Abstract
The discoloration of the fixed metal prosthodontic appliances, which had been removed from the oral cavity, was observed to obtain epidemiological and clinical suggestions to select the dental alloy. This study was performed on 396 fixed metal prosthodontic appliances which were removed from the oral cavity.
The findings were as follows:
1. The appliances were composed of 7 kinds of dental alloy, Au-Pd-Ag-Cu-alloy (74.4%), Ag-alloy (9.8%), Ni-Cr-alloy (9.5%), Au-alloy (4.5%), Amalgam (0.5%), Co-Cr-alloy (0.3%), Titanium alloy (0.3%), and others (0.7%). The appliances observed were full cast crowns (33.1%), bridges (21.0%), fillings or partial veneer crowns (16.7%), resin faced cast crowns (13.1%), connected crowns (6.3%), root caps (2.5%), band crowns (2.3%), porcelain-fused-to-metal-crowns (1.8%), metal cores (1.8%), and attachments (1.5%).
2. The proportionof the discoloration of appliances removed was 69%, and this was about 1.7 timeshigher than before removal (p > 0.01).
3. The discoloration of appliances increased with the duration of use in the oral cavity (p > 0.01), and theappliances of Ag alloy were the most discolored (88.9%, p> 0.05) among 7 kinds of alloy.
4. Discoloration was frequently observed at the soldered portions, inner margin, and basal surfaces of pontic or the lower parts of connectionat the proximal embrasure (p > 0.05).
5. The proximal surfaces adjoiningdiscolored appliances were more discolored than those adjoining nondiscolored appliances (p > 0.01).
6. In patients whose oral prophylaxis status were better, the appliances tended to be less discolored.
