Long-term effects of Ag-containing alloys on mucous tissue present in biopsy samples

The aim of this study was to investigate the long-term effects of alloys containing silver (mainly Ag-Sn alloy) on oral mucous tissue. We observed biopsy tissue specimens from patients diagnosed as having amalgam tattoo and/or metal pigmentation by light and electron microscopy and electron-probe microanalysis (EPMA). In most cases, Ag-Sn alloy was present in the tissue but it could not be confirmed if the alloy originated from amalgam. Distributions of both Ag-S and Ag-Sn have typical patterns. Most Ag forms Ag2S and is stably deposited in three patterns along the collagen, basement membrane, and fibrous cells without inducing any host reaction. On the other hand, Sn forms large granules that contain Ag, S, C, N, P, and Ca, and is in soft state in the tissue. Tissue reactions to the alloy become weaker as time passes.