EQUILIBRIUM VAPOR-PRESSURE OF MERCURY FROM DENTAL AMALGAM IN-VITRO

Objectives. The purpose of this study was to acquire reliable quantita tive data on mercury vapor pressure above the surface of dental amalga m samples in both the as-formed and the abraded state. Methods. The eq uilibrium vapor pressure of mercury from dental amalgam was obtained u sing residual gas analysis in conjunction with a quartz crystal microb alance. The measurements were performed under ultrahigh-vacuum conditi ons. Results. Using the residual gas analyzer, the average mercury vap or pressures measured from the as-formed and abraded dental amalgam su rfaces were 8 x 10(-7) and 1.7 x 10(-4) Pa, respectively. The correspo nding vapor densities are: 6 x 10(-2) mu g/m(3) and 14 mu g/m(3). The average mercury vapor pressures measured from the as-formed and abrade d dental amalgam surfaces using the quartz crystal microbalance were: 2.4 x 10(-6) and 1.0 x 10(-4) Pa, respectively. The corresponding vapo r densities are: 0.2 mu g/m(3) and 8 mu g/m(3). Significance. This pro ject provides a measurement of the equilibrium vapor pressure of mercu ry from as-formed and abraded amalgam surfaces. By definition, the equ ilibrium vapor pressure provides the maximum density of mercury which can be present in the environment above the amalgam. The vapor density of mercury within the oral cavity must be less than this value due to the dynamic nature of the system.