Gingival biopsies obtained from six patients with bluish-grey pigmentations developed after application of metal prosthetic restorations were analysed by transmission electron microscopy and EDX microanalysis. In the lamina propria gingivae dense particles were localized intracellularly in fibroblasts, macrophages and endothelial cells. Extracellular appearance of these particles among collagen fibres was seen in the matrix. In such particles silver and sulphur eventually selenium were found most frequently. The silver content in the tissue was found in the correlation with its content in the prosthetic metal alloys. The occurrence of the macrophages and mast cells in the lamina propria gingivae point to the immunological background of such metal pigmentations.

        Key words: gingiva – pigmentation – metals – TEM, EDX-microanalysis