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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.

A New instrument has been developed suitable for making measurements of the potential and the polarization resistance of the metallic restorations in the oral cavity. An improved measuring electrode has been constructed. The equipment is convenient in clinical routine measurements.

The amounts of certain metallic components (Ag, Cu, Hg,Sn and Zn) in saliva possibly derived from dental metallic restorations and due to galvanic actions, were studied in twelve females. Three of these subjects were selected as they complained of certain oral mucosal symptoms and as, upon clinical examination, they were found to have enhanced galvanic action in terms of increased calculated currents at metallic contacts between restorative materials. The rest oflhe subjects did not experience any such symptoms and served as control groups by different criteria. The saliva concentrations of the various metallic components were determined by atomic absorption spectrophotometry. They were not found to vary between the different groups. The results do not forward any support to the view that galvanic action in the oral cavity can give rise to increased metallic contents in saliva. They therefore question the suggestion that increased galvanic action will cause general toxic reactions through the saliva.