Developmental and postdevelopmental uptake of dietary organic and inorganic selenium into the molar teeth of rats

The mechanism for the uptake of dietary inorganic and organic selenium by the fully developed, mature molar teeth of mother rats and the developing molar teeth of their pups was studied. Pregnant rats received drinking solutions containing either 0.2 ppm selenomethionine plus 0.045 μCi ⁷⁵Se selenomethionine per ml or 0.2 ppm Na₂SeO₃ plus 0.043 μCi Na₂⁷⁵SeO₃ per ml from day 10 of pregnancy until parturition. 13 Days postpartum, the uptake of dietary ⁷⁵Se into developing molar teeth was more extensive than the postdevelopmental uptake onto mature teeth. Developing molar teeth incorporated more ⁷⁵Se from dietary selenomethionine than from selenite, as did many hard and soft tissues studied. The major portion of ⁷⁵Se in enamel and dentine was located in the protein fraction of these dental tissues. Dialysis experiments showed that the selenium in enamel and dentine existed in at least 3 forms: loosely bound selenium, proteinaceous selenotrisulfides and proteinaceous stable selenium. These data and the results of a previous study provide evidence that selenium incorporated into developing proteins as selenotrisulfides or selenoamino acids may be responsible for the increases in dental caries reported in man and experimental animals ingesting somewhat increased amounts of dietary selenium.