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Maternal-fetal transfer of fluoride in pregnant women.

Gas chromatography was used to measure the maternal and fetal plasma inorganic fluoride values at term in 91 women. They were assigned to one of four groups: group A were untreated controls; group B received a single daily dose of 1.5 mg of fluoride (as calcium fluoride) during the final trimester of pregnancy; group C was given a single dose of 1.5 mg of fluoride (as sodium fluoride) and group D was given 2 daily doses of fluoride (as sodium fluoride) totaling 1.5 mg. There was a significant difference between the cord plasma fluoride levels of the newborns in the untreated group (mean: 27.8 micrograms/l) and that of the combined supplemented groups B, C and D (mean: 58.3 micrograms/l). There was no difference between the average fluoride levels in the three supplemented groups. There was no significant effect of maternal age, infant birth weight, gestation or diet during pregnancy on the cord plasma fluoride level. These results indicate that fluoride supplementation during the final trimester of pregnancy will significantly elevate cord plasma fluoride concentrations.

Adult↗

Reactivity of fluoride-containing calcium aluminosilicate glasses used in dental glass-ionomer cements.

The glass component critically determines the properties of glass-ionomer cements (GIC). However, the exact relationship between the composition of the glass and these properties is not yet fully understood. To investigate this relationship, we studied the reactivity of glasses used in commercial GIC in acetic acid solutions, using a pH-stat method. Qualitative differences in the leaching behavior of these glasses can be explained by different pre-treatments. Acid-washing and silanization modify the surfaces of the glass particles, thus inducing a delay of the leaching process, whereas untreated glasses exhibit a fast initial leaching, but their acid reactivity slows very soon. Quantitative differences in acid reactivity can be correlated with the mean chemical composition of the glasses. In this respect, the leaching tends to increase with an increasing ratio of network-dwelling cations to Al3+ ions. These results provide a fundamental basis for the explanation, prediction, and control of cement properties as a function of glass characteristics.

Acetic Acid↗

Caries prevention--fluoride.

A clear understanding of the mechanism of action of fluoride and its pharmacokinetics would ensure appropriate clinical use of fluoride and fluoride-containing modalities. Convincing evidence exists that fluoride has a major effect on the demineralization and remineralization of dental hard tissues, and that it interferes with the acid production from "cariogenic" bacteria. However, it has also been shown to be physiologically harmful if fluoride concentrations and/or exposure periods are inappropriate. In order to establish appropriate clinical concentrations and exposure periods for fluoride administration, this review is concentrated on the theme that fluoride controls but does not prevent caries. The review is organized along classical lines, with a discussion of the role of systemic vs. topical fluoride. Discussion of the systemic effects of fluoride includes ingestion through water fluoridation, fluoride supplements, topical fluoride applications, and dentifrices. The benefits and problems associated with the systemic route of fluoride administration are discussed with special reference to caries control and fluoride's mechanism of action and its toxic effect. The same discussions are focused on the role of the topical effects of fluoride, with particular emphasis placed upon: low vs. high fluoride concentrations; calcium fluoride vs. fluorhydroxyapatite; and fluoride distribution, in both the mouth and in the teeth.

Dental Caries↗

A scanning electron microscope investigation of calcium fluoride-like material deposited during topical fluoride exposure on sound human enamel in vitro.

1. The morphological aspects of globules deposited in vitro when a NaF solution is applied to sound human enamel were studied by scanning electron microscopy. 2. Particles, presumably of calcium fluoride-like material, formed on the surfaces of an unerupted tooth and consisted of subunits showing a "cauliflower" appearance, indicating agglomeration of even smaller particles. The number and size of the crystals increased with time of exposure. 3. These particles represent highly resistant fluoride reservoirs and may be of clinical significance.

Calcium Fluoride↗

Measurement of intrinsic bone quality in vivo by reflection ultrasound: correction of impaired quality with slow-release sodium fluoride and calcium citrate.

The intrinsic (material) quality of cancellous and cortical bone was evaluated in vivo from the measurement of reflection ultrasound velocities in the ulna. In cancellous bone, the reflection ultrasound velocity was inversely correlated with age in normal women (r = -0.48, p = 0.001), with a significantly lower mean value in 32 normal postmenopausal women than in 14 premenopausal women (3124 versus 3341 m/s, p < 0.0001). In 32 untreated osteoporotic women the cancellous bone velocity was lower than in normal postmenopausal subjects (2906 versus 3124 m/s, p = 0.0001). Following treatment with slow-release sodium fluoride plus calcium citrate (mean 2.4 years in 33 osteoporotic patients with no fracture during treatment), the cancellous bone velocity was significantly higher than in untreated osteoporotic women (3082 versus 2906 m/s, p = 0.0002) and was not significantly different from that in normal postmenopausal women. The cortical bone velocity displayed similar trends, but the changes did not attain statistical significance. The measurements were repeated approximately 9 months later in 9 untreated and in 20 treated patients; in 5 additional patients, the measurements were made both before and after 9 months of treatment with slow-release sodium fluoride and calcium citrate. The cancellous bone velocity increased significantly (p = 0.046) in these patients, from 3008 m/s before treatment to 3112 m/s after the first 9 months of treatment. The velocity rose significantly from 3037 to 3167 m/s (p = 0.017) in patients treated for a short time (12-30 months at first measurement), but it did not change in untreated patients or those treated for more than 30 months. Thus, the material quality of cancellous bone decreases with normal aging and is reduced further with the osteoporotic process. This impaired quality may be corrected by treatment with slow-release sodium fluoride plus calcium citrate.

Analysis of Variance↗

Enamel caries formation and lesion progression with a fluoride dentifrice and a calcium-phosphate containing fluoride dentifrice: a polarized light microscopic study.

The effects of a fluoride dentifrice (Colgate Total) and a calcium-phosphate containing fluoride dentifrice (Enamelon) on caries-like enamel lesion formation and progression were evaluated in vitro. One quarter from each tooth (n = 12) was assigned to one of the study groups: 1) control group [artificial saliva only]; 2) Colgate Total; and 3) Enamelon. The dentifrices were applied to the enamel windows (3 minutes, 3 time per day for 14 days). Following treatment, enamel lesions were created with an acidified gel. After lesion initiation, sections were obtained for polarized light microscopy. To evaluate lesion progression, enamel windows with caries-like lesions in each test group were treated again for 14 days, returned to acidified gels for lesion progression, and then sections were obtained for polarized light microscopy. Mean lesion depths (polarized light, water imbibition) were as follows: 1) Lesion Initiation: Control 109 +/- 19 microns, Colgate Total 76 +/- 14 microns, Enamelon 63 +/- 17 microns; 2) First Lesion Progression: Control 164; +/- 24 microns, Colgate Total 124 +/- 22 microns, Enamelon 110 +/- 19 microns; 3) Second Lesion Progression: Control 235 +/- 23 microns; Colgate Total 172 +/- 27 microns, Enamelon 153 +/- 18 microns. Both Colgate Total and Enamelon enhanced the resistance of sound enamel and caries-like enamel lesions to a continuous in vitro cariogenic challenge when compared with matched controls (P < .05, ANOVA, DMR). Enamelon provided a further reduction in lesion depth for all periods when compared with Colgate Total (P > .05, ANOVA, DMR). Addition of bioavailable calcium and phosphate ions to a fluoride dentifrice may improve the ability of enamel to resist caries initiation and subsequent lesion progression.

Analysis of Variance↗

[Mechanism of action of fluorides in local/topical application].

The marked caries reduction in many countries over the last two decades is thought to be mainly the result of the widespread and frequent use of low concentrations of fluorides mainly via toothpastes. This article gives a review on fluoride sources in the oral cavity and discusses the physiochemical mechanisms by which fluoride interacts with enamel during the caries process and its reversal. From this review it becomes clear that fluoride incorporated into the enamel mineral during tooth development has little effect on the caries process. It is the fluoride incorporated posteruptively and in the aqueous phase during the caries challenge that is of primary importance. The most effective caries preventive fluoride regimen, both from a theoretical perspective and as proved clinically, is the frequent (daily) low concentration application of fluoride from toothpastes and/or mouthrinses. High concentrations, however, used at intervals of months or years and administered by the dentist, work initially not only on both de- and remineralisation, but also by providing fluoride as calcium-fluoride or absorbed in early lesions which is subsequently available over prolonged periods.

Calcium Fluoride↗

Efficacy of long-term fluoride and calcium therapy in correcting the deficit of spinal bone density in osteoporosis.

Long-term fluoride therapy for osteoporosis has been shown to increase the thickness of vertebral trabeculae as seen on spinal radiographs. To determine if this qualitative finding represents a measurable increase in spinal bone density, quantitative computed tomography was utilized to measure trabecular vertebral body density (TVBD) in the lumbar spine of 18 female osteoporotic patients, all of whom had been treated with sodium fluoride, 77 +/- 13 mg/day (mean +/- SD), and calcium, 1000 mg/day, for 57 +/- 24 months. TVBD in these fluoride treated osteoporotic patients (132 +/- 82 mg/cm3) was found to be significantly greater than mean TVBD for an age-matched group of untreated female osteoporotic patients (51 +/- 21 mg/cm3, n = 89, p less than 0.001). The value for TVBD in the long-term fluoride treated osteoporotics was not only similar to previously published values for TVBD (104 +/- 30 mg cm3) in normal females of similar age, but was also above the calculated TVBD "fracture threshold" of 100 mg/cm3 for females. Only one of the 18 fluoride treated osteoporotics continued to have spinal fractures during therapy, accounting for 4 fractures per 87.2 patient years of observation, a value which is significantly lower than the published incidence of 76 fractures per 91 patient years for untreated osteoporotic patients (p less than 0.001). Together, these findings demonstrate that long-term fluoride and calcium therapy for osteoporosis increases TVBD in the majority of patients within a reasonable time frame and significantly reduces the risk for spinal fractures.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗

Study of resin-bonded calcia investment: Part 1. Setting time and compressive strength.

This study was carried out to develop a new titanium casting investment consisting of calcia as the refractory material and a cold-curing resin system as the binder. The setting time of the investment was investigated under different N,N-dimethyl-p-toluidine (DMPT) contents in methyl methacrylate monomer (MMA) and benzoyl peroxide (BPO) contents in calcia without any sintering agent. The effects of the sintering agents, which were calcium fluoride (CaF2) and calcium chloride (CaCl2), on the compressive strength of the investments were investigated at room temperature before and after heating to two different temperatures. The shortest setting time (68 minutes) of the investment was obtained at 0.37 DMPT/BPO (1.5 vol% /1.0 mass%) ratio by mass. The highest strength (16.5 MPa) was obtained from the investment which contained 2 mass% CaF2 and was heated to 1,100 degrees C. It was found that the developed calcia investment containing 2 mass% CaF2 has a possibility for use in titanium castings.

Alloys↗

[Renaissance of fluorides and calcium in the treatment of osteoporosis].

After the initial enthusiasm for fluorides in the treatment of osteoporosis there was a regression after some time and a "campaign" against fluorides. Recently in particular after the introduction of monofluorophosphate instead of NaF there is a revival of the use of fluorides in the treatment of osteoporosis, along with Ca, vitamin D and exercise as the classical combination of four. This can be supplemented by HRT in women, thyrocalcitonin, alendronate and other drugs with individual consideration of the optimal combination of these drugs. Also in future fluorides remain the foremost representative of the group of agents stimulating new formation of bone.

Calcium↗

Effect of long-term administration of fluoride on plasma fluoride and calcium in relation to forming enamel and dentin in rats.

Three groups of 1-month-old rats were kept on water containing 0.2, 56.5 and 113 parts/10(6) F-, respectively, for a period of 2 months. These groups were set up in order to study the relationship between long-term administration of high doses of waterborne fluoride, plasma values of fluoride and calcium and changes in forming dentin and enamel of the rat incisor. The microradiographic study revealed that increased levels of fluoride caused a delay in mineralization of the enamel. In the 113 parts/10(6) group the radiolucent areas in the enamel exhibited a distinct periodicity along the tooth, a phenomenon which cannot at present be explained. In the dentin the fluoride interfered with the process of mineralization giving rise to radiolucent and radiopaque banding in the experimental groups. With increasing levels of fluoride in the water supply a significant increase of plasma fluoride was recorded. In contrast the serum calcium values in both experimental groups were reduced to the same extent, which differed significantly from that of the control group. It is concluded that the fluoride doses which are needed to create fluorotic changes in rats may interfere with calcium metabolism and basic mineralization processes.

Amelogenesis↗

Calcium neutralizes fluoride bioavailability in a lethal model of fluoride poisoning.

OBJECTIVES: Acute systemic fluoride poisoning can result in systemic hypocalcemia, cardiac dysrhythmias, and cardiovascular collapse. Topical and intraarterial therapy with calcium or magnesium salts reduces dermal injury from fluoride burns. The mechanism of these therapies is to bind and inactivate the fluoride ion. The purpose of this study is to evaluate the effect of calcium and magnesium to decrease the bioavailability of fluoride in a lethal model of fluoride poisoning. METHODS: In preliminary studies, we determined that fluoride 3.6 mM/kg intraperitoneally in the form of sodium fluoride was uniformly and rapidly fatal in a mouse model. Using this fluoride dose, we performed a controlled, randomized, blinded study of low- and high-dose calcium chloride (1.8 and 3.6 mM/kg intraperitoneally, respectively) and magnesium sulfate (3.6 mM/kg intraperitoneally) to decrease the bioavailability of the fluoride ion. After injection with sodium fluoride, animals were immediately treated with injections of sodium chloride (control), calcium chloride (low- or high-dose), or magnesium sulfate. The major outcome was 6-hour survival using a Cox Proportional Hazard model. RESULTS: All untreated animals died within 60 minutes. Using a Cox Proportional Hazard model, each 1.8 mM/kg dose of calcium chloride administered reduced the risk of death by 33%. Magnesium sulfate treatment was not associated with a hazard reduction. CONCLUSION: Calcium chloride administered simultaneously with sodium fluoride reduces the bioavailability of fluoride poisoning in a mouse model. The equivalent dose of magnesium sulfate does not significantly decrease fluoride bioavailability.

Animals↗