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49 Cards in this Set
- Front
- Back
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What is an admixed alloy? |
Amalgam products that have a combination of both lathe-cut and spherical particles. |
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What is an alloy? |
Metals that are a combination of several elements. |
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What is amalgam? |
Is a metal alloy of which one of the elements is mercury (Hg). |
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What is amalgam alloy? |
Is the silver-tin (Ag-Sn) powdered metal before it is mixed with mercury. |
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What is amalgamation? |
The mixing process of the alloy with the liquid mercury. |
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What is an amalgamator? |
A mechanical device that "shakes" the capsule containing the alloy powder and mercury at high speed, mixing the two components into a plastic mass. |
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What is annealing gold foil? |
The process by which the chemical protectant on the manufactured gold foil is burned off with 100% ethyl alcohol. |
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What is a blended alloy? |
Amalgam products that have a combination of both lathe-cut and spherical particles. |
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What is cohesive gold? |
Is another name for gold foil. |
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What is copal varnish? |
a resin dissolved in a solvent. |
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Define creep. |
A slow change in shape caused by compression. |
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What is delayed expansion? |
When the zinc reacts with water to produce hydrogen gas which causes the amalgam to expand. |
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What is a dental amalgam? |
is made by mixing approximately equal parts (by weight) of a powdered metal alloy with liquid mercury. The powdered metal is predominetly silver. |
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What is direct gold? |
Is another name for gold foil. |
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What is gold foil? |
a foil that is pure or nearly pure gold, that is used to place is small restorations. |
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What are lathe-cut alloys? |
grinding an ingot of metal to produce filings. |
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What is precipitation? |
a process in which a solid is formed from material dissolved in a liquid. |
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What are spherical alloys? |
spray molten metal into an inert atmosphere, and the droplets cool as they fall. |
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What is trituration? |
The mixing process of the alloy with the liquid mercury. |
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What is a triturator? |
A mechanical device that "shakes" the capsule containing the alloy powder and mercury at high speed, mixing the two components into a plastic mass. |
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Define working time? |
The time needed for the dentist to condense and carve the amalgam. |
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Name two kinds of amalgam alloy. |
Lathe-cut - from grinding an ingot
Spherical - from spraying molten metal into an inert atmosphere. |
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When was amalgam initially developed? |
Developed in France in the 1800's. |
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What is the composition of low copper amalgam? |
65% Silver 25% Tin Less than 6% copper 1% zinc (prevents oxidation) |
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What is the function of silver, tin, copper, and zinc in amalgam? |
Silver - Causes the setting expansion, increases strength and corrosion resistance. Tin - causes setting contraction, decreases, strength and corrosion resistance. Copper - functions much the same as silver Zinc - reduces oxidation of the other metals |
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What is the weakest and most corrosion prone phase of low copper? |
Sn-Hg (Tin-mercury) The gamma two phase |
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What % copper is in high copper amalgams? |
10 - 30% copper |
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What two factors affect the handling and performance of amalgam? |
Manufacturer Dentist |
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Amalgam has high _________ strength. |
Compressive strength |
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Amalgam has low __________ strength. |
Shear strength |
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Dental amalgam is not recommended for what class restoration? |
Class IV |
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Why can zinc cause an amalgam to expand? |
It can react with water to produce hydrogen gas. |
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What percent of patients have mercury toxicity? |
0.1% |
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Gold foil restorations are limited to what class restoration? |
Class V |
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Which element is used in the highest amount in an amalgam restoration? |
Mercury |
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Amalgam is strongest in __________ strength after is has set. |
Compressive |
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The elements composing the gamma-two phase (the weakest and most corrosion-prone phase) of the amalgam restoration are? |
Tin and mercury |
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The function of silver in the amalgam reaction is to? |
Increase strength and corrosion resistance. |
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Control of the mercury content during mixing and condensing of amalgam must be carefully considered because? |
The lower the mercury content, the higher the strength and the lower the marginal breakdown. |
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The single most important feature that accounts for the clinical success of amalgam restorations is? |
Marginal seal |
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The manufacturers of dental amalgam control what three things? |
Alloy composition Rate of setting reaction Particle Size |
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An amalgam restoration that has been finished and polished has what three characteristics? |
*Reduces the ability of plaque to adhere *Resists tarnish and corrosion *Is more likely to have continuous margins with tooth structure. |
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In a high-copper amalgam reaction, tin reacts with? |
Copper |
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True or False
The life expectancy of an amalgam restoration is indirectly related to the size of the restoration. As the restoration increases in size, internal stress decreases, as does the life expectancy. |
The first statement is true. the second statement is false. |
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Ashley was condensing an amalgam during lab and she noticed that the triturated amalgam had a softer, "mushy" feel. What type of alloy did she most likely use in the mixed amalgam? |
Spherical alloy. |
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Just after Jennifer triturated her amalgam, the appearance of it was "crumbly" and dry. It already looked set. The amalgam was most likely? |
Over-triturated |
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Amalgam may be used for a variety of restorative procedures. What three things pertain to the use of amalgam? |
*Good service to patients at a reasonable cost *For cingulum pit areas on the lingual of anterior teeth *Amalgam cores |
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It has been reported in the scientific literature that ______% of dental patients have a TRUE mercury allergy. |
0.1% |
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The use of gold foil is limited to small restorations because of its? |
Low strength compared to other restorative materials. |
