adam

The release rate of mercury from a conventional, a dispersed phase or a spherical high copper content amalgam under static conditions in stimulated or artificial saliva has been measured and found to decrease approximately exponentially with time. A higher initial release rate was observed for mercury in stimulated saliva than in artificial saliva during the in vitro experiments. In a pilot study corrosion current was recorded from an amalgam specimen immersed in saliva, and was found to decrease approximately exponentially with time. After brushing the surface of the amalgam during two subsequent periods, in a manner similar to toothbrushing, an increase in corrosion current was measured indicating the removal of loosely bound corrosion products. A model describing the periodical mercury release from an amalgam surface has been proposed.

Fourteen dental casting alloys were analyzed for release of nickel and beryllium into acidic salivary solutions in vitro. Corrosion rates of varying pH levels and time in solution were calculated through the 120-day level, and the possible significance of these rates to allergic reactions or other health hazards were postulated.

One conventional amalgam and two amalgams with higher copper content were stored in contact with various dental casting alloys in phosphate-buffered 0.9% NaCl solution, pH 6, at 37 degrees C during 35 weeks. Every 7 weeks the solutions were changed, and the corrosion was measured by analyzing the solutions for the amount of Cu, Zn, Sn, Hg, Ag, Co, Cr, and Ni. In the first 7 weeks the amalgams immersed in contact with acrylic or Co-Cr alloys released small amounts of elements, whereas the release was larger when the amalgams were in contact with the gold alloys. During the rest of the experiment the release of elements tended towards the same level, independent of the casting alloy in contact. In general, the high copper amalgams released more corrosion products into the solutions than the conventional one. The release of corrosion products was strongly pH-dependent. Changing the solutions more often and saturating the solutions with oxygen decreased the amounts of Hg and Ag released.

A 69-year-old white female presented bilateral lesions of the oral mucosa possibly related to electrogalvanism. The lesions were histologically characterized as lichen planus and as mild epithelial dysplasia on the left and right sides, respectively. They disappeared after removing amalgam restorations opposing the lesions. Epicutaneous patch tests and lymphocyte-transformation tests showed that the patient suffered from a contact allergy to mercury compounds, indicating this as a mechanism by which electrogalvanism may induce lesions of the oral mucosa.

Fifty-four patients referred to the Faculty of Odontology, University of Umeå, for investigation regarding “oral galvanism” were subjected to a general oral investigation. In addition the following parameters were studied: the highest calculated current between two metallic restorations in contact and the electrogustometrically determined threshold value for each person. No differences were found regarding these two parameters between the patients and a control group consisting of 15 persons. However, the general oral investigation had revealed that a relatively large number of patients had periodontal conditions which, together with mucous membrane affections and hypersensitivity reactions could explain some of the unpleasant sensations which bothered them. Furthermore, the results of a stomatognathic investigation which will be presented separately revealed that about three fourths of the patients needed treatment for their stomatognathic and/or temporomandibular joint conditions.

Galvanism is seldom mentioned to the dental student, yet nearly every dentist alters a patient’s galvanic current every time he treats him. Galvanism is electrical current produced by placing dissimilar metals inan electrolyte. Saliva is the electrolyte. The dental dissimilar metal list is seemingly inexhaustive. We place copper, tin, zinc, mercury, silver, gold, platinum, irridium, indium, paladium, cobalt, chromium, nickle and baryllium into this electrolyte. A battery is produced. Electrical current is generated. Electricity doesn’t just exist. It is the simultaneous biproduct of a chemical reaction between the various phases of metallic interaction in the mouth. As electrical current is generated, various ions of these metals are emitted into the saliva. Many of these metals, or their corrosion products, are known toxins. Among them is mercury.