Evaluation of metal ion retention in tooth structure following the removal of dental amalgam restorations: an ex vivo study

BACKGROUND: This study aimed to evaluate the persistence of metal ions within tooth structure after the removal of dental amalgam restorations and to assess the relationship between metal accumulation and restoration size. METHODS: Sixty extracted molar teeth were divided into four groups: control (intact teeth), and teeth with one-, two-, and three-surface amalgam restorations. After storage in artificial saliva, the restorations were removed, and the samples were subjected to acid digestion. Metal ion concentrations (Hg, Ag, Cu, Zn, Sn, Cr, Ni, Co, and Pb) were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Differences between groups were evaluated using the Kruskal-Wallis test followed by Dunn's post-hoc test (α = 0.05). RESULTS: All analyzed metals were detected in tooth structure, including those in the control group. Hg, Cu, Zn, Sn, Cr, Ni, and Co levels were higher in restored teeth compared to controls, whereas Ag and Pb showed higher levels in the control group. A consistent increase with restoration size was observed only for Cr and Ni, while other elements did not show a clear surface-dependent pattern. CONCLUSIONS: Metal ions associated with dental amalgam were shown to persist within tooth structure even after restoration removal. However, accumulation patterns vary among elements and are not solely dependent on restoration size. The clinical significance of these findings remains unclear and requires further investigation.