Impression Materials Flashcards
What are the three major classifications of impression materials?
- Rigid: Edentulous patients
- Plastic: Impression compound, wax
- Elastic
What type of material is used the most?
Elastic
What are some different types of viscoelastic impression materials?
- Hydrocolloids: agar and alginate (Jeltrate)
- Polysulfide: Omniflex
- Silicone: (Aquasil)
- Polyether
- Silicone and polyether combo
For what part of the impression is a light bodied material used?
Right on the prep where detail is needed
What is an example of a thermoplastic material?
Wax: changes states based on temperature
What is a thermoset material?
Irreversible crosslinking changes the physical state of the material
What type of polymerization does not give off any by-products?
Addition polymerization
T/F: When using addition silicone the model should be poured immediately.
FALSE
Delayed pour to allow hydrogen to be liberated
What is an advantage of polyether over silicon?
It is not as hydrophobic
What are some requirements for an ideal impression material?
- Low cost
- Long shelf life
- Biocompatibility
- Pleasant to patient
How would an ideal material act before setting?
- Easy to control
- Control over working time
- Good wetting
What are some ideal properties of materials during setting?
- No dimensional change
2. Short setting time
What are some ideal properties of a material after setting?
- High flexibility
- High tear strength
- No dimensional change (high elastic recovery)
- Compatibility with disinfectants
- Compatibility with die and cast materials
What aspect of an impression will show the most dimensional change?
Height
