Zinc Oxide-Eugenol Cements: IV. Microstructure and

The microstructure of zinc oxide-eugenol cement and the water-leached product was examined by electron microscopy and scan-ning electron microscopy. Crystalline zinc eugenolate, which forms a reaction product, encases and binds unconsumed zinc oxide grains. Water leaching removes zinc euge-nolate and leaves a voided structure bound by zinc hydroxide, which readily disinte-grates. Eugenol is the essential constituent of oil of cloves, a therapeutic agent that has been used for the treatment of odontalgia since the 16th century'; reactions with metal ox-ides were reported by Bonastre in 1827.2,