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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.

Galvanic corrosion of amalgam, induced by contact with a type IV dental casting gold alloy, was determined under simulated oral conditions in an electrochemical cell. The effect of a pellicle layer formed by 1 h exposure to saliva in the oral cavity was determined. Pellicle on the amalgam had no effect on the maximum corrosion rate or the 2 h corrosion charge, whereas pellicle on the gold alloy substantially reduced both these parameters of the conventional low-copper amalgam; the corrosion of the high-copper amalgam was less and was not influenced by pellicle formation.

Base metal alloys which contain nickel are not new to dentistry. For the past 25 years, these alloys with nickel content as high as 73.5 percent, have been used to fabricate denture bases and removable partial dentures.

Sixty-eight consecutive patients (9 males, 59 females) referred for symptoms alleged to be caused by oral galvanism were investigated according to a standardized examination program including clinical examination, epicutaneous patch test with dental materials, haematologic screening, salivary test, calculation of currents created at metallic contacts between restorative materials and testing of electrical taste thresholds. No clinical entity could be identified but recognized clinical conditions that could possibly explain the complaints for which the patients were referred were prevalent. The most common symptoms reported were a smarting sensation in the mouth (71%) and different distant symptoms (47%). As regards oral signs, some of them showed similar prevalences as have been found in a general Swedish population. The main exception was changes at the apex of the tongue – found in 15%. Allergic skin reactions to dental materials were found among 25% of the patients. Mean values of blood and saliva parameters did not differ from what is considered normal. The distribution of currents created by contacting dental metallic restorations showed no deviation from the corresponding currents calculated in a control group. The median value for lowest electrical taste threshold in the group of referred patients was significantly lower than in a control group.

RESULTS Mean mercury levels recorded during the amalgam removal procedure are shown in Fig. 1. Higher vapor levels were obtained with dry cutting than with wet cutting at each distance. Levels for dry cutting remained similar at all distances measured within 24 inches. Samples that were cut wet showed a general decrease in vapor levels as distance increased, although levels at 6 and 12 inches were similar and levels at 24 and 36 inches were equal. Sample means were compared statistically using a Student t-test.

Patient exposure to mercury from dental amalgam and restorative procedures has not been studied as extensively as mercury exposure to dental personnel. One. study found that in a group of 114 adults not undergoing dental treatment, only six had measurable mercury in the urine, and one of those persons was using a mercurial diuretic.’This was compared to a group of 24 persons currently undergoing dental treatment. Of that group five showed mercury in the urine before and after treatment.