Casting Investments Materials in Dentistry

Casting Investments Materials

 

Classification of Investment Materials:

Types Of Casting Defects

1. Based on the Type of Binder Used:

There are three types of investment materials. Based on the type of binder all contain silica as refractory material.

Gypsum-bonded investment: A common type of binder used is alpha hemihydrate.

• Use: For the casting of inlays, bridges, and removable partial denture frameworks using gold alloys and another low-fusing alloy.

Phosphate-bonded investment: Ammonium diacid phosphate is used as a binder.

• Use: For casting high-fusing alloys. For example, fusing noble metal alloys, metal-ceramic alloys, and base metal alloys like nickel-chromium and cobalt chromium

Silica-bonded investments: The silica is the binder. It is derived from ethyl silicate or aqueous dispersion of colloidal silica or sodium silicate.

• They are the alternatives to phosphate-bonded investments for high-temperature casting.
• They are primarily used in the casting of base metal alloy partial dentures.

2. Based on application:

• Type 1: For the construction of inlays, crowns, and other field restorations.
• Type 2: For the construction of complete or partial dentures or other removable partial appliances.
• Type 3: For the construction of casts using brazing procedures.
• Type 4: For the construction of refractory dies.

Classification of Casting Failures: 

1. Distortion
2. Surface roughness
3. Porosity
4. Incomplete casting
5. Contaminated and black casting.