Week 4 Flashcards
The different gypsum stones are classified based on?
Compressive strength
Type IV and V are classified based on?
Percentage of setting expansion
Type I is good for?
Used to mount casts to the articulator, used to be used to capture soft tissue impressions in denture patients.
What is Type II good for?
Rarely used. used in the investment and processing of dentures.
What is Type III Good for?
Diagnostic mounting
Pouring final impressions for denture, its easy to break out the denture after the final processing.
What is type IV good for?
Die stone
Used to fabricate crowns and bridge work.
Good at resisting abrasion
Good for PFM
Gold crowns
Noble/High Noble mettle
What is Type V good for?
High strength high expansion high strength stone
the larger shrinkage upon cooling when an base metal is used.
What is the W/P ratio?
the quotient obtained when the weight (or volume) of the water is divided by the weight of the powder.
as the W/P ratio increases, what happens?
the setting time increases, the strength of the gypsum product decreases, and the setting expansion decreases.
What Type IV high strength low expansion stone is used at ASDOH?
Excalibur
What is the proper way to mix stone with water?
Don’t guess the amount
Mix with spatula for about 15 seconds
Vacuum mix for 20-30 seconds
Type 1 mounting plaster states at ASDOH
W/P?
Working time?
Setting time?
W/P: 63 mL/100g
60-90 seconds
3 Min
When is a bite registration needed to mount?
when MIP is not stable due to missing or flat teeth
What happens when the bite registration is not all the way trimmed?
the bite registration will not sit on the casted stone
all but where the cusp tips articulate must be trimmed
When can a cast be mounted without bite registration?
When MIP is stable
When does a “record base” need to be fabricated?
When a “rock” or tipping will exists between two casts when not enough teeth are present to “tripodize” them.
this provides a platform for a bite registration to be made intraorally.
A record base can be made out of
pink TRIAD (UDMA).
What is the purpose of wax when making a record base?
A wax rim is added to the base to allow for quick adjustment of the height during the record appointment. 2-3 mm of space is created between the rim and teeth.
Why are V notches made in the record base?
V-notches are placed in the wax, so that the registration can be placed back on in the exact orientation every time.
record base must be fabricated of the?
the cast that is to be mounted (master cast). A record base made on another cast will not seat properly when transferred onto a cast from a different impression, even if the same type of impression material and stone is used.
There are two bite registration materials used in the clinic floor. What are they?
What material are they?
Regisil 2x
Take 1 Advanced
Both materials are fast setting PVS materials.
What is Regisil’s working time?
1m 10s
Do not confuse Regisil with?
Do not confuse this material with the medium body PVS as it is also purple in color.