Impression Techniques for Crowns and Bridges Flashcards
Name a polyether impression material
Impregum
What adhesive is used for each impression material?
- Alginate: alginate adhesive.
- Silicones: universal adhesive.
- Polyether: polyether adhesive.
2 advantages and 1 disadvantage of polysulphide impression materials?
- Long working time.
- Good for big undercuts (hence removable pros).
- Smelly.
What are the 2 types of HYDROPHILIC impression materials?
- Alginate.
- Agar (Van R).
2 advantages and 3 disadvantages of polyether impression material?
Advantages:
- Very accurate.
- Less hydrophobic (do not store wet).
Disadvantages:
- Bad taste.
- Very stiff on removal. Stick to undercuts, problem in perio patients!!.
- Messy (if manual mixing).
How do condensation silicones compare to addition silicones (3)?
- Less accurate.
- Cheaper
- Must leave for 24 hours before pouring.
2 advantages of addition silicones? What is a requirement (outside of dry prep).
- Very stable (2 years).
- very accurate.
- Must be left for more than an hour before pouring.
2 condensation cured silicones?
- Xantopren.
- Optosil.
3 types of hydrophobic impression materials?
- Silicones.
- Polysulphides.
- Polyethers.
Which elastomeric impression materials are most rigid when set? What must be done?
- Addition cured silicones.
- Polyethers.
Thus BLOCK UNDERCUTS (buccal sulcus, large interdental spaces, recesses beneath bridge pontics).
What adhesive is used for alginate?
alginate adhesive
What can be used to mix polyether impression materials?
The PENTAMIX (although can also do manual mixing).
2 disadvantages and 1 advantage of Agar?
- Requires special tray with cooling mechanism.
- Requires great care (Cu plated dies).
- Can be VERY ACCURATE.
What impression material has addition and condensation cured versions?
Silicones (hydrophobic)
What is an important consideration when using SILICONE materials for impressions?
Must have a DRY PREPARATION as they are HYDROPHOBIC.
What is agar?
Hydrophilic impression material.
What adhesive is used for silicone impression materials?
universal adhesive
What adhesive is used for polyethers?
polyether adhesive
3 addition cured silicones?
- Aquasil.
- president
- affinis
What is alginate?
Hydrophilic impression material.
Name a polysulphide impression material
Permlastic
4 downsides of alginate?
- Not good for fixed pros.
- Must be poured within less than 24 hours.
- Requires correct tray.
- Easily distorted.
What kind of tray do we need for fixed pros?
a RIGID impression tray.
What can be done to take impressions of difficult arch shapes?
Make a custom/ SPECIAL TRAY.
- made from COLD CURE ACRYLIC.
What is the gold standard impression tray for fixed pros?
Rim lock trays.
2 disadvantages of rim lock trays?
- Cannot cut out of the mouth if stuck.
- Difficult to sterilize.
What material should a special tray NOT be used with? Why?
Polyethers as they are too stiff.
What are the 3 different types of stock trays?
- Plastic solo trays.
- Polycarbonate trays (green, blue, yellow).
- Metal Rim lock trays.
What are plastic solo trays? What are they good for?
- Type of STOCK TRAY.
- Good with ALGINATE.
Are plastic solo trays or polycarbonate trays better?
Polycarbonate trays
What must all trays have?
PERFORATIONS and ADHESIVE
What is the penyamix used for?
- Polyether.
- Heavy body silicone
