1988

Uusheimo, Kari; Rytömaa, Inkeri

The purpose of the present study was to determine the quantity of mercury released into saliva from dental amalgan. Five fillings made from an amalgam labeled by 203Hg-isotope were prepared in plastic cases. The fillings were kept in the saliva at the body temperature (37 ± 3 °C). The saliva was changed first after a 24-hour period, then every second day, later weekly and finally once in a month. The count rate of the released Beta-/gamma-active isotope was measured by means of a liquid scintillation counter. The effect of polishing on the release of mercury was also studied. To this end three of the fillings were polished one week and again four weeks after the insertion. Two unpolished fillings were used as controls. The results from the polished and unpolished fillings differed clearly from each other. Following the polishing day a many fold amount of mercury was released from the polished fillings compared with the unpolished fillings. This difference, however, disappeared after one or at the latest after two days from the polishing. Interestingly over a long time period, more mercury was released from the unpolished than from the polished fillings. Exceptionally high mercury values were occasionally detected in some samples; in these saliva samples small amalgam particles were actually seen by the naked eye. During the first 24 hours 68 % of the total release was observed from the polished fillings and 61 % from the unpolished ones; in two days the percentages were 78 % and 69 %, respectively, and over a period of one week 90 % and 79 %. The average absolute release of mercury was 313 my g per filling in the first day. During the first week the average daily release was 60 my g per filling; during the last month of the experimental follow-up the daily release of mercury was 0.06 my g from the polished fillings and 0.09 my g from the unpolished ones. Except during the first day the daily release of mercury was much lower than the maximum daily exposure limit.