Occlusion - casting impressions Flashcards
What is a dental impression?
a negative imprint of hard (teeth) and soft tissues in the mouth
What is produced after the negative copy?
a positive copy
What material usually makes the positive copy?
dental cast usually in type III dental stone
What are the 2 ways to make a casting impression?
dosing machine/ vacuum
hand/vibration
What is the minimum amount of stone for a dosing machine/vacuum?
at least 200
What is teh correct ratio of water to powder for dosing machine/vacuum?
30:100
water:powder
After mixed by hand what do you do?
place on vibrating table
Why place the mixture on a vibrating table?
let air bubbles rise to the top
What has more air bubbles after mixing?
hand mixed
vacuum should have hardly any
How do you know when youve spatula enough mix into the base former?
fill the base former
give a few taps to remove air bubbles
Do you leave the filled base former on the same side of the bench as the vibrating table or not?
do not leave on same side as vibrating table
Id using a silicone impression, what do you spray it with?
de-bubbiliser
Why spray silicone impression with de-bubbiliser?
relieve surface tension and help stone flow into hydrophobic material
How do you place you impression material into the filling material into impression?
add at one side
tilt wrist and help flow round to fill teeth
When filling the impression, when do you tame the mould off of the vibration table?
once the arch of the teeth is filled enough that the material is just flowing out the heel areas
When do you stop filling the impression?
when the stone is slightly above the level of the impression
How do you level the impression?
turn over and push down
When you invert the filled impression on the stone in the base, what occurs?
watch for a pool of water forming on top of the stone
wait a minute or 2 until this starts to disappear again
What is occurring here?
smoothing down the area where the tongue was as this is much more difficult to do later
What do you use to take the impression off?
plastic knife
Where do you dispose of plastic stick trays was is the waste procedure?
tray and impression go in orange waste bin
removing any material handles and labels
What is the waste procedure for metal tray impressions?
impression removed from metal tray and placed in orange bin
place metal impression tray in the red boxes at hand wash sinks
How do you dispose of custom trays?
remove impression material - place in orange waste
clean up tray and place in the patient case wok box
What is the order to trimming the casting?
even up posterior
stand onbase and trim occlusal plane
trim peripheries
label back end with date impression taken and patient name
