Podcast
Questions and Answers
What is the cause of shrinkage spot porosity in dental casting alloys?
What is the cause of shrinkage spot porosity in dental casting alloys?
- Insufficient venting of the investment
- Under heating of the alloy causing premature solidification of molten metal
- Incomplete wax elimination
- Using too thin sprue (correct)
What causes back pressure porosity in dental casting alloys?
What causes back pressure porosity in dental casting alloys?
- Incomplete wax elimination
- Insufficient venting of the investment (correct)
- Using short sprue
- Improper use of wetting agent on the wax pattern
What leads to surface roughness in dental casting alloys?
What leads to surface roughness in dental casting alloys?
- Improper use of wetting agent on the wax pattern
- Too rapid or over heating of the investment during wax elimination (correct)
- Stiffness and resistance to elastic deformation
- Improper vacuum investing
What causes insufficient feeding of the mold with molten alloy during solidification in dental casting alloys?
What causes insufficient feeding of the mold with molten alloy during solidification in dental casting alloys?
What contributes to the premature solidification of molten metal in dental casting alloys?
What contributes to the premature solidification of molten metal in dental casting alloys?
What may result in improper attachment of the sprue in dental casting alloys?
What may result in improper attachment of the sprue in dental casting alloys?
What does high stiffness in a dental casting alloy allow?
What does high stiffness in a dental casting alloy allow?
Which property is required to resist permanent deformation under masticatory stresses in the mouth?
Which property is required to resist permanent deformation under masticatory stresses in the mouth?
Why is high ductility an important factor in the burnishability of dental casting alloys?
Why is high ductility an important factor in the burnishability of dental casting alloys?
Which metals are considered noble metals in dental casting alloys?
Which metals are considered noble metals in dental casting alloys?
What is the primary purpose of using noble metals in dental casting alloys?
What is the primary purpose of using noble metals in dental casting alloys?
What influences the compatibility of a metal with porcelain in dental casting alloys?
What influences the compatibility of a metal with porcelain in dental casting alloys?
Why must the melting temperature of the metal be higher than the firing temperature of the porcelain in dental casting alloys?
Why must the melting temperature of the metal be higher than the firing temperature of the porcelain in dental casting alloys?
What is the primary requirement for ease of casting in dental casting alloys?
What is the primary requirement for ease of casting in dental casting alloys?
Study Notes
Porosity in Dental Casting Alloys
- Shrinkage spot porosity is caused by inadequate feeding of the mold with molten alloy during solidification.
- Back pressure porosity is caused by air or gas trapped in the mold during the casting process.
Surface Roughness in Dental Casting Alloys
- Surface roughness is caused by the presence of gas or oxide inclusions in the molten alloy.
Insufficient Feeding of the Mold
- Insufficient feeding of the mold with molten alloy during solidification is caused by premature solidification of the molten metal.
Premature Solidification
- Premature solidification of the molten metal is caused by factors such as inadequate temperature control, incorrect alloy composition, or inadequate sprue design.
Improper Attachment of the Sprue
- Improper attachment of the sprue to the mold can result from incorrect sprue design, inadequate wax pattern, or improper investment of the mold.
Stiffness in Dental Casting Alloys
- High stiffness in a dental casting alloy allows for greater resistance to deformation under masticatory stresses.
Properties Required for Dental Casting Alloys
- Resistance to permanent deformation under masticatory stresses requires a property known as stiffness.
- High ductility is an important factor in the burnishability of dental casting alloys.
Noble Metals in Dental Casting Alloys
- Noble metals in dental casting alloys include gold, platinum, and palladium.
- The primary purpose of using noble metals is to provide corrosion resistance and biocompatibility.
Metal-Porcelain Compatibility
- The compatibility of a metal with porcelain is influenced by the thermal expansion coefficient of the metal.
- The melting temperature of the metal must be higher than the firing temperature of the porcelain to ensure a successful bond.
Ease of Casting
- The primary requirement for ease of casting is low viscosity of the molten alloy.
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Description
Test your knowledge of common casting defects in metal alloys with this quiz. Learn about issues such as porosity, incomplete wax elimination, insufficient venting, and more.
