Effect of placing, removing and polishing of amalgam restorations on 24-h urinary mercury concentration

Abstract

Twenty-four-hour urinary mercury concentration were assessed in 43 patients before and after removing old amalgam fillings (8 pts), placing (13 pts), and polishing of amalgam (22 pts). Baseline analyses 8 days before the treatments showed on average 18.5_+7.2 tag mercury mass excreted per 24-h urine samples. The removal of old fillings caused a total excreted mass of 56.34-32.3 tag Hg, the placing of amalgam 45.9_+26.2 lag Hg, and the polishing 56.25_+33.77 tag Hg, respectively, one day after the treatments. When compared with the baseline values, the urinary mass excreted remained significantly elevated during the 8-day follow-up. However, all Hg values measured were below the WHO recommandations for the threshold limits for urinary mercury.