Impression Materials Flashcards
1
Q
Reversible Hydrocolloid (Agar)
A
- Changes btw sol and gel based on temp
- High accuracy
- annoying to use bc need water baths
2
Q
Irreversible Hydrocolloid (Alginate)
Ingredients
accuracy
set
Mix
Good for
Adjust set time
A
- Primary ingredient- diatomaceous earth
- Active ing- Trisodium phosphate, potassium alginate
- Most inaccurate
- Set 3-4 min
- Add Powder to water
- Good for Dx casts
- To decrease setting time
- hot water
- less water
3
Q
Properties of Hydrocolloids
A
- Imbibition
- Absorption of water, distorts
- Syneresis
- Loss of water, distorts
4
Q
Polysulfide rubber
Properties
time to pour
A
- Water byproduct
- Moisturee tolerant
- hydrophobic
- prone to syneresis
- 30-40 min to pour
5
Q
Condensation Silicone
Properties
time to pour
A
- Alcohol byproduct
- Causes shrinkage
- Hydrophobic
- 30 min to pour
6
Q
Polyether
Properties
time to pour
A
- Very stable but easily influenced by water and humidity
- Hydrophilic
- Imbibition
- Very stiff, causing breakage
- 60 min to pour
7
Q
Addition Silicone (PVS)
Properties 2
best 3
Inhibited
A
- No byproducts
- Hydrophobic
- Best fine detail, elastic recovery, dimensional stability
- Inhibited by sulfur in latex gloves, dams
8
Q
Zinc Oxide Eugenol
A
Mucostatic- good for flabby tissue
9
Q
5 sources of Dimensional change
A
- Polymerization shrinkage
- Loss of byproduct
- Thermal contraction
- Imbibition
- Incomplete recovery of deformation bc of viscoelastic behavior
