct restorative materials (Table 1) are what we normally call fillings. They are placed at the same time decay is removed from a tooth and the cavity is prepared. Indirect restorations (Table 2) are built in a laboratory from an impression a dentist takes when the cavity is prepared; they are inserted on a subsequent visit.

Table 1: Comparison of Direct Restorative Dental Materials

FACTORS

AMALGAM

COMPOSITES Direct and Indirect

GLASS IONOMERS

RESIN-IONOMERS

General Description

A mixture of mercury and silver alloy powder that forms a hard solid metal filling. Self-hardening at mouth temperature.

A mixture of submicron glass filler and acrylic that forms a solid tooth-colored restoration. Self- or light-hardening at mouth temperature.

Self-hardening mixture of fluoride containing glass powder and organic acid that forms a solid tooth colored restoration able to release fluoride.

Self or light- hardening mixture of sub-micron glass filler with fluoride containing glass powder and acrylic resin that forms a solid tooth colored restoration able to release fluoride.

Principal Uses

Dental fillings and heavily loaded back tooth restorations.

Esthetic dental fillings and veneers.

Small non-load bearing fillings, cavity liners and cements for crowns and bridges.

Small non-load bearing fillings, cavity liners and cements for crowns and bridges.

Leakage and Recurrent Decay

Leakage is moderate, but recurrent decay is no more prevalent than other materials.

Leakage low when properly bonded to underlying tooth; recurrent decay depends on maintenance of the tooth-material bond.

Leakage is generally low; recurrent decay is comparable to other direct materials, fluoride release may be beneficial for patients at high risk for decay.

Leakage is low when properly bonded to the underlying tooth; recurrent decay is comparable to other direct materials, fluoride release may be beneficial for patients at high risk for decay.

Clinical Considerations

Tolerant to a wide range of clinical placement conditions, moderately tolerant to the presence of moisture during placement.

Must be placed in a well-controlled field of operation; very little tolerance to presence of moisture during placement.

Resistance to Wear

Highly resistant to wear.

Moderately resistant, but less so than amalgam.

High wear when placed on chewing surfaces.

Resistance to Fracture

Brittle, subject to chipping on filling edges, but good bulk strength in larger high- load restorations.

Moderate resistance to fracture in high-load restorations.

Low resistance to fracture.

Low to moderate resistance to fracture.

-Continued-

FACTORS

AMALGAM

COMPOSITES Direct and Indirect

GLASS IONOMERS

RESIN-IONOMERS

Biocompatibility

Well-tolerated with rare occurrences of allergenic response.

Post-Placement Sensitivity

Early sensitivity to hot and cold possible.

Occurrence of sensitivity highly dependent on ability to adequately bond the restoration to the underlying tooth.

Low.

Occurrence of sensitivity highly dependent on ability to adequately bond the restoration to the underlying tooth.

Esthetics

Silver or gray metallic color does not mimic tooth color.

Mimics natural tooth color and translucency, but can be subject to staining and discoloration over time.

Mimics natural tooth color, but lacks natural translucency of enamel.

Mimics natural tooth color, but lacks natural translucency of enamel.

Relative Cost to Patient

Generally lower; actual cost of fillings depends on their size.

Moderate; actual cost of fillings depends on their size and technique.

Moderate; actual cost of fillings depends on their size and technique.

Moderate; actual cost of fillings depends on their size and technique.

Average Number of Visits To Complete

One.

One for direct fillings; 2+ for indirect inlays, veneers and crowns.

One.

One.

Source: ADA, 2002

Table 2: Comparison of Indirect Restorative Dental Materials

FACTORS

ALL-PORCELAIN (ceramic)

PORCELAIN Fused to metal

GOLD ALLOYS (high noble)

BASE METAL ALLOYS (non-noble

General Description

Porcelain, ceramic or glass-like fillings and crowns.

Porcelain is fused to an underlying metal structure to provide strength to a filling, crown or bridge.

Alloy of gold, copper and other metals resulting in a strong, effective filling, crown or bridge.

Alloys of non-noble metals with silver appearance resulting in high strength crowns and bridges.

-Continued-

FACTORS

ALL-PORCELAIN (ceramic)

PORCELAIN Fused to metal

GOLD ALLOYS (high noble)

BASE METAL ALLOYS (non-noble

Principal Uses

Inlays, onlays, crowns and aesthetic veneers.

Crowns and fixed bridges.

Inlays, onlays, crowns and fixed bridges.

Crowns, fixed bridges and partial dentures.

Leakage and Recurrent Decay

Sealing ability depends on materials, underlying tooth structure and procedure used for placement.

The commonly used methods used for placement provide a good seal against leakage. The incidence of recurrent decay is similar to other restorative procedures.

Durability

Brittle material, may fracture under heavy biting loads. Strength depends greatly on quality of bond to underlying tooth structure.

Very strong and durable.

High corrosion resistance prevents tarnishing; high strength and toughness resist fracture and wear.

Cavity Preparation Considerations

Because strength depends on adequate porcelain thickness, it requires more aggressive tooth reduction during preparation.

Including both porcelain and metal creates a stronger restoration than porcelain alone; moderately aggressive tooth reduction is required.

The relative high strength of metals in thin sections requires the least amount of healthy tooth structure removal.

Clinical Considerations

These are multiple step procedures requiring highly accurate clinical and laboratory processing. Most restorations require multiple appointments and laboratory fabrication. Moderate resistance to fracture in high-load restorations. Low resistance to fracture. Low to moderate resistance to fracture.

Resistance to Wear

Highly resistant to wear, but porcelain can rapidly wear opposing teeth if its surface becomes rough.

Highly resistant to wear, but porcelain can rapidly wear opposing teeth if its surface becomes rough.

Resistant to wear and gentle to opposing teeth.

Resistant to wear and gentle to opposing teeth.

Resistance to Fracture

Prone to fracture when placed under tension or on impact.

Porcelain is prone to impact fracture; the metal has high strength.

Highly resistant to fracture.

Biocompatibility

Well tolerated.

Well tolerated, but some patients may show allergenic sensitivity to base metals.

Well tolerated.

Well tolerated, but some patients may show allergenic sensitivity to base metals.

-Continued-

FACTORS

ALL-PORCELAIN (ceramic)

PORCELAIN Fused to metal

GOLD ALLOYS (high noble)

BASE METAL ALLOYS (non-noble

Post-Placement Sensitivity

Sensitivity, if present, is usually not material specific.

Low thermal conductivity reduces the likelihood of discomfort from hot and cold.

High thermal conductivity may result in early post-placement discomfort from hot and cold.

Esthetics

Color and translucency mimic natural tooth appearance.

Porcelain can mimic natural tooth appearance, but metal limits translucency.

Metal colors do not mimic natural teeth.

Relative Cost to Patient

Higher; requires at least two office visits and laboratory services.

Higher; requires at least two office visits and laboratory services.

Higher; requires at least two office visits and laboratory services.

Average Number of Visits To Complete

Minimum of two; matching esthetics of teeth may require more visits.

Minimum of two; matching esthetics of teeth may require more visits.

Minimum of two

Source: ADA, 2002

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