Alginates Flashcards
1
Q
What are three ways alginate can deform?
A
- Syneresis - fluid loss from gel to surface (shrinkage)
- Evaporation (shrinkage)
- Imbibition - swelling if immersed in water (distortion/swelling)
2
Q
THREE advantages of alginates?
A
- Easy to use (simple to make and manipulate)
- Setting time can be manipulated
- Hydrophilic
- Relatively cheap
3
Q
THREE disadvantages of alginates?
A
- Surface detail not very high (records minimal details)
- Not dimensionally stable
- Cannot be poured more than once (single cast)
4
Q
What is the mixing, working and setting times of Halas Alginate used in ADH?
A
At room temp 23 degrees C: > Mixing time (45 secs) > Working time (1 min 45 secs - time to insert into mouth) > Setting time (30 secs - time in mouth) Total: 3 mins (purple to pink)
5
Q
TWO ways setting time of alginate impression material can be manipulated?
A
- Water temp
2. W:P ratio
6
Q
What SEVEN intraoral features should we note before taking impressions?
A
- Dental arch (shape/size)
- Palatal vault shape/size (e.g. Tori/exostosis)
- Axial inclination
- Mobile teeth
- Implants
- Lip tightness
- Food debris
7
Q
What FIVE criteria do we use to critique alginates?
A
MSTAR:
- Mix (homogenous)
- Size (of tray)
- Time (set properly)
- Amount (over/underload)
- Removal (no drag marks)