Dental Casting Alloys Overview
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Questions and Answers

The noble metals used in dentistry include all of the following except?

  • Platinum
  • Palladium
  • Silver (correct)
  • Gold

    • Precious metals in dentistry include which of the following?

  • Gold
  • Platinum
  • Palladium
  • Silver
  • All of the above (correct)

    • Which of the following is the gold content of an 18K gold alloy (by weight percentage)?

  • 75% (correct)
  • 90%
  • 50%
  • 30%

    • Cold foil has which of the following number of carats?

    <p>24</p> Signup and view all the answers

    Dental casting alloys should be compatible with porcelain in order to construct ceramometallic restoration as regard:

    <p>All of the above</p> Signup and view all the answers

    Ag-Pd alloys:

    <p>All of the above</p> Signup and view all the answers

    Which of the following statements are true regarding the grain structure of gold alloys?

    <p>Fine-grained alloys generally are more ductile than coarse-grained alloys</p> Signup and view all the answers

    The fineness of a 24 Carat gold alloy is:

    <p>1000</p> Signup and view all the answers

    The purpose of adding small amounts of tin and indium to high-carat gold alloys used in the construction of ceramo-metallic is:

    <p>To form oxides that bond with ceramic</p> Signup and view all the answers

    A Type IV partial denture gold alloy exceeds a base-metal alloy in numerical value in

    <p>Modulus of elasticity</p> Signup and view all the answers

    The gold content of Economy gold is:

    <p>42 to 58%</p> Signup and view all the answers

    To avoid tarnish & corrosion of economy dental gold alloys:

    <p>Copper &amp; silver % should be balanced to avoid the precipitation of silver rich phase</p> Signup and view all the answers

    Which of the following elements is not noble by the ADA definition?

    <p>Zn</p> Signup and view all the answers

    Grain refiners act in casting alloys by making the grains smaller:

    <p>True</p> Signup and view all the answers

    Resistance of noble metals to corrosion is due to their:

    <p>A &amp; C</p> Signup and view all the answers

    5% of ______ has a pronounced effect on whitening the color of gold alloy and it decreases the greening of silver and reddening of copper.

    <p>palladium</p> Signup and view all the answers

    All of the following are properties of Iridium EXCEPT:

    <p>It constitutes 0.005% of the alloy</p> Signup and view all the answers

    The highest % elongation of gold alloys is present in:

    <p>Type I</p> Signup and view all the answers

    To achieve heat treatment of noble metal alloys, the relative ratio of Cu: Au should be:

    <p>Less than 12:88</p> Signup and view all the answers

    Compared to Au-Cu₃, the super-lattice Au-Cu formed in the gold-copper system:

    <p>Is more preferable to be used in dental restorations</p> Signup and view all the answers

    The disadvantages of base metal dental casting alloys include:

    <p>All of the above</p> Signup and view all the answers

    Chromium should not exceed 30% in base metal alloys:

    <p>All of the above</p> Signup and view all the answers

    An increase by 0.2% over the desired percentage of carbon in base metal alloys

    <p>gives a too hard and brittle alloy</p> Signup and view all the answers

    Which of the following elements improves fluidity of the molten base metal alloys:

    <p>Silicon and manganese</p> Signup and view all the answers

    Aluminum is added to base metals containing nickel in order to:

    <p>Increase strength of the alloy through formation of nickel aluminide intermetallic compound</p> Signup and view all the answers

    ..............has a pronounced effect on increasing strength and rigidity of base metal alloys:

    <p>All of the above</p> Signup and view all the answers

    Shaping titanium without melting and casting is known as:

    <p>Sintering</p> Signup and view all the answers

    Casting of titanium is a highly technique sensitive procedure due to:

    <p>All of the above</p> Signup and view all the answers

    Is/are used a substitute for gold alloys type IV:

    <p>B &amp; C</p> Signup and view all the answers

    For base metal alloys:

    <p>Pickling is desirable to improve their surface finish</p> Signup and view all the answers

    Using the non reducing zone of the gas- air torch during melting of the gold alloy causes:

    <p>Alloy discoloration that can be removed by pickling</p> Signup and view all the answers

    In noble metal casting alloys, platinum may be substituted by

    <p>palladium</p> Signup and view all the answers

    Which of the following elements act as a grain refiner in base metal alloys:

    <p>Molybdenum</p> Signup and view all the answers

    Of the following common metals used in dentistry, the lowest melting point of 960°C is of

    <p>silver</p> Signup and view all the answers

    Biocompatibility of gold alloys is related their:

    <p>Nobility</p> Signup and view all the answers

    Resistance of base metal alloys to corrosion is due to their:

    <p>Passivity</p> Signup and view all the answers

    Biocompatibility of base metal alloys is related their:

    <p>Passivity</p> Signup and view all the answers

    Nickel when added to base metal alloys, increases its

    <p>Ductility</p> Signup and view all the answers

    Which one of the following types of alloys not respond to heat treatment

    <p>Co-Cr alloys</p> Signup and view all the answers

    The material of choice for root form dental implants is

    <p>Titanium</p> Signup and view all the answers

    Beryllium free nickel chromium alloys are introduced now because:

    <p>Beryllium vapor is carcinogenic</p> Signup and view all the answers

    Nickel free nickel chromium alloys are introduced now because:

    <p>Nickel is allergic to some patients</p> Signup and view all the answers

    Zinc in gold alloys:

    <p>Acts as scavenger</p> Signup and view all the answers

    Copper in gold alloys:

    <p>Is important in heat treatment</p> Signup and view all the answers

    Which of the following is used in polishing base metal alloys:

    <p>Electropolishing</p> Signup and view all the answers

    Pickling is performed after casting of :

    <p>Cobalt chromium alloys</p> Signup and view all the answers

    The most powerful grain refiner in noble metal dental casting alloys is

    <p>iridium</p> Signup and view all the answers

    The primary oxygen scavenger in noble metal casting alloys is

    <p>zinc</p> Signup and view all the answers

    Type IV gold casting alloys are used for fabricating

    <p>Removable partial denture frameworks</p> Signup and view all the answers

    -------may be present as a grain refiner in dental gold alloy as it has a high melting point.

    <p>Iridium</p> Signup and view all the answers

    A noble metal casting alloy containing iridium will have

    <p>All of the above</p> Signup and view all the answers

    All of the following metals have a whitening effect on gold alloys, except

    <p>Copper</p> Signup and view all the answers

    An alloy contains 18 parts gold and 6 parts other metals. The alloy is

    <p>750 fine</p> Signup and view all the answers

    All of the following are grain refiners of noble metal casting alloys, except

    <p>Iron</p> Signup and view all the answers

    Usually gold casting alloys are softened heat treated, by heating at

    <p>700 °C for 10 min and then quenching</p> Signup and view all the answers

    Casting should be done under well controlled vacuum atmosphere in base metal alloys to avoid:

    <p>All of the above</p> Signup and view all the answers

    Because of its low density casting of Co-Cr alloys should be done by the use of :

    <p>Special designed casting machine using centrifugal and air pressure casting force under well controlled vacuum atmosphere.</p> Signup and view all the answers

    All of the following are properties of cobalt - chromium - nickel alloy, except:

    <p>They can be casted in normal environment</p> Signup and view all the answers

    Signup and view all the answers

    Study Notes

    Dental Casting Alloys

    • Noble Metals (Dentistry): Gold, platinum, palladium, silver are included
    • Precious Metals (Dentistry): Gold, platinum, palladium, and silver are included
    • 18K Gold Alloy (Weight %): 75%
    • Carats of Cold Foil: 12
    • Dental Casting Alloy Compatibility: Compatible with porcelain, especially in terms of coefficient of thermal expansion and modulus of elasticity
    • Ag-Pd Alloys: Low density, low elongation; alternative to gold alloys, with tendency to gas absorb during melting and casting
    • Gold Alloy Grain Structure: Fine-grained alloys are generally stronger but less ductile than coarse-grained alloys
    • 24 Karat Gold Fineness: 1000
    • Indium and Tin in Gold Alloys: Improve corrosion resistance, lower fusing temperature, improve bonding with ceramic
    • Type IV Gold Alloy: Excels base metal alloys in compressive strength, casting shrinkage, hardness, and specific gravity
    • Economy Gold Content: 32-42%

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    Dental Casting Alloys PDF Past Paper

    Description

    Explore the characteristics of dental casting alloys, including noble and precious metals like gold and platinum. This quiz covers the composition, compatibility, and structural properties of various gold alloys in dentistry. Test your knowledge on the qualities essential for dental applications.

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