Zoe -Zinc Oxide Eugenol

Describe the Zinc Oxide Eugenol Cement.
Answer:

These cements are of low strength, are the least irritating of all dental cement, and have an obtundent effect on dentin.

Composition of  Zinc oxide eugenol cement.

Powder:

Liquid:

Setting Reaction of Zinc oxide eugenol cement:

The setting reaction and microstructure are the same as that of ZOE impression paste.

In the first reaction hydrolysis of zinc oxide to its hydroxide takes place. Water is essential for reaction.

ZnO   +   H₂O   →   2O  Zn (OH)₂

The reaction proceeds as a typical acid-base reaction

Zn (OH)₂  +   2HE    →    ZnE₂  +  2H₂O
Base      Acid            Salt
(Zinc     (Eugenol)    (Zinc eugenolate)
hydroxide)

The chelate formed is an amorphous gel that tends to crystallize imparting strength to the set mass.

Manipulation of Zinc oxide eugenol cement:

The powder/liquid ratio is 4: 1 to 6: 1 by weight.

• The bottoms are shaken gently.
• A measured quantity of powder on liquid is dispensed onto a cool glass slab.
• The bulk of the powder is incorporated into liquid and is spatulated thoroughly in a circular motion with stiff bladed stainless steel spatula
• Small increments are then added until the mix is complete.