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'Calcium fluoride-like' material formed in partially demineralized human enamel in vivo owing to the action of fluoridated toothpastes.

In this paper are presented the results of a chemical analysis of partially demineralized enamel lesions positioned under plaque in vivo for 3 weeks. During the experimental period the samples were brushed with fluoridated or non-fluoridated toothpaste systems. After the experiment the fluoride and protein uptake was determined. Furthermore, KOH extractions of the lesions were carried out and the solutions analyzed for calcium, fluoride, and phosphate. The results show that 'CaF2-like' material is most likely formed inside lesions during the in vivo period. This in indicated from chemical analysis, Raman spectroscopy, and SEM observations. The amount of CaF2-like material is on the order of 0.1 wt% if we consider its formation all over the enamel lesions, or 1 wt% if we assume its formation in interprismatic regions of the enamel only. About 40% of the fluoride taken up from toothpaste systems is in the form of CaF2-like material. In vivo there is a substantial influx of proteins (approximately 0.3%) and also a very large influx of phosphate ions. The effect of CaF2-like material is most likely strongly dependent on conditions in the lesion, such as pH change.

Calcium↗

Acute fluoride poisoning after ingestion of sodium fluoride tablets.

Between 1978 and 1983, at least 20 children with fluoride poisoning were admitted to two major children's hospitals in Brisbane. Data on telephone calls received by Poisons Information Centres in Australia about fluoride toxicity show that Brisbane, the water supply of which is not fluoridated, received approximately twice as many calls per head of population as were received in Sydney and Melbourne. Concern is also expressed at the standard of packaging of fluoride tablets currently marketed in Australia. A treatment plan for cases of acute fluoride poisoning after oral ingestion is presented.

Acute Disease↗

[Significance of fluorides in chronic hemodialysis with reference to fluoridation of drinking water].

The metabolism of fluorides in impaired renal function is described. The use of fluoridized drinking-water in the production of dialysis fluid is discussed controversial. In patients treated by chronic hemodialysis the plasma fluoride level rises at a content of 1 mg fluoride per liter dialysis fluid. A relevant effect on the state of health is not certain established today. Therefore, it will be advised to the use of fluoride-free dialysis water. Its production should be made by use of a reverse-osmosis unit.

Fluoridation↗

Determination of inorganic fluoride in blood with a fluoride ion-selective electrode.

Inorganic fluoride in whole blood, serum, or plasma has been determined with a fluoride ion-selective electrode by adding the 0.5- to 2.0-mL sample to 20 mL of water containing a buffer and fluoride, 25 micrograms/L. The fluoride concentration in the sample is calculated from the resulting cell potential difference recorded after equilibrating for 10 min. This novel method has the advantages of simplicity, accuracy, and high precision, standard deviations for 5 to 7 replicate determinations of fluoride ranging from +/- 1.7 to +/- 2.4 micrograms/L. For whole blood from donors living in an area with fluorinated drinking water, the F- concentration was 20 to 60 micrograms/L.

Animals↗

The relative caries-inhibiting efficacy of amine fluoride and sodium fluoride in compatible dentifrices--results of a consensus conference.

A conference concerning the caries-inhibiting efficacy of dentifrices that contain amine and sodium fluorides compared relevant clinical studies and found that both fluoride compounds contribute to the maintenance of dental health. Because of the differing test conditions, the study results cannot, however, be compared. Thus, there is no definite scientific proof of the superiority of one fluoride compound, and no such proof will exist until dentifrices containing amine fluoride and sodium fluoride are tested in a direct clinical comparison.

Amines↗

In vitro fluoride uptake, distribution and retention by human enamel after 1- and 24-hour application of various topical fluoride agents.

The in vitro fluoride acquisition by human enamel after a 1-hour and 24-hour application of APF, Duraphat (a resin varnish) or Fluor Protector (a polyurethane varnish) and subjection to various procedures was determined. Fluoride acquisition was the greatest in teeth treated with Fluor Protector and the least in APF-treated teeth. Fluoride uptake and distribution were increased by prolonging the contact time between the varnishes and enamel, and fluoride retention was decreased after subsequent exposure to synthetic saliva.

Acidulated Phosphate Fluoride↗

In vivo enamel fluoride uptake from and caries inhibition by topical fluoride agents.

Acidulated phosphate fluoride (APF), Duraphat or Fluor Protector, was applied to the molar teeth of rats fed a cariogenic diet. The first maxillary molar teeth were subjected to a microbiopsy procedure for fluoride analysis and the mandibular molars scored for caries. All three topical fluoride agents produced a significant increase in the fluoride content of the outermost 5.0 micron of enamel. Only APF produced a significant reduction in caries incidence at all sites.

Acidulated Phosphate Fluoride↗

Comparative study of fluoride bioavailability following the administration of sodium fluoride alone and in combination with different calcium salts.

To assess whether an interval of a few hours would be advisable between an intake of sodium fluoride (NaF) and that of calcium salts when treating osteoporotic patients with vertebral collapse, we carried out three pharmacokinetic studies in 12 healthy fasting volunteer subjects to compare the fluoride bioavailability provided by NaF alone and NaF combined with two calcium salts. The results were as follows: (1) When NaF is accompanied by calcium, the fluoride peak level is lower and delayed. (2) Fluoride absorption varied greatly among individuals in both experiments, but none of the 6 subjects proved to be nonabsorbers. (3) The areas under the curves obtained with each of the three preparations were not significantly different, but 24-h urinary fluoride was significantly lower in volunteers receiving simultaneously NaF and calcium salts than in volunteers receiving only NaF.

Adult↗

Topographical distribution of fluoride in iliac bone of a fluoride-treated osteoporotic patient.

The electron microprobe was used to display the topographical distribution pattern of fluoride (F) at the microscopical level in the iliac bone of an osteoporotic patient treated with fluoride. Composite x-ray image of F K alpha emission revealed a high concentration of fluoride in the periosteal and endosteal bone layers, in the cancellous bone, and in certain osteons, which corresponded to the bone formed during the period of fluoride treatment. Fluoride was also concentrated around the Haversian canals in the vicinity of the capillary blood vessels by a diffusion process. Morphometric analysis showed that more cancellous bone than cortical bone is formed.

Aged↗

[Investigations on the elimination of fluoride in urine after drinking waters containing different quantities of fluoride (author's transl)].

20 volunteers were given 0.71 of water per day over a period of 10 weeks. Three different types of water were used--with traces of fluoride, with about 0.5 mg/1 fluoride and with about 11 mg/1 fluoride. A highly significant correlation was found between the intake of fluoride with the water and its elimination with the urine. About 50% of the fluoride taken in was eliminated on the same day.

Adolescent↗

[Biological monitoring of fluoride-exposed workers in Switzerland: development of the internal fluoride burden in the last 10 years].

In Swiss plants a risk of industrial fluorosis exists only for workers in the aluminum industry (electrolysis of Al2 O3, raffination of aluminium). Exposure to fluorides is assessed by ambient monitoring, by health surveillance (early detection of fluorosis) and by biological monitoring (urinary fluoride determinations, pre-shift und post-shift). The results of biological monitoring in the 4 plants in Switzerland are presented (1976/77-1986; 1977 264 workers, 1986 242 workers). During the period from 1976/77-1986 a significant reduction of the urinary fluoride excretion in exposed workers was observed. This reduction was correlated in time with technical measures to reduce external fluoride exposure of workers. Urinary fluoride excretion was within limits of biological exposure indices at the end of the observation period in all plants (on group base). Therefore the risk of industrial fluorosis seems to be eliminated in newly engaged workers and significant lowered in the other workers of the Swiss aluminium industry.

Body Burden↗

Influence of fluoride on secretory pathway of the secretory ameloblast in rat incisor tooth germs exposed to sodium fluoride.

Fluoride, which is an environmental toxicant, is a potent inducer of mottled enamel in humans and rats. To define the influence of fluoride on the secretory pathway in enamel fluorosis, mottled enamel was induced in the incisor tooth germs of rats by subcutaneous injections of sodium fluoride for 4 days, and then morphological and cytochemical changes of the secretory ameloblast were examined in the tooth germs with HRP-labeled lectin (Con A, GS-I, SBA and PNA) and En3 antibody labeling amelogenins. The accumulation of small vesicles on the route of the secretory pathway between the rER and the Golgi apparatus, disorder of Golgi stacks, and formation of abnormal large granules in distal cytoplasm were seen in the secretory ameloblast. Lectin staining patterns of the secretory ameloblast indicated the disturbance of the vesicular transport between the rER and the Golgi apparatus, and disorganization of the Golgi stack. Immunolabeling of the cell showed disruption of the sorting and fusion process on the secretory pathway. These results suggest that the fluoride disturbs the intracellular transport in the synthesis-secretory pathway of the ameloblast, and that this effect of fluoride on the synthesis-secretory pathway participates in the formation of enamel fluorosis.

Ameloblasts↗

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.

Animals↗

Highly sensitive and rapid method for determination of fluoride ion concentrations in serum and urine using flow injection analysis with a fluoride ion-selective electrode.

An apparatus for flow injection analysis (FIA) was developed to measure very low fluoride ion concentrations (<1 micromol/l). The analytical conditions of the apparatus were investigated, and the instrument was used to determine fluoride ion concentrations in serum and urine. All interferences caused by serum and urine matrices were eliminated using the proposed method. The recovery was almost 100.0% for serum and urine samples. The precision was within 4%. The results of determination of fluoride ion concentrations in the NIST Standard Reference Material of urine, SRM 2671a, agreed with the certified values. The detection limits in serum and urine were 0.016 and 0.16 micromol/l, respectively. The assay throughput was 15 samples/h in serum and 24 samples/h in urine. The mean fluoride ion concentrations in serum and urine samples from 53 young Japanese women were 0.383+/-0.158 micromol/l and 0.207+/-0.103 mg/g Cr, respectively. There was a significant correlation (r=0.39, p<0.01) between serum and urine fluoride ion concentrations.

Adult↗

Binding of phosphate, aluminum fluoride, or beryllium fluoride to F-actin inhibits severing by gelsolin.

Actin exhibits ATPase activity of unknown function that increases when monomers polymerize into filaments. Differences in the kinetics of ATP hydrolysis and the release of the hydrolysis products ADP and inorganic phosphate suggest that phosphate-rich domains exist in newly polymerized filaments. We examined whether the enrichment of phosphate on filamentous ADP-actin might modulate the severing activity of gelsolin, a protein previously shown to bind differently to ATP and ADP actin monomers. Binding of phosphate, or the phosphate analogs aluminum fluoride and beryllium fluoride, to actin filaments reduces their susceptibility to severing by gelsolin. The concentration and pH dependence of inhibition suggest that HPO4(2-) binding to actin filaments generates this resistant state. We also provide evidence for two different binding sites for beryllium fluoride on actin. Actin has been postulated to contain two Pi binding sites. Our data suggest that they are sequentially occupied following ATP hydrolysis by HPO4(2-) which is subsequently titrated to H2PO4-. We speculate that beryllium fluoride and aluminum fluoride bind to the HPO4(2-) binding site. The cellular consequences of this model of phosphate release are discussed.

Actins↗

Prevalence of dental fluorosis in children from non-water-fluoridated Halmstad, Sweden: fluoride toothpaste use in infancy.

OBJECTIVES: To determine the prevalence and severity of dental fluorosis in children aged 7-9 years from non-water-fluoridated Halmstad, Sweden, and to relate the results to their reported fluoride exposure history during infancy. MATERIAL AND METHODS: In Spring 2002, a questionnaire distributed to a cluster random sample of 1039 parents enquired into their child's early oral health behaviors and included a "photographic toothpaste menu". The permanent upper anterior teeth (13-23) were examined clinically (+10% repeats) using a modified Thylstrup-Fejerskov Index. RESULTS: Complete data were available for 53% (n=548) of the sampled children. The prevalence offluorosis at any level was 49% (95% CI: 45-54%), and of fluorosis with esthetic concern (TF score > or =3) 4% (95% CI: 3-6%). Based on repeat observations, reliability was good (kappa = 0.82). There was no statistically significant increased risk of dental fluorosis prevalence associated with any of the fluoride exposure risk factors examined, including reported usage of (1000 ppm) fluoride toothpaste from time of first deciduous tooth eruption. CONCLUSIONS: While there were low levels of dental fluorosis of esthetic concern, half the children had some degree of dental fluorosis. The prevalence of dental fluorosis was not explained by the risk factors, including fluoride toothpaste usage as explored in this study.

Age Factors↗

Release of fluoride from fluoride-containing chewing gum.

The release of fluoride from fluoride-containing chewing gum and the fluoride concentration in whole saliva was measured at different intervals after the start of the chewing procedures. The residual fluoride contents were 78, 32, and 6% of the initial 0.25 mg in the gum after chewing for 2, 5, and 10 min, respectively. When chewing for 10 min, the salivary fluoride increased from 0.05 to 11.7 and 15.3 parts/10(6) after 2 and 5 min, respectively, followed by a fall to 3.9 parts/10(6) after 10 min. Concentrations exceeding the preintake level were still recorded 60 min after the start of the chewing.

Adult↗

Caries development after substitution of supervised fluoride rinses and toothbrushings by unsupervised use of fluoride toothpaste.

In a nonfluoridated community of Finland, where fortnightly fluoride rinsing with 0.2% sodium fluoride has been used for nearly two decades, a total of 313 children 7-8 yr old were recruited and randomly divided into two groups. 206 children completed the 3-yr trial. The control group (n = 94) participated in the rinsing program which included supervised toothbrushings, while the test group (n = 112) received a new fluoride toothpaste tube (0.15% F) for home use every second month. Annual dental recordings, treatment plannings and the treatment itself were all carried out by one clinician. At the end of the study the number of caries-free children of the toothpaste group was lower (P < 0.01) and the caries increment higher (P < 0.05) than that of the mouthrinse group. Out of the mean of four dental visits per child and year some 1.5 were prophylactic by nature. No differences were found between the number of treatment visits, time or prophylactic care of the two groups. Unsupervised use of fluoride toothpaste may not be a sufficient substitute for the school-based fortnightly fluoride rinses and supervised toothbrushings in caries prevention of children with erupting permanent teeth.

Child↗