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Fluoride toothpastes, rinses, and tablets.

Only from the mid-1950's has therapeutic benefit been obtained via dentifrices, initially with stannous fluoride-then monofluorophosphate-containing products which remained stable and efficacious. Altered abrasive systems followed, and both sodium fluoride and monofluorophosphate/sodium fluoride mixtures were introduced as active anti-caries agents, with recent meta-analysis indicating that sodium fluoride > monofluorophosphate/sodium fluoride > monofluorophosphate. With respect to fluoride levels, clear dose-response relationships have been demonstrated. However, at < 1000 ppm F, the situation is less certain. Since the mid-1980's, anticalculus fluoride dentifrices have been marketed, and have been shown to have similar caries-reducing potential as their non-calculus-inhibiting control formulae. Finally, one study has been described where a sodium fluoride dentifrice successfully reduced root caries. Of the many fluoride formulations used for caries-inhibiting mouthrinsing [e.g., acid phosphate fluoride (100-3000 ppm F), sodium fluoride (45-3000 ppm F), stannous fluoride (100-250 ppm F), ammonium fluoride (1000 ppm F), and amine fluoride (250 ppm F)], sodium fluoride would seem to be the preferred agent. Furthermore, rinse frequency is deemed more important than fluoride ion concentration, but caution is urged re the volumes and concentrations to be used by children, no rinsing being recommended below 4 years. Combination of a 440-pp-F sodium fluoride and 0.05% chlorhexidine school-administered rinse appears to have increased the caries-inhibiting benefit as compared with sodium fluoride alone. Fluoride supplements have reduced deciduous caries from 14 to 93%, and in the permanent dentition, from 20 to 81%.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluorides↗

Fluoride: benefits and risks of exposure.

This summarizes current knowledge of the benefits and risks of fluoride ingestion. The preponderance of evidence indicates that fluoride can reduce the incidence of dental caries and that fluoridation of drinking water can provide such protection. Due to the ubiquitous nature of exposures to fluoride sources other than drinking water, it is currently impossible to draw firm conclusions regarding the independent effect of fluoride in drinking water on caries prevalence using an ecologic study design. Moderate dental fluorosis occurs in 1 to 2% of the population exposed to fluoride at 1 mg/l in drinking water and in about 10% of the population at 2 mg/l; moderate/severe fluorosis occurs in variable percentages ranging up to 33% of the population exposed to fluoride at 2.4 to 4.1 mg/l in drinking water. The issue of whether moderate or severe dental fluorosis represents an adverse health effect is still controversial. There is no evidence of skeletal fluorosis among the general U.S. population exposed to drinking water fluoride concentrations lower than 4 mg/l. Radiographically detected osteosclerosis after chronic exposure to fluoride in drinking water at 8 mg/l was not associated with clinical symptoms. Reports of crippling skeletal fluorosis associated with low concentrations of fluoride in drinking water in tropical countries have been attributed to other dietary factors. The available data suggest that some individuals may experience hypersensitivity to fluoride-containing agents. Further studies on hypersensitivity are required. There is no evidence of increased incidence of renal disease or renal dysfunction in humans exposed to up to 8 mg fluoride per liter in drinking water. Structural changes in kidneys of experimental animals have been detected at doses exceeding 1 to 5 mg fluoride per kilogram per day. Based on four case reports, individuals with renal insufficiency who consume large volumes of naturally fluoridated water at 2 to 8 mg/l are possibly at increased risk of developing skeletal fluorosis. Studies on the effects of fluoride in individuals with renal insufficiency are needed. There is no evidence that chronic exposure to concentrations of fluoride reported to be greater than 2 mg/l in drinking water increases human cancer mortality or incidence. A study of lifetime exposure to fluoride on cancer incidence in rats and mice has been completed, but assessment for cancer has not been completed. There is no evidence that fluoride is genotoxic except in some in vitro assays at cytotoxic concentrations. There is no in vivo evidence that fluoride affects human cellular enzyme activities.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

[Effect of tea on fluoride in plaque and saliva].

OBJECTIVE: To evaluate whether tea drinking in a Chinese way in the Chinese population would affect fluoride in plaque and saliva. METHODS: Two groups of students were involved. Group 1, 41 subjects, did not drink tea regularly. Group 2, 34 subjects, drank tea every day in a very regular way. During a study period of three weeks, Group 2 was requested to drink selected (known fluoride concentration) types of tea, and subdivided by the type of tea they drank into two subgroups, Groups 2a and 2b. Group 2a drank lower fluoride tea, while Group 2b drank higher fluoride tea. Plaque and saliva samples were collected at the 2nd and the 3rd end of week, respectively. Fluoride levels were determined with fluoride selective electrode. RESULTS: Both plaque and saliva fluoride were higher in the tea drinking group compared with non-tea drinking group. Plaque fluoride in tea drinking group at the end of three week was significantly higher than the value of non-tea drinking group (t test, P = 0.02). In tea drinking group, three week plaque fluoride was higher than two week plaque. Plaque fluoride level was also significantly corresponded to fluoride in tea. Drinking higher fluoride tea resulted in higher fluoride in plaque. But saliva fluoride was not shown the correlation with tea. CONCLUSION: Tea is an important fluoride source. Plaque is a main resorvior of fluoride. Saliva has not the ability to store fluoride up. When considering tea as a fluoride source, the type of tea which may contain different concentration of fluoride should be borne in mind.

Dental Plaque↗

Fluoride concentration in foods from Iran.

Knowledge of fluoride intake is important in optimizing the caries-preventive role of fluoride, and the measurement of fluoride intake usually requires information on the fluoride concentration in foods and drinks. Most information comes from developed countries and there are no data on fluoride concentration in foods in Middle Eastern countries including Iran. The aim of the study was to: (a) describe a modification to the silicon-facilitated diffusion method for determining fluoride concentration, (b) provide information on fluoride content of foods in Iran to supplement food tables for the Middle East, and (c) determine the effect of variation in the fluoride concentration of drinking water on the fluoride concentration of prepared foods. Five hundred and ten samples of 84 popular foods and drinks were collected from three areas of Iran where water fluoride concentrations were 0.32, 0.58 and 4.05 mg/L. The mean recovery of fluoride added to food samples before diffusion was 98 +/- 5%. Values for duplicate analysis of 20 food samples were within 0.03 microgram F/g. Most of the samples of foods and drinks came from the area with 0.32 mg F/L in water supplies. For 30 of the 84 items, fluoride concentration was below 0.1 microgram/g. Fluoride concentrations in the cereals group (which constituted much of the diet) were mainly between 0.2 and 0.3 microgram/g, when prepared for consumption. It was concluded that: (a) modification of a published method for determining fluoride concentration of foods appeared to be an advance, (b) values for fluoride concentration of foods commonly consumed in Iran showed variation between groups but were in broad agreement with published data, and (c) concentration of fluoride in water influences positively fluoride concentration in foods cooked in water, but the increase in foods was less than the increase in fluoride concentration in water.

Fluoridation↗

Is the fluoride/creatinine ratio of a spot urine sample indicative of 24-h urinary fluoride?

OBJECTIVE: The main aim of this study was to determine how representative the fluoride/creatinine (F/Cr) ratio of a spot urinary sample is of the fluoride content of a 24-h urine sample in young children aged 12-36 months. Subsidiary objectives were to: (a) evaluate the use of 24-h urine samples in monitoring fluoride exposure and (b) estimate the retention of fluoride in very young children. METHODS: Seven healthy children residing in a fluoridated area completed the study. Dietary information was obtained using a 3-day estimated food diary followed by an interview on the fourth day. Samples of foods and drinks were analysed for fluoride content. Ingestion of fluoride from toothpaste was also measured. A 24-h urine sample and a morning spot urine sample were collected from each child. RESULTS: The mean age of the children was 32 months (range: 16-36 months). The mean total daily intake of fluoride was 0.71 (+/-0.41) mg or 0.05 (+/-0.02) mg/kg bodyweight, of which 37% came from the diet, the remainder being from toothpaste ingestion. None of the children used any other sources of fluoride such as fluoride tablets or fluoridated salt. The mean F/Cr ratio was 1.49 (+/-0.63) mg F/g creatinine. A positive correlation (Pearson's correlation=0.76, P=0.05) between fluoride excretion estimated using the F/Cr ratio in a morning spot urine sample and fluoride excretion in a 24-h urine sample was found. There was also a positive correlation (Pearson's correlation=0.83, P=0.02) between total daily fluoride intake and 24-h urinary fluoride excretion. Less than half (43%) of the total daily fluoride intake was retained in the body. CONCLUSIONS: The F/Cr ratio of a morning spot urine sample may be used to estimate mean 24-h urinary excretion of fluoride and therefore has potential application for larger-scale epidemiological studies where 24-h samples are impractical. Estimates of 24-h urinary fluoride excretion can be used to gauge fluoride exposure.

Beverages↗

Sources of fluoride intake in children.

Wide variations in fluoride intake among children make estimating fluoride intake difficult. This paper discusses the various sources of fluoride intake among children, beginning with a review of the fluoride concentrations of water and other beverages, foods, and therapeutic fluoride products. A review of previous studies' estimates of fluoride intake from diet, dentifrice, fluoride supplements, fluoride mouthrinses, and gels, as well as total fluoride intake also is presented. Then, estimates of fluoride intake among young children of different age groups are summarized, and examples demonstrating the high level of variability of fluoride intake, both from individual sources and in total, are presented. Lastly, this paper discusses the implications of our current level of knowledge of children's fluoride intake, and presents recommendations for the use of fluoride for children in light of this current knowledge. The major recommendations are that: (1) the fluoride content of foods and beverages, particularly infant formulas and water used in their reconstitution, should continue to be monitored closely in an effort to limit excessive fluoride intake; (2) ingestion of fluoride from dentifrice by young children should be controlled, and the use of only small quantities of dentifrice by young children should be emphasized; and (3) dietary fluoride supplements should be considered a targeted preventive regimen only for those children at higher risk for dental caries and with low levels of ingested fluoride from other sources.

Adolescent↗

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↗

Professional topical fluoride applications--clinical efficacy and mechanism of action.

All currently used topical fluoride agents deposit soluble fluoride as calcium fluoride on enamel or in lesions. Calcium fluoride serves as a source of fluoride for the formation of fluorapatite. The latter phase is formed when pH drops in plaque, not during topical application. The potential for calcium fluoride formation should probably be increased in topical fluoride agents. In countries with low caries prevalence, the clinical recommendations for topical fluoride need to be reconsidered. Toothpaste is the basic fluoride regimen recommended for everybody. The need for additional fluoride supplementation depends on caries activity. There is no distinct difference in the caries-preventive effects of concentrated fluoride solutions, gels, or varnishes. Thus, the choice of method depends on costs, convenience, patient acceptance, and safety. The use of fluoride varnishes has proven to be a feasible and safe method of fluoride application. With fluoride varnishes, the amounts of fluoride exposure can be better controlled, and less chair-time is required compared with conventional solutions and gels. No dose-response effect to concentrated fluoride agents is apparent, and the benefit of frequent application is not clearly established. In individuals with the most severe cariogenic challenge, combinations of fluoride and antimicrobials may give better clinical effects than fluoride alone.

Calcium Fluoride↗

[Fluoride intake and excretion in children of Hermosillo, Sonora, Mexico].

OBJECTIVE: To estimate the fluoride intake and urinary excretion among 8-9 year-old school children. MATERIALS AND METHODS: A cross-sectional study was conducted from February to November 1997. Study subjects were 31 male children from Hermosillo, Mexico, living in three neighborhoods with different drinking water fluoride levels. Fluoride intake was measured through water intake and collection of food samples ingested in 24 hr. Fluoride excretion was measured in 24-hour urine samples. The fluoride concentration was measured by the potentiometer method using a fluoride-specific ion electrode. RESULTS: Statistically significant differences of fluoride levels in drinking water were found in the 3 different neighborhoods: 2.77, 0.78 and 0.54 mg/L, respectively (p < 0.01). The daily mean intake of fluoride for the neighborhood with the highest fluoride level was 5.41 mg/d, while mean intakes for the other two neighborhoods were 2.31 and 1.51 mg/d, respectively. Thirty-two percent of the children had fluoride intake above the recommendation values for this age group; sixty per cent of these children lived in the neighborhood with the highest fluoride level. Drinking water accounted for 63% of total fluoride intake, and the mean water intake was 1.8 liters. The mean excretion of fluoride was 1.61 mg/24 hours (range 0.18 to 8.1 mg/24 hr). Stepwise multiple regression showed an association between drinking water fluoride and fluoride urinary excretion (R2 = 0.56 p < 0.001). CONCLUSIONS: Fluoride intake in the neighborhood with the highest fluoride level was twice the daily recommended value for 8-9 year-old children. Drinking water was the main source of fluoride intake. The English version of this paper is available at: http://www.insp.mx/salud/index.html.

Child↗

Studies of fluoride metabolism in man. A review and report of original data.

The dietary intake of fluoride and the fluoride excretions in urine and stool were determined under controlled conditions in man. Fluoride balance studies have shown that the urinary fluoride corresponds to 50--60% of the intake, the fecal fluoride was very low, corresponding to 6% of the intake, and approximately 1 mg fluoride was retained per day during an average fluoride intake of 4.3 mg/day. The fluoride intake depended on the amount of fluoridated water consumed. The dietary fluoride content ranged from 1.2 to 1.5 mg/day. During the intake of supplemental fluoride the fluoride excretions increased but the ratio of the urinary/fecal fluoride was similar. Added fluoride is well retained. Following its discontinuation, very small amounts of the retained fluoride are excreted for several days. Inorganic elements, such as calcium, phosphorus, and magnesium, which have been shown to decrease the intestinal absorption of fluoride in animals were ineffective in man, while aluminum, given as aluminum-containing antacids, markedly decreased the intestinal absorption of fluoride and thereby decreased the retention of fluoride.

Adult↗

Total and free fluoride in toothpastes from some non-established market economy countries.

In 101 fluoride toothpastes, bought in local shops in Burkina Faso (n = 3), China (n = 5), Myanmar (n = 22), Nepal (n = 19), Philippines (n = 13), Syria (n = 22), Togo (n = 7) and Vietnam (n = 10), the total and free ionisable fluoride concentrations were established. The total fluoride concentration of the toothpastes was determined by gas liquid chromatography. The amount of soluble fluoride was measured after dilution in artificial saliva and treatment of the supernatants with acidic phosphatase. The free fluoride concentration in this mixture was measured with a fluoride electrode. Twenty-five percent of all toothpastes contained less than 738 ppm total fluoride, and another 25% contained between 738 and 977 ppm fluoride. Regarding free ionisable fluoride the 25th, 50th, and 75th percentile contained < or =275, 780 and 990 ppm fluoride, respectively. Of the 61 toothpastes with declared fluoride concentration, 75% contained a total F concentration of > or =89% of the declared concentration. In 25% of these toothpastes the free ionisable fluoride was < or =55% of the declared fluoride, and in another 25% of the pastes the free ionisable fluoride concentration was > or =89% of the declared fluoride. In conclusion, deficiencies were found regarding the total as well as the free ionisable fluoride concentration of toothpastes bought in non-established market economy countries. Unclear labelling concerning the type and concentration of fluoride was often encountered. A need for quality control of fluoride toothpastes is recommended.

Africa↗

Salt fluoridation and general health.

Salt fluoridation is a systemic form of fluoride supplementation, leaving it to the consumer whether he wants fluoride supplements or not, but thereafter not requiring special dependability for daily compliance. Most German drinking water has low fluoride concentrations. The estimated fluoride intake in German children is between 100 and 300 micrograms/day, and in adults, between 400 and 600 micrograms/day. Male subjects have higher mean intakes than females. From 70 to 90% of the salt intake of 10 to 13.5 g/day in German adults comes from commercially prepared foods. This leaves about 1 to 4 g of salt to be added as table salt at the individual level and to become the source of supplementary fluoride. To increase fluoride intake by at least 500 micrograms/d, and to prevent an additional intake of more than 3000 micrograms/day, it may be necessary to have salt at a fluoride level of around 500 micrograms/g or to include one commercial food to be prepared with fluoridated salt, e.g., bread. A salt fluoride concentration of 250 micrograms/g does not present a risk of dental fluorosis. However, clear recommendations about systemic fluoride supplementation must be given as long as there are fluoride tablets, fluoride-rich mineral waters, and fluoridated table salt available simultaneously. Persons at risk for hypertension from salt consumption require different means of fluoride supplementation. By and large, in areas of low drinking water fluoride, fluoridated table salt has the potential to become a means of systemic supplementation comparable with drinking water fluoridation.

Adolescent↗

Experiments on the initiation of calcium fluoride formation with reference to the solubility of dental enamel and brushite.

As calcium fluoride formation following topical application of fluoride may be responsible for at least some of the caries-reducing effect of fluoride, the concentration of fluoride necessary to induce its formation were examined. The aim was to determine the degree of supersaturation with respect to calcium fluoride necessary for inducing its spontaneous precipitation, with close reference to its possible formation and retention on dental hard tissue when topical fluoride solutions are used clinically. Powdered enamel or brushite were suspended for 4 h in aqueous solutions buffered at pH 7.2 and 5.0. After the equilibration, ion concentrations were determined and degrees of saturation with respect to apatite and brushite were calculated. In aqueous solutions at pH 7.2 and 5.0 with similar concentrations as those found in the equilibrated suspensions the fluoride concentration was adjusted to from 5 to 500 parts/10(6). After 2 h of gentle agitation the supernatant was analysed, the precipitate (if any) isolated and examined by X-ray diffraction. Initiation of spontaneous calcium fluoride formation required a calcium fluoride ion-activity product of 10(-7.6) or more, 300 parts/10(6) fluoride were necessary to initiate calcium fluoride formation in neutral solution saturated with enamel, and the increased solubility of enamel apatite at low pH allowed calcium fluoride formation from solutions with as low as 100 parts/10(6) fluoride. When phosphate was present in the solution a competing apatite formation could mask the calcium fluoride formation. In neutral solutions saturated with respect to brushite, spontaneous fluorapatite formation was initiated by 100 pats/10(6) fluoride. With 200 parts/10(6) fluoride a further competing formation of calcium fluoride occurred.

Calcium Fluoride↗

Severe dental fluorosis in a Tanzanian population consuming water with negligible fluoride concentration.

OBJECTIVES: To identify risk factors for dental fluorosis that cannot be explained by drinking water fluoride concentration alone. METHODS: Two hundred eighty-four Tanzanian children ages 9 to 19 (mean 14.0+/-SD 1.69), who were lifetime residents at differing altitudes (Chanika, 100 m; Rundugai, 840 m; and Kibosho, 1,463 m; Sites 1, 2, and 3 respectively) were examined for dental fluorosis and caries. They were interviewed about their food habits, environmental characteristics and use of a fluoride-containing food tenderizer known locally as magadi. Meal, urine, water and magadi samples supplied by the participants were analyzed for fluoride content. Urine samples were also analyzed for creatinine concentration. Four magadi samples from Sites 1 and 3 were analyzed for complete element composition. RESULTS: Of the 13 water samples from Site 2, 10 contained > or =4 mg/L F, ranging from 1.26 to 12.36 mg/L with a mean+/-SD of 5.72+/-4.71 mg/L. Sites 1 and 3 had negligible water fluoride of 0.05+/-0.05 and 0.18+/-0.32 mg/L respectively. Mean TFI fluorosis scores (range 0-9) for Site 2 were high: 4.44+/-1.68. In Sites 1 and 3, which both had negligible water fluoride, fluorosis scores varied dramatically: Site 1 mean maximum TFI was 0.01+/-0.07 and Site 3 TFI was 4.39+/-1.52. Mean DMFS was 1.39+/-2.45, 0.15+/-0.73 and 0.19+/-0.61 at Sites 1, 2, and 3, respectively. There were no restorations present. Urinary fluoride values were 0.52+/-0.70, 4.34+/-7.62, and 1.43+/-1.80 mg/L F at Sites 1, 2, and 3, respectively. Mean urinary fluoride values at Site 3 were within the normal urinary fluoride reference value range in spite of pervasive severe pitting fluorosis. Meal and magadi analyses revealed widely varied fluoride concentrations. Concentrations ranged from 0.01 to 22.04 mg/L F for meals and from 189 to 83211 mg/L F for magadi. Complete element analysis revealed the presence of aluminum, iron, magnesium, manganese, strontium and titanium in four magadi samples. There were much higher concentrations of these elements in samples from Site 3, which was at the highest altitude and had severe enamel disturbances in spite of negligible water fluoride concentration. An analysis of covariance model supported the research hypothesis that the three communities differed significantly in mean fluorosis scores (P<0.0001). Controlling for urinary fluoride concentration and urinary fluoride:urinary creatinine ratio, location appeared to significantly affect fluorosis severity. Urinary fluoride:urinary creatinine ratio had a stronger correlation than urinary fluoride concentration with mean TFI fluorosis scores (r=0.43 vs r= 0.25). CONCLUSIONS: The severity of enamel disturbances at Site 3 (1463 m) was not consistent with the low fluoride concentration in drinking water, and was more severe than would be expected from the subjects' normal urinary fluoride values. Location, fluoride in magadi, other elements found in magadi, and malnutrition are variables which may be contributing to the severity of dental enamel disturbances occurring in Site 3. Altitude was a variable which differentiated the locations.

Adolescent↗

Patterns of fluoride intake from birth to 36 months.

OBJECTIVES: Dental fluorosis prevalence has increased in the United States, Canada, and other nations due to the widespread availability of fluoride in many forms, with fluoride ingestion during the first three years of life appearing most critical in fluorosis etiology. With few contemporary studies of fluoride ingestion in this age group, the purpose of this paper is to describe patterns of estimated fluoride ingestion from birth to 36 months of age from water, dentifrice, and dietary fluoride supplements and combined. METHODS: Repeated responses to separate series of questions about water intake, use of fluoride dentifrice, and use of fluoride supplements were collected by questionnaire as part of the longitudinal Iowa Fluoride Study and used to estimate fluoride intake. Estimated intake is reported by source and combined at different ages. Effects of subject age and other covariates on fluoride intake were assessed using regression methods appropriate for the analysis of correlated data. RESULTS: For most children, water fluoride intake was the predominant source, especially through age 12 months. Combined daily fluoride intake increased through 9 months, was lower at 12 and 16 months, and increased again thereafter. Mean intake per unit body weight (bw) was about 0.075 mg F/kg bw through 3 months of age, 0.06 mg F/kg bw at 6 and 9 months, 0.035 mg F/kg bw at 12 and 16 months, and 0.043 mg F/kg bw from 20-36 months. Depending on the threshold chosen (e.g., 0.05 or 0.07 mg F/kg bw), variable percentages of the children exceeded the levels, with percentages greatest during the first 9 months. Regression analyses showed fluoride intake (mg F/kg bw) from 1.5-9 months to decrease with increasing child's age, mother's age, and mother's education, with a complex three-way interaction among these factors. From 12-20 months, fluoride intake increased with increasing child age and decreased with increasing mother's age. No statistically significant relationships were found for fluoride intake from 24-36 months. CONCLUSIONS: There is considerable variation in fluoride intake across ages and among individuals. Longitudinal studies may be necessary to fully understand the relationships between fluoride ingestion over time and development of fluorosis.

Adult↗

Elevated serum fluoride concentrations in women are not related to fractures and bone mineral density.

Epidemiologic studies of the relations between drinking-water fluoride levels and bone mineral density (BMD) and fracture are characterized by disparate conclusions and an absence of information about individual circulating fluoride levels. This study relates serum fluoride concentrations, which reflect individual fluoride exposures, to BMD and bone fractures. Data are from 1300 female residents of 3 small communities in which the water fluoride concentrations were 52.6 or 210.4 micromol/L. Circulating serum fluoride concentrations were assessed by ion-specific electrode. Fluoride intake was estimated from interviews describing water and water-based beverage consumption and duration of residence in the community. BMD was measured by dual-energy X-ray densitometry and single-photon densitometry. Self-reported fractures were confirmed by medical record abstraction. The mean serum fluoride concentration in the high-fluoride community, 2.11 +/- 0.05 micromol/L, was significantly higher than serum fluoride concentrations in the control and high-calcium communities with water fluoridation to 52.6 micromol/L. The mean serum fluoride concentrations in these latter 2 communities were 1.6 +/- 0.04 and 1.22 +/- 0.05 micromol/L, respectively. Serum fluoride was not significantly related to BMD after adjusting for covariates including age and body size. The mean distal radius BMD, however, was significantly higher in the high-fluoride community. Serum fluoride concentrations were not related to incident osteoporotic fractures with 4 y of observation. Serum fluoride concentrations were not associated with BMD or osteoporotic fractures among female residents of communities with water fluoride concentrations of 52.6 or 210.4 micromol/L.

Absorptiometry, Photon↗

Excretion of retained fluoride in man.

In fluoride studies performed in man the excess fluoride excretions in urine and stool over and above the base-line excretions were determined following the discontinuation of fluoride supplements. The fluoride supplements contained either 9.1 mg fluoride as sodium fluoride, given daily for 32 days, or 7.6 mg fluoride as fish protein concentrate (FPC), given daily for 26 days. Following discontinuation of these fluoride supplements the excess fluoride excretions were low and of short duration, in most cases for 6-12 days. Since the fluoride supplements were given for a known period of time, the fluoride retention could be calculated from the fluoride balances, and the excess fluoride excretion corresponded to 9.1% of the retained fluoride given as NaF and to 14.1% of the retained fluoride given as FPC. The excess fluoride was predominantly excreted via the kidney, i.e., 87% of the total excess fluoride excretion was passed in urine and only 13% in stool.

Adult↗

Pharmacokinetics of fluoride in man and its clinical relevance.

A large number of parameters will influence and mediate the activity and the pharmacological response of dental fluoride products after systemic or topical treatment. This report reviews some aspects of the pharmacokinetics of fluoride in man, fluoride bio-availability, plasma kinetics, and kinetics of fluoride in saliva and plaque fluid. Pharmacokinetic studies in growing dogs show that 90% of a single injected fluoride dose is retained shortly after birth, but at maturity it decreases to about 50%. The degree of fluoride accumulating in calcifying tissues seems to be strongly related to age. The bio-availability of fluoride from swallowed fluoride toothpaste is shown to be decreased if the toothpaste is ingested close to a meal. Several studies show that fluoride exerts its cariostatic effects through the liquid phase surrounding the enamel. The importance of fluoride in the fluid environment of the teeth and the kinetics of fluoride in saliva are discussed. Clinical studies using different slow-release fluoride systems indicate that they are promising cariostatic agents--in particular intra-oral slow-release devices and lozenges. A new micro-analytical method to study the kinetics of fluoride in plaque fluid collected from single tooth sites has been developed. Preliminary studies show that the clearance of fluoride from plaque fluid is slowest in the upper incisor region, followed by the molar region, and faster in the lower incisor region. A site-by-site study of the concentration of fluoride in plaque fluid after topical fluoride administration could be extremely beneficial in optimization of the methods and recommended safety regimens for fluoride therapy.

Biological Availability↗