Fluoridation and Tooth Decay

The main component of tooth enamel is a mineral called hydroxyapatite, Ca5(P04)30H. Some foods contain acids or produce acids in the mouth, and acid dissolves tooth enamel, which leads to tooth decay. 

One way to help prevent tooth decay is by using fluoride. Fluoride reacts with hydroxyapatite in a doubledisplacement reaction. It displaces the 0H group in hydroxyapatite to produce fluorapatite, Ca5(P04)3F. Studies show that calcium fluorapatite is about 20% less soluble than hydroxyapatite in acid. Therefore, fluoride lowers the incidence of tooth decay. 

Explain In combustion reactions, substances combined with oxygen usually result in a fire or explosion. What remains afterwards is usually ash or fine particles, which often do not contain all of the elements found in the reactants. Explain what happens to the missing elements in terms of conservation of matter. 

How can molecular models and formula-unit ionic models be used to balance chemical equations and classify chemical reactions  

Examine the partial equations in Groups A-E. Using different-colored gumdrops to represent atoms of different elements, make models of the reactions by connecting the appropriate atoms with toothpicks. Use your models to (1) balance equations (a) and (b) in each group, (2) determine the products for reaction (c) in each group, and (3) complete and balance each equation (c). Finally, (4) classify each group of reactions by type. 

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The toxic nature of fluoride ion, F, is not confined to its presence in HF. It is toxic in soluble fluoride salts, such as NaF. At relatively low levels, such as about 1 ppm, used in some drinking water supplies, fluoride prevents tooth decay. At excessive levels, fluoride causes fluorosis, a condition characterized by bone abnormalities and mottled, soft teeth. Livestock are especially susceptible to poisoning from fluoride fallout on grazing land as a result of industrial pollution. In severe cases, the animals become lame and even die. 

Stannous fluoride Fluoride Treat tooth decay, prevent tooth plaque and inflammation of gums Flo-Gel, Gel-Kam 0.4... 

The discussion about trace elements or minerals, their role, their optimal concentrations, and of how these may be vital to health and well-being continues. The water fluoridation controversy, of fluoride vs. tooth decay, is related. How much is not enough, and how much is too much Not only with regard to fluoride addition to public water supplies, but with regard to the intervention of the state. Should the state doctor all municipal water supplies to maintain a uniform and apparently optimal mineral content When is it and when is it not the state s business ... 

In spite of these trends, opposition to the use of fluorides against tooth decay remains strong in the United States and other parts of the world. Opponents are not convinced that there is sufficient evidence for the claims that fluoridation decreases the rate of tooth decay. They suggest that fluorides may cause cancer and a host of other health problems. And they argue that fluoridating public water supplies removes the choice that individuals should have as to whether or not they want to use fluorides in their dental health program. 

The primary use of stannous fluoride is in toothpastes, dental rinses, and fluoride treatments for teeth. Fluorides prevent tooth decay in two ways. First, fluorides kill bacteria that cause tooth decay. Second, fluorides react with other chemicals in the mouth to make new enamel to replace enamel destroyed by bacteria or worn away by mechanical processes. Studies suggest that stannous fluoride also has other beneficial effects, including preventing gingivitis (inflammation of the gums) and bad breath. 

In the early 1900s, scientists discovered that people whose drinking water naturally contained fluoride (F ) ions had fewer cavities than people whose water did not. At the proper levels, fluoride strengthens tooth enamel, which prevents tooth decay. In an effort to improve public health, fluoride has been artificially added to drinking water supplies since 1945. In the United States today, about 62% of the population drinks artificially fluoridated drinking water. The American Dental Association and public health agencies estimate that water fluoridation reduces tooth decay by 40 to 65%. 

Fluorides retard tooth decay by forming a hard, acid-resisting calcium fluoride layer in the reaction SnFj + Ca(OH>2 CaFj + Sn(OH)2. If at the time of a treatment there are 239 mg Ca(OH>2 on the teeth and the dentist uses a mixture that contains 305 mg SnF2, has enough of the mixture been used to convert all of the Ca(OH)2 If no, what minimum additional amount should have been used If yes, by what number of mUbgrams was the amount in excess ... 

It is noteworthy that there are only small margins of safety between beneficial and hazardous doses for (1) fluoride, which may cause severe defects of teeth and bones and (2) selenium which is suspected of being a cause of liver damage and tooth decay. 

Studies have proven conclusively that fluoride is an effective tooth decay preventative. As a result, in the late 1960s and 1970s, many... 

Sodium fluoride (NaF), in the concentration of one ppm, is added to municipal drinking water to help reduce tooth decay. It is also used as an insecticide, fungicide, and rodenticide, as well as in the manufacture of adhesives, disinfectants, and dental products. 

C.M. Jones, G.O. Taylor, J.G. Whittle, D. Evans, D.P. Trotter, Water fluoridation, tooth decay in 5 year olds, and social deprivation measured by the Jarman score Analysis of data from British dental surveys. Br. Med. J. 315 (1997) 514-517. 

Fluoride ion tends to replace the isoelectronic ion OH- in solids. In particular, hydroxyapatite, Cas O OH, the chief constituent of tooth enamel, reacts slowly with aqueous fluoride to form fluoroapatite, which is harder and more resistant to tooth decay. The dental profession therefore advocates fluoride treatments at the time of regular dental checkups, and also (primarily to provide for the dental health of children) the presence of 0.7-1.0 ppm natural or added F in drinking water. Too much (>4 ppm) F in water, however, is acknowledged to cause mottling of teeth and bone sclerosis. Thus, the range of concentrations over which fluoride in public drinking water is considered to be beneficial is rather narrow. 

It is recommended that drinking water contain 1.6 ppm fluoride (F ) for prevention of tooth decay. Consider a reservoir with a diameter of 4.50 X 102 m and a depth of 10.0 m. (The volume is where r is the radius and h is the height.) How many grains of F should be added to give 1.6 ppm How many grams of sodium fluoride, NaF, contain this much fluoride ... 

There are as many salts as there are acids and bases. Sodium cyanide, NaCN, is a deadly poison. Saltpeter, which is potassium nitrate, KN03, is useful as a fertilizer and in the formulation of gunpowder. Calcium chloride, CaCl2, is used ro deice roads, and sodium fluoride, NaF in toothpaste, prevents tooth decay. The acid-base reactions forming these salts are shown in Table 10.1. 

A high sucrose diet promotes decay.11 While most people have some trouble with tooth decay, 1 or 2 per thousand remain totally free of caries and seem to be immune. Many factors must affect resistance to caries. For example, individuals vary in the kinds and numbers of bacteria present on teeth and in the structure of tooth enamel.0 Addition of fluoride ion to water supplies at a level of lppm (0.05 mM) is generally believed to reduce the incidence of tooth decay. However, caries has been declining in many developed countries at rates that are the same for water with or without fluoride.p q If teeth escape caries periodental disease, caused by bacteria, is often a major problem for older people.1... 

In spite of its toxicity and extreme reactivity, fluorine is widely used for the manufacture of polymers such as Teflon, (C2F4) . Fluorine is also important in the production of UF6, used in the separation of uranium isotopes for nuclear power plants, and fluoride ion is added to toothpaste in the form of NaF to help prevent tooth decay. 

Fluorine is used in the form of fluorides in drinking water and toothpaste because it reduces tooth decay by hardening the enamel on teeth. 

Finally, a little chlorine gas is added, which sterilises the water and kills any remaining bacteria. Excess chlorine can be removed by the addition of sulfur dioxide gas. The addition of chlorine gas makes the water more acidic and so appropriate amounts of sodium hydroxide solution are added. Fluoride is sometimes added to water if there is insufficient occurring naturally, as it helps to prevent tooth decay. 

Fluoridation of water is often used to help reduce tooth decay. However, whereas levels of 1 ppm are commonly used, excessive fluoride levels (>2 ppm) can be a problem and need to be corrected. Analytical Technology Inc. manufactures a fluoride-sensitive ISE for this purpose [152]. 

Other important inorganic compounds of fluorine include uranium hexafluoride, UF6, a volatile substance that was used to separate 238U from the fissionable 235U by gaseous diffusion in the Manhattan Project. Sodium fluoride, NaF, is often added to drinking water and to toothpaste in order to reduce the incidence of tooth decay. 

The tin(II) halides are much less volatile than the corresponding tin(IV) compounds in fact, they are probably ionic, containing Sn2+ and X- ions. Tin(II) chloride in aqueous solution is commonly used as a reducing agent. Tin(II) fluoride (stannous fluoride) was for many years added to toothpaste to help prevent tooth decay. It has since been replaced by sodium fluoride. 

Fluoride is a monovalent anion. It appears not to be an essential nutrient, as raising animals on a fluoride-defidenl diet over three generations has been found not to impair growth and reproduction. Fluoride has proven to be of value in reducing the rate of dental caries (tooth decay). There has been much interest in the possibility that fluoride can prevent and reverse osteoporosis, though such effects have not been proven. 

The effect of fluoride in ptevenring dental caries was recognized when it was found that levels of tooth decay were low in regions of the world where the water supply naturally contained high levels of fluoride. In some regions, the levels of fluoride are so high that they cause a harmless mottling of the teeth called "fluorosis." Both the first set and the permanent set of teeth benefit from dietary fluoride. Water and other fluids account for most of our fluoride intake. 

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