[Studies related to the discoloration in the surrounding gingiva of fixed prosthesis. 2. Detection period of silver-sulfate and the effects of metal alloys].

The purpose of this study is to investigate the relationship between gingival discoloration and Ag2S. Minute granules of dental alloys were embedded in the gingiva during a 5-11 months span, and their histological and colorimetric analyses were undertaken. Results showed the following; 1. Cases of low melting silver alloy, 12% Au-Ag-Pd alloy, and Ni-Cr alloy all resulted in gingival discoloration, but it did not occur during the specified experimental period. 2. Regardless of the size of the granules or time, the electron microanalyser showed no signs of sulfer detection in cases of low melting silver alloy. However, in the case of 12% Au-Ag-Pd alloy, sulfer was detected 5 months later for only those granules having the size of 0.2-0.3 microns. No sulfer was detected in cases of Ni-Cr alloy. 3. Although no proliferation of inflammatory cells were observed around those areas surrounding the 12% Au-Ag-Pd alloy granules, they appeared in cases of the low melting silver alloy and Ni-Cr alloy.