Composition
The chemical composition of ZOE is typically:
- Zinc oxide, ~69.0%
- White rosin, ~29.3%
- Zinc acetate, ~1.0% (improves strength)
- Zinc stearate, ~0.7% (acts as accelerator)
- Liquid (Eugenol, ~85%, Olive oil ~15%)
ZOE impression pastes are dispensed as two separate pastes. One tube contains zinc oxide and vegetable or mineral oil; the other contains eugenol and rosin. The vegetable or mineral oil acts as a plasticizer and aids in offsetting the action of the eugenol as an irritant.
Oil of cloves, which contains 70% to 85% eugenol, is sometimes used in preference to eugenol because it produces less burning sensation for patients when it contacts the soft tissues. The addition of rosin to the paste in the second tube facilitates the speed of the reaction and yields a smoother, more homogenous product.
Canada balsam and Peru balsam are often used to increase flow and improve mixing properties. If the mixed paste is too thin or lacks body before it sets, a filler (such as a wax) or an inert powder (such as kaolin, talc, or diatomaceous earth) may be added to one or both of the original pastes.
Read more about this topic: Zinc Oxide Eugenol
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