Alginate Impression Material Flashcards
What’s the material characteristics?
-in terms of measurement.
weighing powder is most accurate way to dispense
What’s the composition of alginate?
Sodium Alginate Calcium Sulfate Sodium Phosphate Filler Potassium Fluoride
_________ alginate –> _________ alginate? in the presence of water
Na+ alginate –> Ca2+ alginate
What’s the function of Sodium phosphate?
Retarder: Slows down the rxn to allow time to work with the material
Role of Calcium Sulfate?
Reactor
Role of Potassium fluoride?
Improves gypsum surface
Do you use cool water or warm water with alginate?
use COOL water
What’s the meaning behind poor dimensional stability?
Can only be poured once»_space; making only one cast
What are the three problematic environmental factors when dealing with alginate?
Syneresis
Imbibition
Evaporation
What is syneresis?
Fluid loss during setting, squeezing water from btwn polysaccharide or alginate chains
–> shrinkage –> Distortion of cast.
This is why you need to pour impression ASAP.
What is imbibition?
The uptake of water in gel state –>Expansion
– This is why you don’t soak your impression mold in water, you rinse and spray it with disinfectant.
What is evaporation?
Water loss due to environmental conditions.
retard dimaensional changes –> wrap it in wet paper towel and pour ASAP.
- leads top shrinkage.
What is the degree of evaporation dependent on?
Depends on the amount of humidity in the room.
