zinc oxide eugenol impression

This material is used for recording edentulous ridges in a close fitting special tray or the patients existing dentures. The material is mixed in a 1:1 paste ratio and used in thin sections only (2-3mm) as a wash impression.

Vaseline is used as a separating agent on those areas requiring protection (soft tissues, skin etc). Firm pressure is used during impression taking.


Constituents of a typical zinc oxide eugenol paste are:

  2. Zinc oxide
  3. Inert oils (plasticiser)
  4. Gum rosin (increases setting time and improves cohesion)
  6. Eugenol
  7. Zinc acetate/Mg Cl (accelerator)
  8. Fillers (talc or kaolin)

Some pastes contain a substitute for eugenol e.g. a carboxylic acid./chlorothymol NON EUGENOL TYPE The 2 pastes come in contrasting colours and are dispensed in a 1:1 ratio. They are mixed to give a paste of even colour.

Setting time

The set material contains both some unreacted zinc oxide and eugenol.

Any movement of the tray as the paste is hardening will lead to a deformed, inaccurate impression.

Setting time

  1. Types: S.T
  2. Type I: hard minutes
  3. Type II: soft minutes
  4. Accelerators: water, magnesium chloride, zinc acetate or alcohol.
  5. Retarders: inert oils such as olive oils, mineral oil.
Factors affecting the setting time

Setting time depends on:

  1. Accelerator additives (e.g. zinc acetate, acetic acid)
  2. Retarders (inert oils such as olive oils, mineral oil.
  3. Exposure to moisture on mixing or the addition of water will accelerate the reaction
  4. Increasing temperature causes a faster setting reaction
  5. Cooling the glass slab and mixing spatula will increase ST Setting time is normally 4-5 minutes.
Advantages & Disadvantages
  1. Dimensional stability
  2. Good surface detail
  3. Can be added to
  4. Cannot be used in very deep undercuts
  5. Only sets quickly in thin section
  6. Eugenol allergy in some patients