Alginate, elastomeric, gypsum

Question 1

An irreversible hydrocolloid consisting of salts of a colloidal acid polysaccharide obtained from seaweed and composed of mannuronic acid residues; used in dental impression materials is called what/

Answer 1

Alginate

Question 2

What is the chemical reaction of alginate?

Answer 2

Ca2+ (Sol) + Alginate (Gel) → CaAlginate

Question 3

What are the physical properties of alginate?

Answer 3

Setting Time: 1.5-5 minutes
Elastic Recovery: 98.2%
Flexibility: 8-15%
Tear Strength: 0.8-0.9 kN/m

Question 4

What is the reaction of gypsum?

Answer 4

Calcium Sulfate Hemihydrate + Water = Calcium Sulfate Dihydrate + Heat

Question 5

Rubber-like polymers that show an elastic behavior at the time of load application are called what?

Answer 5

elastomeric

*used to be more accurate and have less of a chance of tearing than alginate

Question 6

What three ways are used to mix elastomeric compounds?

Answer 6

• Hand mix (tube/tub
• automix (cartridge unit dose)
• Motor mix (sausage)

Question 7

What are the different elastomeric components and what are their properties?

Answer 7

• pre-polymer:Reacts to forms polymer
• Catalyst: accelerates reaction
• filler:controls consistency
• Addition of silicones: H gas as a byproduct
• Polyether: no byproducts

Question 8

What are possible clinical mistakes of using elastomeric compounds?

Answer 8

1-Latex gloves contaminate it–use vinyl
2-drags- improper seating
3-Ledges- seating tray too fast, insufficient wash material
4-lending of LB and HB–latex contamination
5-Voids–poor retraction, improper use of syringe
6-Pulls–working time exceeded, tray removed
7-Tears–poor retraction, early removal of tray