I. Gedalia

Fluoride in the Surface Enamel of Teeth from the Same Mouth

Attention has recently been focused on the fluoride content of the surface enamel. It was found that after the tooth erupts into the oral cavity, the surface enamel incorporates additional fluoride from drinking water, food, and saliva.-6 There is now evidence that the surface enamel has a much higher fluoride content than the whole enamel 4 This study was undertaken to examine the surface-enamel fluoride content of various areas of sound and various teeth from the same mouth. The findings are correlated with the tooth age.

The fluoride content of teeth and bones of human foetuses

Abstract The fluoride content of femora, mandibles and teeth was determined in 203 foetuses, aged 4–9 months, in areas supplied by drinking water containing 0.05–0.1 p.p.m. F (low) and 0.5–0.6 p.p.m. F (medium). In medium (115 cases) F drinking water areas in the mean fluoride content in bones and teeth increases with increasing age of the foetus (the highest increase is in the femur and the lowest in the teeth), whereas in low (88 cases) F drinking water areas no such increase is found. Significant differences between the mean fluoride content of the femur, mandible and teeth of corresponding ages from medium F areas are demonstrated. The corresponding differences in low F areas were not significant. Significant correlation coefficients between the fluoride content of the femur, mandible and teeth of the older foetuses in the low and medium F areas were evident. Differences between the mean fluoride content in bones and teeth of corresponding ages from low and medium F areas are demonstrated, the significance increasing with the foetal age. Difference in blood flow, vascularity and crystal size between femur, mandible and teeth may, perhaps, account for the different fluoride contents of these hard tissues.

X-ray diffraction and scanning electron microscope investigations of fluoride-treated dentine in man

Abstract Root surfaces of human teeth and powdered dentine were treated in vivo and in vitro with 2 per cent neutral and acidulated (0.1 M H 3 PO 4 ) NaF solutions for varying periods. The root surfaces were examined by scanning electron microscopy (SEM) and the ashed dentine powder by X-ray diffraction. Fluoride determinations were carried out in the F-treated material. CaF 2 formation was detected up to a maximum amount of 0.7 per cent in the dentine powder following a 5-day treatment with acidulated NaF solution. The SEM micrographs revealed granular precipitates mainly in the peritubular and intertubular regions, decreasing as a function of the fluoride release following the washing effects of oral fluids in vivo and saline immersion in vitro . Precipitated fluoride compounds blocking mechanically or labile fluoride in the organic matrix of dentine blocking biochemically the transmission of stimuli are suggested as desensitization factors.

Placental transfer of fluorine in the human fetus.

Summary Samples of the blood from pregnant women shortly before delivery, placentas at full term and cord blood, were analyzed for fluorine. All subjects drank from the same water source which contained about 0.55 ppm fluorine. The results suggest that the placenta plays an active role in accumulation of fluorine and its transfer to the fetus. We are indebted to Miss Pearl Weiskopf for statistical analysis and to Natan Portuguese for technical assistance.

The strontium content of bones and teeth of human foetuses

Abstract The concentration of strontium was determined in bone and tooth ash of human foetuses 5–9 months old from regions with different water supplies (Beer-Sheva, Jerusalem and Tel-Aviv). The material was collected about 8 yr ago. Strontium was detected in the femoral and mandibular bones as early as the fifth month of foetal development (the earliest age for which material was available) and the concentrations were similar in all areas. The strontium concentration increased significantly from the 5th to the 7th month in the bone ash of the foetuses from the Beer-Sheva area, but no such increase with age was found in foetuses from the Tel-Aviv area. The concentration of strontium in the bone ash of 7–9 months old foetuses from Jerusalem was similar to that in foetuses of corresponding age from the Tel-Aviv area. The concentration of strontium in the tooth ash of 7–9 months old foetuses of each area was similar to and paralleled that of the bones of a corresponding age. It is suggested that the differences between the strontium concentrations of the hard tissues of the foetuses in the Beer-Sheva area on the one hand and the Tel-Aviv and Jerusalem areas on the other are due to differences in the strontium contents of the drinking water supplied during pregnancy. It is of interest that present drinking water sources, some of which were in use at the time the material was collected, have a higher strontium content in the Beer-Sheva area than in the Tel-Aviv and Jerusalem areas.

Fluorine Content of Superficial Enamel Layer and Its Correlation with the Fluorine Content of Saliva, Tooth Age, and DMFT Count:

With the increasing use of fluorides for the prevention of dental caries, studies of the fluorine content of teeth have gained much in importance. Research on tooth fluorine has been confined mainly to determination of the fluorine content of either separated enamel and dentin-6 or whole-tooth substance.7 Such studies have shown that the fluorine content of the enamel, the dentin, and whole teeth is proportional to the fluorine content of the drinking water and food-3 5, 6 and inversely proportional to the DMFT count.47 Recently, attention has been focused on the fluorine content of the superficial enamel layer. It was found that after the tooth erupts into the oral cavity, the superficial enamel incorporates additional fluorine from drinking water, food, and saliva.fr4 No attempt has so far been made to correlate the fluorine content of the superficial layer of the enamel of human teeth with the DMFT count. The present investigation was undertaken to determine whether correlations exist between the fluorine content of the superficial enamel of human teeth and (a) the fluorine content of the saliva, (b) the age of the erupted teeth, (c) the DMFT count.

Fluoride metabolism in pregnant rats.

Summary The F metabolism was compared in pregnant and non-pregnant rats of 170 g weight. In the bones, F content was similar in both groups, and when F supply exceeded 14.55 ppm, there was a pronounced increase in bone F content. In fetal bones, the increase appeared at lower levels of supply, i.e. 5.2-14.55 ppm. In the blood, F levels were similar in pregnant and non-pregnant rats. At intakes exceeding 14.55 ppm, there was only a slight increase in blood F in both groups. In the urine, F levels increased in both groups similarly, and rather steeply with increased F intake, thus indicating immediate removal of any F surplus with the urine in pregnant and non-pregnant rats. It is stressed that this metabolism is different from that observed in pregnant women, who tend to retain an F surplus-during pregnancy.

Effects of fluoride intake on disuse atrophy of bone in rats.

Summary The effects of fluoride intake on disuse atrophy of the femoral bone were investigated in rats after severing the right sciatic and femoral nerves. X-ray radiograms of the femora were made. Calcium content of the blood, specific gravity, ash percentage and calcium and fluoride content of both femora were determined in operated and non-operated rats drinking distilled or fluoridated (25 ppm) water for 2 months after starting the experiment. The results showed that fluoride counteracts the typical bone atrophy syndrome; it reduces the calcium content of the serum and prevents bone resorption. It is suggested that increased bone resorption is prevented by a reprecipitation of calcium as fluorapatite of low solubility on the surface of the bone crystals. Acknowledgement is made gratefully to Ziporah Pinchevski for technical assistance in this study.

Chemically distinct stages in developing human fetal enamel

Abstract Chemical analyses and the appearance of developing enamel from maxillary first incisors of human fetuses aged 5–9 months distinguished two stages during this period of development. The first corresponded to the production of forming enamel, which was soft, translucent and partially mineralized, and the second to the maturation or secondary mineralization of enamel. The final stage in enamel development, i.e. the mature, hard enamel is, however, generally absent in the tooth of the 9 month old fetus. The concentrations of P and Ca of the forming enamel in the tooth axis did not change significantly, varying between 9–12 and 21–26 per cent by weight, respectively. However, the P and Ca concentrations rose steeply across the boundary between the forming and the maturing enamel to reach a maximum value of 17 and 35 per cent, respectively, in the second stage.

Fluoride deposition in the bones of rats determined by fluoride and X-ray diffraction analysis

Rats were given drinking water containing up to 300 parts/10(6) F and the conversion of hydroxyapatite to fluoridated apatite was estimated chemically and by X-ray diffraction. The differences of the mean fluoride uptakes from the very different concentrations of fluoride given were significant. Prolonged washing of the bones with demineralized water released 5-10 per cent from the fluoride uptake. Formation of fluoridated apatite was evident by decreases in the a parameter of the hydroxyapatite phase. In the washed bones, there was no appreciable transformations in the a parameters. The co-existence of Mg-containing beta-Ca3(PO4)2 with the apatite phase was detected in heated bone samples. The amount of beta-Ca3(PO4)2, its dependence on the age of the bones and its Mg content are interdependent.