Week 3 PP

Question 1

What is an irreversible hydrocolloid?

Answer 1

-Supplied as a powder and mixed with water to form a viscous sol
-Once in the mouth the sol forms a gel through a series of chemical reactions which cannot be reversed
-Often called alginate

Question 2

What is a Reversible Hydrocolloid?

Answer 2

-Also called agar impression material
-Supplied as a gel
-Heated to change from gel to sol

Question 3

Why would a dentist request preliminary impressions?

Answer 3

-Diagnostic casts / study models

• Custom trays (trays made to fit patient dentition, made when generic tray cannot be used)
• Provisional coverage (to have a template of the original teeth before dentist shaves off the enamel, original tooth template will serve to make temporary crown or bridge before)

-Orthodontic appliances

• Pretreatment and post treatment (provide visual of what dentition/teeth looked like before and after treatment)