FINALS DM | PPT Casting Alloys

Economy

new material performs the same function as the old but at a lower cost

Performance

new material performs better than the old in some desirable way, as in the processing method, handling characteristics, or delivery system

Processing method, handling characteristics, delivery system

Example for Perfomance

Esthethics

new material provides a more esthetic result.

1933

COBALT-CHROMIUM AND NICKEL-CHROMIUM ALLOYS

1959

PORCELAIN-FUSED-TO-METAL PROSTHESES

1971

THE END OF THE BRETTON WOODS SYSTEM

1976

THE MEDICAL AND DENTAL DEVICES ACTTHE MEDICAL AND DENTAL DEVICES ACT

1996

THE EUROPEAN MEDICAL DEVICES DIRECTIVE

1998

THE CLEAN AIR ACTS

High noble (HN), noble (N), predominantly based metal (PB)

Alloy classification by noble metal content

High noble

Must contain more than or equal to 40% Ag and more than or equal to 60% by weight noble metal elements

Noble

Must contain more than or equal to 25% by weight of noble metal elements

Predominantly base metal

Contain more than or equal to 25% by weight of noble metal elements

Noble metals

group of seven metals that are resistant to corrosion and tarnish in the mouth

Gold, palladium, platinum, rhodium, ruthenium, iridium, osmium

Metals under Noble Metal

Gold, palladium, platinum

Lowest melting temperatures of the seven noble metals, are currently of major importance in dental casting alloys

Base metal alloys

both all-metal and metal-ceramic prostheses because of their oxide formation at room temperature

Platinum, copper, silver, palladium

High noble and Noble Alloys

Platinum

Increases the hardness and elasticity of gold and raises the melting temperature of the alloy.

Copper

Sufficient quantity relative to the gold content, renders the alloy heat-treatable.

Silver

Forms solid solutions with gold and palladium

Gold-copper alloys

Silver is effective in neutralizing the reddish color of copper.

Palladium-based alloys

Silver is needed to develop the white color of the alloys

Palladium

Good range of solubility with several metals, such as gold, silver, and copper, and an ability to impart good mechanical properties.

Silver, copper, gold

Palladium has good range of solubility with several metals including:

Palladium

Excellent tarnish/corrosion resistance and is relatively biocompatible.

Gold-based alloys

Generally yellow in color

Type 1 gold alloys

Soft and designed for inlays supported by teeth and not subjected to significant mastication forces.

Type 2 alloys

Widely used for inlays because of their superior mechanical properties, but they have less ductility than type 1 alloys

Type 3 alloys

Used for constructing crowns and onlays for high-stress areas

Type 4 gold alloys

Used in high-stress areas such as bridges and partial denture frameworks.

Copper, silver, and palladium

Changes of alloy color caused by the reduction in gold content are compensated for by an increase in ____, ____, and ____.

Higher silver and copper content

What reduces the corrosion resistance of gold-based alloys?

Softening heat treatment

Referred to as an solution heat treatment

Tensile strength, proportional limit, and hardness

What are reduced by such treatment (heat treatment of gold-copper alloys)?

Ductility

What are/is increase during the heat treatment of gold-copper alloys?

Softening heat treatment

Indicated for structures that are ground or reshaped plastically to a different form, either in or out of the mouth.

Silver-palladium alloys

These alloys are white and predominantly silver in composition but contain at least 25% palladium to provide nobility and increase tarnish resistance

White and predominantly silver

Composition of silver-palladium alloys

ISO Standard

Specific for casting gold alloys

ADA Specification No. 5

All alloys that pass the tests for toxicity and tarnish

Noble (including high noble), predominantly base metal, CP TI and titanium alloys

Alloys for all-metal prostheses

Silver-palladium alloys

Have poor castability and require precise control of casting and mold temperature to produce acceptable castings

Silver-palladium alloys

Poor castability

Silver-palladium alloys

Require precise control of casting and mold temperature

Silver-palladium alloys

Major limitation is greater potential for tarnish and corrosion

Greater potential for tarnish and corrosion

Major limitation of Silver-palladium alloys

Palladium

Causes the alloy (silver-palladium alloy) to lose its reddish color and acquire a gold color

Silver, copper and gold

Added to increase ductility and improve castability of the alloy (silver-palladium alloy) for dental applications

Chromium

Base metal alloys rely on this element for corrosion resistance

Chromium

Oxidizes to form a thin layer of chromium oxide and improves corrosion resistance

Nickel-chromium and cobalt-chromium

Two main groups of base metal dental alloys

Beryllium

Improves castability and promotes the formation of a stable metal oxide for porcelain bonding

Ni, Co, Cr, Mo

Four major elements of the base metal alloys

Aluminum, beryllium, carbon, copper, cerium, gallium, iron, manganese, niobium, nitrogen, ruthenium, silicon, titanium, tungsten, yttrium, zirconium

Addition to four major elements (Ni, Co, Cr, Mo) of base metal alloys which improves manipulation and mechanical properties includes:

Beryllium

Refines grain size, w/c increases strength and lowers fusion temperature of alloys, which improves castability

Manganese and silicon

Improve castability of the alloys

Carbon

Forms carbides with any of the components of the alloy that increase hardness, yield strength but decreases ductility

Aluminum

Increases both tensile and yield strength of Ni-Cr

Nitrogen

Incorporated in the alloys during casting in ambient air, improves overall quality of the casting

Titanium and titanium alloys

First reported application was in 1977

1977

Titanium and titanium alloys were first reported application in ___

Titanium and titanium alloys

Can be used for all-metal and metal-ceramic prostheses, implants, and RPD frameworks

Titanium

Most biocompatible metal used for dental restorations produced with prostheses

Titanium alloys

Highly resistant to sag deformation

Caustic NaOH-based solution or silicon nitride coatings

Are used to improve the bond between cast CP Ti and dental porcelain

Ti-6Al-4V

Most widely used titanium alloys in dentistry

Niobium

Has replaced vanadium

Ti-6Al-4V

Stronger than CP Ti but may pose health hazards due to slow release of aluminum and vanadium

a, near a, a-B, and B

Four possible types of titanium alloys

Aluminum, carbon, nitrogen, and gallium

Alpha-phase stabilizers of titanium alloys

Molybdenum, cobalt, nickel. niobium, copper, palladium, tantalum, and vanadium

Beta-phase stabilizers of titanium alloys