Blood and urine fluoride concentrations associated with topical fluoride applications on dog gingiva

The circulatory uptake and urinary excretion of topical fluoride were investigated by applying a sodium fluoride solution containing 18F for six min to healthy gingiva of four adult dogs. Blood and urine samples were taken a regular intervals. Maximal fluoride in blood represented 0.02-0.05% of the applied dose and occurred four min after completion of the application. By 6.0 h, 0.02-0.06% of the applied dose had been excreted in urine. Preliminary data showed that this represented about 8.8% of the fluoride absorbed through the gingiva.