It is now accepted that Cu-enriched dental amalgam corrodes in saline environments through electrochemical activity of the copper containing phases, eta and epsilon, the gamma 1 (Ag2Hg3) and possibly the unreacted alloy. As a result of such corrosion, mercury, as well as copper, tin and silver ions are capable of being released. Preliminary work in this laboratory has indicated that palladium additions to Cu-rich amalgams will improve the corrosion resistance of copper rich amalgams, however, the mechanism is not well understood. Furthermore, Pd has been shown to promote the formation of beta AgSn, which deleteriously affects trituration and mechanical properties of resultant amalgams. Fortunately, it appears that the beta to gamma transformation can be thermally activated with mechanical property improvement. The mechanism of that transformation is not understood. Finally, Pd can be shown to develop affinity for Sn and essentially acting as a replacement for Cu in eliminating gamma 2. The effect on mechani-al properties of amalgams with Pd-Cu and Pd-S-phases replacing Cu-Sn phases is unknown. This proposal therefore, attempts to: a. Characterize the microstructural changes in the phases of Cu-rich dental amalgam accompanying Pd addition by fabricating the components and phases and studying them by x-ray diffraction and SEM/EDS techniques. b. Carefully elucidate the electrochemical properties of these phases by polarization techniques. c. Formulate, based upon the results obtained in (a) and (b), an amalgam composition or compositions which will display minimal electrochemical activity in chloride and saliva-like environments and then adjust its particle size, morphology and structure to produce optimal tensile strength and creep properties.
| Lin, T H; Chan, C C; Chung, K H (1994) Metal release from high-copper amalgams containing palladium. Zhonghua Yi Xue Za Zhi (Taipei) 53:146-53 |
| Chern Lin, J H; Chung, K H; Greener, E H (1992) Microstructures of admixed amalgams produced from Pd-containing dispersants. Dent Mater 8:85-8 |
| Chern Lin, J H; Greener, E H (1991) Microstructures of Pd-containing dispersants for admixed dental amalgams. Dent Mater 7:254-7 |
| Mante, F; Chern Lin, J H; Moser, J B et al. (1989) Effects of noble metals on the corrosion behavior of dental amalgam. Northwest Dent Res 1:16-7 |
| Greener, E H; Chung, K H; Lin, J H (1988) Creep in a palladium-enriched high-copper amalgam. Biomaterials 9:213-7 |
