Corrosion Testing in the Mouth

Abstract

The purpose of our studies was to determine the corrosive behavior of dental restorative alloys in the mouth and, at the same time, to examine them from a dental health point of view. The conclusions are as follows :
1. Even the copper alloy which is commonly supposed to have a high degree of corrosion actually has as small weight loss in the mouth as 0.022 to 0.034 mg/cm² for a day.
2. The type of amalgam which is widely used in many countries today has the weight loss in vivo as little as 0.0063 mg/cm² a day.
3. The basic reason why these alloys are not corroded as is generally supposed is that the salivary secretion has the benefit of keeping the mouth clean. It is also due to the fact that the saliva works to inhibit the corrosion of alloys.
4. As it became clear by our testing that 1950 Ministry of Welfare corrosion test was not realistic as a means of expressing the corrosive behavior of dental alloys, it was removed from the specifications.
5. Within the same oral cavity, the degree of corrosion varies from area to area, that is, anterior teeth, posterior teeth, occlusal, buccal to lingual or proximal surface. By observing the copper alloy restorations after they were removed, the corrosion is most pronounced on the proximal surface.