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fluoride

  (flʊr-, flōr'-) pronunciation
n.

A binary compound of fluorine with another element.

[FLUOR(INE) + –IDE.]


 
 
Food and Nutrition: fluoride

The ion of the element fluorine. Although it occurs in small amounts in plants and animals, and has effects on the formation of dental enamel and bones, it is not considered to be a dietary essential and no deficiency signs are known.

Drinking water containing about 1 part per million of fluoride protects teeth from decay, and in some areas fluoride is added to drinking water to achieve this level. Naturally, the fluoride content of water ranges between 0.05 and 14 ppm. Effect in preventing caries first observed by a dentist, Frederick Motley, in Colorado Springs, 1916.

Water containing more than about 12 ppm fluoride can lead to chalky white patches on the surface of the teeth, known as mottled enamel. At higher levels there is strong brown mottling of the teeth and inappropriate deposition of fluoride in bones known as fluorosis.

 
Dental Dictionary: fluoride(s)

n

A salt of hydrofluoric acid, commonly sodium or stannous (tin).

 
Sports Science and Medicine: fluoride

A salt of hydrofluoric acid containing the fluoride ion; or any compound containing the element fluorine. Fluorides are found in bones and teeth. It has been added to water to harden teeth and protect them against decay. In the USA, the Recommended Dietary Allowance is 1.5-4.0 mg. Tea and seaweeds are good sources. Excess fluoride intake may increase the risk of osteoporosis.

 
Food & Culture Encyclopedia: Fluoride

Fluoride is an important trace element in human nutrition. Daily exposure to small quantities is widely considered to be vital for maintenance of sound tooth structure. Ingested or systemic fluoride has long been known to offer significant benefit when supplied during tooth formation in childhood. More recently, topical exposure (that is, making fluoride available at the tooth surface) has been shown to provide benefits throughout life, even for older adults.

Sources of Fluoride

Water, rocks, soil, and living tissue all have naturally occurring fluoride as a constituent. Crystalline and carbonate minerals containing fluoride are common throughout the earth's near-surface crust. As water flows through the environment, fluoride and many other ions dissolve from sedimentary rock layers and soil into aquifers, streams, rivers, and oceans. Dissolved ions are essential for humans and all living things. Fluoride ions are absorbed directly from the water we drink.

Fluoride in Bone and Tooth Tissue

Fluoride ions taken systemically can become incorporated within bone and tooth tissue. Although bones and teeth have an organic matrix, it is their inorganic or crystalline hydroxyapatite composition that gives them their strength and hardness. Living human cells use available calcium and other minerals to form strong hydroxyapatite matrices. When fluoride ions are also available to the cells, an additional material called fluorapatite is formed. Integration of a small amount of fluorapatite within a hydroxyapatite matrix may produce a more durable substance than is found with hydroxyapatite alone.

Topical Mechanism

Fluoride ions can also provide a very strong surface or topical effect for teeth when available on a regular basis. One such effect is that topical fluoride inhibits the ability of some bacteria to produce dental plaque by blocking the function of important intracellular bacterial enzymes. Much more significantly, topical fluoride also leads to reduced demineralization and increased remineralization of enamel surfaces.

Bacterial Acid and Chemical Balance

Demineralization of a tooth occurs when bacteria create an acidic or low pH environment at the tooth surface. The acidity dissolves hydroxyapatite, releasing positively charged calcium ions and negatively charged carbonate and phosphate ions into saliva. When normal saliva flow dilutes the acidity, the positive and negative ions recombine and remineralize the surface.

This cycle represents a balance. Diets rich in fermentable carbohydrates such as mono-and disaccharides, which are relatively simply sugars, disrupt the balance. They stimulate some oral bacteria to produce dental plaque and acid. Dental plaque is a substance that attaches to tooth enamel and is colonized by the bacteria that form it. Once such a colony is established, each ingestion of fermentable carbohydrate causes approximately one half-hour of intense acid production by the bacteria. This burst of acid production lowers the pH near the tooth surface, demineralizing large amounts of hydroxyapatite. The balance is disrupted and, as the cycle is repeated, it damages the tooth's surface.

Topical Fluoride and Stronger Enamel

When sufficient amounts of negatively charged fluoride ions are routinely present topically at the tooth surface, a different pattern emerges for this cycle. The balance of demineralization and remineralization actually builds fluoride into the tooth's surface structure. Over long exposure to fluoride in saliva, more and more fluoride is incorporated, and the enamel surface becomes stronger. A much greater increase in acidity is then necessary before a destructive imbalance in the cycle will be initiated. This surface or topical effect is thought to be the primary means by which fluoride prevents dental caries.

Benefits of Community Water Fluoridation

In studies of many communities over several decades, it has become clear that there is great benefit to maintaining proper fluoride levels in the public water supply. A concerted public health effort throughout the decades since the 1950s has led to the maintenance of fluoride at these levels in many public water supplies.

Community water fluoridation is intended to provide fluoride at concentrations ranging from 0.7 to 1.2 ppm. Coincidentally, this is about the same concentration of fluoride that is found in ocean water. Levels are adjusted within this range regionally and throughout the year. This provides lower concentrations of fluoride when people are likely to drink more water and higher concentrations when less water consumption is expected.

Without other significant sources of fluoride during the 1950s and 1960s, community water fluoridation produced reductions of 40 to 50 percent in the number of cavities or dental caries among children. Their teeth had enamel that was more resistant to caries both when it was formed and throughout life.

Other countries have assessed a variety of alternative means for delivering protective levels of fluoride. These have included supplementation with tablets or drops, salt fluoridation, and milk fluoridation. However, in the United States, fluoridation of public water as part of purification treatment remains the most effective and economical means for providing this benefit to communities. Currently about 60 percent of the U.S. population has fluoride maintained at these levels in their drinking water.

In the 1980s, it became clear that the positive effects of water fluoridation were not limited to developing teeth. Studies of people age sixty-five and older showed that it was beneficial even when all of the fluoride exposure took place after tooth eruption. Those who lived in communities with fluoridated water as adults had significantly lower rates of dental caries on exposed tooth root surfaces than comparable older adults without fluoridated water.

Fluoride and Osteoporosis

There has been interest in potential positive effects of fluoride supplementation on increased bone density. When ingested, fluoride is absorbed primarily from the upper gastrointestinal tract and is excreted in urine. Fluoride that is not excreted is deposited in calcified tissues—bones and teeth.

Osteoporosis, loss of bone density, is an increasingly prevalent problem in the U.S. population among both men and women. Unfortunately, research to date does not suggest a useful effect of fluoride on bone strength, even when it is supplemented at concentrations twenty times greater than that found in fluoridated water.

Early Research on Fluoride

It was research on the effects of prolonged intake of excessive amounts of naturally occurring fluoride that led scientists to understand the protection afforded by healthy fluoride levels. In the 1930s, a dentist in Colorado, Dr. Frederick McKay, became curious about a brown surface stain seen on some of his patients' teeth. These teeth often had a rough and porous surface texture, yet they were also far less prone to develop dental caries.

McKay's early observations led to a long series of investigations. It became clear that this problem, a severe form of fluorosis, resulted from very high levels of naturally occurring fluoride in drinking water. McKay's water samples had fluoride concentrations as much as fourteen times greater than that recommended today for community water systems. These investigations led to the discovery that when fluoride was present at the low levels that are now widely used, it offered powerful protection from dental caries without any adverse effects.

Reevaluation of Fluoride Use

By the 1990s, the wide availability of fluoridated water led scientists to reevaluate fluoride use practices. Particular attention was paid to the potential for a diffuse exposure to fluoride throughout the population. Many packaged foods are processed in communities with fluoridated water, becoming sources of small amounts of fluoride to those who consume them. Far more important, however, is the use of toothpaste and other products containing fluoride. It was concluded that community water fluoridation levels remain appropriate, but that greater care must be taken in the use of fluoride toothpaste.

Levels of fluoride in treated drinking water are extremely low when compared to concentrations in common therapeutic products. For example, fluoride concentration in over-the-counter fluoride mouth rinses is generally about 230 parts per million (ppm); toothpastes contain about 1,000 ppm; prescription home-use mouth rinses and home-use gels range from 1,000 to 5,000 ppm; professionally applied fluoride gels contain 10,000 to 12,300 ppm; and professionally applied fluoride varnishes contain about 22,000 ppm.

The additional sources of fluoride, primarily toothpaste, have led to lower rates of dental caries in U.S. communities not provided with fluoridated water. However, even with these lower background rates of dental caries in the population, it is estimated that community water fluoridation alone still provides an additional reduction of 20 to 40 percent in dental caries when comparison is made to caries rates for Americans who do not have fluoridated water but who use fluoride toothpaste.

Fluoride Issues for the Future

During the reevaluation of fluoride in the 1990s, concerns were raised regarding the potential for fluorosis. In contemporary studies of fluorosis in the U.S. population, nearly all observed cases have been classified as "very mild" or "mild." These are categories of "white-spot" discoloration that are usually only apparent to a dentist conducting an intraoral examination. Ingestion of fluoride toothpaste is considered the primary explanation for these white-spot discolorations.

Children are likely to swallow toothpaste while brushing, ingesting an unintended and excessive amount of fluoride. The most effective strategy for avoiding mild fluorosis is to limit children to a pea-sized quantity of toothpaste at each brushing. This quantity is adequate for caries prevention and oral hygiene, but it should not lead to development of fluorosis.

Use of infant formula and some baby foods has also raised a degree of concern. Because of infants' very small body mass, the proper intake of systemic fluoride is lower than that for slightly older children. Some studies have identified varying levels of fluoride in these products, some approaching levels that are associated with increased risk for very mild or mild fluorosis in infants. Physicians and dentists are urged to use caution in prescribing fluoride supplements for infants and very young children living in communities without fluoridated water because they might be consuming these fluoride-containing products.

The U.S. Environmental Protection Agency has set a standard of 4.0 ppm as the maximum allowable fluoride level in drinking water. Within the United States, fluoride levels in drinking water are actually maintained at about one-fourth of this level. However, in some developing countries, particularly in southern Asia and northern Africa, natural fluoride is present at extremely high levels. In India, for example, a study sponsored by the World Health Organization found natural fluoride levels exceeding 1.5 ppm in about 8 percent of samples, with some concentrations as high as 22.0 ppm. In such areas, public health workers actively engage in efforts to reduce fluoride exposure and eliminate fluorosis.

Conclusion

Nearly one hundred organizations with related expertise, including the World Health Organization, the U.S. Public Health Service, the American Medical Association, the American Public Health Association, the American Society for Clinical Nutrition, the American Society for Nutritional Sciences, the International Association for Dental Research, the FDI World Dental Federation, and the American Cancer Society have recognized the importance of daily fluoride intake for dental health. Particularly when supplied through community water fluoridation, ensuring adequate dietary fluoride exposure has been an extremely safe and cost-effective public health measure. Fluoride is a trace element that has extremely important personal and public health benefits for promotion and maintenance of optimal oral health.

Bibliography

American Dental Association. "Statement on Water Fluoridation Efficacy and Safety." Available at http://www.ada.org/prof/prac/issues/statements/fluoride2.html.

American Dental Association. "Fluoride and Fluoridation."Available at http://www.ada.org/public/topics/fluoride/facts-intro.html.

American Dietetic Association. "Position of the American Dietetic Association: The Impact of Fluoride on Health." Journal of the American Dietetic Association 100 (2000): 1208–1213.

Burt, Brian A., and Stephen A. Eklund. Dentistry, Dental Practice, and the Community 5th ed. Philadelphia: W.B. Saunders, 1999.

Clarkson, John J., and Jacinta McLoughlin. "Role of Fluoride in Oral Health Promotion." International Dental Journal 50 (2000): 119–128.

Ekstrand, J., and A. Oliveby. "Fluoride in the Oral Environment." Acta Odontologica Scandinavica 57 (1999): 330–333.

Gillcrist, James A., David E. Brumley, and Jennifer U. Blackford. "Community Fluoridation Status and Caries Experience in Children." Journal of Public Health Dentistry 61 (2001): 168–171.

Griffin, S. O., K. Jones, and S. L. Tomar. "An Economic Evaluation of Community Water Fluoridation." Journal of Public Health Dentistry 61 (2001): 78–86.

International Collaborative Research on Fluorides: Research Needs Workshop, sponsored by the National Institute of Dental and Craniofacial Research, May 1999. "International Collaborative Research on Fluoride." Journal of Dental Research 79 (2000): 893–904.

National Institutes of Health (NIH). "Diagnosis and Management of Dental Caries Throughout Life." Consensus Statement 2001, March 26–28, Vol. 18, No. 1.

Office of the Surgeon General. Oral Health in America: A Report of the Surgeon General. Rockville, Md.: U.S. Department of Health and Human Services, 2000.

Stephen, K. W. "Fluoride Prospects for the New Millennium: Community and Individual Patient Aspects." Acta Odontologica Scandinavica 57 (1999): 352–355.

ten Cate, J. M., and Cor van Loveren. "Fluoride Mechanisms." Dental Clinics of North America 43 (1999): 713–742.

Warren, John J., and Steven M. Levy. "Systemic Fluoride: Sources, Amounts, and Effects of Ingestion." Dental Clinics of North America 43 (1999): 695–711.

—Rob Berg

 
Science Dictionary: fluoride
(floor-eyed, flawr-eyed)

Any of a number of naturally occurring compounds of the element fluorine. Fluorides have been found to be effective in preventing tooth decay and are routinely added to drinking water in most jurisdictions.

 
Veterinary Dictionary: fluoride

Any binary compound of fluorine. See also fluorine.

 
Word Tutor: fluoride
pronunciation

IN BRIEF: A salt containing a nonmetallic univalent element belonging to the halogens

pronunciation Many cities add fluoride to their drinking water to help the citizens to have healthy teeth.

 
Wikipedia: fluoride
This article is about the chemical ion F −. For the addition of fluoride ions to water supplies, see Water fluoridation.

Fluoride is the ionic form of fluorine. Fluorides are organic and inorganic compounds containing the element fluorine. As a halogen, fluorine forms a monovalent ion (−1 charge). Fluoride forms a binary compound with another element or radical. Examples of fluoride compounds include hydrofluoric acid (HF), sodium fluoride (NaF) and calcium fluoride (CaF2), and uranium hexafluoride (UF6).

Occurrence

Fluoride compounds, usually calcium fluoride, are naturally found in low concentration in drinking water and some foods, such as tea, seaweed, and fish bones (as in fish soup).

Water with underground sources are more likely to have higher levels of fluoride, while the total concentration in seawater has an average concentration of 1.3 parts per million (ppm).[1] Fresh water supplies generally contain between 0.01-0.3 ppm, while the ocean contains between 1.2 and 1.5 ppm.[2]

Applications

Hydrofluoric acid is used in the etching of glass and other industrial applications, including integrated circuit manufacturing.

Fluoride, as a concentrated gel, foam, or varnish, is used as a prescription drug.[3] Fluorine is also part of certain drug molecules to resist detoxification in the liver by the Cytochrome P450 oxidase because the strong C-F bonds are not easily broken. This is to ensure that orally administered medication are not inactivated before reaching the blood stream.[citation needed]

Fluoride ion has a very significant use in synthetic organic chemistry. The silicon-fluorine chemical bond is quite strong. Silyl ether protecting groups can be easily removed by the addition of fluoride ion. Sodium fluoride or tetra-n-butylammonium fluoride (TBAF) are the most common reagents used.

In biochemistry, fluoride salts are commonly used to inhibit the activity of serine/threonine phosphatases.

Sulfur hexafluoride is a nearly-inert, non-toxic propellant. Uranium hexafluoride is used in the separation of isotopes of uranium between the fissile isotope U-235 and the non-fissile isotope U-238 in preparation of nuclear reactor fuel and atomic bombs.

Water fluoridation

Main article: Water fluoridation

Fluoride containing compounds such as sodium fluoride, calcium fluoride, and sodium monofluorophosphate are commonly added to toothpaste, drinking water, prescribed treatments, and other commercially available oral hygiene products because fluoride increases the resistance of the enamel to decay. Originally, sodium fluoride was used to fluoridate water; however, hexafluorosilicic acid (H2SiF6) and its salt sodium hexafluorosilicate (Na2SiF6) are more commonly used, especially in the United States.

Some studies suggest that fluoridation is associated with a median decline in the number of children with cavities of 12.5%, and a median decline of 2.25 teeth with cavities. [4] The fluoridation of water is not without critics, however (see Water fluoridation controversy).

Salt fluoridation

In countries where large, centralized water systems are uncommon, salt fluoridation is sometimes used as an alternative to water fluoridation. In countries where salt fluoridation is common, such as Switzerland, France, and Jamaica, among many others, caries experience has also decreased in groups using fluoridated salt compared to groups using salt without fluoride. [5][6]

Toxicology

Acute

In high concentrations, fluoride compounds are toxic and can cause death. In mice, the LD50 is estimated to be 184 milligrams of stannous fluoride per kilogram of body mass.[7] An individual report involving fatality following the accidental administration of fluoride ion to a child at 5 mg/kg was cited by G. M. Whitford in 1987,[8] while after experimenting on himself in 1899, Herbert H Baldwin reported symptoms of acute toxicity (e.g. gastrointestinal upset) occurred at doses as low as 0.1-0.3 mg/kg.[9]

When ingested directly, fluoride compounds are readily absorbed by the intestines. Over time, the compound is excreted through the urine, and the half life for concentration of fluorine compounds is on an order of hours. It is thought that fluoride is taken out of circulation by the body and trace amounts become bound in bone. Urine tests are a good indication of high exposure to fluoride compounds in the recent past.

Skin or eye contact with many fluoride compounds in high concentrations is dangerous. In case of accidental swallowing, milk, calcium carbonate, or milk of magnesia is given to slow absorption. Eye or skin contact is treated by removing any contaminated clothing and flushing with water.

Chronic

Fluoride ions replace hydroxide ions in calcium hydroxyapatite, Ca5[(PO4)3OH], in teeth, forming calcium fluoroapatite, Ca5[(PO4)3F], which is more chemically stable and dissolves at a pH of 4.5, compared to 5.5 pH for calcium hydroxyapatite. This is generally believed to lead to fewer cavities, since stronger acids are needed to attack the tooth enamel. In 1951, Joseph C. Muhler and Harry G. Day of Indiana University reported their research results on stannous fluoride as a tooth decay preventive and the university first sold the technology to Procter & Gamble to use in Crest toothpaste. Groups that have evaluated available studies and support water fluoridation include The American Dental Association (ADA), World Health Organization (WHO), and some other health organizations which recommend raising the fluoride level of municipal water supplies to a level between 0.7 and 1.2 ppm.

The most widely accepted adverse effect of low concentration fluoridation at this time is fluorosis [4]. It is a condition caused by 'excessive' intake of fluorine compounds over an extended period of time, and can cause yellowing of teeth. The definition of 'excessive' in the context of fluorosis falls on the order of parts per million and is generally accepted to mean significantly higher than the 0.7 to 1.2 ppm amounts recommended for fluoridated water. However, dosage is crucial to adverse effects, and therefore, what concentration is problematic will depend on the amount of fluoride ingested, how much is absorbed, and the weight of the person ingesting it. For this reason, many doctors have advised against using fluoridated water to make up formula for infants.

Contested claims


Main article: Water fluoridation controversy

Some opponents of fluoridation have expressed concern that fluoride damages body function. One of the key concerns is that fluoride can weaken bone strength, leading to an increase in hip and wrist fracture [10]. Additional concerns of fluoridation opponents include the potential for fluoride to damage the brain[11], reduce thyroid function[12], and cause bone cancer in adolescent boys[13]. While a recent review from the US National Research Council supports concerns that fluoride may cause some of these effects, at least at high doses[14], however, more than 100 national and international health service agencies and professional organizations continue to accept that there are benefits of community water fluoridation in preventing dental decay.[15]

See also

References

  1. ^ Fluoride in Drinking-water: Background document for development of WHO Guidelines for Drinking-water Quality. World Health Organization, 2004, page 2. Page accessed on February 22, 2007.
  2. ^ Environmental Health Criteria 227: Fluorides. World Health Organization, 2002, page 38. Page accessed on February 22, 2007.
  3. ^ Centers for Disease Control and Prevention. Fluoridation - Other fluoride products. Page accessed on March 22, 2007.
  4. ^ a b McDonagh M S, Whiting P F, Wilson P M, Sutton A J, Chestnutt I, Cooper J, Misso K, Bradley M, Treasure E, & Kleijnen J. (2000). "Systematic review of water fluoridation". British Medical Journal 321 (7265): 855-859. DOI:10.1136/bmj.321.7265.855. 
  5. ^ Estupiñán-Day, S R; Horowitz H, Warpeha R, Sutherland B, Thamer M (2001). "Salt fluoridation and dental caries in Jamaica". Journal of Community Dentistry and Oral Epidemiology 29: 247-252. 
  6. ^ Fabien, V; Obry-Musset A M, Hedelin G, Cahen P M (1996). "Caries prevalence and salt fluoridation among 9-year-old schoolchildren in Strasbourg, France". Journal of Community Dentistry and Oral Epidemiology 24: 408-411. 
  7. ^ Tin(II) Fluoride MSDS
  8. ^ Whitford, G. M.. "Fluoride in Dental Products". Journal of Dental Research 66 (5): 1056. 
  9. ^ Baldwin, H. B. (1899). "The Toxic Action of Sodium Fluoride". Journal of the American Chemical Society 21 (6): 517-521. DOI:10.1021/ja02056a008. 
  10. ^ Colquhoun, John. Why I Changed My Mind about Fluoridation', Perspectives in Biology & Medicine 1997;41,27-44. Page accessed 23 February, 2007.
  11. ^ National Research Council. Neurotoxicity and Neurobehavioral effects' Fluoride in Drinking Water: A Scientific Review of EPA's Standards (2006). Page accessed 23 February, 2007.
  12. ^ National Research Council. Effects of the Endocrine System' Fluoride in Drinking Water: A Scientific Review of EPA's Standards (2006). Page accessed 23 February, 2007.
  13. ^ Environmental Working Group. Harvard Study: Strong Link Between Fluoridated Water and Bone Cancer in Boys' April 5, 2006. Page accessed 23 February, 2007.
  14. ^ National Research Council. Fluoride in Drinking Water: A Scientific Review of EPA's Standards Page accessed 23 February, 2007.
  15. ^ National and International Organizations that Support Fluoride, from the Massachusetts Coalition for Oral Health website, page accessed March 19, 2006.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

 
Translations: Fluoride

Dansk (Danish)
n. - fluorid, fluormetal

Nederlands (Dutch)
fluoride

Français (French)
n. - fluorure

Deutsch (German)
n. - Fluorid

Ελληνική (Greek)
n. - (χημ.) φθοριούχο άλας, φθορίδιο

Italiano (Italian)
fluoruro

Português (Portuguese)
n. - fluoreto (m) (Quím.)

Русский (Russian)
фторид, фтористое соединение

Español (Spanish)
n. - fluoruro

Svenska (Swedish)
n. - fluorid, fluorförening

中文（简体） (Chinese (Simplified))
氟化物

中文（繁體） (Chinese (Traditional))
n. - 氟化物

한국어 (Korean)
n. - (화학) 불화물

日本語 (Japanese)
n. - フッ化物

العربيه (Arabic)
‏(الاسم) الفلوريد‏

עברית (Hebrew)
n. - ‮פלואוריד, מלח של חומצת פלור‬

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
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