Preliminary Impressions

Question 1

What are some inelastic/rigid impression materials?

Answer 1

plaster
zinc oxide-eugenol
impression compound
wax

Question 2

What are some elastic impression compounds?

Answer 2

hydrocolloids
polysulfides
polyethers
silicones

Question 3

What are some examples of irreversible hydrocolloids?

Answer 3

alginate
salts of alginic acid

Question 3

What are irreversible hydrocolloids made of?

Answer 3

• diatomaceous earth 60%
• calcium sulfate 16%
• potassium alginate 15%
• zinc oxide 4%
• potassium titanium fluroid 3%
• sodium phosphate 2%

Question 3

What is calcium sulfate and potassium alginate in an irreversible hydrocolloid?

Answer 3

reactors

Question 4

What is diatomaceous earth in an irreversible hydrocolloid?

Answer 4

filler which increases strength and stiffness and produces a smooth texture

Question 5

What is sodium phosphate in an irreversible hydrocolloid?

Answer 5

retarder

Question 6

What does zinc oxide do in an irreversible hydrocolloid?

Answer 6

influences setting time

Question 7

What does potassium titanium fluoride do in an irreversible hydrocolloid?

Answer 7

ensures a dense, hard stone cast surface

Question 8

What impressions should you use liquid hold adhesive on?

Answer 8

plastic impression trays only
(not metal or silicone)

Question 9

What impressions should you use PVS on?

Answer 9

silicone trays (NOT METAL)

Question 10

What are the steps for a max alginate impression?

Answer 10

1. size correct tray and modifty borders if needed
2. have patient wipe palate with gauze
3. mix thoroughly
4. load tray and set aside
5. preload palatal vault with material
6. seat tray while retracting lips/cheeks
7. hold tray very still for 3 minutes
8. remove in one firm motion
9. inspect, rinse, disinfect

Question 11

What should a maxillary preliminary impression include?

Answer 11

• residual ridge
• buccal and labial vestibules
• frenal attachments
• fovea palatinae and vibrating line
• palate
• tuberosities
• hamular notches

Question 12

What are the steps for mandibular alginate impression?

Answer 12

1. patient in upright position
2. size tray
3. powder and room temp water
4. mix, load tray, set aside
5. preload buccal vesibules
6. partially seat tray in mouth, patient lifts and protudes tongue
7. have patient close halfway and pull lip out
8. seat and hold tray for 3 minutes
9. remove, inspect, rinse, and disinfect

Question 13

What should the mandibular impressions contain?

Answer 13

• residual ridges
• retromolar pads
• buccal shelf areas
• external oblique ridges
• frenal attachments
• retromylohyoid spaces
• alveololingual sulcus
• labial and buccal vestibules