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[Effects of high fluoride intake on the fluoride of femora, teeth and some biochemical indexes in rats].

In order to approach practicable indexes for assessing the effects of the products which are intended to be used to prevent endemic fluorosis, Wistar rats were fed with fluoridated water(50 mg/L) for four weeks. After only one week treated with fluoride, a higher activity of NAG(N-acetyl-beta-D-glucosaminidase) in urine, ChE(cholinesterase) in blood and increased urinary excretion of fluoride (compared with the control, P < 0.01) were observed, and these changes were lasted to the end of the fourth week of the study, but hydroxyproline in serum and urine had not been changed in both groups. After four weeks, the fluoride levels in the femora and teeth of fluoride treated group were ten times higher than that of the control group. According to the results, fluoride in bones and teeth must be taken as key indexes, the activities of NAG in urine and ChE in blood should be taken into consideration for assessing the effects of fluoride protagonist.

Acetylglucosaminidase↗

[Comparison of the effect of fluoride and non-fluoride dentifrices on enamel demineralization and remineralization in vitro].

OBJECTIVE: The purpose of the experiment is to investigate the effect of fluoride dentifrices in China on the intact and artificial caries-like bovine enamels. METHODS: The artificial caries-like lesions were created by dipping the teeth into an acid buffered solution. Both the bovine intact enamels and the artificial caries-like enamels were assigned tooth brushing 20 times every half an hour with 3 kinds of fluoride dentifrices and one kind of non-fluoride dentifrices respectively. The amount of calcium dissolved by lactic acid was determined as the susceptibility of demineralization by atomic adsorption spectrometry (AAS). RESULTS: The group treated with fluoride dentifrice showed significantly less demineralization than the non-fluoride group (P < 0.02). The effect of inhibition of acid solubility in artificial caries-like enamel after tooth brushing is significantly greater than that in intact enamel. CONCLUSION: Fluoride dentifrices in this experiment can prevent both intact enamel and artificial caries-like enamel from acid solubility after tooth brushing, and it seems that the effect of the fluoride dentifrices on the redemineralization is greater than the reduction of enamel solubility.

Animals↗

Fluoride-inhibited calcium ATPase of sarcoplasmic reticulum. Magnesium and fluoride stoichiometry.

The sarcoplasmic reticulum (SR) CaATPase is inactivated by fluoride in the presence of magnesium (Murphy, A. J., and Coll, R. J. (1992) J. Biol. Chem. 267, 5229-5235). The inactive complex is very stable and can be isolated free of other components by 48 h of dialysis at 4 degrees C (Murphy, A. J., and Coll, R. J. (1992) J. Biol. Chem. 267, 16990-16994). In this study, we used a fluoride-specific electrode to determine that the amount of tightly bound fluoride in the complex was 9.4 +/- 2 nmol mg-1 SR protein. The rate constant of inactivation was very similar to the rate constant of fluoride incorporation and varied directly as the square of the fluoride concentration. Luminal Ca2+ accelerated reactivation of the inhibited enzyme, and the rate constants of activity regain and fluoride release were very similar. Although required for inhibition, added magnesium did not accelerate reactivation. Analysis for magnesium using antipyrylazo III of the inhibited enzyme showed 4.1 +/- 0.4 nmol mg-1 SR protein. As there is much evidence in the literature supportive of an estimate of calcium pumps equal to approximately 4-5 nmol mg-1 SR protein, our results indicate that each inhibited enzyme contains two tightly bound fluorides and one tightly bound magnesium.

Animals↗

[Fluoride status of a community and fluoride concentration in its drinking water].

Despite the low fluoride (F) content of the drinking water (less than 0.05 mg/l), an optimum to above optimum daily F intake was shown for the community in Tshikundamalema (Republic of Venda, Southern Africa). In order to evaluate the biological availability of fluoride in the diet, the assimilation of the fluoride ion in enamel was tested. Six age groups (selected according to WHO criteria) consisting of 10 individuals each were used in the study. Enamel biopsies (2N HCl0(4); 3,143 mm2; 8 seconds) were conducted on the mid-labial surfaces of the central maxillary incisors. The fluoride concentrations of the etching solutions were analyzed according to the potentiometric analytical method. The calcium concentrations were determined by means of a flame spectrophotometer. The F content of the outer 10 microns in the enamel of the community was examined in relation to the total daily intake of fluoride for the community. The results obtained from the study showed that, the F content of the enamel of the community (x = 1,133 pg/micrograms; 10 microns depth of etch) correlated with the F intake of the community (x = 3.15 mg F/day). Thus the F content of the diet was biologically available to the body. However, between age groups and sexes, no correlation could be found between the fluoride status and the fluoride intake.

Adolescent↗

The effect of fluoride impregnated dental floss on enamel fluoride uptake in vitro and streptococcus mutans colonization in vivo.

The conclusions reached from this investigation can be summarized as follows: Fluoride can be incorporated into unwaxed dental floss. Placement of the fluoride impregnated dental floss in acid-buffer solution results in the release of most of the fluoride in the floss. Interproximal surfaces of teeth treated in vitro with fluoride impregnated dental floss acquired significantly (approximately three fold) more enamel fluoride than those treated with plain dental floss. The number of in vivo interproximal areas harboring Streptococcus mutans was reduced significantly after treatment with fluoride impregnated dental floss. Further studies should be done to establish the biological, physiochemical, manufacturing, and practical aspects of fluoride impregnated dental floss.

Adult↗

Salivary and urinary fluoride levels after 1-month use of fluoride-releasing removable appliances.

Forty children aged 8-10 years participated in this study. Half (n =20) of them used orthodontic appliances which contained fluoride-releasing devices embedded in the lingual surface of the appliance and the other half used orthodontic appliances prepared from a fluoride-releasing acrylic polymer. Prior to the adjustment of appliances and after 1, 7, 14, 21 and 30 days salivary and urinary samples were collected and the fluoride concentrations were determined. The mean fluoride release was highest during the first week. However, the values decreased considerably after that and the curves for the two groups became parallel. The results indicate that fluoride-releasing removable appliances could be useful for a prolonged release of low concentrations of fluoride without any systemic effect.

Calcium Fluoride↗

The effect of time of exposure on fluoride uptake by human enamel from acidulated fluoride solutions in vitro.

Fluoride uptake on and in enamel during topical application of acidulated solutions was studied. The variables were different time intervals and different pH levels of the treatment solutions. The experiment was carried out with human enamel exposed to 2% NaF solutions, pH 3.5 and 5.5, for 30 sec, 60 sec, 5 min, and 60 min. The amounts of fluoride formed on (as calcium fluoride) and in (as fluorapatite) enamel were determined by chemical assessments, and scanning electron microscopy provided the visualization of the deposits on the surface. It could be demonstrated that the two pH levels caused deposition of large amounts of calcium fluoride and that almost twice as much was deposited at pH 3.5 as at 5.5. The amount of deposit increased rapidly with time of exposure in both situations compared with similar experiments with neutral fluoride solutions. Firmly bound fluoride was incorporated in the enamel only during the 60-min incubation.

Calcium Fluoride↗

Mandibular bone fluoride levels and occurrence of fluoride induced dental lesions in populations of wild red deer (Cervus elaphus) from Central Europe.

Mandibular bone fluoride concentrations as well as frequency and intensity of fluoride-induced dental lesions were studied in four red deer populations from Czechia and Germany exposed to different levels of environmental fluoride. The degree of fluorosis in the permanent cheek teeth was recorded by a scoring system and the individual mandibles assigned to one of three categories (unfluorosed, slightly to moderately fluorosed, and markedly to severely fluorosed) on the basis of the tooth scores. An increase in the frequency and severity of dental fluorosis was positively associated with an increase in bone fluoride level, which itself was significantly different between the four samples. In all samples, the rate of bone fluoride accumulation was higher in younger than in older deer. The results of this study show that frequency and intensity of dental fluorosis can be used as valid indicators of increased fluoride exposure of deer populations, and thus as a quick, easy, economic and reliable means of monitoring fluoride pollution in areas inhabited by wild deer.

Journal Article↗

Tooth wear, solubility and fluoride concentration of molar-tooth surfaces in rats maintained on simultaneous or separate intake of food and fluoridated drinking water.

Eighty rats, 20 days old, were fed a hard pellet diet and deionized or fluoridated (25 parts/10(6) F-) drinking water respectively for 40 days. Half were maintained on simultaneous food and water intake for 3 h, daily, and the remainder on separate intake of food for 3 h followed by drinking water for 3 h, daily. Scanning electron micrographs of the occlusal surface of right maxillary first molars were used for scoring wear. The mandibular and left maxillary molar surfaces were used for solubility and fluoride concentration determinations. Intake of food and water separately did not affect wear significantly, whereas solubility and fluoride concentration of the molar surfaces were significantly increased. Wear, solubility and fluoride of the molar surfaces respectively were highly significantly increased in the rats provided with fluoridated water. Increase in fluoride uptake is due in part at least to the increase in sites available for uptake due to tooth wear. Acid dissolution of worn tooth-surface enamel is greater than that of intact enamel.

Animals↗

Fluoride in serum and bone during treatment of osteoporosis with sodium fluoride, calcium and vitamin D.

Thirteen patients with primary osteoporosis were treated for two years with sodium fluoride (NaF), calcium and dihydrotachysterol (group A). The dose of NaF was modified according to the serum fluoride concentration, which was kept as constant as possible between 0.20 and 0.25 microgram/ml. In patients with bone fluoride content greater than or equal to 0.20% a significant increase in the volumetric density and in the surface percentage covered with osteoid and with osteoblasts was observed. A second group of 7 patients with primary osteoporosis was also treated for 2 years with calcium and dihydrotachysterol, but without fluoride (group B). In these patients no significant change in the volumetric density or in the surface percentage covered with osteoid or osteoblasts was found. Patients in group A with a bone fluoride content less than 0.20% could not be distinguished from the patients in group B. Based on the available data an advice was given for the dosage of NaF in patients with osteoporosis. Regular assessment of the serum fluoride concentration remains advisable.

Adult↗

In vitro dentine fluoride uptake from three fluoride-containing composites and their acid resistance.

OBJECTIVES: The purpose of this study was to determine the dentine fluoride uptake from three fluoride-containing composites (FluorEver, FluoroCore and Pertac-Hybrid) and to investigate their ability to affect the resistance of dentine to an artificial caries challenge. METHODS: Three dentine slabs were prepared from each tooth. The baseline, total and bound fluoride concentrations of each tooth were determined by three successive abrasion biopsies performed on each slab followed by adjusting to standardized depths of 10 microns. Next, dentine slabs ligated with the composites were suspended in synthetic saliva for 1 week. After removal of the composites, these specimens and controls were immersed in an artificial caries medium (pH 4.5) for 5 days. Each slab was sectioned and analysed by quantitative microradiography. RESULTS: The results indicate that dentine acquired significantly different amounts of fluoride from the three composites. The acid resistance of dentine in contact with the composites was also significantly different among the composites and followed the same order as for fluoride uptake. CONCLUSIONS: Dentine fluoride uptake and artificial caries inhibition were significantly greater with FluorEver followed by FluoroCore and Pertac-Hybrid.

Biopsy↗

Risk factors for enamel fluorosis in optimally fluoridated children born after the US manufacturers' decision to reduce the fluoride concentration of infant formula.

This case-control study investigated risk factors for enamel fluorosis in optimally fluoridated children, born after the US infant formula industry voluntarily reduced the fluoride content of their products. Analysis was performed on 233 children, aged 10-14 years. Case-control status was determined using the Fluorosis Risk Index (FRI). Risk factor exposure was ascertained via a mailed questionnaire. Logistic regression analyses revealed a strong association between mild-to-moderate enamel fluorosis on early forming (FRI classification I) enamel surfaces and both fluoride supplement use (odds ratio (OR)=5.95, 95% confidence interval (CI) 1.06-33.53), and early fluoride toothpaste use (OR=6.35, 95% CI 1.21-33.40). The authors found a suggestive, but nonsignificant, association between fluorosis on these enamel surfaces and infant formula in the form of powdered concentrate (OR=4.33, 95% CI 0.73-25.66). There was a strong association between mild-to-moderate fluorosis on later forming (FRI classification II) enamel surfaces and infant formula use in the form of powdered concentrate (OR=10.77, 95% CI 1.89-61.25), fluoride supplement use (OR=10.83, 95% CI 1.90-61.55), and early fluoride toothpaste use (OR=8.37, 95% CI 1.68-41.72). No association was observed between the use of ready to feed infant formula and enamel fluorosis.

Adolescent↗

Short-term bactericidal activity of chlorhexidine gel, stannous fluoride gel and amine fluoride gel tested in periodontal pockets.

The short-term bactericidal effect of 2% chlorhexidine gel, 4% stannous fluoride gel or amine fluoride gel containing 1.25% fluoride on the subgingival microflora was determined in 40 periodontal pockets of 10 patients. The antimicrobial gels or placebo gel were applied in 5-9 mm deep periodontal pockets 3 times within 10 min. Before and 30 min after the applications, samples were taken of the subgingival microflora for determination of the total number of bacteria as well as the number of black pigmented Bacteroides. Reductions of the total number of bacteria were found in all test groups. The reductions found in the pockets treated with chlorhexidine gel or stannous fluoride gel were significantly greater than the reduction found in the pockets treated with a placebo gel. A significant reduction of black-pigmented Bacteroides was found after treatment with chlorhexidine gel or amine fluoride gel. It is concluded that 2% chlorhexidine gel or 4% stannous fluoride gel has a more than 99% reduction effect on the microflora of periodontal pockets within 30 min after application.

Adult↗

Evaluation of a school-based fluoride mouthrinsing and clinic-based sealant program on a non-fluoridated island.

For many years the children of Guam have experienced a high prevalence of dental caries. Surveys conducted on the fluoride-deficient island found that caries levels were double those of US mainland children. In 1976 a school-based fluoride mouthrinse program was initiated involving over 22,000 children in grades kindergarten through eight in weekly rinses with 0.2% neutral NaF. A clinic-based dental pit and fissure sealant program was added in 1984 to the fluoride mouthrinse program. Over 15,000 children participated annually in the sealant program where more than 75,000 teeth were sealed the first year. After 8 yr of fluoride mouthrinsing (1976-1984) mean DMFS scores were 1.79 surfaces per child lower compared to baseline, a decrease of 0.22 DMFS per child per year. During this period proximal DMFS scores decreased 61%, buccal-lingual surfaces 31%, and occlusal surfaces 7%. After 2 yr of fluoride mouthrinsing and sealant application combined overall DMFS scores decreased an additional 2.34 surfaces per child, a reduction of 1.17 DMFS per child per year. Most of this decline took place on pit and fissure surfaces. For the 10-yr period a reduction of 4.13 DMFS per child was seen--a decline from 7.06 DMF at baseline to 2.93 DMF surfaces per child in 1986. This long-term evaluation indicates that dental sealants when used in combination with fluoride mouthrinse were particularly effective in lowering the prevalence of dental caries. Schoolchildren in participating grades on Guam now have dental caries rates close to those of US schoolchildren.

Adolescent↗

Calcium fluoride formation on enamel and its influence on uptake of fluoride in the apatitic lattice.

Human dental enamel was exposed to a pH 4 buffer containing 150 parts/10(6) fluoride. It was found that due to the arising degrees of saturation with respect to calcium fluoride and apatites, surface enamel dissolved coincident with a formation of calcium fluoride. The calcium fluoride redissolved while it kept the liquid saturated with respect to this salt. During this second period, fluorapatite was formed while hydroxyapatite dissolved. Finally, all calcium fluoride was dissolved and the unreacted fluoride was taken up in the apatitic lattice. The results are discussed with reference to the conditions of the oral cavity and enamel solubility experiments.

Apatites↗

South Australian kindergarten children: effects of fluoride tablets and fluoridated water on dental caries in primary teeth.

Dental examinations of approximately 5,000 kindergarten children each year over a seven-year period provided the data for a comparative study of the effects of fluoride tablets and fluoridated water on primary teeth. The lifetime use of fluoridated water resulted in caries-free teeth in 80 per cent of children aged 3-4 years, 67 per cent of those aged 4-5 years, and 55 per cent of those aged 5-6 years. After a lifetime use of daily fluoride tablets the percentages were 87, 74, and 72, respectively. When neither fluoridated water nor tablets were available, the percentages were 69, 49, and 41, respectively. Water fluoridation is the most efficient public health measure because only seventeen per cent of the children taking tablets received them daily throughout life.

Australia↗

Influence of fluoridated salt on urinary fluoride excretion of adults.

After the introduction of fluoridated table salt in the staff cafeteria (VZM) of the Heidelberg University Medical and Dental School, the opportunity was taken to determine urinary fluoride excretion of those eating their main daily meals there. Subjects collected 24-hour urine in three fractions (mornings, afternoons, evenings/nights) before fluoridated table salt was introduced in the VZM, and at 6, 12 and 24 months afterwards. The fluoride concentration in the urine was determined. After 24 months, 127 of the original 200 test persons (study group) and 33 of the 60 persons in the control group could be examined. During this period, each participant in the study group took an average of 3.1 of the main meals each week at noon in the VZM. After fluoridated table salt was introduced at the VZM, fluoride excretion increased only in the afternoon urine of the test group; in this respect, the baseline examination disclosed an average of 33.98 +/- 21.18 microg/h, while the follow-up examinations revealed averages of between 39.72 +/- 22.58 and 42.44 +/- 26.16 microg/h. This difference was statistically significant (Kruskal-Wallis test, p < 0.05). It is recommended that in studies of similar questions, fractions of urine should be collected over 24-hour periods.

Adolescent↗

Prevalence of dental caries and dental fluorosis in students, 11-17 years of age, in fluoridated and non-fluoridated cities in Quebec.

The purpose of this study was to evaluate the difference in dental caries and fluorosis prevalence in 936 randomly selected life-long residents selected from public and private schools in Trois-Rivières (1.0 ppm F in 1987) and Sherbrooke (less than 0.1 ppm F), Que., Canada. Students, 11-17 years of age, were examined for dental caries using the National Institute for Dental Research criteria and for dental fluorosis using the Tooth Surface Index of Fluorosis. Because of an inconsistent fluoridation history in Trois-Rivières, comparisons were carried out between two age strata: students 11-14 years of age who consumed for a longer duration suboptimally fluoridated water than those in the second stratum: students 15-17 years of age. Only public school students, 15-17 years of age, from Trois-Rivières had significantly lower mean filled surface and decayed, missing, and filled tooth surface (DMFS) scores (28 and 24%, respectively) than similar students in Sherbrooke. Among private school students, differences were not found, except in the youngest age group in Sherbrooke who had significantly lower mean DMFS than similar students from Trois-Rivières. The prevalence of fluorosis was 45.6% and 58.0% in Trois-Rivières public and private schools, respectively, and 31.1% and 30.1% in Sherbrooke public and private schools, respectively. The use of fluoride tablets was significantly associated with fluorosis. This study showed that water fluoridation benefitted students from public schools and that the risk factors for dental fluorosis were the use of fluoridated water and fluoride tablets.

Adolescent↗