Patricia Wallace-Durbin
Dec 1, 1954
Citations
1
Influential Citations
79
Citations
Quality indicators
Journal
Journal of Dental Research
Abstract
THE metabolism of minute amounts of fluoride has become a subject of considerable interest in recent years, because of the fluoridation of municipal water supplies as an aid in combating dental caries." 2 At the present time there are few extensive data available on the distribution of small amounts of fluorides in the normal animal body with the exception of that found in the bones, teeth, and excreta.'6 One of the major reasons for this lack of data is the difficulty involved in the chemical analysis of fluorine when the amounts present are less than 1 ppm. Radioactive tracer technics have been used successfully in the study of the metabolism of many elements that are found in the animal body in trace amounts, such as zinc and cobalt.8' 9 The only useful isotope of fluorine, F'8, has a very short half life'0 (112 minutes), which places serious limitations on its effectiveness as a biologic research tool. This isotope emits positrons (0.64 mev.) which result in annihilation radiation (photons)." Until recently, investigators who wished to use F18 were faced not only with the rapid decay of the isotope, but also with the considerable difficulties encountered in the measurement of the radiations. The measurement either of the positrons, which are absorbed to a large extent in the mass of the samples themselves, or of the annihilation photons, using an ordinary Geiger-Muller counter, is quite inefficient and requires the use of large amounts of radioactive fluorine. To date, there are only four reports of the use of radiofluorine in biologic investigations. Volker, Hodge, Wilson, and Van Voorhis12 and Volker, Sognnaes, and Bibby13 determined the uptake of F18 in the teeth and bones of the rat thirty minutes after its administration. Wills14 studied the secretion of F18 in the saliva of cats, and Myers, Hamilton, and Becks15 studied the transfer of F18 to the teeth by topical application. With the perfection of the scintillation crystal counter,'6 most of the problems heretofore encountered in the measurement of F18 were greatly reduced, the counting efficiency for the photons was substantially increased, and there was thus no longer a need to be concerned with the self-absorption of the positrons in the mass of the samples. The experiments presented here were designed to shed some light on the following problems: the distribution of F18 in the tissues and organs of the normal rat and the possible effects of the route of administration, the presence of moderate (milligram) amounts of stable fluoride, and the age of the animals on this distribution.