THE EFFECT OF FLUORIDE INGESTION ON THE COMPOSITION AND SOLUBILITY OF MINERALIZED TISSUES OF THE RAT

¹ National Institute of Dental Research, National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare, Bethesda, Md.

When rats are given fluoride at the level of 100 ppm in the drinking water under the conditions of this experiment, the calcium content of the bone is not increased with the increase in fluoride content. It was also shown that there is a tendency for the magnesium content of the tissues to increase with increase in fluoride content.

Additional evidence has been obtained to show that the material formed by the in vitro reaction of fluoride ions with dentin and bone may be fluorapatite probably produced by ionic exchange and recrystallization, and shows reactions similar to that produced by the in vivo reaction with fluoride (solubility and hydroxyl exchange). However, when enamel is treated in vitro the reaction presumably takes place mostly on the outer surfaces because of the inability of fluoride ion to penetrate to the hidden area of the crystal. This is probably because of the extremely slow thermal aging of enamel as opposed to that of bone and dentin. Fluoride, however, is incorporated throughout the tissue in the in vivo reaction.