The Effect of Certain Additive Agents on the Physical Properties of Zinc Oxide—Eugenol Mixtures

¹ Indiana University School of Dentistry, Indianapolis, Indiana

A study was made on the effect of selected additive agents upon certain properties of zinc oxide and eugenol.

Addition of o-ethoxybenzoic acid (EBA), if in approximately equal parts with eugenol, produced significant increases in compressive strength. It simultaneously increased solubility and decreased the setting time. Solubility also increased slightly by the addition of silica and zinc acetate. Addition of polystyrene was more effective in increasing the strength when present in mixtures containing EBA.

Zinc oxide produced from the thermal decomposition of zinc carbonate did not increase the strength of the mixtures studied but did decrease the setting time and tackiness of the mix.

Although not markedly altering strength, the addition of fused silica improved the handling characteristics of the mixtures when in a concentration of at least 10 per cent in the powder.

Substitution of methyl methacrylate for polystryrene increased the stability of the solution and had an effect comparable to the polystyrene on strength and solubility.

Inflammatory reactions in the connective tissue of the rat were mild for all mixtures tested.

Zinc acetate effectively accelerated the set of all mixtures.

The exact effect of agents added to mixes of zinc oxide and eugenol depends on the particular combination employed and the property being evaluated. Further research may make possible materials of this type having physical properties comparable or superior to zinc phosphate cements.