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How Dental Restoration Materials Compare

Stephen Barrett, MD.
Robert S. Baratz, MD, DDS, PhD

Dental restorations can be classified into two types. Direct restorations are done by inserting filling material directly into the tooth. Indirect restorations are fabricated outside of the mouth.

In recent years, there has been a marked increase in the development of esthetic materials made of ceramic and plastic. These mimic the appearance of natural teeth and are more esthetically pleasing where they will be visible. But the strength and durability of traditional materials still make them useful, particularly in the back of the mouth where they must withstand the extreme forces that result from chewing. The traditional materials include gold, base metal alloys, and dental amalgam.

Amalgam, produced by mixing mercury and other metals, is still the most commonly used filling material. Some people have expressed concern about amalgam because of its alleged mercury content. In fact, amalgam is composed mostly of complex compounds where the mercury is bound chemically to the other ingredients. Although mercury by itself is classified as a toxic material, the mercury in amalgam is chemically bound to other metals to make it stable and therefore safe for use in dental applications. In fact, amalgam is the most thoroughly studied and tested restorative material now used. Compared to the rest, it is durable, easy to use, and inexpensive. The safety and effectiveness of amalgam have been reviewed by major U.S. and international scientific and health bodies, including the American Dental Association; the National Institutes of Health; the U.S. Public Health Service; the Centers for Disease Control and Prevention; the Food and Drug Administration; and the World Health Organization. All have concluded that amalgam is a safe and effective material for restoring teeth.

The charts below are reproduced with the kind permission of the American Dental Association, which developed them to help dentists explain the relative advantages and disadvantages of the materials used in fillings, crowns, bridges and inlays. They provide a simple overview of the subject based on the current dental literature and are not intended to be comprehensive. The attributes of a particular restorative material can vary from case to case depending on a number of factors.

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.

 

Overall Durability

 

Good to excellent in large load-bearing restorations. Good in small-to-moderate size restorations. Moderate to good in non load-bearing restorations poor in load-bearing. Moderate to good in non load-bearing restorations; poor in load-bearing.
Cavity Preparation Considerations Requires removal of tooth structure for adequate retention and thickness of the filling. Adhesive bonding permits removing less tooth structure. Adhesive bonding permits removing less tooth structure. Adhesive bonding permits removing less tooth structure.
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.
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.

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.
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.
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.
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

© American Dental Association. Updated, February 21, 2002

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This article was posted on April 23, 2002.