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PubMed1995

Effect of stopping fluoride administration on the distribution profiles of fluoride in three different kinds of rat bones.

The aim of this work was to explore the reduction of fluoride concentrations in the skeleton after stopping experimental fluoride administration. Fluoride was administered to the rats at varying doses (0, 50, 100 ppm in drinking water) and for different lengths of time (4, 13, 25 weeks). A series of fluoride concentrations across the full thickness of humerus, parietal bone, and vertebra arch in rats were measured by means of an abrasive micro-sampling technique. The distribution profiles of fluoride from periosteal to endosteal surfaces, which were apparently related to the histological structure of these bones, were U shaped in the humerus, V shaped in the parietal bone, and W shaped in the vertebra arch. The average fluoride concentrations in the bones increased significantly with each increasing dose and length of fluoride administration. The relative increments were similar between the different regions or the different bones. After stopping fluoride administration, on the other hand, the relative reduction of the average fluoride concentrations in the bones were 30-100%. They were greatly related to the length after stopping fluoride administration and the dose and length of fluoride administration, but also dependent upon the type of bone and the region examined.

Animals↗
PubMed2000

The fluoride content of antlers as an indicator of fluoride exposure in red deer (Cervus elaphus): A historical biomonitoring study.

Bone fluoride concentrations were analyzed in 141 red deer antlers grown between the 17th/early 18th century and 1997, that originated from four study areas (Arnsberg, Bad Berleburg, Dämmerwald, Schmidtheim) in the federal state of North Rhine-Westphalia, Germany. Fluoride concentrations in the specimens ranged between 27.7 and 1, 392.1 mg F(-)/kg ash and varied significantly both between samples collected during different time-spans in the same area and between samples taken from different study areas over the same period. For antlers (n = 8) collected prior to 1860 in the study areas Arnsberg and Schmidtheim, values between 27.7 and 78.7 mg F(-)/kg ash were recorded. It is assumed that antler fluoride contents in this range are quite close to baseline levels for these regions, i.e., represent concentrations largely unaffected or only slightly influenced by fluoride from anthropogenic sources. With the onset and expansion of large-scale industrial activities, bone fluoride concentrations in the antler samples markedly increased over these baseline values, indicating fluoride deposition from industrial emissions into the red deer habitats. In the later 1980s and the 1990s, a pronounced decline in antler fluoride content was observed, which is attributed to the reduction of industrial fluoride discharges due to effective emission control programs. However, even the lowest fluoride values recorded for antlers grown in the 1990s (study area Schmidtheim, n = 10, range 158.5-367.3 mg F(-)/kg ash) clearly exceeded the concentrations found in the antlers collected prior to 1860, thereby indicating an additional fluoride burden from anthropogenic sources on the recent populations. The present study has corroborated the view that antlers are good indicators of fluoride exposure in deer. The facts that they grow during a seasonally fixed time-span and thus constitute relatively well "naturally standardized" samples and are often kept over long periods of time make antlers suitable monitoring units for historical biomonitoring studies.

Animals↗
PubMed2002

Fluoride uptake and distribution in enamel and dentin after application of different fluoride solutions.

The aim of this in vitro study was to examine the fluoride accumulation in enamel and dentin after short- and long-term application of four fluoride solutions, including a casein-based fluoride preparation. Cubical enamel and dentin specimens were cut out from extracted, caries-free, human third molars. The buccal surface of each specimen was moistened for 5 min or 24 h with 10 microl of the control or one of the four test solutions Olaflur, Oleaflur, sodium fluoride, or experimental fluoride containing hydrolyzed casein. The specimens were ground in 20- microm steps and the fluoride content was determined in each enamel and dentin layer. After application of the fluoride solutions, significantly more fluoride was associated with the superficial layer up to 20 microm. The values were 3-4 times higher in enamel and 4-8 times higher in dentin after 5-min application time and 10-24 times higher than the initial fluoride content in both hard tooth tissues after 24-h application time. Focusing on the experimental solution, the fluoride levels in enamel and dentin were somewhere in the order of the values of sodium and amine fluoride solutions. However, a tendency towards higher values could be observed after application of the experimental solution.

Amines↗
PubMed1986

The effect of fluoride in phosphoric acid on enamel fluoride uptake and the tensile bond strength of an orthodontic bonding resin.

Decalcification that occurs adjacent to bonded orthodontic brackets is of great concern to orthodontists. Among the many procedures suggested to overcome this problem is the addition of fluoride to the phosphoric acid (H3PO4) etching solution. The purposes of this study were to determine the loss of fluoride from the acidic etching solutions, to evaluate the effect of various fluoride concentrations in H3PO4 on the tensile bond strength of an orthodontic bonding resin, to determine the amount of total and bound fluoride acquired by etched enamel, and to evaluate the effect of these etching solutions on enamel by scanning electron microscopy. Solutions of 50 m/m% H3PO4 containing 0 and approximately 0.01, 0.04, 0.08, 0.2, 0.4 and 0.9% fluoride were prepared. The fluoride concentrations in the etching solutions remained stable up to 3 months after preparation. The tensile bond strengths of the bonding resin to the etched enamel surfaces were not significantly different. Enamel acquired the greatest amount of total fluoride from H3PO4 solutions containing 0.215% fluoride while the bound fluoride acquired by enamel from the fluoride-containing etching solutions was not significantly different. The addition of fluoride to H3PO4 did not impede the etching effect on enamel.

Acid Etching, Dental↗
PubMed1997

Fluoride level in saliva after bonding orthodontic brackets with a fluoride containing adhesive.

The fluoride level in saliva is considered an important parameter in caries prevention. Elevation of the salivary fluoride level by a fluoride-releasing orthodontic bonding adhesive would most likely be beneficial in the prevention of enamel caries. In this study, the fluoride level in saliva was measured after bonding brackets with a visible light-curing adhesive containing fluoride (12.4 wt% total F). The fluoride released from the adhesive has been shown in a previous study to inhibit demineralization adjacent to orthodontic brackets in vivo. Twenty-four patients each had 20 brackets bonded and saliva samples taken before bonding (t = 0) and after 1, 3, and 6 months. The participants were requested to brush daily with a fluoride toothpaste during the study period. The saliva fluoride analysis was done with the microdiffusion method. The analysis of the saliva showed fluoride levels (+/- SD) of 0.011 +/- 0.007, 0.011 +/- 0.009, 0.0011 +/- 0.007, and 0.012 +/- 0.008 ppm at t = 0, 1, 3, and 6 months, respectively. There was no significant difference at the 5% level. The study indicated indirectly that the caries inhibiting effect of the orthodontic adhesive shown previously was most likely due to a localized fluoridation of the cariogenic environment rather than to an elevation of the fluoride level in saliva.

Adhesives↗
PubMed2002

Modulation of fluoride toxicity in rats by calcium carbonate and by withdrawal of fluoride exposure.

In order to assess the effect of calcium on the toxic effects of fluoride, adult female Wistar rats were treated with sodium fluoride (NaF, 500 ppm in drinking water) alone or in combination with calcium carbonate (CaCO3, 50 mg/ kg by oral intubation) daily for 60 days. Food, water and fluoride intake were measured daily for 60 days. Body weight gain, exploratory motor activity, rota-rod motor coordination, dental structure, activities of acetylcholinesterase (AchE, brain and skeletal muscle) and Na+ K+ ATPase (erythrocyte membrane and skeletal muscle) and the concentrations of protein (serum and skeletal muscle), calcium (serum) and fluoride (serum) were determined in these animals 24 hr after the last treatment. The same parameters were tested in another group, 60 days after withdrawal of NaF exposure (500 ppm in drinking water daily for 60 days). NaF treatment decreased food and water intake, reduced body-weight gain and impaired exploratory motor activity and rota-rod performance. Dental lesions, inhibition of the activities of AchE and N+ K+ ATPase and a decrease in the concentration of protein, and serum calcium were also observed in these animals. These effects were accompanied by a marked elevation of fluoride concentration in the serum. CaCO3 decreased the concentration of fluoride in the serum of NaF-treated animals. A decrease in serum fluoride concentration was found also after NaF withdrawal. A prevention of locomotor behavioural, biochemical and dental toxicities of fluoride was observed both in these groups. It is concluded that the dose of CaCO3 used in the present study has a potential to prevent the toxicity of fluoride by maintaining serum fluoride at a less toxic level. Further, the toxic effects of fluoride are reversible if its exposure is withdrawn for 2 months.

Acetylcholinesterase↗
PubMed1980

Serum inorganic fluoride: changes related to previous fluoride intake, renal function and bone resorption.

1. Inorganic fluoride concentrations were determined in serum and urine specimens of 24 subjects receiving a standardized low fluoride intake. Serum fluoride was directly correlated with previous intake and appeared to reflect bone fluoride stores. 2. A positive correlation between creatinine and fluoride clearance was found. However, striking reductions in fluoride clearance, which resulted in increases in serum fluoride, were not usually seen until the creatinine clearance was below 25 ml/min. 3. Parathormone produced an increase in serum fluoride and thyrocalcitonin a decrease, probably by their action on bone. 4. Six patients with chronic increased bone resorption had elevated fluoride concentrations. In five, when treatment was successful, serum fluoride fell. Interpretation of the data from this group of patients is complicated by initially low filtration rates associated with hypercalcaemia and hypercalciuria. 5. The sensitivity of the serum fluoride concentration to previous intake, glomerular filtration and the intensity of bone resorption suggests that the human organism exerts no direct homeostatic control over this ion.

Adolescent↗
PubMed2002

[New recommendations concerning the fluoride content of toddler toothpaste - consequences for systemic application of fluoride].

A group of experts from 4 European countries who gathered at a convention at Basel in November 1998, arrived at the recommendation to increase the fluoride (= F) content of toddler toothpastes from 250 ppm to 500 ppm. It was recommended to make parents brush the children's teeth with a pea-size piece of this toothpaste once a day, starting when the first deciduous teeth were erupting. Routine application of F-tablets would no longer be routinely prescribed, but restricted to individual indications in special high caries risk cases. This recommendation did not consider previous ones and was based exclusively on new scientific, mainly epidemiological evidence. In April 2000 the recommendation was officially issued by the German scientific dental association DGZMK.A careful case-control study resulted in the analysis of the risk to develop mottling of enamel under the influence of fluoridated water (1 ppm F) and fluoride toothpaste (1000 ppm F) when used in early childhood. It was found that excessive use of the fluoride toothpaste doubled the fluorosis risk, whereas when fluoride supplements (tablets, drops) were given the risk was about 20 times higher than without a fluoride supplement. Experiments in Germany and the Netherlands had shown that remineralisation of enamel under influence of 500 ppm F is achieved much more quickly than under application of 250 ppm F. A panel of WHO experts came to the conclusion that there was no evidence for the effectiveness of toothpastes containing less than 500 ppm. Statistics from the Netherlands have shown that the amount of fluoride tablets sold there is barely sufficient for the use by a quarter of all children 0 to 4 years old. In contrast to this low level of acceptance of fluoride tablets, fluoride toothpastes is widely accepted. It is their extensive use which explains the marked improvement of dentitions among the youth in this country during the last 20 years; the influence of topical fluoride gels, varnishes and other preventive measures was much less, and a reduction of sugar consumption (by the way less than 10 % of what it was in 1970) seems to have been the least important factor. The new recommendations based on topical rather than systemic fluoride application are better for preventive, toxicological, psychological and didactic reasons and should be implemented as soon as possible.

Administration, Oral↗
PubMed2002

Fluoride concentration in supragingival dental plaque after a single intake or habitual consumption of fluoridated milk.

The aim of this study was to evaluate the fluoride concentration in supragingival dental plaque after single and repeated intakes of fluoridated milk. The study group consisted of 22 schoolchildren, young adults and adults of both sexes, 8-41 years of age. After a 2-week fluoride depletion period and 3 days of plaque accumulation, 200 ml of fluoridated milk (1g F) was ingested along with a standardized lunch meal. Plaque samples were collected immediately before the intake and after 30, 120 and 240 min. From the adult participants (n = 9) additional samples were collected after 12 and 18 h. After a fluoride-free washout period of at least 2 weeks, the whole experimental procedure was repeated after 4 consecutive daily intakes of fluoridated milk. The fluoride concentration was determined after micro-diffusion with a fluoride selective electrode. The results showed a statistically significant 3-fold increase of the plaque fluoride levels up to 4 h after the intake. At 12 and 18 h after the intake, the recorded levels went gradually back to baseline. There was no significant difference between the fluoride concentrations in the supragingival plaque after the single intake compared with the repeated intakes. In conclusion, the findings support the suggestion that milk is a suitable vehicle for local fluoride administration into the oral cavity, also when consumed together with a meal.

Adolescent↗
PubMed2005

Fluoride tablet programs in healthy elderly subjects: distribution of fluoride in saliva and plaque with tablets in different sites.

Based on root caries data and oral sugar clearance pattern, vestibular surfaces of upper incisors and lower molars may be regarded as risk areas along with the proximal surfaces. The aim of the present study was to use this information in improving fluoride tablet programs for the elderly. Six healthy elderly males with full dental arches took part. Flavored and unflavored tablets dissolved passively either under the tongue or in the vestibule close to the root caries risk areas. Salivary fluoride was determined at five to six intra-oral sites with a micro-sampling technique at intervals up to 10 min tablet use. Plaque samples were collected from single tooth surfaces before and after tablet use, and analyzed for total fluoride and total protein by micro-techniques. Salivary fluoride exposure to root caries risk areas was strongly increased when fluoride tablets were placed in the vestibule in these areas. The unflavored tablet gave higher fluoride retention in saliva than did the flavored brand. Plaque fluoride levels tended to be above baseline in the first couple of hours after tablet use, and then to decline. In the caries risk areas, at vestibular surfaces of lower posterior and upper incisor teeth, most of the fluoride taken up in plaque had been lost after 5 h and a bread meal, whereas in the non-risk areas it was largely retained. The study demonstrated that fluoride exposures to the vestibular caries risk areas can be strongly increased by placing fluoride tablets close to them. An unflavored tablet seemed to give higher exposures than a flavored one. The rapid loss of fluoride from plaque in slow clearance risk areas indicates that more than one daily treatment would be required for elderly caries risk subjects.

Administration, Oral↗
PubMed1981

Renal fluoride excretion and plasma fluoride levels during and after enflurane anesthesia are dependent on urinary pH.

To determine the effects of urinary pH on fluoride ion excretion and the resulting plasma fluoride concentration during and after enflurane anesthesia, renal function, plasma inorganic fluoride levels, and fluoride excretion were studied in two groups of patients pretreated with either NH4Cl or acetazolamide to produce acidic or alkaline urine, respectively. During anesthesia, urinary flow rate, inulin clearance (Cin) and para-aminohippurate (PAH) clearance (CPAH) were 7, 61, and 43 per cent of control values in the acidic-urine group and 22, 74, and 57 per cent of control values in the alkaline-urine group, respectively. Fractional fluoride clearances (CF/CIN) during anesthesia and operation were 0.06 +/- 0.05 in the acidic-urine group (urinary pH 5.08) and 0.68 +/- 0.23 in the alkaline-urine group (urinary pH 8.16). Values of total fluoride excretion during the same period were 0.06 +/- 0.04 mg and 0.87 +/- 0.29 mg, respectively. Mean maximal plasma levels of fluoride were 26.3 +/- 7.3 microM in the acidic-urine group and 13.5 +/- 2.4 microM in the alkaline-urine group. The differences between groups in fluoride clearance, fluoride excretion, and plasma fluoride levels were all statistically significant. The data clearly show that renal fluoride clearance is closely related to urinary pH.

Acetazolamide↗
PubMed1986

Caries levels and patterns in head start children in fluoridated and non-fluoridated, urban and non-urban sites in Ohio, USA.

The purpose of the study was to determine caries levels and prevalences of previously identified caries patterns in low income children in the primary dentition in Ohio, USA. Children were examined from urban fluoridated (n = 505), urban non-fluoridated (n = 395), non-urban optimal fluoride (n = 183), and non-urban suboptimal fluoride (n = 227) sites. Caries scores were similar for the two sites having optimal fluoride; scores from fluoridated sites were lower than scores from the two suboptimal fluoride sites. Children from all four sites were caries-free ranging from 36% in the urban non-fluoridated site to 50% in the non-urban optimally fluoride site. More children in the suboptimal fluoridated sites had smooth surface lesions than in the optimally fluoridated sites. More children with defect associated lesions had fewer than six (chi 2 = 222; P less than 0.01) carious surfaces than did children with smooth surface lesions.

Child, Preschool↗
PubMedDate not supplied

In vitro fluoride uptake by enamel from different amine fluoride concentrations.

The aim of this in vitro study was to examine whether the concentration of amine fluoride solution influences the uptake of fluoride by enamel after topical treatment. Four slabs were prepared from each of 31 impacted third molars and selected at random so that one slab from each tooth was present in each group. One group of slabs served as an untreated control (D). The slabs of the other three groups were shaken for 3 min in an amine fluoride solution on 3 successive days: group A (1% F), group B (0.5% F) and group C (0.25% F). The amounts of KOH-soluble fluoride produced with 1 and 0.5% amine fluoride solution did not differ significantly and were superior to 0.25% amine fluoride solution. A statistically significant increase in structurally bound fluoride was observed in groups A, B and C compared with control group D. The difference in the amounts of structurally bound fluoride was significant only between 1 and 0.25% F concentrations. These data suggest that the fluoride content in an amine fluoride solution (1%) can be decreased by half without reducing its ability to form alkali-soluble or structurally bound fluoride. The results of this study are consistent with those of previous clinical studies.

Cariostatic Agents↗
PubMed1988

Histological, histometrical and fluoride electrode studies of the effects of fluoride on the mandibular condyles in growing newborn rats.

The effects of fluoride on the mandibular condyles in growing newborn rats were studied by histological, histometrical and fluoride electrode methods. The layer of cartilage of the mandibular condyle in the animals administered 5, 15, 25 and 35 mg/kg of fluoride for 3 weeks displayed a significant increase in thickness when compared with that of the mandibular condyle in the control animals. The thickening of the cartilage layer was proportioned to the amounts of fluoride administered. The volumetric density of cancellous bone of the condyle in the animals administered 25 and 35 mg/kg of fluoride also increased significantly when compared with that of the condyle in the control animals. The trabeculae of cancellous bone of the condyle in these animals contained large amounts of osteoid. The cancellous bone of the condyle in the animals of the four fluoride groups showed a significantly higher fluoride concentration when compared with that of the condyle in the control animals. The fluoride concentration proportionally increased with the amounts of fluoride administered. The results of the present study indicate that the morphologic changes and the fluoride concentrations in the mandibular condyles of rats receiving fluoride were closely correlated with each other.

Animals↗
PubMed1991

Competition between fluoride-resistant and fluoride-sensitive Streptococcus mutans in rat dental plaque.

The experiments were designed to study the effects of fluoride on the competition between a fluoride-sensitive strain of Streptococcus mutans (C180-2) and a fluoride-resistant mutant (S. mutans C180-2FR) in rat dental plaque. Competition was induced either by superinfecting rats or by co-caging rats infected with either strain with non-infected rats. Sodium fluoride was applied in diet and drinking water (60 ppm F), as daily brushings with a 1% F solution, or as a combination of both administrations. The fluoride applications favoured S. mutans C180-2FR, but not enough to outcompete the parent strain successfully under all conditions. Fluoride protected rat dental plaque harbouring S. mutans C180-2FR against colonization by the parent strain. In rats not previously infected with S. mutans, the fluoride in diet and drinking water in combination with the fluoride brushings favoured S. mutans C180-2FR in colonizing rat dental plaque. However, the fluoride applications did not benefit S. mutans C180-2FR in colonizing plaque in which the parent strain was already present. Human dental plaque may be colonized by fluoride-resistant S. mutans strains after spontaneous mutation in response to a fluoride pressure. Our data suggest that this pressure may also provide an ecological advantage to this mutant to colonize the dental plaque.

Animals↗
PubMed1995

Urinary fluoride excretion in Jamaica in relation to fluoridated salt.

The purpose of this study was to compare the urinary fluoride levels in subtropical Jamaica just before the beginning of salt fluoridation (250 mg/kg salt) in 1987 and again 20 months later. Four age groups were studied in three locations with low to intermediate fluoride concentrations in the drinking water. The averages of supervised, timed morning fluoride excretions ranged between 12.1 and 27.9 micrograms/h prior to fluoridation as compared with 23.7-67.4 micrograms/h 20 months after the beginning of the sale of fluoridated salt. The fluoride excretions obtained from 24-hour collections ranged from 169 to 485 micrograms/24 h in 1987 and increased to 304-657 micrograms/24 h in 1989. In 1987, the morning fluoride excretions approximated those of French and Swiss children who had a low fluoride intake, but the fluoride levels of 1989 were similar to the data obtained from children who had an intake of 1.2-1.7 mg F/day or consumed fluoridated water.

Adolescent↗
PubMed1993

Protective effect of topically applied fluoride in relation to fluoride sensitivity of mutans streptococci.

The aim of the present in vitro experiments was to determine whether the protection of enamel by topically applied fluoride against demineralization by bacterial acids would depend on the fluoride sensitivity of the bacteria. Glucose-agarose gel suspensions of fluoride-sensitive and fluoride-resistant mutans streptococci were placed on bovine enamel specimens with different amounts of fluoride. One group of specimens was untreated, a second group had been pretreated with a F-lacquer, and a third group had been pretreated with the F-lacquer and rinsed subsequently with a KOH-solution, to remove deposited CaF2. After 22-hour incubations at 37 degrees C, the amounts of calcium and lactate and the pH of the agarose gels were determined. This procedure was repeated on three consecutive days. Two parent S. mutans strains, one parent S. sobrinus strain, and five fluoride-resistant derivatives were tested. Both pretreatments gave a significant protection to the enamel specimens. For the S. mutans strains, the degree of protection did not depend on the fluoride sensitivity of the strains. For the S. sobrinus strains, the results suggested a reduced protection against demineralization by the fluoride-resistant derivatives. Only from the second group of enamel specimens was enough fluoride released for inhibition of bacterial metabolism. Presumably, it was released by the dissolution of CaF2. It is concluded that a possible adaptation of mutans streptococci in dental plaque to frequent exposures to fluoride will not necessarily decrease the caries-preventive effects caused by topically applied fluoride agents.

Adaptation, Biological↗
PubMed1994

Mode of action of fluoride: application of new techniques and test methods to the examination of the mechanism of action of topical fluoride.

Modern techniques in dental research continue to assist in the study of the mode of (anticaries) action of topical fluorides. The Plaque Glycolysis and Regrowth Model (PGRM) facilitates the standardized assessments of antimicrobial effects on plaque following use of test formulations in vivo without complications arising from coincident mineral reactivity. In vivo plaque glycolysis testing demonstrates that topically applied fluoride, at conventional levels found in dentifrices, has only modest effects on the metabolic (acid-producing) activity of dental plaque. Any 'plaque' contribution to fluoride efficacy must come from more subtle effects on plaque acidogenicity than those measured in PGRM. The 19-FMAS NMR (Magic Angle Spinning Nuclear Magnetic Resonance) technique provides unambiguous measures of the reaction products of F-enamel interactions. Studies have revealed a new 'reaction product' of fluoride-enamel interactions--designated as Non-Specifically-Adsorbed Fluoride, NSAF. This species, along with FAP (fluoroapatite), FHAP (fluorohydroxyapatite), and CaF2 (calcium fluoride), contributes to the remineralization/demineralization benefits of fluoride. pH cycling and in situ denture chip studies permit quantitative assessments to be made of the relative benefits of fluoride in promoting remineralization and in inhibiting demineralization. Results from pH cycling/in situ experiments are strongly supportive of Koulourides' 'Acquired Acid Resistance' concept, describing fluoride's decay-preventive effects. The continued application of new analytical/physical techniques and testing regimens to the study of fluoride anticaries mechanisms may lead to the development of improved fluoride agents/treatment modalities for the prevention of dental caries.

Analysis of Variance↗