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PubMed1986

Amounts of fluoride in self-administered dental products: safety considerations for children.

With the increased use of various fluoride preparations for caries prevention, all dental personnel should know their potential toxicity and the margins of safety associated with their use. An understanding of the body's mechanisms for handling fluoride provides a rational basis for assessing the possible risks of excessive fluoride ingestion. Five to 10 g of sodium fluoride is considered a certainly lethal dose for a 70-kg adult. One quarter of the certainly lethal dose can be ingested without producing serious acute toxicity and is known as the safely tolerated dose. Comparisons of certainly lethal and safely tolerated doses for commonly used fluoride agents and procedures show that they can be applied with little or no risk of adverse acute effects, as long as they are used judiciously. If their use is abused, there is a risk of illness or even death. If amounts of fluoride close to the certainly lethal dose are ingested, the speed of initiating proper treatment is critical for survival. Vomiting should be induced, if it is not spontaneous; fluoride-binding liquids, such as milk or liquid or gel antacids, administered; and the patient taken to the nearest hospital for emergency care. Frequent ingestion of low but excessive quantities of fluoride during the period of tooth formation can lead to dental fluorosis. Particular concern is warranted for the ingestion of fluoride-containing toothpastes by young children and the inappropriate use of dietary fluoride supplements in communities with sufficient fluoride already present in drinking water.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1981

Effect of excessive exposure to sodium fluoride on composition and crystallinity of equine bone tumors.

Sodium fluoride (5 mg/kg of body weight) was fed for 20 months to horses with hereditary multiple exostoses (HME), a skeletal disorder that primarily affects endochondral bones during skeletal development. Rib biopsies were performed on both HME horses not fed fluoride (control) and HME horses that were fed fluoride to obtain comparable specimens for chemical analyses and x-ray diffraction. Fluoride content of the rib from a horse fed fluoride for 20 months was approximately 20 to 30 times higher than that from a control horse. Fluoride content of the bone tumors was higher than those of normal bones in both control and fluoride-fed horses. The effect of fluoride uptake on the Ca/P ratio was slight. The Ca/P ratios did not differ significantly between tumorous and normal ribs. X-ray diffraction studies showed that the crystallinity (ie, crystal size/perfection) of the mineral apatite in tumor of the rib from the control horse was lower than that of normal bone from the same rib. Fluoride, however, induced a marked change in the crystallinity at both the tumorous and the normal bone sites. The crystallinity of the tumor apatite in the fluoride-fed horse exceeded that of normal bone in the control horse. Otherwise, there were not demonstrable fluoride-induced gross or radiographic changes in the bone tumors.

Animals↗
PubMed2005

Effect of topical fluoride application on toothbrushing abrasion of resin composites.

OBJECTIVES: This in vitro study assesses toothbrushing abrasion of a microfill (Heliomolar Radioopaque) and a hybrid composite (Herculite XRV) after application of two acidic fluoride agents. METHODS: Thirty-six specimens of each resin composite were fabricated, ground flat and polished. Subsequently the 36 samples of each material were evenly assigned to three groups. In the first group, samples were treated with the fluoride varnish Bifluorid 12 (5.5% F, pH 5.6), in the second group with Elmex Fluid (1.25% F, pH 4.3). In the third group, specimens remained unfluoridated (controls). After 8h, the samples were subjected to toothbrushing abrasion (2000 brushing strokes, load: 250 g) in an abrasive slurry. Fluoridation and brushing abrasion were repeated twice. Afterwards, abrasion of the materials was quantitatively determined with a laser profilometer and statistically analyzed (ANOVA). RESULTS AND SIGNIFICANCE: With Herculite both, Bifluorid 12 (P = 0.0001) and Elmex Fluid (P = 0.0001) led to a significant increase of brushing abrasion compared to the non-fluoridated group. However, no significant difference was observed between the two fluoridation regimes. Heliomolar showed a tendency towards higher abrasion after treatment with Elmex Fluid compared to Bifluorid 12 (P = 0.0496) and the non-fluoridated group (P = 0.0496), whereas treatment with Bifluorid 12 yielded no significant difference compared to the non-fluoridated Heliomolar specimens. Fluoridation of Herculite resulted in a 106-121% increase of abrasion, whereas Heliomolar only showed an increase by 5-30%. Application of the acidic fluoride products used led to an increase in toothbrushing abrasion of the tested composite restorative materials. However, clinical long-term studies are needed to determine the effect of topical fluoride regimes on resin composite materials.

Acrylic Resins↗
PubMed2000

Fluoride release/uptake from newer glass-ionomer cements used with the ART approach.

PURPOSE: To determine the fluoride ion release/uptake of two conventional glass-ionomer cements (GICs) manufactured for use with the ART approach (Fuji IX GP, Ketac-Molar), as compared with that of a resin-modified GIC (Fuji II LC). MATERIALS AND METHODS: 15 specimens of each material were prepared and placed in vials with artificial saliva and stored at 37 degrees C. The solution was replaced weekly for 6 wks, and the fluoride ions released were measured in ppm each week. After 6 wks, the 15 specimens of each material were divided into three equal groups and placed into three fluoride recharging agents (1.23% APF gel, 1.1% neutral NaF and 0.001% CaF2) for 4 min at 23 degrees C. Fluoride ion measurements of the recharged specimens were carried out at 1 day, 2 days, then weekly for another 6 wks. RESULTS: All freshly-mixed specimens showed the highest fluoride ion release after 1 week, then the release rates dropped quickly to become largely stabilized after 3 wks. After one 4-min exposure to APF gel the initial fluoride ion release increased significantly for all materials. The highest rates were during the first day, but then dropped very quickly to again become largely stabilized after usually 3 wks. Exposure to NaF and CaF2 did not usually result in significantly sustained fluoride ion release by any material. The order of release/uptake for all three agents was Fuji II LC > Fuji IX GP > Ketac-Molar. The mechanism of fluoride ion release after the application of different fluoride recharging agents is not clear. It may occur partly by washout of recharge agents that are retained in the pores and cracks of the restorative materials, for APF gel is viscous and difficult to wash off completely with deionized water; by erosion of surfaces by low pH agents, or by the subsequent release of fluoride ions from within the cement matrix.

Acidulated Phosphate Fluoride↗
PubMed2003

Fluoride toothpastes for preventing dental caries in children and adolescents.

BACKGROUND: Fluoride toothpastes have been widely used for over three decades and remain a benchmark intervention for the prevention of dental caries. OBJECTIVES: To determine the effectiveness and safety of fluoride toothpastes in the prevention of caries in children and to examine factors potentially modifying their effect. SEARCH STRATEGY: We searched the Cochrane Oral Health Group's Trials Register (May 2000), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2000), MEDLINE (1966 to January 2000), plus several other databases. We handsearched journals, reference lists of articles and contacted selected authors and manufacturers. SELECTION CRITERIA: Randomized or quasi-randomized controlled trials with blind outcome assessment, comparing fluoride toothpaste with placebo in children up to 16 years during at least one year. The main outcome was caries increment measured by the change in decayed, missing and filled tooth surfaces (D(M)FS). DATA COLLECTION AND ANALYSIS: Inclusion decisions, quality assessment and data extraction were duplicated in a random sample of one third of studies, and consensus achieved by discussion or a third party. Authors were contacted for missing data. The primary measure of effect was the prevented fraction (PF) that is the difference in caries increments between the treatment and control groups expressed as a percentage of the increment in the control group. Random effects meta-analyses were performed where data could be pooled. Potential sources of heterogeneity were examined in random effects meta-regression analyses. MAIN RESULTS: Seventy-four studies were included. For the 70 that contributed data for meta-analysis (involving 42,300 children) the D(M)FS pooled PF was 24% (95% confidence interval (CI), 21 to 28%; p<0.0001). This means that 1.6 children need to brush with a fluoride toothpaste (rather than a non-fluoride toothpaste) over three years to prevent one D(M)FS in populations with caries increment of 2.6 D(M)FS per year. In populations with caries increment of 1.1 D(M)FS per year, 3.7 children will need to use a fluoride toothpaste for three years to avoid one D(M)FS. There was clear heterogeneity, confirmed statistically (p<0.0001). The effect of fluoride toothpaste increased with higher baseline levels of D(M)FS, higher fluoride concentration, higher frequency of use, and supervised brushing, but was not influenced by exposure to water fluoridation. There is little information concerning the deciduous dentition or adverse effects (fluorosis). REVIEWER'S CONCLUSIONS: Supported by more than half a century of research, the benefits of fluoride toothpastes are firmly established. Taken together, the trials are of relatively high quality, and provide clear evidence that fluoride toothpastes are efficacious in preventing caries.

Adolescent↗
PubMed2004

Fluorides for the prevention of white spots on teeth during fixed brace treatment.

BACKGROUND: White spots can appear on teeth during fixed brace treatment because of early decay around the brace attachments. Fluoride is effective at reducing decay in susceptible individuals and is routinely prescribed in various different forms to patients during orthodontic treatment. OBJECTIVES: To evaluate the effectiveness of fluoride in preventing white spots during orthodontic treatment and to compare the different modes of delivery of fluoride. SEARCH STRATEGY: We searched the Cochrane Oral Health Group's Trials Register (to 22 August 2002); CENTRAL (The Cochrane Library Issue 3, 2002); MEDLINE (January 1966 to July 2003); EMBASE (January 1980 to week July 2003). Authors of trials were contacted for further data. SELECTION CRITERIA: Trials were selected if they met the following criteria: a randomised or quasi-randomised clinical trial, involving the use of a fluoride-containing product compared with no use or use of a non-fluoride control and enamel demineralisation was assessed during or after orthodontic treatment. DATA COLLECTION AND ANALYSIS: Six reviewers independently, in duplicate, extracted data. The primary outcome was the difference in the presence or absence of white spots between experimental and control patients for parallel design studies, and between experimental and control quadrants, for split-mouth design studies. Potential sources of heterogeneity were examined. Sensitivity analyses were undertaken for the items assessed for quality and publication bias. MAIN RESULTS: The primary outcome of the review was the presence or absence of white spots by patient at the end of treatment. Secondary outcomes included any quantitative assessment of enamel mineral loss or lesion depth. Other outcomes such as differences in size and severity of white spots, any patient based outcomes, such as perception of white spots could not be included because there were insufficient data. Fifteen trials, with 723 participants, provided data for this review. None of the studies fulfilled all of the methodological quality assessment criteria. There is some evidence that a daily sodium fluoride mouthrinse reduces the severity of enamel decay surrounding a fixed brace (weighted mean difference for lesion depth -70.0; 95% CI -118.2 to -21.8) and that use of a glass ionomer cement for bracket bonding reduces the prevalence (Peto OR 0.35; 95% CI 0.15 to 0.84) and severity of white spots (weighted mean difference for mineral loss -645 vol%.microm; 95% CI -915 to -375) compared with composite resins. REVIEWERS' CONCLUSIONS: There is some evidence that the use of topical fluoride or fluoride-containing bonding materials during orthodontic treatment reduces the occurrence and severity of white spot lesions, however there is little evidence as to which method or combination of methods to deliver the fluoride is the most effective. Based on current best practice in other areas of dentistry, for which there is evidence, we recommend that patients with fixed braces rinse daily with a 0.05% sodium fluoride mouthrinse. More high quality, clinical research is required into the different modes of delivering fluoride to the orthodontic patient.

Dental Caries↗
PubMed1995

Physical model for lesion formation in the presence of low levels of solution fluoride.

A quantitative physical model is presented for the formation of subsurface carious lesions in the presence of low levels of solution fluoride. Calculations using independently determined model parameters are in agreement with mineral density profiles measured in bovine enamel lesions. The proposed mechanism is controlled by fluoride in the following way: as fluoride diffuses into enamel, it is rapidly adsorbed to enamel crystallites, resulting in very low microenvironmental fluoride concentrations, so long as the crystals are not saturated with respect to fluoride adsorption. The result of this saturable adsorption is a widening band of fluoride-saturated crystals near the surface, beneath which the microenvironmental fluoride concentrations are negligible. In the saturated band, the microenvironmental fluoride concentration in the pore solution is high enough to suppress dissolution, while in the deeper, relatively fluoride free region, dissolution can occur. In addition to predicting observed mineral density profiles, the model also predicts the demarcation in solution conditions between the regime where subsurface lesion formation occurs and that where the dissolution pattern is that of surface erosion; and the lack of insensitivity of dissolution rate to hydrodynamics in the presence of low levels of fluoride, as contrasted to the square root of stirring rate dependency observed in the absence of fluoride.

Animals↗
PubMed1993

Fluoride increases net 45Ca uptake by SaOS-2 cells: The effect is phosphate dependent.

Previous in vitro studies have shown that the effect of fluoride to increase avian osteoblast-like cell proliferation was dependent on the phosphate concentration. In vitro studies have further revealed that fluoride could also have direct effects on osteoblast-like cells to increase phosphate uptake and transiently increase cytosolic calcium. The current studies were intended to determine whether fluoride could increase net 45Ca uptake by human osteosarcoma (SaOS-2) cells and, if so, whether those effects would also be phosphate dependent. The results of these studies indicate that fluoride increased net 45Ca uptake by SaOS-2 cells, with biphasic dose and time dependencies. After 30 minutes of exposure, net 45Ca uptake was increased to a greater extent by 50 microM fluoride (217 +/- 16% of control, P < 0.001) than by 200 microM fluoride; and the stimulatory effect of 100 microM fluoride on net 45Ca uptake was greater after 20 minutes (187 +/- 22% of control, P < 0.001) than after 60 minutes (122 +/- 7% of control, P < 0.05). These effects of fluoride to increase net 45Ca uptake were dependent on the phosphate concentration in the medium. Fluoride had no effect on net 45Ca uptake in medium containing 0.4 mM phosphate, but increased net 45Ca uptake in medium containing 1.2 or 2.0 mM phosphate (P < 0.005). As the phosphate concentration was increased, the biphasic fluoride dose-response curve was shifted to a lower range of fluoride concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1995

Histomorphometric analysis of iliac crest bone biopsies in placebo-treated versus fluoride-treated subjects.

In a 4-year controlled, prospective trial, histomorphometric analysis was used to compare the tissue-level skeletal effects of fluoride therapy in 43 postmenopausal women (75 mg NaF/day) with those of 35 matching placebo subjects; all subjects received 1500 mg/day elemental calcium supplement. In addition to an initial, baseline biopsy, a second biopsy was obtained after 6, 18, 30 or 48 months. Measurements were made on a third biopsy obtained from 8 subjects following at least 72 months of fluoride therapy. The change in cancellous bone volume or trabecular thickness in fluoride-treated subjects was not different from a change in placebo-treated subjects. However, paired analysis in the fluoride-treated subjects indicated that bone volume was increased between the first and second biopsies (p < 0.005). Both osteoid length and width were significantly increased in fluoride compared with placebo subjects; however, only the osteoid surface increased linearly (r = 0.63, p < 0.001). The mineral apposition rate and relative tetracycline-covered bone surface were not different between fluoride and placebo treatment, although they were decreased in both groups in the second biopsy. The tetracycline-covered bone surface returned to normal in the third biopsy. Definitive evidence for osteomalacia is a prolonged mineralization lag time, which following fluoride treatment was found to be increased 9-fold in the second biopsy and 4-fold in the third biopsy. Further evidence for osteomalacia was increased osteoid thickness by 6 months, evidence of focal areas of interstitial mineralization defects, and broad tetracycline labels of low fluorescence intensity. In the third biopsies, osteoclastic resorption was observed beneath osteoid seams. Fluoride therapy increased the cortical width compared with placebo treatment (p < 0.02), and increased the osteoid surface in Haversian canals, but did not change the osteoid width, resorption surface or cortical porosity. After an initial rise, serum fluoride levels remained constant, and the urine values fell slightly. The bone fluoride concentration rose throughout the treatment period, and was correlated with the change in osteoid-covered bone surface (r = 0.56, p < 0.001). Although we found definitive evidence for osteomalacia, the cause of the osteomalacia was not determined in this study. On the other hand, the presence of bone resorption beneath unmineralized osteoid and of osteocyte halos is suggestive of hyperparathyroidism. Thus, it is possible that the strong stimulus for bone formation brought about by fluoride therapy resulted in relative calcium deficiency.

Aged↗
PubMedDate not supplied

Endemic chronic fluoride toxicity and dietary calcium deficiency interaction syndromes of metabolic bone disease and deformities in India: year 2000.

Epidemiological studies during 1963-1997 were conducted in 45,725 children exposed to high intake of endemic fluoride in the drinking water since their birth. Children with adequate (dietary calcium > 800 mg/d) and inadequate (dietary calcium < 300 mg/d) calcium nutrition and with comparable intakes of fluoride (mean 9.5 +/- 1.9 mg/d) were compared. The toxic-effects of fluoride were severe and more complex and the incidence of metabolic bone disease (rickets, osteoporosis. PTH bone disease) and bony leg deformities (genu valgum, genu varum, bowing, rotational and wind-swept) was greater (> 90%) in children with calcium deficiency as compared to < 25% in children with adequate calcium who largely had osteosclerotic form of skeletal fluorosis with minimal secondary hyperparathyroidism. The syndrome of skeletal fluorosis and associated metabolic bone disease and deformity is a unique clinical entity classified as a variant of osteosclerotic form of skeletal fluorosis. This syndrome chiefly results from the biological impact of excess fluoride, low calcium, high PTH and 1,25 (OH)2D3 separately and through their interactions on bone structure and metabolism as studied by radiology, bone scanning, bone histomorphometry and relevant metabolic and endocrine laboratory investigations. Metabolically active and vascular bones of children accumulate fluoride at faster and greater rate than adults (at the sites of active growth). In calcium deficient children the toxic effects of fluoride manifest even at marginally high (> 2.5 mg/d) exposures to fluoride. Fluoride toxicity also exaggerates the metabolic effects of calcium deficiency on bone. The findings strongly suggest that children with calcium deficiency rickets reported in the literature should be re-investigated for possible fluoride interactions. Deep bore drinking water supply with fluoride < 0.5 ppm and improvement of calcium nutrition provide 100% protection against the toxic effects of fluoride and are recommended as the cost effective and practical public health measures for the prevention and control of endemic fluorosis.

Adolescent↗
PubMed2003

Effect of fluoride pretreatment on the solubility of synthetic carbonated apatite.

The purpose of this research was to address the following question: How is the solubility of fluoride-pretreated carbonated apatite (CAP) in aqueous acidic media related to the equilibrium solution fluoride and/or the CAP adsorbed fluoride levels? A CAP sample prepared by a precipitation method at 70 degrees C containing approximately 6% carbonate was fluoride-treated (F adsorption from neutral aqueous solutions) to yield a approximately 1000 ppm F CAP and a approximately 3300 ppm F CAP. Metastable equilibrium solubility distributions were determined in acetate buffers at pH 5.0. Solution fluoride, calcium, phosphate, and pH were determined from the equilibrated solutions. The equilibrium solution fluoride levels were extremely low, e.g., as low as approximately 0.10 ppb to approximately 0.30 ppb at 50% dissolved for the two CAP preparations. The approximately 3300 ppm F CAP yielded a lower solubility than the approximately 1000 ppm F CAP (shift in the mean pKHAP value of 1.5-2 units). This can be attributed to the lower solution F(-) for the sample containing approximately 1000 ppm fluoride compared with the approximately 3300 ppm fluoride-containing CAP. These important findings suggest that a fluoride treatment simply may provide an adsorption fluoride depot for subsequent release, providing a solution fluoride effect upon the CAP solubility and not necessarily any intrinsic alteration of the mineral solubility.

Apatites↗
PubMed1992

Fluoride uptake in hard tissues of fetal guinea pigs in response to various dose regimens.

This study was designed to explore various aspects of maternal-fetal fluoride metabolism. In its first phase, 57 female guinea pigs were bred and randomly assigned to a control group (I) or one of three experimental groups: (II) 3 parts/10(6) fluoride in drinking water, (III) a single daily oral dose and (IV) 3 parts/10(6) fluoride in water and a single daily oral fluoride dose. The total mean doses received by groups II and III were similar. The total mean dose received by group IV was approximately double that for groups II and III. Samples of maternal plasma, and fetal bone and enamel were collected on the 57th day of gestation. In its second phase, 53 pregnant guinea pigs were given drinking water containing 0, 2, 4, 6 or 8 parts/10(6) fluoride during gestation. On the 57th day of gestation samples of maternal and fetal enamel were collected. All samples in both phases of the study were assayed for fluoride using the microdiffusion, ion-selective electrode method. In the first part of the study, mean fetal enamel fluoride by group was: I, 21.6 parts/10(6); II, 38.6 parts/10(6); III, 33.5 parts/10(6); IV, 54.9 parts/10(6). In the second phase, maternal enamel was linearly related to the fluoride dose. The same was true for fetal enamel except at the 8 parts/10(6) fluoride level in the water where there was no increase over the 6 parts/10(6) group. At all dose levels, fetal enamel fluoride uptake was approximately an order of magnitude less than maternal enamel fluoride uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1987

Fluoride therapy for osteoporosis: characterization of the skeletal response by serial measurements of serum alkaline phosphatase activity.

Optimum use of fluoride therapy for osteoporosis requires a sensitive and convenient index of the skeletal response to fluoride. Since previous studies had shown that serum alkaline phosphatase activity (SALP) was increased in response to fluoride therapy, we examined serial measurements of SALP in 53 osteoporotics treated with 66 to 110 mg of sodium fluoride (NaF) for 12 to 91 months. SALP was increased in 87% of the subjects during therapy with fluoride. The increase in SALP was thought to reflect the osteogenic action of fluoride based on the findings that SALP correlated with both trabecular bone area (r = .81, P less than .001) and osteoid length (r = .67, P less than .01) in iliac crest biopsies, predicted increased bone density on spinal radiographs in response to fluoride therapy with an 87% accuracy, and predicted decreased back pain in response to fluoride with a 91% accuracy. In addition, the SALP response to fluoride was seen earlier than other therapeutic responses as indicated by the findings that the tau 1/2 for the SALP response (ie, time for 1/2 of the patients to show a significant response) was significantly less (1.2 +/- 0.3 yr) than that for the pain response (1.6 +/- 0.3 yr, P less than .05) or that for the radiographic response (3.7 +/- 0.5 yr, P less than .001). Although most patients responded to fluoride with an increase in SALP, evaluation of the kinetics of the SALP response to fluoride revealed marked interpatient variation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Characterization of a rapidly responding animal model for fluoride-stimulated bone formation.

Sodium fluoride (NaF) is the single most effective agent for increasing bone volume in the osteoporotic skeleton. However, the mechanism of fluoride-stimulated bone formation is not known, and investigation has been hampered by the lack of a suitable animal model. Young chicks show a rapid skeletal response to NaF that resembles the human skeletal response. This occurs at serum fluoride concentrations comparable to those obtained in humans. Fourteen-day-old chicks treated with NaF (4.2 mM NaF in the drinking water) for 2 weeks showed increases in bone-forming surface in the tibial metaphysis (130% of untreated controls, P less than 0.002), with no change in the number of osteoblasts per length of forming surface (104% of control). The NaF dose dependence of the change in bone-forming surface was biphasic, being optimal at 23 microM fluoride. Linear correlations were observed between dietary NaF and serum fluoride (r = 0.996, P less than 0.001), and serum fluoride and bone fluoride concentrations (r = 0.98, P less than 0.001). Correlations were also observed between the amount of alkaline phosphatase activity in the tibia and the serum fluoride concentration (r = 0.88, P less than 0.03), the serum fluoride concentration and the tibial ash weight (r = 0.93, P less than 0.01), and the bone fluoride concentration and tibial ash weight (r = 0.95, P less than 0.01). Preliminary studies of the time dependence of the skeletal fluoride response in young chicks revealed no difference between 2 weeks and 4 weeks of treatment (bone-forming surface increased to 124% and 139% of controls in separate studies, P less than 0.01 for each).(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed2005

The dentin sialoprotein (DSP) expression in rat tooth germs following fluoride treatment: an immunohistochemical study.

UNLABELLED: Fluoride is known to alter expression of dentin matrix proteins and affect their posttranslational modifications. OBJECTIVE: The objective of our study was to examine dentin sialoprotein (DSP) expression in the early and late bell stages of development of the first molar tooth germs in rats treated with fluoride. DESIGN AND METHODS: Pregnant dumps were divided into three groups. They were fed a standard diet and from the fifth day of pregnancy, each group received either tap water (with trace amounts of fluoride), tap water with a low concentration of fluoride, or tap water with a high concentration of fluoride. Changes in DSP expression and distribution were visualized by immunohistochemistry. RESULTS: Immunoreactivity for DSP was detected in the cervical regions of the early bell stage in tooth germs of the 1-day-old animals. The earliest reaction was visible in the control group and the group supplemented with the low fluoride concentration (F(L)) but not in the group supplemented with the high fluoride concentration (F(H)). In early bell stages across all experimental groups, the immunoreactivity to DSP was observed in the cusp tip regions and was localized to preameloblasts, young and mature odontoblasts, dental pulp cells, predentin, and dentin. Generally, more intense positive staining for DSP was detected in animals supplemented with the high fluoride concentration. In the late bell stage found in the 4-day-old control group and the group supplemented with the low fluoride concentration, immunoreactivity for DSP was less intense compared with younger animals. However, immunoreactivity was greater in the group treated with the high dose of fluoride. In this group, the positive immunostaining for DSP, especially in young ameloblasts, was prolonged and relatively strong. CONCLUSIONS: Fluoride supplementation causes changes in the developmental pattern of DSP expression and its distribution in rat tooth germs.

Administration, Oral↗
PubMed2006

Dose-effect relationship between drinking water fluoride levels and damage to liver and kidney functions in children.

Although a dose-effect relationship between water fluoride levels and damage to liver and kidney functions in animals has been reported, it was not demonstrated in humans. To evaluate the effects of drinking water fluoride levels on the liver and kidney functions in children with and without dental fluorosis, we identified 210 children who were divided into seven groups with 30 each based on different drinking water fluoride levels in the same residential area. We found that the fluoride levels in serum and urine of these children increased as the levels of drinking water fluoride increased. There were no significant differences in the levels of total protein (TP), albumin (ALB), aspartate transamine (AST), and alanine transamine (ALT) in serum among these groups. However, the activities of serum lactic dehydrogenase (LDH), urine N-acetyl-beta-glucosaminidase (NAG), and urine gamma-glutamyl transpeptidase (gamma-GT) in children with dental fluorosis and having water fluoride of 2.15-2.96 mg/L and in children having water fluoride of 3.15-5.69 mg/L regardless of dental fluorosis were significantly higher than children exposed to water fluoride of 0.61-0.87 mg/L in a dose-response manner. In contrast to children with dental fluorosis and having water fluoride of 2.15-2.96 and 3.10-5.69 mg/L, serum LDH activity of children without dental fluorosis but exposed to the same levels of water fluoride as those with dental fluorosis were also markedly lower, but the activities of NAG and gamma-GT in their urine were not. Therefore, our results suggest that drinking water fluoride levels over 2.0mg/L can cause damage to liver and kidney functions in children and that the dental fluorosis was independent of damage to the liver but not the kidney. Further studies on the mechanisms and significance underlying damage to the liver without dental fluorosis in the exposed children are warranted.

Acetylglucosaminidase↗
PubMed2004

Determination of fluoride ions released from resin-based dental materials using ion-selective electrode and ion chromatograph.

OBJECTIVES: The aim of this study was to investigate the quantities of total and free fluoride ions released from four resin-based composites containing fluoride (Heliomolar (HE), UniFil S (UF), Beautifil (BE) and Reactmer paste (RP)) and one glass ionomer cement (Ketac-Fil Plus Aplicap (KF)). METHODS: Five disk specimens of each material were prepared and the fluoride release was measured at 1, 2, 4, 7, 14, 21 and 28 days. The amounts of total and free fluoride ions released from materials were measured by using an ion-selective electrode (ISE) and ion chromatography (IC). Data were statistically analyzed using a t-test at a significant level of 0.05. RESULTS: For HE, fluoride release is undetectable using the ISE but was detected by the IC method. There were no significant differences in the free and total fluoride ions released from UF and BE (p>0.05). For RP, the free fluoride ions were significantly lower than the total fluoride ions after 4 days (p<0.05). KF showed significant difference between total and free fluoride ions at 7 and 28 days (p<0.05). CONCLUSIONS: The nature of the fluoride incorporated into dental materials affected the amounts of free and total fluoride ions released from materials.

Acrylic Resins↗
PubMed2005

Factors influencing the removal of fluoride from aqueous solution by calcined Mg-Al-CO3 layered double hydroxides.

Layered double hydroxides (LDH) calcined at different temperatures (denoted as CLDH) have been demonstrated to recover their original layered structure in the presence of appropriate anions. In the light of this so-called "memory effect", a study of removal of fluoride from aqueous solution by calcined Mg-Al-CO(3)-LDH has been carried out. The LDH calcined at 500 degrees C had the highest capacity of removal of fluoride ion, because of retention of its intrinsic structure. The CLDH with an Mg/Al ratio of 2 has a remarkable ability to adsorb anions. The adsorption loading is higher for the calcined Mg-Al-LDH than for calcined Zn-Al and Ni-Al-LDH. The influence of varying the conditions for removal of fluoride, such as the pH of aqueous solution, the initial fluoride concentration, the dosage of adsorbent, and temperature on removal of fluoride have been investigated. The influence of co-existing anions in fluoride aqueous solution indicates that the percentage of removal of fluoride increased in order PO(4)(3-) < Cl(-) approximately SO(4)(2-) < Br(-) << NO(3)(-). It was found that maximum removal of fluoride from aqueous solutions was obtained in 6h at pH 6.0 with an initial concentration of 50 mg/L, and that the retention of fluoride ions by the CLDH material was 98% or higher. The residual fluoride concentration was found to be 0.4 mg/L with an initial concentration of 20 mg/L, which meets the national standard for drinking water quality. The Freundlich isotherm and Langmuir isotherm were used to fit the data of equilibrium experiments. The results of X-ray diffraction, FT-IR and TG-MS demonstrate that the adsorption phenomenon is accompanied by rehydration with concomitant uptake of fluoride ions to rebuild the initial layered structure.

Adsorption↗