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[Influence of fluoride varnish of different concentration on microhardness of enamel surface]

Varnish is a new type oral material which develops rapidly in recently years,It have had extensive study abroad.It is one of the topical application of fluoride,among them,fluoride-sodium varnish have more significant effect on prevention of dental caries.This study observed the changes of microhardness of cramels after applying fluorid-sodium varnish of different concentration to enamel surfaces.Enamels were randomly parted into three groups,A.B and C.Before fluoride application,the microhardness of enamels were detected,and no significant difference were found among three groups,After that,0.5%,1.5%,2.7% fluoride-sodium varnish were daubed respectively on the three groups enamel surfaces for 24h.The microhardness of enamels were detected again.The results showed all the microhardness of enamels have significant increase statistically after applying fluoride-sodium varnish of different concentration.But,for 0.5% fluorid-Sodium varnish,the increase of microhardness of enamels was only one half of the other two group,which suggested in some concentration range,the fluoride concentration increased one time,the microhardness of enamels increased about one time, but the increase of microhardness of enamels was not synchronized with the increase of fluoride concentration.The increase of microhardness of enamels is almost the same between the two high concentration fluoride-sodium varnish groups,and there in no significant difference statistically.That is when some fluoride concentration were reached,the microhardness of enamels won't increase any more.By the experiment,the writer suggests 1.5% fluorid-sodium varnish is the best on prevention of dental caries.

Journal Article↗

Fluoride salts are no better at preventing new vertebral fractures than calcium-vitamin D in postmenopausal osteoporosis: the FAVOStudy.

Although fluoride salts have been shown to be capable of linearly increasing spinal bone mineral density (BMD) in postmenopausal osteoporosis, the effects of this gain in density on the vertebral fracture rate remain controversial. We conducted a 2-year multicenter, prospective, randomized, double-masked clinical trial in 354 osteoporotic women with vertebral fractures (mean age 65.7 years). They received either fluoride (208 patients), given as sodium fluoride (50 mg/day) or as monofluorophosphate (200 mg/day or 150 mg/day), or a placebo (146 patients). All patients received daily supplements of 1 g of calcium (Ca) and 800 IU of vitamin D2 (D). A 1-year open follow-up on Ca-D was obtained in 124 patients. After 2 years the fluoride group and the Ca-D group had increased their lumbar BMD by 10.8% and 2.4% respectively (p = 0.0001). However, the rate of patients with at least one new vertebral fracture, defined by semiquantitative assessment and evaluable on an intention-to-treat basis in 89% of patients, was similar in the fluoride groups and the Ca-D group. No difference between the three fluoride regimens was found. The percentage of patients with nonvertebral fractures was not different in the fluoride and Ca-D groups (1.9% and 1.4% respectively for hip fractures). A lower limb pain syndrome occurred more frequently in the fluoride groups. In the 124 patients followed for 1 year after cessation of fluoride therapy, the percentage of patients with at least one new vertebral fracture after 36 months was identical to the percentages in the previous fluoride group and the Ca-D group. We conclude that fluoride-Ca-D regimen was no more effective that Ca-D supplements for the prevention of new vertebral fractures in women with postmenopausal osteoporosis.

Aged↗

Acid resistance of enamel exposed to fluoride-containing orthodontic cements.

In a previous study enamel fluoride uptake from fluoride-containing orthodontic cements was evaluated after a 21-day period. The enamel fluoride uptake from a zinc phosphate cement (A), a zinc phosphate cement containing 5 per cent stannous fluoride by weight (B), and a silicophosphate cement (C) was compared. The results indicated that there was a net loss of fluoride from enamel beneath the orthodontic bands cemented with A while the enamel beneath B and C acquired significant amounts of fluoride. The purpose of the present study was to evaluate enamel fluoride uptake after 12 weeks and the effect of the fluoride uptake or loss by the enamel on acid resistance. Five teeth each had bands cemented with cements A, B and C, respectively, and were individually suspended in synthetic saliva for 12 weeks at 37 degrees C. Following this period the bands were removed, the cements were carefully cleaned off the teeth, and the crowns of the teeth were individually suspended in a lactic acid buffer at pH 4 for 4 weeks. Each tooth crown was then sectioned longitudinally and examined microradiographically to study the degree of enamel demineralization. Characteristic subsurface enamel carieslike lesions were noted on all the specimens studied. The carieslike lesions in the enamel exposed to the fluoride-containing cements were considerably reduced. The enamel which had acquired fluoride from the fluoride-containing cements was apparently more resistant to artificial caries attack.

Acids↗

Fluoride in drinking water and human urine in northern and central Poland.

The fluoride concentration in drinking water and in urine of the inhabitants of 94 localities in Northern and Central Poland was determined. The analyses were performed potentiometrically using a fluoride-specific electrode. In most of the localities the fluoride concentration in water was < 0.3 mg/l, which is far below the recommended level for caries control. In these communities fluoridation of water is advised. In six localities the water fluoride concentration was 1.2 mg/l. The elevated water fluoride is of natural (Malbork) as well as of anthropogenic (Wiślinka) origin. The mean fluoride level in the urine in the investigated localities was 1.10 mg/l (range 0.10-2.67 mg/l). No significant correlation between the concentration of fluoride in drinking water and human urine was found in this study. This suggests that the elevated fluoride level in urine may be caused not only by the water fluoride, but also by the inhalation of dust particles containing fluoride, and by the diet.

Child↗

Position of the American Dietetic Association: the impact of fluoride on health.

Fluoride is an important element for mineralization of body tissues. The use of topical and systemic fluoride for oral health has resulted in major reductions in dental caries and its associated disability. Fluoridation of public water supplies has been endorsed by over 90 professional health organizations as the most effective dental public health measure in existence. Still, about half of the US population fails to receive the maximum benefits possible from community water fluoridation and the use of fluoride products. Fluoride also plays a role in bone health. The role of high doses of fluoride for prevention of osteoporosis is undergoing active study and is considered experimental at this point. Dietetics professionals should routinely monitor and promote the use of systemic and topical fluorides, especially in children and adolescents. The American Dietetic Association strongly reaffirms its endorsement of the use of systemic and topical fluorides, including water fluoridation, at appropriate levels of intake, as an important public health measure. However, clients should be cautioned that experimental use of high intakes of fluoride should be avoided unless they are participating in clinical trials.

Administration, Topical↗

Current and future role of fluoride in nutrition.

Fluoride continues to be the cornerstone of dental caries prevention in North America and throughout the world, and there are a variety of sources of fluoride that may contribute to the dietary intakes of fluoride. Although the severe effect of chronic exposures to high levels of fluoride--skeletal fluorosis--is extremely rare in North America, dental fluorosis has become more prevalent. To address the increase in dental fluorosis prevalence, recommendations have been made to reduce fluoride ingestion early in life. These recommendations have included the introduction of lower concentration fluoride dentifrice for use by young children, labeling of the fluoride concentration of bottled water, and revised fluoride supplement guidelines to reduce or eliminate their use. Because our knowledge is incomplete regarding the amount, duration, and timing of fluoride ingestion that can result in dental fluorosis, however, further research is clearly needed before definitive recommendations can be made regarding the use of fluorides, including recommended intakes of fluoride in the diet.

Dental Caries↗

Enzymatic release of sequestered cows' milk fluoride for analysis by the hexamethyldisiloxane microdiffusion method.

The concentrations of diffusible and total fluoride in cows' milk samples from areas with widely different fluoride levels in drinking water were determined using a fluoride electrode. The diffusible fluoride was determined by direct hexamethyldisiloxane microdiffusion while for total fluoride, samples were subjected to either open ashing or digestion with proteolytic enzymes before microdiffusion. Magnesium nitrate was studied as a new fixative for milk during open ashing and compared with magnesium acetate. Diffusible fluoride ranged from 0.024 to 0.28 microgram ml-1 while total fluoride ranged from 0.05 to 0.31 microgram ml-1. The use of proteolytic enzymes before microdiffusion resulted in total fluoride measurement. It was concluded that all fluoride in milk is inorganic in nature with the bound fluoride being physically or chemically sequestered in the milk proteins. The proposed method is convenient for total fluoride analysis in milk.

Animals↗

FLUORIDE METABOLISM IN ACACIA GEORGINAE GIDYEA.

1. The metabolism of fluoride in seedlings and small plants of Acacia georginae has been studied with the idea of finding the conditions under which the plant makes fluoroacetate in the laboratory. 2. Individual seedlings vary in the extent to which they take up fluoride and convert it into a form other than inorganic which is here called ;organic' fluoride, F(org.). The differences between the toxicity of A. georginae Gidyea trees may therefore be genetic in origin. 3. The uptake of fluoride from solutions 0.525-1.05mm (10-20p.p.m.) was not large. In 1-4 days it reached 8 p.p.m. in the aerial parts and 16 p.p.m. in the roots. Unlike the distribution of the halogen in grass, total fluoride was greater than inorganic fluoride. It was almost a rule that more ;organic' fluoride was present in the roots than in the aerial parts. 4. With higher concentrations of fluoride 10.5-15.75mm (200-300p.p.m.) much larger amounts of fluoride were taken up, especially by the roots, and much more apparent organic fluoride was formed. 5. pH had a large influence upon the intake, this being lowest at an initial pH8.4 and highest at pH4.0. The pH outside this range was not investigated. Some observations have been made with a view to clarifying the biochemical paths for the synthesis of the C-F bond. 6. There is no evidence that chloride is an intermediary in synthesis. 7. Succinate is not accumulated in fluoride-stressed plants, suggesting that succinate dehydrogenase is not inhibited. 8. Enolase does not appear to be inhibited in vivo.

Acacia↗

Drinking water fluoridation and bone.

Drinking water fluoridation has an established role in the prevention of dental caries, but may also positively or negatively affect bone. In bone fluoride is incorporated into hydroxylapatite to form the less soluble fluoroapatite. In higher concentrations fluoride stimulates osteoblast activity leading to an increase in cancellous bone mass. As optimal drinking water fluoridation (1 mg/l) is widely used, it is of great interest, whether long-term exposition to artificial water fluoridation has any impact on bone strength, bone mass, and -- most importantly -- fracture rate. Animal studies suggest a biphasic pattern of the effect of drinking water fluoridation on bone strength with a peak strength at a bone fluoride content of 1200 ppm followed by a decline at higher concentrations eventually leading to impaired bone quality. These changes are not paralleled by changes in bone mass suggesting that fluoride concentrations remain below the threshold level required for activation of osteoblast activity. Accordingly, in most epidemiological studies in humans bone mass was not altered by optimal drinking water fluoridation. In contrast, studies on the effect on hip fracture rate gave conflicting results ranging from an increased fracture incidence to no effect, and to a decreased fracture rate. As only ecological studies have been performed, they may be biased by unknown confounding factors -- the so-called ecological fallacy. However, the combined results of these studies indicate that any increase or decrease in fracture rate is likely to be small. It has been calculated that appropriately designed cohort studies to solve the problem require a sample size of >400,000 subjects. Such studies will not be performed in the foreseeable future. Future investigations in humans should, therefore, concentrate on the effect of long-term drinking water fluoridation on bone fluoride content and bone strength.

Biomechanical Phenomena↗

Efficiency of fluoride programs in the light of reduced caries levels in young populations.

Since the late 1930s, when the efficacy of fluoride in caries prevention was first detected, various efficient methods for fluoride delivery have been developed. Nowadays, fluoride is used for caries prevention on a global scale, the most widely used methods being fluoridated toothpaste and water fluoridation. The latter is a typical community-based prevention method, whereas the former method relies on individual motivation. The goal of an efficient community-based fluoride program is to maintain a constant low level of fluoride in as many mouths as possible at as low a cost as possible. Initially, water fluoridation and other community-based programs were highly efficient, but nowadays in societies in which the major part of the population is using fluoride toothpaste and caries levels are low, population-based programs show a low efficiency. As an example, even though water fluoridation was withdrawn in Kuopio, there have been no dramatic effects on the dental health of children and youths. In societies with well-attended, community-based, free dental health care for children and youths, the dental motivation of individuals is, in general, very high and the use of fluoride for caries prevention may be taken care of at the individual level.

Cariostatic Agents↗

Thirty years of fluoridation: a review.

Fluoride contributes to stability of both teeth and bones and to reduction of caries, especially if ingested before eruption of teeth. Reduction of caries continues at about 60% in persons drinking fluoridated water only as long as fluoride washes over teeth. One-half the population of the US does not have access to water with an optimal fluoride concentration of about 1 mg/L. Misinformation about fluoridation contributes to reluctance of communities to supplement the natural but inadequate fluoride of those water supplies. Fluoridation of water has no positive or negative effect on incidence or mortality rates due to cancer, heart disease, intracranial lesions, nephritis, cirrhosis, mongoloid births, or from all causes together. The collective decision to increase the natural fluoride content of water supplies is not an infringement of civil rights, nor does it establish a precedent in the binding sense of the law. Supplemental fluoride in water makes it available to all members of the community in a safe, practical, economical and reliable manner. Fluoridation saves money in dental costs and time lost from work. Fluoridation is an appropriate action of government in promoting the health and welfare of society.

Abnormalities, Drug-Induced↗

Review of fluoride exposures and ingestion.

The literature on fluoride intake/ingestion was reviewed critically to determine the current exposure to fluorides for children living in non-fluoridated and fluoridated areas in North America. Fluoride from all sources except mouthrinses and professionally applied topical fluorides was considered, including ingestion from foods and beverages, as well as intake from the use of fluoride dentifrice and dietary fluoride supplements. Data from all of these sources were used to produce estimates of mean daily ingestion. Studies consistently have identified substantial variation in ingestion among individuals. These analyses demonstrated that a substantial proportion of individuals had exposure or ingestion well beyond that of the mean for each source, and often 10-20% received up to several times as much exposure as the mean. Some children probably ingest sufficient fluoride from a single source to exceed the "optimal" fluoride intake recommended from all sources, and are therefore at increased risk of fluorosis. This review highlighted the substantial variation and complexity of fluoride ingestion. Appropriate consideration of these aspects is warranted in efforts to ensure a margin of safety favoring dental caries prevention while limiting objectionable fluorosis.

Child↗

Fluorosis risk in grade 2 students residing in a rural area with widely varying natural fluoride.

OBJECTIVES: This pilot study was performed to determine the prevalence of dental fluorosis and the association between fluorosis and a number of risk factors in a group of second grade students in a rural, non-fluoridated area of Ontario, Canada. METHODS: Of 1739 students screened during routine health surveillance, 1367 had erupted maxillary central incisors. Fluorosis was scored on these children using the Tooth Surface Index of Fluorosis (TSIF). A fluoride exposure questionnaire and water sample vial was sent home from school with each child. RESULTS: Valid responses were obtained for 752 children (55%). The prevalence of fluorosis in respondents was 23.3%, with 4.9% scoring TSIF of 2 or more. In bivariate analysis, several variables were significantly associated with the prevalence and/or severity of fluorosis. These included: water fluoride concentration, breast-feeding duration, professionally applied topical fluoride, fluoride supplement use, bottle-feeding, fluoridated mouthwash use, and early parental toothbrushing with toothpaste. In logistic regression analysis limited to children living at the current residence for 4 years or more, only four variables had significant independent effects. These were water fluoride concentration, breast-feeding duration, fluoride supplement use, and fluoridated mouthwash use. CONCLUSIONS: These findings indicate that fluorosis is an important concern in non-fluoridated areas. Fluoride supplements should not be recommended unless an independent home water test is performed. Breast-feeding for 6 months or more may protect children from developing dental fluorosis in the permanent incisors.

Analysis of Variance↗

Scanning electron microscope and electron microprobe study of reactions of stannous fluoride and stannous chloride with dental enamel.

Stannous fluoride but not stannous chloride has shown a caries inhibiting effect in animal studies. The effect of aqueous solutions of stannous fluoride and stannous chloride on dental enamel surfaces was investigated by scanning electron microscope and analytical electron microprobe. Some large globules and a continuous layer of small globules were observed after stannous fluoride treatment. The large globules were soluble in both water and alkali, whereas the small ones were only soluble in alkali. Both fluoride and tin were found to be present on the enamel surfaces by the electron microprobe after stannous fluoride treatment. The fluoride could not be detected after immersion in distilled water whereas alkali treatment removed the tin. The large fluoride-containing globules may consist of calcium fluoride as this substance is known to be slightly soluble in water and soluble in alkali. Stannous chloride treatment gave a layer of small tin-containing globules with properties similar to the layer formed on enamel treated with stannous fluoride. It is therefore suggested that the tin-containing layer is not associated with caries protection whereas calcium fluoride-like deposition on the enamel probably is a factor in the caries inhibition caused by stannous fluoride.

Dental Enamel↗

A critique of topical fluoride methods (dentifrices, mouthrinses, operator-, and self-applied gels) in an era of decreased caries and increased fluorosis prevalence.

Within the last 20 years there has been a decrease in the caries prevalence of US schoolchildren, a change in the intraoral caries pattern, and a slowing of the progress of lesions. Simultaneously, the prevalence of enamel milder, cosmetically acceptable forms and is more noticeable in fluoride-deficient communities than those with optimal or above-optimal water fluoride concentrations. Circumstantial evidence indicates that a principal contributor to the caries decline is the extensive use of fluoride dentifrices. Conversely, although use of a fluoride dentifrice can add to the total daily amount of ingested fluoride in preschool children, there is little evidence to suggest that dentifrice ingestion is a principal factor causing the fluorosis increase. The value of fluoride methods may be assessed in relative or absolute terms. The relative, or percentage, caries reduction attributed to fluoride mouthrinses and gels appears to be a property intrinsic to the methods themselves and generally is little affected by the caries activity of the population being treated. Conversely, the absolute, or numerical, caries reduction is dependent upon the level of disease in the population. Thus, the reported caries decline reduces the number of surfaces prevented from developing caries, even though the percentage reduction remains substantially unchanged. Although inadvertent ingestion of fluoride can result from the use of mouthrinses and gels, there is little evidence to suggest that they have contributed to the fluorosis increase. When using topical methods, prudence should prevail to avoid ingestion of fluoride. Fluoride dentifrices should continue to be used routinely, and although lower potency dentifrices may be considered, the literature does not provide strong support for their need. Use of fluoride mouthrinses and gels for individual patients should be predicted upon their caries activity or risk. Use of these methods in public health programs is a matter of cost-effectiveness, which will be influenced by the caries prevalence of the target population.

Adolescent↗

An economic evaluation of community water fluoridation.

OBJECTIVE: The purpose of this research was to assess the local cost savings resulting from community water fluoridation, given current exposure levels to other fluoride sources. METHODS: Adopting a societal perspective and using a discount rate of 4 percent, we compared the annual per person cost of fluoridation with the cost of averted disease and productivity losses. The latter was the product of annual dental caries increment in nonfluoridated communities, fluoridation effectiveness, and the discounted lifetime cost of treating a carious tooth surface. We obtained or imputed all parameters from published studies and national surveys. We conducted one-way and three-way sensitivity analyses. RESULTS: With base-case assumptions, the annual per person cost savings resulting from fluoridation ranged from $15.95 in very small communities to $18.62 in large communities. Fluoridation was still cost saving for communities of any size if we allowed increment, effectiveness, or the discount rate to take on their worst-case values, individually. For simultaneous variation of variables, fluoridation was cost saving for all but very small communities. There, fluoridation was cost saving if the reduction in carious surfaces attributable to one year of fluoridation was at least 0.046. CONCLUSION: On the basis of the most current data available on the effectiveness and cost of fluoridation, caries increment, and the cost and longevity of dental restorations, we find that water fluoridation offers significant cost savings.

Adolescent↗

Water fluoridation, osteoporosis, fractures--recent developments.

BACKGROUND: Optimal (1ppm) water fluoridation is seen as the most socially equitable way to prevent dental caries, however concerns about the safety of fluoridation are periodically raised. METHODS: Research on effects on bone published since the 1991 National Health and Medical Research Council report on water fluoridation was reviewed. RESULTS: Thirty-three studies were identified. Adverse effects in animal feeding studies were only seen at doses much greater than those currently used in artificial water fluoridation. The majority of animal studies showed no effect or a beneficial effect of low fluoride doses. The results of ecological studies were conflicting. One of the two cohort studies showed an increase in fracture incidence at fluoride levels four times greater than optimal water fluoridation and the other showed no effect after 20 years' optimal fluoridation. The cross-sectional studies showed a favourable effect on bone mineral density. The clinical trials predominantly showed increased bone density in several sites associated with fluoride treatment of 9-22.6mg fluoride per day for one-four years. CONCLUSION: These studies provide a substantial body of evidence that fluoride at up to 1ppm does not have an adverse effect on bone strength, bone mineral density or fracture incidence.

Adult↗

The influence of saliva on the formation of calcium fluoride-like material on human dental enamel.

After a topical fluoride application two resulting features can be observed and measured: the formation of calcium fluoride and a decrease in caries incidence. For the formation of solid calcium fluoride the source of calcium may be either the enamel itself or remaining saliva or--in plaque--plaque fluid and calculus. The aim of the present study was to examine whether saliva through its calcium content has any influence on the amount of calcium fluoride formed by a topical fluoride treatment of enamel. The roots and the fissure systems of 64 freshly extracted intact third molars were covered with nail varnish and allocated to eight groups of 8. Half of the groups were put in fresh paraffin-stimulated saliva for 5 min after which surplus of saliva was shaken off whilst the other groups remained in distilled water. The teeth were given a 2-min topical treatment with either distilled water (control), neutral 0.2% NaF, neutral 2% NaF or 2% NaF acidified with 0.1 mol/l H3PO4. After the topical treatment the teeth were rinsed in running tap water for 5 min, dried and revarnished before determination of calcium fluoride. It was found that the amount of calcium fluoride formed depended on the concentration of fluoride (the higher the fluoride concentration, the higher was the amount of calcium fluoride), the acidity of the solution (presumably due to the increase in available calcium through enamel dissolution) and the presence of saliva (presumably due to its calcium content and its mucinous nature). As there was always more calcium fluoride formed in the presence of saliva, thorough drying of the teeth prior to topical treatments may be superfluous.

Analysis of Variance↗