Available in three viscosities
Polyether polymer Cross linked to form rubber
Colloidal silica Acts as filler
Glycol ether (or) phthalate Plasticizer
Alkyl aromatic sulfonate Initiates cross linking
Colloidal silica Filler
Pleasant odour and taste
Setting time is short 3.5minutes, mixing time is 30 seconds
Good dimensional stability
Curing shrinkage is 0.24%
Polyether absorbs water and can change in dimension. So should not be stored in contact with water or in humid climates
It is extremely stiff
Tear strength is 3000gm/cm2
Hydrophilic, has good compatibility with stone
Can be electroplated
Good shelf life i.e., more than 2 years.
IMPRESSION MAKING WITH ELASTOMERS
It involves five steps:::
- Preparing a tray
- Preparing the material
- Making impression
- Removing the impression
- Preparing stone casts and dies
PREPARING A TRAY:
Impressions are usually made with custom trays. Perforated stock trays are used for making impression in putty.
To prepare a custom tray, an alginate impression is made and stone cast is constructed
Teeth are covered with modeling wax (1 or 2 sheets approximately 3-4mm) to act as spacer and stops are provided
Custom tray is prepared with tray material
Slightly roughened surface of tray inside improves retention.
PREPARING THE MATERIAL:
Materials are provided in two paste tubes
Same length of materials should be dispensed on to mixing pad
Catalyst paste is first collected on to spatula and then distributed over the base
Mixing should be thorough, uniform in colour with no streaks of base of catalyst
If one of the components is in liquid form such as catalyst for condensation silicone, a length of base is dispensed from tube onto the mixing pad and a drop of catalyst is added for each unit length of base.
Putty consistence are dispensed by volume using equal number of scoops and kneaded.
Automatic mixing and dispensing devices are available used for light, medium and heavy body consistencies.
It consists of a double barrel gun with mixing tip. The tip consists of spiral inside. The mixing tips vary in diameter length and size of the tip opening for specific consistency.
POLYETHER IMPRESSION MATERIALS
It has the advantages over hand mixing
Less air bubbles