Alginate Impression Material

Question 1

What is the most accurate way to dispense alginate impression material?

Answer 1

Weighing the powder

Question 2

What is the role of sodium phosphate (Na3PO4) in alginate?

Answer 2

Retarder

Question 3

How can you minimize air entrapment when mixing alginate powder?

Answer 3

Always add powder to water

Question 4

What are the three environmental factors of alginate impression dimensional stability?

Answer 4

Syneresis, imbibition, evaporation

Question 5

What is Syneresis?

Answer 5

Fluid loss during setting squeezing water from b/w polysaccharide or alginate chains - results in shrinkage, distortion of cast

Question 6

What is Imbibition?

Answer 6

Uptake of water in gel state - don’t soak with water. Rinse and spray w/ disinfectant

Question 7

What is Evaporation?

Answer 7

Water loss due to environmental conditions.
Depends on amount of humidity in room
Can cause shrinkage.
To retard dimensional changes - wrap in wet paper towel and pour ASAP