The primary goal of this application is to determine the mechanism by which changes in the formulation of the alloy reduce mercury (Hg) release from dental amalgam. A series of alloys will be prepared to test specific hypotheses about the effect of palladium (Pd) additions, silver (Ag) and tin (Sn) ratio, and copper (Cu) content. The composition of the pre-trituration alloys and the resulting amalgams will be evaluated by scanning electron microprobe and scanning transmission electron microscopy with micro-diffraction and XEDA to correlate changes in Hg release with microstructure. In addition, amalgams will be prepared from alloys mixed with pure Hg and indium (In)-Hg alloys to further understand the effect of indium on reducing Hg release, and to produce minimal Hg-releasing formulations. The investigators expect to identify commercially viable amalgams with reduced Hg vaporization during setting and after abrasion, and reduced Hg dissolution. The physical properties of these amalgams will be evaluated to verify that they are adequate for clinical use and to further describe the effect of composition on properties. Dynamic dissolution into both neutral saline and acidic solutions, as well as thermal properties, will be assessed to correlate the stability of the amalgams with composition. Finally, Hg release from aged amalgams will be correlated with changes in their microstructure. The primary hypothesis is that Hg release will be minimized when the Ag-Hg matrix phase of amalgam is most effectively stabilized and its surface oxidized and that this is accomplished by maximizing the amount of Sn present in the gamma one matrix. There are four aims: to identify the mechanism by which additions of Pd, changes in the Cu content, and alterations in the Ag and Sn concentrations in dental amalgam alloy affect the vaporization of Hg; to identify the mechanism by which those variables affect the dissolution of Hg from dental amalgam; to verify that the new alloys produce amalgams with acceptable physical properties; and to verify that the amalgams are stable over a two year period.
| Koike, M; Ferracane, J L; Adey, J D et al. (2004) Initial mercury evaporation from experimental Ag-Sn-Cu amalgams containing Pd. Biomaterials 25:3147-53 |
| Koike, Marie; Ferracane, Jack L; Fujii, Hiroyuki et al. (2003) Evaluation of the amalgamation reaction of experimental Ag-Sn-Cu alloys containing Pd using a mercury plating technique. Dent Mater J 22:280-91 |
| Okabe, T; Elvebak, B; Carrasco, L et al. (2003) Mercury release from dental amalgams into continuously replenished liquids. Dent Mater 19:38-45 |
| Ohmoto, K; Nakajima, H; Ferracane, J L et al. (2000) Mercury evaporation from amalgams with varied mercury contents. Dent Mater J 19:211-20 |
| Ferracane, J; Adey, J; Wiltbank, K et al. (1999) Vaporization of Hg from Hg-in amalgams during setting and after abrasion. Dent Mater 15:191-5 |
| Nakajima, H; Wataha, J C; Rockwell, L C et al. (1997) In vitro cytotoxicity of amalgams made with binary Hg-In liquid alloys. Dent Mater 13:168-73 |
| Nakajima, H; Akaiwa, Y; Hashimoto, H et al. (1997) Surface characterization of amalgam made with Hg-In liquid alloy. J Dent Res 76:610-6 |
| Okabe, T; Ohmoto, K; Nakajima, H et al. (1997) Effect of Pd and In on mercury evaporation from amalgams. Dent Mater J 16:191-9 |
| Nakajima, H; Lorenzana, E; Ferracane, J L et al. (1996) Initial mercury evaporation from amalgams made with in-containing commercial alloys. Dent Mater J 15:168-74 |
| Horasawa, N; Nakajima, H; Ferracane, J L et al. (1996) Cyclic voltammetry of dental amalgams. Dent Mater 12:154-60 |
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