Investment Materials Flashcards
1
Q
What are four types of investment materials used in dentistry?
A
Dental stone or plaster
Gypsum bonded materials
Phosphate bonded materials
Silica bonded materials
2
Q
What is an investment material?
A
A ceramic material which is suitable for forming a mould in which a metal or alloy is cast.
3
Q
What is the temperature limit for using gypsum as an investment material?
A
Limited to alloys with a melting point of less than 1200 degrees C
4
Q
What are the three stages of silica investment?
A
Prepare stock solution
Gelation
Drying
5
Q
What are the ideal properties of investment materials?
A
Porosity - release trapped gases
Expansion - to counter the alloy shrinking on cooling
Strength - to withstand pressures during casting
Stability - avoid voids in cast alloy
