Impressions for Complete Dentures

Question 1

what should primary impressions aim to do?

Answer 1

accurately record clinical relevant landmarks without excessive tissue distortion

Question 2

what are primary impressions used for?

Answer 2

To construct models (casts):
- treatment planning
- construction of special trays

Question 3

What can be done to stock trays if they don’t fit patient?

Answer 3

Modified with
- green stick
- soft red wax
- putty
- can reduce extension of tray with acrylic bur

Question 4

What are the limitations of stock trays?

Answer 4

• trays not made to measure
• peripheral extensions are often over/under extended
• limited sizes available

Question 5

what materials are used for denture impressions?

Answer 5

• alginate
• denture compound

Question 6

What are the clinical procedure steps of taking impressions?

Answer 6

• select & try in trays (manipulate cheeks, lips, tongue)
• apply adhesive over tray (and putty/wax etc if used)
• mix alginate & load tray
• seat loaded tray
• border mould muscles while supporting tray
• remove witch sharp sudden movement

Question 7

when taking a lower impression what must you ask the patient to do?

Answer 7

stick their tongue out
- to get correct sulcus depth

Question 8

What are special trays typically made of?

Answer 8

acrylic resin PMMA

Question 9

What should the spacing thickness of special trays intended to be used with alginate be?

Answer 9

3mm

Question 10

How are impressions disinfected before being sent to lab/

Answer 10

• rinse in running water to remove saliva, blood or debris
• disinfect for 10 mins in PERFORM solution
• cover impressions with damp paper towel
• label & place in plastic laboratory bag