Casting alloys can be classified in several ways: by their noble metal content, mechanical properties, principal elements, dental application, or number of alloying elements. The desirable properties of casting alloys include biocompatibility, appropriate melting range, hardness, corrosion resistance, and low casting shrinkage. Newer alternatives to casting like CAD-CAM allow fabrication of restorations from non-castable materials like titanium and help avoid issues with impressions or shrinkage.

1. Casting Alloys
Dr. Deepak K Gupta

2. Syllabus
• Historical background,
• desirable properties of casting alloys.
• Alternatives to cast metal technology: direct filling gold, amalgam, mercury free condensable
intermetallic compound - an alternative to metal casting process CAD-CAM process for metal &
ceramic inlays - without need of impression of teeth or casting procedure,
• pure titanium, most bio compatible metal which are difficult to cast can be made into crowns with
the aid of CAD -CAM technology.
• Another method of making classification of casting alloys : By function & description.
• Recent classification, High noble (HN), Noble (N) and predominantly base metal (PB) Alloys for
crown & bridge, metal ceramic & removable partial denture.
• Composition, function constituents and application, each alloy both noble and base metal
• Properties of alloys: Melting range; mechanical properties, hardness, elongation, modulus of
elasticity, tarnish and corrosion.
• Casting shrinkage and compensation of casting shrinkage.
• Biocompatibility - Handling hazards & precautions of base metal alloys; casting investments used.
• Heat treatment : Softening & hardening heat treatment.
• Recycling of metals, Titanium alloys & their application, properties & advantages.
• Technical considerations in casting.
• Heat source, furnaces

3. Introduction
• An alloy is a substance composed of two or
more elements at least one of which is a
metal, possess metallic properties and holds
metallic bonds.
– To improve the mechanical and physical
properties metals are alloyed with other metals or
metalloids.
– Alloys are usually produced by melting two or
more metals, together above their melting
temperature

4. Classification
• Dental casting alloy is classified by various
means.
– Noble metal content
– Mechanical properties
– Principal elements
– Dental application
– According to number of alloys

5. Classification : NOBLE METAL
CONTENT
Alloy Type Total Noble Metal Content
High noble (HN) Must contain ≥40% Au and ≥60% by
weight of noble metal elements
Noble (N) Must contain ≥25% by weight of
noble metal elements
Predominantly base (PB) Contains <25% by weight of noble
metal elements
Base metal
American Dental Association (1984)

6. Classification : Mechanical Properties
Type Descriptor Yield strength
(Mpa)
Examples
Type I Soft 80 Inlays (least stress)
Type II Medium 180 Inlays and onlays
Type III Hard 270 Onlays, thin cast backing, pontics, full
crown, saddles
Type IV Extra hard 360 Saddles, bars, clasps, crown, bridges
and partial denture framework

7. Classification : Principal Element
• Gold Alloys
• Silver Alloys
• Palladium Alloys
• Nickel Alloys
• Cobalt Alloys
• Titanium Alloys

8. Classification : Dental Application
• All Metal restoration
– High Noble (Au-Ag-Pd, Au-Pd-Cu-Ag)
– Noble (Ag-Pd-Au-Cu, Ag-Pd)
– Predominantly base metals (CpTi, Ti-Al-V, Ti-Al-Nb, Ni-Cr-Mo-Be, Ni-Cr-
Mo, Co-Cr-Mo)
• Metal Ceramic Restoration
– High Noble (Au-Pt-Pd, Au-Pd-Ag(5-12%), Au-Pd-Ag (>12 %), Au-Pd )
– Noble (Pd-Au, Pd-Au-Ag, Pd-Ag, Pd-Cu-Ga)
– Predominantly base metals (CpTi, Ti-Al-V, Ti-Al-Nb, Ni-Cr-Mo-Be, Ni-Cr-
Mo, Co-Cr-Mo)
• Partial Denture Framework
– High Noble (Au-Ag-Cu-Pd)
– Noble
– Predominantly base metals (CpTi, Ti-Al-V, Ti-Al-Nb, Ni-Cr-Mo-Be, Ni-Cr-
Mo, Co-Cr-Mo)

9. Classification : Number of Metal
• Binary alloys (Two constituents)
• Ternary alloys (Three constituents)
• Quartenary alloys (Four constituents)

10. Desirable Properties of Casting Alloy