The overall goal of this continuation application is to develop dental amalgams which release significantly lower levels of mercury than current commercial amalgams. Our studies have suggested that the development of amalgams with gamma 1 (Ag-Hg) matrices containing large amounts of readily oxidized metals, such as tin and indium, should result in amalgams with significantly reduced mercury release. This reduction would result from the formation of an inhibiting surface oxide, as well as to a reduction in the vapor pressure of the mercury releasing phases of amalgam. The three specific aims are: #1) To develop a series of binary and ternary alloys containing mercury with varying concentrations of readily oxidized metals, i.e. indium, tin and zinc, which can be used as-the liquid phase for trituration with common dental amalgam alloy powders; #2) To fully characterize the properties of the amalgams produced from the most promising alloys developed in aim one; and #3) To explain the properties and mercury release characteristics for the most promising amalgams by examining their microstructure, matrix phase composition, and vapor pressure and thermal stability. To accomplish the aims, binary liquid alloys of mercury and indium and ternary liquid alloys of mercury, indium and tin or zinc, will be mixed with four different types of common dental amalgam alloy powders to produce amalgams. An initial screening of approximately 24 amalgams will be conducted by determining mercury vaporization during setting, and by comparing one-hour compressive strength, creep and dimensional change to the ANSI/ADA Specification #1 minimum values for amalgams. Formulations which pass the screening process will be fully characterized in specific aim #2 by quantitating mercury vaporization after abrasion, 1-day and 7-day compressive strength, flexural strength, working time and handling, corrosion resistance; dissolution of elements during static and dynamic corrosion, and cytotoxicity. Finally, a full evaluation of microstructure and phase analysis will be performed by scanning electron microprobe, limited surface analysis data will be collected by Auger spectroscopy, and thermalgravimetry and differential scanning calorimetry will be used to measure vapor pressure and thermal stability of the amalgams.
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| 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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