Gallium-Palladium Alloys as Dental Filling Material

The remarkable ability of liquid gallium to wet the surfaces of many solids, including human teeth (1), has stimulated interest in gallium alloys as possible filling materials in dentistry (1, 2). A number of gallium alloys which possess some of the properties necessary in dental filling materials have been reported (1-4). Several have also been described by C. W. Austin, Jr., at the National Bureau of Standards, and J. P. Lyle, of the Aluminum Corporation of America. Most of these alloys were subsequently found to lack other necessary properties such as strength, corrosion resistance, or tolerance by biological tissues. A more inert alloying ingredient is apparently needed to make the gallium alloys nonreactive in the oral environment. Such requirements lead to a consideration of the metals, such as gold and the metals of the platinum group in the periodic table, as possible alloy ingredients. Since palladium is the least expensive of the noble metals, it was selected for further investigation as a constituent of gallium alloys.