Fluoride Bioavailability Research Articles

Milk fluoridation for the prevention

The aim of this review is to give an overview of 55 years experience of milk fluoridation and draw conclusions about the applicability of the method. Fluoridated milk was first investigated in the early 1950s, almost simultaneously in Switzerland, the USA and Japan. Stimulated by the favourable results obtained from these early studies, the establishment of The Borrow Dental Milk Foundation (subsequently The Borrow Foundation) in England gave an excellent opportunity for further research, both clinical and non-clinical, and a productive collaboration with the World Health Organization which began in the early 1980s. Numerous peer-reviewed publications in international journals showed clearly the bioavailability of fluoride in various types of milk. Clinical trials were initiated in the 1980s - some of these can be classed as randomised controlled trials, while most of the clinical studies were community preventive programmes. These evaluations showed clearly that the optimal daily intake of fluoride in milk is effective in preventing dental caries. The amount of fluoride added to milk depends on background fluoride exposure and age of the children: commonly in the range 0.5 to 1.0 mg per day. An advantage of the method is that a precise amount of fluoride can be delivered under controlled conditions. The cost of milk fluoridation programmes is low, about € 2 to 3 per child per year. Fluoridation of milk can be recommended as a caries preventive measure where the fluoride concentration in drinking water is suboptimal, caries experience in children is significant, and there is an existing school milk programme.

Fluoride Gastrointestinal Absorption from Na2FPO3/CaCO3- and NaF/SiO2-Based Toothpastes

Depending on toothpaste formulation, part of the fluoride is insoluble and would not be totally absorbable in the gastrointestinal tract, thus changing dental fluorosis risk estimation. This hypothesis was tested with formulations with either all fluoride in a soluble form (NaF/SiO₂-based toothpaste, 1,100 µg F/g as labeled, 1,129.7 ± 49.4 µg F/g soluble fluoride as analyzed) or with around 20% of insoluble fluoride (Na₂FPO₃/CaCO₃-based toothpaste, 1,450 µg F/g as labeled, 1,122.4 ± 76.4 µg F/g soluble fluoride as analyzed). Toothpastes were evaluated either fresh or after accelerated aging, which increased insoluble fluoride to 40% in the Na₂FPO₃/CaCO₃-based toothpaste. In a blind, crossover clinical trial conducted in five legs, 20 adult volunteers ingested 49.5 µg of total fluoride/kg body weight from each formulation or purified water (control). Whole saliva and urine were collected as bioavailability indicators, and pharmacokinetics parameters calculated showed significantly (p < 0.05) lower fluoride bioavailability for Na₂FPO₃/CaCO₃ toothpaste, which was reduced further after aging. A significant correlation between the amount of soluble fluoride ingested, but not total fluoride, and fluoride bioavailability was found (r = 0.57, p < 0.0001). The findings suggest that the estimated fluorosis risk as a result of ingestion of Na₂FPO₃/CaCO₃-based toothpastes should be calculated based on the toothpaste’s soluble rather than total fluoride concentration.

Fluoride bioavailability in saliva during acute psychological stress

Abstract The aim of this study was to investigate the influence of acute stress on salivary fluoride bioavailability. Acute psychological stress was induced using a standardized model of public speaking. The saliva of male subjects was collected before and after the public speaking task and immediately, 10, 30, and 120 minutes after tooth brushing according to the Bass method with a dentifrice containing amine fluoride (AmF) or oral hygiene tablets containing sodium fluoride (NaF). Subjective psychological responses to public speaking were evaluated using the State-Trait Anxiety Inventory (STAI). Saliva cortisol levels were analyzed as an objective stress marker. The saliva secretion rate was measured both before and after public speaking. Saliva fluoride content was measured. Group comparisons were calculated using a univariate analysis of variance (ANOVA). In all analyses, the alpha-level was set at 0.05. Public speaking significantly increased state anxiety (p&lt;0.001) and salivary cortisol concentrations (p&lt;0.001). Acute stress did not influence salivary secretion rates. In the AmF group, stressed individuals exhibited statistically significant (p=0.044) lower fluoride concentration in saliva compared with the nonstressed subjects Acute psychological stress reactions do not cause hyposalivation but decrease fluoride bioavailability after using a dentifrice containing AmF. Fluoride bioavailability during acute stress is dependent on fluoride formulation.

Kinetics of fluoride bioavailability in supernatant saliva and salivary sediment

The assessment of the fluoride kinetics in whole saliva as well as in the different salivary phases (supernatant saliva and sediment) is essential for the understanding of fluoride bioavailability. ObjectivesTo assess the fluoride content, provided by sodium fluoride and amine fluoride, in the supernatant saliva and in salivary sediment. MethodsSeven trained volunteers were randomly attributed to 2 groups in a cross-over design and brushed their teeth in the morning for 3min with a product containing either sodium fluoride or amine fluoride. Saliva was collected before, immediately after tooth brushing and 30, 120, and 360min later and measured. The samples were centrifuged 10min at 3024×g. Fluoride content of the supernatant saliva and of the sediment was analysed using a fluoride sensitive electrode. All subjects repeated the study cycles 2 times, and statistical analyses were made using the nonparametric sign test for related samples, the Wilcoxon–Mann–Whitney-test for independent samples. ResultsThere was a significant increase in fluoride immediately after tooth brushing in both groups in saliva and sediment. The distribution of fluoride between salivary sediment and supernatant saliva (ratio) varied considerably at the different collection times: decreased from 17.87 in baseline samples of saliva to 0.07 immediately and to 0.86 half an hour after tooth brushing in the sodium fluoride group and from 14.33 to 2.85 and to 3.09 in the amine fluoride group. Furthermore after 120min and after 360min after tooth brushing the ratio increased from 17.6 to 31.6 in the sodium fluoride group and from 20.5 to 25.76 in the amine fluoride group. No difference was found in the sediment–supernatant saliva ratio between the sodium fluoride and the amine fluoride groups 360min after tooth brushing. ConclusionFor the assessment of fluoride kinetics in whole saliva it is necessary to pay attention to at least four factors: fluoride formulation, time after fluoride application, fluoride concentration in supernatant saliva and fluoride concentration in salivary sediment. This study was approved by the Ethical Committee of the University of Witten/Herdecke permission 21/2008.

Fluoride bioavailability in saliva and plaque

BackgroundDifferent fluoride formulations may have different effects on caries prevention. It was the aim of this clinical study to assess the fluoride content, provided by NaF compared to amine fluoride, in saliva and plaque.MethodsEight trained volunteers brushed their teeth in the morning for 3 minutes with either NaF or amine fluoride, and saliva and 3-day-plaque-regrowth was collected at 5 time intervals during 6 hours after tooth brushing. The amount of collected saliva and plaque was measured, and the fluoride content was analysed using a fluoride sensitive electrode. All subjects repeated all study cycles 5 times, and 3 cycles per subject underwent statistical analysis using the Wilcoxon-Mann-Whitney test.ResultsImmediately after brushing the fluoride concentration in saliva increased rapidly and dropped to the baseline level after 360 minutes. No difference was found between NaF and amine fluoride. All plaque fluoride levels were elevated after 30 minutes until 120 minutes after tooth brushing, and decreasing after 360 minutes to baseline. According to the highly individual profile of fluoride in saliva and plaque, both levels of bioavailability correlated for the first 30 minutes, and the fluoride content of saliva and plaque was back to baseline after 6 hours.ConclusionsFluoride levels in saliva and plaque are interindividually highly variable. However, no significant difference in bioavailability between NaF and amine fluoride, in saliva, or in plaque was found.

Effect of dietary fluoride derived from Antarctic krill (Euphausia superba) meal on growth of yellowtail (Seriola quinqueradiata)

Yellowtail (Seriola quinqueradiata) is the most important cultured marine fish in Japan. Dietary fish meal for yellowtail in aquaculture was replaced with 0.0%, 15.4% and 100.0% Antarctic krill meal (KM0, KM15, and KM100) and with 0.0%, 15.4%, and 100.0% low-fluoride krill meal (LFK0, LFK15 and LFK100). The fish was fed to duplicate fish groups for 92d (KM trial) or 75d (LFK trial), and fish growth was monitored.Dietary fluoride (F−) concentrations (mgkg−1) were 110, 160, and 580 (KM0, KM15, and KM100, respectively) and 98, 120, and 190 (LFK0, LFK15, and LFK100, respectively). The growth during the experimental period, weight gain, feed intake, specific growth rate, and feed efficiency in fish fed the KM100 diet were markedly lower than the other experimental groups, which showed no marked differences in growth performance.After the experiment, dorsal muscle fluoride concentrations in each group were below the detectable limit (1mgkg−1), but vertebral bone fluoride concentrations increased with increasing proportion of KM to 655 (KM0), 870 (KM15), and 2150 (KM100) mgkg−1. With increasing LFK in the feed, vertebral bone fluoride concentrations (mgkg−1) increased slightly from 500 (LFK0) to 655 (LFK15), and 695 (LFK100). No histopathological changes were detected in the liver tissue in any experimental group.It has been reported that the fluoride bioavailability was reduced with increasing water hardness, however, the dietary fluoride derived from KM exoskeleton accumulates in vertebral bones of marine fish with growth inhibition, as has already been shown for freshwater fish. Vertebral bone fluoride concentrations in two krill-eating Antarctic marine fish in the wild were 33000mgkg−1 (Champsocephalus gunnari) and 15000mgkg−1 (Notothenia rossii), but they did not show any adverse effect of growth. Therefore, fish bone fluoride accumulation apparently depends on fish species rather than the salinity of the habitat. Consequently, krill exoskeleton must be removed during the processing of Antarctic krill if indeed these krill are to be used as fish feed. However, LFK can completely replace dietary fish meal without apparent adverse effects.

Dietary calcium supplementation reduces the bioavailability of fluoride from krill shell and NaF in rainbow trout ( Oncorhynchus mykiss) reared in fresh water

The use of Antarctic krill ( Euphausia superba) in fish feeds may be limited by a high fluoride level. The aim of this experiment was to investigate the bioavailability of dietary fluoride from either krill shell or sodium fluoride (NaF) to rainbow trout ( Oncorhynchus mykiss). The second aim was to investigate if the fluoride bioavailability was affected by adding calcium to the feed. Five experimental diets were produced; one control diet and four test diets containing 700 mg fluoride kg − 1 either from NaF or from krill shell, with or without added calcium chloride (15 g Ca kg − 1 ). Triplicate groups of fish were given one meal in excess of appetite prior to sampling. Five fish from each replicate tank were terminally sampled for blood; 0, 1, 3, 6, 9, 12, 15, 18, 24, and 36 h postprandial. Fluoride in blood plasma was used as an indicator of fluoride absorption. Fish fed NaF showed a clear peak in plasma fluoride of 1.17 mg l − 1 3 h postprandial, followed by a rapid decline. The fish fed krill shell did not obtain a clear peak but had a maximum fluoride plasma concentration (C max) of 0.32 mg l − 1 3 h postprandial. The addition of dietary calcium reduced the fluoride uptake in fish fed the NaF diet by nearly 100%, while adding calcium to the diets with krill shell reduced the uptake of fluoride to nearly the half. To conclude, fluoride from krill shell had a lower bioavailability than fluoride from NaF. Dietary calcium was an efficient way to reduce the fluoride uptake of rainbow trout reared in fresh water.

Influence of Individual Saliva Secretion on Fluoride Bioavailability

The aim of this preliminary investigation was to compare the individual saliva secretion rate with the fluoride bioavailability in saliva after using sodium fluoride and amine fluoride.Methods:To assess oral fluoride kinetics 10 highly trained volunteers brushed their teeth with one of the formulations and saliva was collected. The amount of saliva was measured, and the fluoride content was determined. Data underwent statistical analysis using the Mann-Whitney-U test and Pearson correlation. The ex vivo experiment I included individual saliva collection of the same volunteers. Then the oral hygiene products were solved in equal amounts of whole saliva (ex-vivo experiment II), and the fluoride content was measured. Finally, both products were dispersed in distilled water (ex-vivo experiment III) to calculate the dissociation of both products in water.Results:In vivo results of fluoride content after 3 min. tooth brushing demonstrated a negative correlation with saliva secretion: for NaF r = -0.695 (p<0.01) and for amine fluoride r = -0.446 (p<0.01). The in-vitro experiment I resulted for NaF in 251.7±22.4 µg/g fluoride and for amine fluoride in 171.7±14.4 µg/g.Conclusions:Fluoride bioavailability of saliva after exposure to NaF was higher compared to amine fluoride. The individual secretion rate changes the fluoride content and normal secretors keep the fluoride availability longer.

Effect of Long-term Fluoride Exposure on Growth, Nutrient Utilization and Fluoride Kinetics of Calves Fed Graded Levels of Dietary Protein

In order to assess the influence of dietary protein levels on the fluoride (F) bioavailability, 30 crossbred calves (6-8 months; approximately 104 kg BW) initially exposed to different dietary protein levels were allotted into six groups in a 3 × 2 factorial design. The factors included three different levels of protein viz. normal (100%; NP), low (75%; LP), and high (125%; HP) as per Kearl recommendations besides two levels of supplemental fluorine (as sodium fluoride) at 0 or 200 mg/kg diet. The animals were fed on the respective concentrate mixture and wheat straw for 210 days. A metabolism trial was conducted at 200 days post-feeding to study digestibility, plane of nutrition, and nutrient balances. The final body weight at the end of 210 days was lower (p < 0.01) in animals fed 200 mg/kg F (164.2 ± 8.92 kg) compared to those fed no F (200.7 ± 8.05 kg). Calves on LP diets attained lower (p < 0.05) average daily gain in comparison to NP or HP fed calves. The F-supplemented calves exhibited lower (p < 0.01) voluntary feed intake than their non-supplemented control. The digestibility of proximate nutrients other than ether extract exhibited higher (p < 0.01) values in F-fed calves attributable chiefly to reduced consumption of dry matter. The calves fed extra F retained lower mean daily nitrogen; calcium, and phosphorus compared to the calves fed no F. The mean daily intake, excretion, and retention of F were higher (p < 0.01) in the F-supplemented calves. A significant (p < 0.01) interaction between protein levels and F was evident in the urinary excretion of F; calves on LP diet exhibiting lower urinary excretion. Consequently, the bioavailability of F tended to be higher on LP than NP or HP diets. From the results, it is concluded that protein levels in the diet do not impart significant influence on susceptibility to fluorosis in crossbred calves. However, the bioavailability of F tended to increase on diets low in protein.

In vivo delivery of fluoride and calcium from toothpaste containing 2% hydroxyapatite

Objective: To measure the in vivo delivery of fluoride and calcium of a new oral health toothpaste containing zinc citrate trihydrate, hydroxyapatite, potassium citrate and α-tocopherol acetate (Vitamin E) compared to standard fluoride toothpaste. Methods: The new toothpaste contained 2% hydroxyapatite and 0.1% Vitamin E acetate (α-tocopherol acetate). It also included an anti-caries agent (1.1% sodium monofluorophosphate) an antigingivitis agent (2% zinc citrate trihydrate) and an anti-sensitivity agent (potassium cit-rate). Two studies were carried out. In study 1 the bio-availability of fluoride was measured in plaque after brushing with the test and a clinically tested fluoride toothpaste (control). In study 2 the effect of the test toothpaste on calcium levels in saliva and on the tooth surface was investigated compared to a toothpaste without added hydroxyapatite. Results: The fluoride concentration in plaque after brushing with the test and control toothpaste was significantly higher in both groups than before brushing (p<0.001). The difference in post-brushing fluoride concentration between the two groups was not statistically significant. The calcium concentration in saliva after brushing with the test toothpaste was higher than after brushing with the control toothpaste. The difference between the two means was statistically significant (p<0.001). Mean calcium concentration in tooth surface swab samples were significantly higher in the test group than in the control group (p<0.001). Conclusion: Plaque fluoride concentration was significantly increased after brushing with a new toothpaste containing 2% hydroxyapatite. The concentration of calcium in saliva and on the tooth surface was significantly increased compared to a standard toothpaste.

Urinary fluoride output in children following the use of a dual-fluoride varnish formulation

Objective:This study evaluated the bioavailability of fluoride after topical application of a dual-fluoride varnish commercially available in Brazil, when compared to Duraphat™.Material and methods:The urinary fluoride output was evaluated in seven 5-year-old children after application of the fluoride varnishes, in two different phases. In the first phase (I), children received topical application of the fluoride varnish Duofluorid XII (2.92% fluorine, calcium fluoride + 2.71% fluorine, sodium fluoride, FGM™). After 1-month interval (phase II), the same amount (0.2 mL) of the fluoride varnish Duraphat (2.26% fluorine, sodium fluoride, Colgate™) was applied. Before each application all the volunteers brushed their teeth with placebo dentifrice for 7 days. Urinary collections were carried out 24 h prior up to 48 h after the applications. Fluoride intake from the diet was also estimated. Fluoride concentration in diet samples and urine was analyzed with the fluoride ion-specific electrode and a miniature calomel reference electrode coupled to a potentiometer. Data were tested by ANOVA and Tukey's post hoc test (p<0.05).Results:There were significant differences in the urinary fluoride output between phases I and II. The use of Duofluorid XII did not significantly increase the urinary fluoride output, when compared to baseline levels. The application of Duraphat caused a transitory increase in the urinary fluoride output, returning to baseline levels 48 h after its use.Conclusions:The tested varnish formulation, which has been shown to be effective in in vitro studies, also can be considered safe.

Sodium monofluorophosphate as a source of fluoride added for nutritional purposes to food supplements - Scientific Opinion of the Panel on Food Additives and Nutrient Sources added to Food

SUMMARY Following a request from the European Commission to the European Food Safety Authority (EFSA), the Scientific Panel on Food Additives and Nutrient Sources added to Food (ANS) was asked to provide a scientific opinion on the safety of sodium monofluorophosphate added for nutritional purposes as a source of fluoride in food supplements and on bioavailability of fluoride from this source. The present opinion deals only with the safety of sodium monofluorophosphate as a source of fluoride and the bioavailability of the fluoride from this source. The safety of fluoride itself, in term of amounts that may be consumed, is outside the remit of this Panel. Available literature on sodium monofluorophosphate and sodium fluoride suggests that sodium monofluorophosphate is hydrolysed in fluoride and phosphate ions and the Panel concludes that fluoride bioavailability will be to an extent comparable to the one from sodium fluoride. The most sensitive effect of fluoride exposure in humans is dental fluorosis and conclusions of comprehensive evaluations indicate that genotoxicity and carcinogenicity are not of concern for fluoride exposure in humans. Long-term clinical interventions trials have suggested that monofluorophosphate is better tolerated than other common sources of fluoride 1 For citation purposes: Scientific Opinion of the Panel on Food Additives and Nutrient Sources added to Food on a request from the Commission on disodium fluorophosphate added for nutritional purposes to food supplements. The EFSA Journal

Fluoride availability from natural resources in The Gambia - implications for oral health care

Changing food patterns in combination with ineffective oral hygiene measures and insufficient bioavailability of fluoride from drinking water and other sources seem to impair the dental health status in developing countries, especially in the younger population. Therefore, preventive programmes in controlling dental caries progression should be based on local conditions. For mapping the drinking water fluoride content throughout The Gambia, samples of water from rural community wells, public water taps, commercial mineral water, and from the Gambia-River were measured. Additionally, fluoride concentrations of locally extracted table salt and green tea were determined. Showed the need for supplementary fluoride intake, because natural dietary fluoride availability is very low. Age-related recommendations for oral health care and for additional fluoride bioavailability are given, taking into account local socio-economic conditions in the Republic of The Gambia and similar developing countries.

Bioavailability of fluoride administered as sodium fluoride or monofluorophosphate to humans

A double-bind cross-over study was conducted on four healthy subjects, aged 19–29 years, in order to determine the relative bioavailability and other pharmacokinetics features of fluoride (F) after single oral administration in fasting conditions of 2 mg F as sodium F (NaF) or sodium monofluorophosphate (MFP). The bioavailability was evaluated on the basis of the plasma levels and of the urinary excretion of F. Blood was sampled before and during the 8 h after the administration of the test solutions. For F excretion urine was sampled 12 h before the study and over the 8 h after the administration. Data were tested for statistically significant differences by ANOVA and Tukey's post hoc tests, and also by Student's t-test ( p < 0.05). For the two formulations, the pharmacokinetics of F in plasma was characterized by a rapid absorption and by a peak ( C max = 0.1 μg/mL) which was reached 20 min after administration, followed by a biphasic elimination. In the 8 h following the administration the urinary excretion of F accounted for 35–41% of the administered dose, without significant differences between the two formulations. The AUCs (±S.D.) for NaF and MFP were 21.15 (±0.58) and 19.04 (±1.75) min μg mL −1, respectively, and were not significantly different ( p = 0.079). Based on the AUC and C max of F in plasma and on the urinary excretion of F during the 8 h following administration, the relative bioavailabilities of the two F formulations were equivalent.

Determination of bioavailable fluoride from sepiolite by “in vivo” digestibility assays

This work presents a study of the bioavailability and distribution of fluoride in tissues of animals (Wistar rats) which were fed with a poultry feeding that contains sepiolite as an additive. The determination of fluoride concentration was carried out by potentiometric measurements using a fluoride selective electrode. The quantification was done using the standard addition method with enough accuracy and precision in all the assays. The results demonstrate that fluoride present in sepiolite is not bioavailable. The digestion process does not extract all the fluoride from sepiolite, so sepiolite can be use in poultry feedings without any risk. These studies have contributed to the discussions at EU level about extraction procedures and F − determination in feed material of mineral origin.

Uptake of Fluoride, Aluminum and Molybdenum by Some Vegetables from Irrigation Water

Water is the major source of fluoride (F) in fluorosis endemic areas although food materials also contribute considerable amount to total intake. Plants take up F from irrigating waters and this uptake is influenced by some inorganic constituents in water and soil. In the present study five commonly consumed vegetables (amaranth ( Amaranthus gangeticus) , spinach (Coriandrum sativum), cabbage, tomato and lady's finger) were grown applying irrigation water containing 10 ppm F. In addition amaranth and coriander were grown with aluminium (Al) and/or molybdenum (Mo) to study their effect on F bioavailability. Fluoride levels were higher in edible parts of all vegetables compared to controls irrigated with water containing 0.3 ppm F. Fluoride contents (mg/ kg dry wt) with tap water and fluoridated water were 0.71 vs 1.70 for spinach, 3.88 vs 20.29 for amaranth, 0.12 vs 0.17 for cabbage, 0.14 vs 0.43 for lady's finger and 0.12 vs 0.2 for tomato (P < 0.01). The levels of calcium (Ca) and phosphorous (P) a re high in amaranth although their causal relaltion to high fluoride bioavailability in this plant is not known. Molybdenum (Mo) a nd Al reduced fluoride intake by amaranth (Al showing marked effect) but not by coriander. Al + Mo reduced fluoride uptake by both plants. Molybdenum intake was reduced by F in coriander and by Al in amaranth. F + Al had much less effect on Mo uptake. Fluoride reduced Al uptake by amaranth and coriander. Mo or Mo + F had no effect on Al uptake by amaranth but reduced the uptake by coriander. Fluoride uptake was highest in amaranth and lowest in cabbage among the vegetables studied.

The interrelationship between diet and oral health

Diet and nutrition impact on many oral diseases, in particular dental caries. Consumption of fluoridated water coupled with a reduction in non-milk extrinsic sugar intake is an effective means of caries prevention. However, studies on the fluoride concentration of bottled waters suggest increased consumption of these waters, in preference to fluoridated tap water, would lead to a marked decrease in caries protection. Concerns have been raised about the bioavailability of fluoride from artificially-fluoridated water compared with naturally-fluoridated water. This issue has been addressed in a human experimental study that has indicated that any differences in fluoride bioavailability are small compared with the naturally-occurring variability in fluoride absorption. Research has unequivocally shown sugars to be the main aetiological factor for dental caries, and information on intakes guides health promotion. Repeat dietary surveys of English children over three decades indicate that levels of sugars intake have remained stable, while sources of sugars have changed considerably, with the contribution from soft drinks more than doubling since 1980. Dental caries eventually leads to tooth loss, which in turn impairs chewing ability causing avoidance of hard and fibrous foods including fruits, vegetables and whole grains. A very low intake (<12 g/d) of NSP and fruit and vegetables has been found in edentulous subjects. Provision of prostheses alone fails to improve diet. However, initial studies indicate that customised dietary advice at the time of denture provision results in increased consumption of fruits and vegetables, and positive movement through the stages of change. Feasible means of integrating dietary counselling into the dental setting warrants further investigation.

Bioavailability of Fluoride in Drinking Water: a Human Experimental Study

It has been suggested that systemic fluoride absorption from drinking water may be influenced by the type of fluoride compound in the water and by water hardness. Using a human double-blind cross-over trial, we conducted this study to measure c(max), T(max), and Area Under the Curve (AUC) for plasma F concentration against time, following the ingestion of naturally fluoridated hard and soft waters, artificially fluoridated hard and soft waters, and a reference water. Mean AUC over 0 to 8 hours was 1330, 1440, 1679, 1566, and 1328 ng F.min.mL(-1) for naturally fluoridated soft, naturally fluoridated hard, artificially fluoridated soft, artificially fluoridated hard, and reference waters, respectively, with no statistically significant differences among waters for AUC, c(max), or T(max). Any differences in fluoride bioavailability between drinking waters in which fluoride is present naturally or added artificially, or the waters are hard or soft, were small compared with large within- and between-subject variations in F absorption. Abbreviations used: F, fluoride; AUC, Area under the Curve for plasma F concentration against time; AUC(0-3), Area under the Curve for plasma F concentration against time for 0 to 3 hours following water ingestion; AUC(0-8), Area under the Curve for plasma F concentration against time for 0 to 8 hours following water ingestion; c(max), maximum plasma F concentration corrected for baseline plasma F and dose (i.e., F concentration of individual waters); T(max), time of c(max).

Concentration and bioavailability of fluoride in mouthrinses prepared in dispensing pharmacies

Considering the importance of medication quality control and that mouthrinses for dental caries prevention have commonly been prepared in dispensing pharmacies, this study assessed formulations containing 0.05% NaF acquired from 6 dispensing pharmacies in the city of Piracicaba, S.P. The mouthrinse formulations were purchased in 3 separate periods and coded from A to F. Fluoride ion (F-) concentration was determined in all formulations in the 3 periods, and in those acquired in the 3rd period, the bioavailability of fluoride with dental enamel with caries-like lesions and the pH of products were evaluated. A solution of 0.05% NaF and distilled deionized water were used, respectively, as positive and negative controls. In the bioavailability analysis, fluoride present in dental enamel was determined removing, by acid etching, two layers of enamel; fluoride in the acid extract was determined with a specific electrode. The mouthrinses prepared in 5 pharmacies presented a F- concentration close to the expected value, except for the product prepared in one of them, in which a mean of 0.01% NaF was found. All products were more efficient than the negative control (p<0.05) in terms of reactivity with dental enamel, but differences among them were observed with regard to the positive control (p<0.05). The data suggest that a quality control program should be implemented in dispensing pharmacies to guarantee the quality of fluoridated mouthrinses formulated.

Total and acid-soluble fluoride content of infant cereals, beverages and biscuits from Brazil

Total fluoride (TF) and HCl 0.01 M (‘gastric juice’)-soluble fluoride (SF) were analysed in infant foods, beverages and calcium-rich biscuits. Samples were divided into seven categories: children cereals (A), chocolate-flavoured milk (B), soy beverages (C), filled biscuits (D), non-filled biscuits (E), wafer biscuits (F) and corn starch biscuits (G). Mean TF concentrations ± SD (amplitude, unit µg F ml−1 or µg F g−1) were: (A) 4.25 ± 3.04 (0.20 − 7.84, n = 6); (B) 0.34 ± 0.47 (0.05−1.27, n = 6); (C) 0.15 ± 0.07 (0.09−0.29, n = 8); (D) 8.44 ± 1.76 (7.65−10.47, n = 4); (E) 12.41 ± 1.15 (10.69−13.68, n = 4); (F) 0.35 ± 0 (0.34−0.36, n = 4) and (G) 7.77 ± 1.12 (6.86−8.68, n = 2). Five samples of cereals, one sample of chocolate-flavoured milk and 10 samples of biscuits were analysed for SF. In cereals analysed for SF, all fluoride was soluble, while for the chocolate-flavoured milk, approximately 50% of TF was soluble. Regarding the biscuits analysed for SF approximately 20% of TF was soluble. It was observed that some of the cereals and beverages, and most of the biscuits analysed, might be important contributors to total daily fluoride intake. When consumed just once per day, cereals and beverages might supply up to 25% of the maximum recommended daily fluoride intake (0.07 mg F kg−1 body weight) for a 2-year-old child (12 kg). For the filled, non-filled and corn starch biscuits, when 3, 32 or 20 units of them, respectively, are consumed just once per day, they may supply up to 16% of the maximum recommended daily fluoride intake. However, only approximately 25% of fluoride absorption occurs from the stomach and 75% from the small intestine. Therefore, a higher fluoride bioavailability is possible.