Journal of Dental Research, Vol 63, 137-140, Copyright © 1984 by International & American Associations for Dental Research Online Journals
Cements containing syringic acid esters -- o-ethoxybenzoic acid and zinc oxide
G. M. Brauer and J. W. Stansbury
Fissure caries is reduced when syringic acid is incorporated into a
cariogenic diet of rats. It was therefore of interest to synthesize n-hexyl
and 2-ethylhexyl syringate and to evaluate the properties of cements with
these compounds as ingredients. Liquids containing the esters dissolved in
o-ethoxybenzoic acid (EBA) - when mixed with powders made up from zinc
oxide, aluminum oxide, and hydrogenated rosin - hardened in from four to
nine min. Properties of the cements were determined, when possible,
according to ANSI/ADA specification tests. Depending on the powder-liquid
ratio employed, we obtained compositions with varying physical properties
desirable for different dental applications. The syringate cements,
compared with the commonly used ZOE materials, have improved compressive
and tensile strength, lower water solubility, do not inhibit
polymerization, and are compatible with acrylic monomers. These cements
pass, and mostly greatly exceed, the requirements for ZOE-type restorative
materials. They also bond significantly to resins, composites, and
non-precious metals. The bond strength is somewhat less than that of
n-hexyl vanillate-EBA cement, but greatly exceeds the adhesion to various
substrates of ZOE luting agents. Cements containing n-hexyl syringate were
somewhat brittle. Best results were obtained with liquid compositions
containing 5% 2-ethylhexyl syringate, 7% n-hexyl vanillate, and 88% EBA,
which yielded non-brittle materials. These cements, because of the
syringate ingredient, may possess caries-reducing properties. Thus, perhaps
in conjunction with fluoride additives, they would be useful as insulating
bases, pulp capping agents, root canal sealers, soft tissue packs, or
intermediate restoratives.
