I. Zipkin

X-ray diffraction analysis of the effect of fluoride on human bone apatite

Abstract 1. 1. X-ray diffraction studies were performed on a series of human bones containing varying amounts of fluoride. A rise in fluoride content was accompanied by an increase in bone apatite crystal size and/or a decrease in crystal strain in a direction perpendicular to the c-axis, with the mean crystal size in the c-axis direction remaining at a value of 96 ± 9.6 A regardless of the fluoride content. Details and criticism of the X-ray methods are given and a new template X-ray method is described for obtaining an estimate of crystallinity of poorly crystallized apatite samples. Evidence is furnished to show that fluoride substitutes for hydroxyl ion in the bone apatite phase. 2. 2. It is suggested that the improvement of crystallinity results from the increased crystal growth rate following a greater nucleation rate both of which are due to the higher supersaturation resulting from the presence of fluoride in the serum and the final crystalline phase. 3. 3. It is also suggested that a more stable bone apatite is produced by (a) the improved crystallinity and (b) the isomorphous substitution of fluoride in the apatite structure.

Relation of the fluoride content of human bone to its chemical composition

Abstract A comprehensive study is presented on the composition of human bone over a wide range of skeletal fluoride concentrations. Thus, sixty-nine samples of human bone, comprising iliac crest, rib and vertebra obtained from twenty-three individuals 26–90 years of age who had consumed drinking water containing up to 4.0 p.p.m. fluoride for 10–87 yr prior to demise, were analysed for calcium, phosphorus, magnesium, sodium, potassium, carbon dioxide and citrate. The percentage of calcium and phosphorus in the dry, fat-free bones was normal although they contained as much as 0.4% fluoride. No relation was apparent between the fluoride present in bone ash over a tenfold range in concentration and its calcium or phosphorus content. With increased levels of fluoride in the ash (0.08–0.8%) there was a slight increase in magnesium and a decrease in carbon dioxide. The citrate content decreased markedly with increased fluoride. A slight decrease in sodium and little or no change in potassium were noted. The data support the hypothesis that fluoride is deposited in mature bone largely at the expense of surface limited ions.

Small-angle X-ray diffraction analysis of the effect of fluoride on human bone apatite

Abstract Small-angle X-ray diffraction studies were performed on a series of human rib samples containing varying amounts of fluoride. The results show that a rise in fluoride content was accompanied by a decrease in the area of the interface between the mineral apatite phase and the remaining bone tissue. Detailed analysis of the results suggest that this decrease can only be accomplished by an increase in the mean volume and concomitant decrease in the number of the apatite crystallites. Further considerations suggest that the improvement in “crystallinity” as measured by wide-angle X-ray diffraction, as reported in previous publications, can be accounted for entirely by this increase in crystallite size. Apparently these progressive changes in bone mineral can be tolerated by the individual without producing significant physiological consequences.

Frequency of eating as a factor in experimental dental caries

Abstract Caries activity on each of three caries-test diets was directly related to length of time that food was available to the animal and not due to the amount of food consumed. Increased caries activity was also demonstrated following the injection of ethylene diamine tetraacetic acid (EDTA). These results suggest that increased oral retention, whether resulting from changes in the feeding regimen or changes in the biologic status of the animal, may be the common causative factor associated with increased caries activity.

The effect of fluoride on the citrate content of the bones of the growing rat.

Abstract The vertebra, tibia-fibula and mandible of 47 day old rats receiving 0, 10, 50 and 100 p.p.m. F in the drinking water for 25, 55 and 114 days were analysed for fluoride and citrate. The concentration of citrate decreased with age in control rats receiving no supplemental fluoride. The bones of rats receiving 10, 50 and 100 p.p.m. F showed a progressive decrease in citrate concentration related to the fluoride content at each period of sacrifice (25, 55 and 114 days on experiment). The total citrate content increased with age in the three bones examined but less total citrate was deposited as the concentration of fluoride administered was increased. Possible mechanisms to explain the inverse relation between the fluoride and the citrate content of bone are discussed.

Reduced Caries in Offspring of Rats Receiving Tetracycline During Various Prenatal and Post-Partum Periods

Summary Offspring of mothers receiving tetracycline during various prenatal and postpartum periods showed markedly less caries activity during subsequent 60-day post-weaning assay period. Tetracycline administration did not adversely affect litter production, weight gains, diet intake or fluid consumption in either mother or offspring.

The citrate content of teeth and bones of human foetuses

Abstract The citrate content of femora, mandibles and teeth was determined in 192 human foetuses, aged 4–9 months, in areas supplied by drinking water containing about 0.1 ppm F (low) and about 1 ppm F (elevated). In low (80 cases) and elevated (112 cases) F drinking water areas the mean citrate content in bones and teeth decreases with increasing age of the foetus. No significant differences between the mean citrate content of the foetal skeletal tissues of corresponding ages from low and elevated F areas were demonstrated. Significant differences were demonstrated between the mean citrate content of the femora and the mandibles, as compared to that of the teeth at corresponding ages. There were significant correlation coefficients between the citrate contents of the femora and the mandibles. The different growth patterns of bone and teeth may account for the differences in the citrate contents of these hard tissues.

Odontogenic hamartomas in an inbred strain of mouse (str/1n).

Summary Hamartomas of the incisor teeth develop in 48 of 62 mandibles of one-year or older STR/1N mice that had been fed a soft diet. Development of the lesions was further increased by incorporation of 50 PPM of NaF in the drinking water. Comparable growths were never seen in A/LN mice whether they received fluoride or not, nor in STR/IN mice eating a pelleted chow. We are indebted to Dr. Paul N. Baer for valuable suggestions and to Mrs. Priscilla Auvil for technical assistance.

Caries potentiating effect of ethylene diamine tetraacetic acid in the rat.

Summary The addition of 0.5% EDTA to a cariogenic diet appeared to potentiate caries to a marked degree in the white rat. Concomitantly, the hematocrit value is significantly lowered, and almost complete inhibition of incisor pigmentation is found. These effects of EDTA do not seem to be associated with its ability to decalcify rat molar teeth in vivo. Citrate and calgon added to a cariogenic diet and present in the drinking fluid do not significantly increase the severity of caries.

Fluoride content of urinary and biliary tract calculi.

Summary Thirty-three samples of urinary and 9 samples of biliary tract calculi from individuals with known histories of exposure to water-borne fluoride were analyzed for fat, ash, calcium, phosphate and fluoride. (1) Concentration of fluoride in urinary tract calculi was significantly higher than that in the bones. (2) Mean concentration of 0.25% fluoride in urinary tract calculi of individuals from low fluoride area was not significantly different from that (0.37%) of calculi of individuals whose drinking water contained 2.6 ppm fluoride. (3) No relation was apparent between the calcium and fluoride concentrations of urinary tract calculi. (4) Fluoride was present in biliary tract calculi in very low concentration (0.000-0.006%).