Abstract
The investigation was carried out to clarify the gingival discoloration caused bya silver alloy metal core. Experiments were performed on the following four different clinicaltypes of metal core restorations: Type 1, post crown type, ready-prepared; Type II, shoulderedjacket crown preparation, ready-prepared; Type III, shouldered jacket crown preparation, preparedfrom Type I with gum protection ; Type IV, shouldered jacket crown preparation, preparedfrom Type I with inflicting a wound on gingival epithelium. Three months after setting themetal cores, 24 teeth in 3 adult dogs with pinkish gingivae were examined macroscopically, histopathologically and transparent electron microscopically. Depositions, which were foundon the gingival tissue of Type IV, were given electron-probe microanalysis for detecting elements.
Macroscopically, gingival discoloration was found on the gingiva of Type IV only. Lightmicroscopically, many black or dark-brown depositions were observed in the lamina propria ofthe gingival tissue of Type IV. Electron-microscopically, these depositions were seen to consistof a fragmentary dense central core of silver alloy surrounded by a halo of lower electron densitymaterial consisting of fine particles and filaments. Large numbers of smaller particles wereseen within histiocyte-like cells. Very fine particles were also observed along the basal laminaof gingival epithelium. Components of the depositions and fine particles were elementallyanalyzed by an electron-probe microanalyser: Silver and sulphur were detected.
