Impression Materials (Dental Impression Compound) Flashcards
Used to record accurately the dimensions of the oral tissues and their spatial relationships.
Used to make an accurate replica or mold of the hard and soft oral tissues.
Impression materials
Negative reproduction are copy of the oral tissues.
Impression
And by filling the impression with newly mixed model material, a ___________ is made that can be removed after the model material has set.
Positive cast
The positive copy of the oral structures
Cast
True or false. PLEASE READ!
General procedure in impression taking:
- Prepare the necessary instruments and materials.
- Selection of correct impression tray.
- Proportioning and mixing of impression material.
- Loading of impression tray and impression taking.
- Pouring of model material separation of impression and cast.
True
Explain the setting mechanisms of impression material?
Thermoplastic
- softening and hardening of materials influenced by TEMPERATURE CHANGE
- reusable or reversible
Thermosetting
- Setting is due to CHEMICAL REACTION of it’s components
- not reusable or irreversible
Explain the flexibility of impression materials what are the types of and there is now
Inelastic
- not flexible
- for edentulous patient
Elastic
- flexible
- for BOTH edentulous and dentulous patients
What are the types of rigid impression materials
- ZOE Paste
- Impression Plaster
- Dental Compound
What type of compound of a material is this:
- Thermoplastic
- Hardens at 37 °C (mouth temperature)
- Adequate flow can be attained at 45°C
- Low thermal conductivity
- Pressure applied during manipulation may cause dimensional change due to residual stress
- Should not be stored in warm environment - Overheating can deteriorate the quality of the material volatile components will evaporate
Dental impression compound
- Considered as an obsolete impression material and it is no longer used in taking impression.
- Nowadays it is used in mounting cast or an articulator, bite registration.
- Making impression for maxilla facial prosthesis
Impression plaster
What composition does this belongs to:
- Calcium sulfate hemihydrate
- Inorganic salts like _________ or _________. It is used to adjust the setting time 3 to 5 minutes and lessen the dimensional change during setting to 0.06%
Impression Plaster
- Potassium nitrate and sulfate
Used as wash impression in edentulous patient
Zinc oxide eugenol impression paste (ZOE)
Where does this composition belongs to:
- The composition comes into 2 collapsible tubes.
Base, tube 1 - _______ in color
- Zinc oxide
- oils - fixed vegetable oil or mineral oil
- additives - fillers
Catalyst, tube 2 - _________ in color
- eugenol
- oils
- resin
- additives - fillers
- ________ - accelerator, yields a smoother and
more homogeneous mix.
Zinc oxide eugenol (ZOE) Impression paste
True or false.
The product of chemical reaction: zinc oxide eugenol impression paste
- Zinc eugenolate - amorphous chelate
- Unreacted zinc oxide
True
Properties of ZOE impression paste:
- Initial setting time: _________
- Final setting time: __________
- setting time is shortened by: ______________
- high humidity, __________ is the amount of water vapor in the air compared to the maximum amount of water vapor which that volume of air at the same temperature could carry.
- it is expressed in percentage.
- contrasting color
- increase in temperature
- accurate -0.1% dimensional change
- adequate adhesion to trade compound or acrylic tray compound
- ___________ used to remove ZOE from patient slips and face
- 3 to 5 minutes
- Less than 10 minutes
- Adding water on eugenol paste
- Relative humidity
- Oil of glove
