Corrosion of dental metallic materials by dental treatment agents

Currently, dental bleaching and fluoride treatment agents are popular for esthetic purposes and prevention of plaque and caries formation. The corrosive effect of these agents on dental metallic materials has not been well documented. It was an objective of this in vitro study to evaluate and compare chemical and electrochemical corrosion behavior of seven metallic dental materials in commercially available fluoride and bleaching agents. Fluoride treatment agents were tested on Ti-6Al-4V and 17-4 stainless steel. Discoloration on these alloys was examined by a colorimeter and the naked eyes. Bleaching agents were tested on commercially pure titanium, Ni-Co-Mo alloy, type IV gold alloy, and amalgam. Electrochemical corrosion tests were also conducted for these materials, using each treatment agent as an electrolyte. All tested materials suffered from discoloration, which mostly disappeared after brushing. The fluoride-treated 17-4 stainless steel indicated severe intergranular attack, causing localized Cr depletion. The bleaching agents made the passivation layer on the metallic materials unstable. Within the limitations of this study, although these treatments are indicated for patients (enamel), it is proven that these agents are contraindicated for dental metallic materials.