Zinc oxide eugenol (ZOE) cement is a dental material used primarily for temporary applications due to its sedative effect on the pulp and antimicrobial properties, though it has low strength and high solubility compared to permanent cements. 

Composition and Setting

ZOE cement is an oil-based material supplied as a powder and a liquid. 

• Powder: The primary ingredient is zinc oxide, with additives like white rosin (to reduce brittleness), zinc acetate, and zinc stearate as accelerators and plasticizers.
• Liquid: The main component is eugenol (derived from clove oil), a weak acid, with olive oil as a plasticizer. 

The setting reaction is an acid-base reaction that results in the formation of an amorphous chelate called zinc eugenolate. The presence of water is essential for this reaction, which is why humidity and higher temperatures accelerate the setting time. The final set cement consists of unreacted zinc oxide particles embedded in a matrix of zinc eugenolate.