Polyether Rubber Impression Material

Polyether impression materials were introduced in Germany in the late 1960s. They are known for their excellent mechanical properties and dimensional stability, but they are also stiff, have a short working time, and are relatively expensive.

Packaging

Supplied as base and accelerator in collapsible tubes
- Accelerator tube is smaller
Initially available in a single viscosity with a third thinner tube
Now available in:
- Light body
- Medium body
- Heavy body

Common Brands

Impregum F (Premier)
Ramitec
Polyjel (Dentsply)

Composition

Component	Base	Accelerator
Polymer	Polyether polymer	Aromatic sulfonate ester (crosslinker)
Additives	Colloidal silica (filler), plasticizer	Colloidal silica, phthalate or glycolether

Setting Reaction

Involves crosslinking of aziridine rings in branched polyether chains
Catalyzed by aromatic sulfonate ester
The main polymer chain consists of ethylene oxide and tetrahydrofuran
Exothermic reaction with a 4–5°C rise in temperature

Properties

Pleasant odor and taste
Sulfonic ester can irritate the skin
- Avoid direct contact; mix thoroughly
Setting time: 6–8 minutes
Mixing time: 30 seconds
- Heat reduces setting time
Excellent dimensional stability
- Low curing shrinkage (0.24%)
- Low permanent deformation (0.8–1.6%)
- However, polyethers absorb water
  - Avoid prolonged exposure to moisture or humid environments
Very stiff (flexibility ~3%)
- Harder than polysulfides
- 4 mm tray spacing recommended
- Removing impressions from undercuts is difficult—handle with care
Good tear strength (3000 g/cm)
Hydrophilic
- Performs well in moist environments
- Best compatibility with stone among all elastomers
Electroplatable with silver or copper
Shelf life: Excellent—over 2 years
High accuracy: Detail reproduction up to 20 microns

⚠️ Caution: Impression materials may be inhibited by chemicals in retraction cords (e.g., epinephrine, iron sulfate).
Prolonged exposure can lead to surface stickiness due to depolymerization.

Manipulation of Polyether Rubber Impression Material

Paste Form

Usually supplied in two tubes (base and accelerator), with a third thinner sometimes included to adjust viscosity.
The catalyst amount is small, and ratio is displayed on the mixing pad.
Mix the base and accelerator using a spatula for 30 seconds.
The material must be handled quickly due to short working time.
If thinner is provided, it should be added to modify viscosity based on clinical needs.