Podcast
Questions and Answers
What are the benefits of using amalgam in dental restorations?
What are the benefits of using amalgam in dental restorations?
Inexpensive, ease of use, proven track record, familiarity, and resin-free (less allergies than composite)
What types of restorations are ideal for amalgam usage?
What types of restorations are ideal for amalgam usage?
Moderate to large restorations, restorations not in highly esthetic areas, restorations with heavy occlusal contacts, and restorations that extend to the root surface
What is a contraindication for using amalgam in dental restorations?
What is a contraindication for using amalgam in dental restorations?
Esthetically prominent areas of posterior teeth, history of allergy to mercury or other amalgam component
When might a dentist choose to use a different material over amalgam?
When might a dentist choose to use a different material over amalgam?
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What is the primary concern when considering the use of amalgam for a patient?
What is the primary concern when considering the use of amalgam for a patient?
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What is the minimum percentage of zinc required for an amalgam alloy to be classified as zinc-containing?
What is the minimum percentage of zinc required for an amalgam alloy to be classified as zinc-containing?
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What is the primary function of copper in dental amalgam?
What is the primary function of copper in dental amalgam?
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What is the main advantage of using spherical alloys?
What is the main advantage of using spherical alloys?
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What is the role of indium in dental amalgam?
What is the role of indium in dental amalgam?
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What is the classification of amalgam alloys based on copper content?
What is the classification of amalgam alloys based on copper content?
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What is the characteristic of amalgams made from lathe-cut powders or admixed powders of lathe-cut and spherical powders?
What is the characteristic of amalgams made from lathe-cut powders or admixed powders of lathe-cut and spherical powders?
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What is the main component of the matrix formed during the setting reaction of amalgam?
What is the main component of the matrix formed during the setting reaction of amalgam?
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What is the strongest phase of amalgam and corrodes the least?
What is the strongest phase of amalgam and corrodes the least?
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What is the percentage of volume of set amalgam formed by the gamma phase?
What is the percentage of volume of set amalgam formed by the gamma phase?
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What is the primary function of mercury in dental amalgam?
What is the primary function of mercury in dental amalgam?
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Study Notes
Why We Use Amalgam
- Inexpensive
- Easy to use
- Proven track record of over 150 years
- Familiarity with the material
- Less allergies than composite resin
Indications and Contraindications for Amalgam Restoration
- Indications: moderate to large restorations, restorations not in highly esthetic areas, restorations with heavy occlusal contacts, restorations that cannot be well isolated, restorations that extend to the root surface, foundations, abutment teeth for removable partial denture, and when cost is a concern for the patient
- Contraindications: esthetically prominent areas of posterior teeth, patients with a history of allergy to mercury or other amalgam components, and small class VI restorations
Alloy Composition
Historical Composition
- GV Black believed amalgam should consist of 67% silver, 27% tin, 5% copper, and 1% zinc
Modern Composition
- Silver and tin are the main components
- Unspecified amounts of other elements such as copper, zinc, gold, and mercury are allowed
Effects of Elements on Amalgam Properties
- Copper: increases expansion, retards setting time, enhances strength
- Tin: decreases flow, increases strength and hardness, reduces setting time
- Zinc: increases plasticity and strength, increases setting time, increases flow, and decreases porosity
- Mercury: activates reaction, increases expansion, increases strength, reduces flow, and reduces creep and marginal breakdown
- Indium: decreases surface tension, reduces amount of mercury necessary, reduces emitted mercury vapor
- Palladium: reduces corrosion, increases luster
Classification of Amalgam Alloys
- Particle geometry and size: irregular (lathe-cut), spherical, admixed
- Copper content: low-copper, high-copper
- Number of particle types: 1, 2
- Zinc content: Zn-containing, Zn-free
Important Knowledge
- Amalgams from lathe-cut powders or admixed powders tend to resist condensation better
- Spherical powders are extremely plastic and require less mercury
- Amalgam alloys may be supplied in pellets, powder, or pills
Basic Structure (Setting Reaction)
- Setting reaction forms different phases, including silver, mercury matrix containing filler particles of silver-tin
- Filler particles can be in various shapes: irregular, spherical, or a combination
- Matrix formed during setting reaction can be gamma 1 (silver-mercury) or gamma 2 (tin-mercury)
Conventional Low-Copper Alloys
- Gamma (γ) phase is the strongest and corrodes the least
- Forms 30-50% of the volume of set amalgam
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Description
Learn about the advantages of amalgam restoration, including its affordability, ease of use, and proven track record. Understand the indications and contraindications of amalgam restoration in dentistry.
