The effect of surface finish on the anodic polarization of a conventional spherical amalgam.

The corrosion of carved, burnished, polished, and burnished--polished samples of a conventional spherical amalgam was studied by anodic polarization in Ringer's solution. The effect of the variation of the mercury content from 40 to 60 wt% on the corrosion of burnished or polished samples was also investigated. It was found that burnished and burnished--polished samples corrode the least and carved samples the most. The current-density peak associated with gamma2 was of greater magnitude in polished specimens than in burnished specimens throughout the range of mercury concentrations investigated. It is hypothesized that lower porosity and more ready passivation of the surface due to a high amount of gamma2 are the reasons that burnished samples corroded less than polished samples in this anodic polarization test.