Equilibrium vapor pressure of mercury from dental amalgam in vitro

Structural segregation in GSR from mercuric primers. A preliminary study

Since the second half of the XX century, primer mixtures based on mercury fulminate have become a rare occurrence on small ammunition markets in Western Europe and North America. As a consequence, Hg-containing gunshot residue (GSR) particles have not been as deeply investigated as residues from lead-based primer mixtures. As a matter of fact, no mention of GSR particles from mercuric primers is made by the current ASTM standard procedure for gunshot residue analysis. However, those laboratories dealing with ammunition and firearms produced in Eastern Europe or Asia still have a forensic interest in Hg-containing GSR. In this paper, a brief description of chemical composition and inner morphology of GSR particles from three different mercuric primers is reported. Regarding composition, arguments are given to promote SbSnHg residues to Characteristic of GSR particles when mercuric primers are discharged. From a morphological point of view, presence of inner nodules and other inhomogeneities were shown in GSR particles milled in a FIB/SEM. Moreover, mercury vaporization under the electron beam was observed for a particle reduced to a lamella. Mercury evanescence in GSR was interpreted in terms of mercury segregation during particle formation and higher mobility of Hg atoms in presence of defects (vacancies) in a strained lattice.

Investigation of two mercury vapor collection techniques

OBJECTIVES

The purpose of this investigation was to develop and test two in vitro mercury vapor collection techniques: a closed bottle technique (CB) and an intraoral flow (IOF) technique.

METHODS

Amalgam samples were prepared in acrylic first molars (#30) with standardized Class I preparations. In the CB technique, samples were placed in either a 25, 100 or 500 ml bottle (n = 5). Vapor was analyzed with the Jerome M-411 using a syringe method over a 7 day period. In the IOF technique an impression of the lower right quadrant of a Typodont was taken with PVS impression material leaving a 5 mm space over #30. Samples were analyzed with the Jerome M-411 connected to the impression tray via tygon tubing at the buccal surface. Average mercury vapor release rates and standard deviations were calculated for each method. Data were analyzed by two-way ANOVA followed by Tukey HSD pairwise analysis for significant findings (alpha = 0.05).

RESULTS

Both techniques indicated mercury vapor release was dependent on volume. The largest bottle, 500 ml, yielded a significantly greater (p < or = 0.00) amount of mercury vapor within the CB systems. In the IOF technique, the addition of air flow over the restoration demonstrated a significant increase (p < or = 0.05) in mercury vapor released compared to the sealed IOF technique.

SIGNIFICANCE

A method for mercury vapor analysis was developed for possible intraoral application. The IOF method with direct air flow removes possible saturation effects found in a CB system, while limiting external variables, which may contribute to errors associated with in vivo measurements.