Clinical Behavior of o-Ethoxybenzoic Acid-Eugenol-Zinc Oxide Cements

Zinc oxide-eugenol cement is well tolerated by the tissues. ' It acts as a palliative on the dental pulp2 and seals the cavity margins better than zinc phosphate cement.-5 The effects of zinc phosphate cement on tissue or on the pulp are unpredictable and may vary from mild to severe. ' 6, I The solubility and disintegration of zinc oxide-eugenol in dilute organic acids are less than that of zinc phos-phate cement.8 Zinc oxide-eugenol cement has, however, the disadvantages of long setting time and poor strength.9 To reduce the setting time of zinc oxide-eugenol cement, chlorides, nitrates, acetates, and hydrogenated rosin have been used.10'" The setting time and, to some extent, the strength and hardness of the cement may also be controlled by the manufacturing process of the zinc oxide, by addition of salts, especially zinc salts, and by controlling the moisture content."' To increase the strength of the zinc oxide-eugenol cement, Messing'2 has added up to 10 per cent polystyrene to the eugenol and obtained a slight decrease in the solubility and slight increases in the 24-hour compres-sive strength and hardness of the cement. Roland and others'3 reported that addition of dicalcium phosphate doubled the com-pressive strength of zinc oxide-eugenol ce-ment. More recently, Brauer and co-workers have described cements containing chelating agents other than eugenol.'4 '7 With the ex-ception of their higher coefficients of thermal expansion, cements containing o-ethoxy-