Fluoride uptake in hard tissues of fetal guinea pigs in response to various dose regimens

Abstract

This study was designed to explore various aspects of maternal-fetal fluoride metabolism. In its first phase, 57 female guinea pigs were bred and randomly assigned to a control group (I) or one of three experimental groups: (II) 3 parts/10 6 fluoride in drinking water, (III) a single daily oral dose and (IV) 3 parts/10 6 fluoride in water and a single daily oral fluoride dose. The total mean doses received by groups II and III were similar. The total mean dose received by group IV was approximately double that for groups II and III. Samples of maternal plasma, and fetal bone and enamel were collected on the 57th day of gestation. In its second phase, 53 pregnant guinea pigs were given drinking water containing 0, 2, 4, 6 or 8 parts/10 6 fluoride during gestation. On the 57th day of gestation samples of maternal and fetal enamel were collected. All samples in both phases of the study were assayed for fluoride using the microdiffusion, ion-selective electrode method. In the first part of the study, mean fetal enamel fluoride by group was: I, 21.6 parts/10 6; II, 38.6 parts/10 6; III, 33.5 parts/10 6; IV. 54.9 parts/10 6. In the second phase, maternal enamel was linearly related to the fluoride dose. The same was true for fetal enamel except at the 8 parts 10 6 fluoride level in the water where there was no increase over the 6 parts/10 6 group. At all dose levels, fetal enamel fluoride uptake was approximately an order of magnitude less than maternal enamel fluoride uptake. In this model system, fetal enamel fluoride uptake was linearly related to dose, except at 8 parts 10 6 fluoride in the drinking water. Uptake was similar if the fluoride dose was given in the water or as a single daily oral dose. Fluoride uptake in fetal enamel is much lower than in maternal enamel.