[Gingival pigmentation caused by dental amalgam. An ultrastructural study].

The aim of this investigation is the ultrastructural analysis of biopsies of human gingiva pigmented by the metallic deposits from dental amalgam. The size, the nature and the distribution of the particles are studied by light and electron microscopy and by energy dispersive spectrometry (EDS). Fragments and particles of different size and composition are observed. No traces of mercury are detected in any examined samples. In contrast, very fine grains (0.01 to 0.05 microns in diameter) of a silver compound are observed to be preferentially bound to intracellular membranes and to extracellular structural components. Tissue modifications in the gingival epithelium as well as in the connective tissue can accompany the pigmentation phenomenon. The different metabolic pathways of the metals diffusing from the amalgams are discussed.