Intermediate Restoratives from n-Hexyl Vanillate-EBA-ZnO-Glass Composites

Abstract

Vanillate esters such as n-hexyl vanillate (HV) dissolved in a suitable chelating agent - e.g., o-ethoxybenzoic acid (EBA) - react with zinc oxide, aluminum oxide, and hydrogenated rosin powder to yield non-eugenol-containing cements that do not inhibit polymerization and are compatible with acrylic monomers. These cements can be modified by adding methyl methacrylate, or the less-volatile, higher-molecular-weight dicyclopentenyloxyethyl, or cyclohexyl methacrylate to the HV-EBA liquid, and silanized glass to the powder. On incorporating a suitable initiator-accelerator system, one can prepare powder-liquid mixes that have good working properties and harden in five to 10 min. The cured materials containing monomethacrylate ingredients have compressive and tensile strength one and one-half to three times that of eugenol-based intermediate restoratives. Cements with even better mechanical properties are obtained using dimethacrylates as monomeric components. Storage stability of the liquids comprising vanillates-EBA and monomethacrylates is excellent. The vanillate-EBA-dimethacrylate liquid containing amine accelerators polymerizes within days when left standing at 45°C The cement composites adhere strongly to composites, non-precious metals, or porcelains. Rupture of the bond occurs cohesively within the cement. Because of their high strength, low solubility, and excellent adhesion, these cements, subject to their biocompatibility with dental tissues, show great promise as intermediate restorative resins and in the repair of fractured porcelain or porcelain-to-metal crowns and bridges.