Impression Material

Question 1

What are the clinical classification of impression materials?

Answer 1

• Mucostatic

- Mucocompressive

Question 2

What type of impression does a MUCOSTATIC impression material give?

Answer 2

Undisplaced mucosa

Question 3

What type of impression does a MUCOCOMPRESSIVE impression material give?

Answer 3

Impression of displaced soft tissue

• Records mucosa under load

Question 4

What is an example of a mucostatic impression material?

Answer 4

• Zinc oxide eugenol (low viscosity)

Question 5

What is an example of a mucocompressive impression material?

Answer 5

• Impression compound (high viscosity)

Question 6

What are the types of elastic impression materials?

Answer 6

• Hydrocolloids
  
  • -> Alginate (irreversible)
• Elastomers
  
  • -> Polyethers (impregum)
  • -> Silicone (PVS)

Question 7

What are the types of non-elastic impression materials?

Answer 7

• Impression compound (greenstick and red impression compound sticks)
• Impression paste (ZOE)

Question 8

What are the possible errors when taking an impression with polyether?

Answer 8

• Poor adhesion of impression to tray
• Lack of occlusal detail (impression seated out of working time)
• Ledges (out of working time, seated too fast, too little wash)
• Drags (insufficient material, out of WT, seated too fast)
• Delamination (wash partially set/ insufficient, tray seated too fast)
• Seating error (movement of impression after seating)
• Surface inhibition (contact with glove/ uncured resin/ provisional materials)
• Contact of tooth with tray
• Inconsistent mixing

Question 9

What type of (elastomeric) silicone impression materials are there?

Answer 9

• Conventional (PDS)

- Addition Cured (PVS); what we use

Question 10

What material is used for dentate and edentate patients?

Answer 10

DENTATE = elastic

EDENTATE = elastic/ non-elastic

Question 11

What material should be poured up for construction of a CoCr RPD?

Answer 11

Improved stone