Dental Casting Alloys

Dental Casting Alloys

Are essential components used to create precise, long-lasting, and biocompatible prostheses like crowns, bridges, and removable partial dentures (RPDs).

Age Hardening

Process of hardening certain alloys by controlled heating and cooling, which usually is associated with a phase change.

Antiflux

A substance such as graphite that prevents flow of molten solder on areas coated by the substance.

Base Metal

A metal that readily oxidizes or corrodes.

Coping

Metal substructure for a cast-metal or veneered-metal prosthesis.

Copy Milling

Process of cutting or grinding a desired shape to the same dimensions as a master pattern in a manner similar to that used for cutting a key blank from a master key.

Flux

Compound applied to metal surfaces that dissolves or prevents the formation of oxides and other undesirable substances that may reduce the quality or strength of a soldered or brazed area.

Lost Wax Technique

Process in which a wax pattern, prepared in the shape of missing tooth structure, is embedded in a casting investment and burned out to produce a mold cavity into which molten metal is cast.

Noble Metal

Gold and platinum group metals (platinum, palladium, rhodium, ruthenium, iridium, and osmium), which are highly resistant to oxidation and dissolution in inorganic acids.

Postsoldering

Process of brazing or soldering two or more metal components of a prosthesis after the metal substructure has been veneered with a ceramic.

Presoldering

Process of brazing or soldering two or more metal components of a prosthesis before a ceramic veneer is fired or hot-pressed on the metal structure.

Soldering

Process of building up a localized metal area with a molten filler metal or joining two or more metal components by heating them to a temperature below their solidus temperature.

Welding

Process of fusing two or more metal parts through the application of heat, pressure, or both, with or without a filler metal, to produce a localized union across an interface between the workpieces.

1907

(Year) The lost wax process.

1932

(Year) Classification of gold-based.

1933

(Year) Cobalt-chromium and nickel-chromium alloys.

1959

(Year) Porcelain-fused-to-metal prosthesis.

1971

(Year) End of the Bretton Woods system.

1976

(Year) The medical and dental services act.

1996

(Year) The European medical devices directive.

1998

(Year) The clean air act.

Gold

Dental gold alloys were originally classified by their ____ content, expressed in carats or fineness.

24 - 1000

Carat measures the parts of gold per __ parts of alloy, while fineness measures parts per ____.

Noble

Alloys are categorized by the amount of _____ metals.

Noble Metals

These metals resist corrosion and tarnish, making them valuable for dental use.

Precious

“________” metals refer to high economic value, but not all are noble.

Inlays

Type 1; soft.

Onlays

Type 2; medium.

Full crowns, pontics

Type 3; hard.

Bridges, partial dentures

Type 4; extra hard.

Clasps and frameworks

Type 5; very hard.

Noble - Noble - Base

High _____ and _____ alloys can be used for all types, while ____ metals are more limited to metal-ceramic or removable applications.

No

Do noble metals corrode easily?

Base Metals

These metals form passive oxide films that prevent corrosion.

Oxide

(Porcelain Bonding) _____ should be light in color for esthetics.

Elastic Modulus

Measures resistance to elastic flexing.

300

Alloys with yield strength >___MPa generally perform well in the mouth.

Hardness

Ability to resist indentation, scratching, or wear.

Ductility

Ability to undergo plastic deformation without fracturing. Measured by percent elongation.

Fatigue Resistance

Ability to withstand repeated load cycles without fracture.

Alloys for All Metal Prostheses

These alloys are used when esthetics are not the main concern. They must be strong, corrosion-resistant, and easy to cast.

Gold

____-based systems have been the historical standard due to excellent corrosion resistance, ease of manipulation, and predictable long term performance.

Gold Copper Alloys

May undergo heat treatment/age-hardening to increase strength; heat treatment allows manipulation of microstructure to improve hardness for various prosthetic needs.

Silver Palladium Alloys

Developed to reduce cost while maintaining acceptable mechanical properties.

Silver Palladium Alloys

Higher palladium improves corrosion resistance; addition of silver helps workability. Their lower density makes restorations lighter.

Chromium

Base metal alloys rely on _______, which forms a protective oxide layer for corrosion resistance and strength.

Ni-Cr

(Predominantly Base-Metal Alloys) Used mainly for crowns/FDPs.

Co-Cr

(Predominantly Base-Metal Alloys) Used for RPDs due to high strength.