Dental Casting Defects Quiz and Flashcards

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Questions and Answers

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?

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?

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?

Using short sprue Signup and view all the answers

What contributes to the premature solidification of molten metal in dental casting alloys?

Under heating of the alloy Signup and view all the answers

What may result in improper attachment of the sprue in dental casting alloys?

Using short sprue Signup and view all the answers

What does high stiffness in a dental casting alloy allow?

Equal stress distribution under restoration Signup and view all the answers

Which property is required to resist permanent deformation under masticatory stresses in the mouth?

High yield stress Signup and view all the answers

Why is high ductility an important factor in the burnishability of dental casting alloys?

To improve marginal adaptation Signup and view all the answers

Which metals are considered noble metals in dental casting alloys?

Gold, platinum, palladium, iridium, and rhodium Signup and view all the answers

What is the primary purpose of using noble metals in dental casting alloys?

Resistance to tarnish and corrosion Signup and view all the answers

What influences the compatibility of a metal with porcelain in dental casting alloys?

Coefficient of thermal expansion and contraction Signup and view all the answers

Why must the melting temperature of the metal be higher than the firing temperature of the porcelain in dental casting alloys?

To have high sag resistance Signup and view all the answers

What is the primary requirement for ease of casting in dental casting alloys?

Sufficient fluidity to fill the mold Signup and view all the answers

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.