Alginate Impressions Flashcards
1
Q
what is the very first step in taking alginate impressions of a typodont?
A
replace tooth with an edentulous peg
2
Q
what are the items needed for alginate impressions?
A
-alginate
- measuring scoop
- plastic impression trays (one upper one lower)
- mixing bowl
- yellow stone
3
Q
which impression tray has a palatal coverage?
A
maxillary
4
Q
what shape is the tray for the mandible?
A
horseshoe shape
5
Q
what is beading wax used for?
A
to extend the tray if needed (mostly not needed)
6
Q
what are the steps of taking a typodont impression?
A
- mix 3 scoops of alginate with 3 sections of water using the measuring cylinder (cold water)
- mix until smooth (mixture sets after 5 minutes)
- place mixture in the tray and place over upper teeth
- wait until set
- separate tray from typodont
- pour up the impression with yellow stone
- repeat for lower arch
7
Q
where is stone added to impressions?
A
on the vibrator
8
Q
how do you mix yellow stone?
A
- weigh 100g of stone and add to mixing bowl and then add 30 ml of water
- place bowl in palm of hand and spatulate the mixture while making contact with inner surface of the bowl so no powder is left unmixed
- mixing should be accomplished in one direction WITHOUT a beating action
- mix for 30 sec and never more than 60 sec
- once mixture is homogenous, bowl is placed on vibrator to get rid of air bubbles (or tapped vigorously on bench)
9
Q
how do you pour the stone model?
A
- hold the impression tray by the handle and press firmly against vibrator
- add small amounts of stone on one side at the retro-molar pad area of the lower or tuberosity area of the upper
- tip the impression to make the stone flow
- after teeth are covered add the remaining stone
10
Q
what do you never do when pouring model?
A
- never leave spilled material on the vibrator
- do not allow stone to spill over the tray
11
Q
What are the steps of creating the base?
A
- allow the innervated tray to set a bit and then slightly scrape lines into the cast
- you can use base formers or mounds of stone
- mix a thicker consistency of stone and place models on top of them
