Dental caries water fluoridation

This much is certain there has been a dramatic decline in the incidence of dental caries since fluoridation of water supplies became widespread. This is doubly fortunate inasmuch as the safety of mercury amalgams, the... 

Fluoridation of potable water suppHes for the prevention of dental caries is one of the principal uses for sodium fluoride (see Water, municipal WATER treatment). Use rate for this appHcation is on the order of 0.7 to 1.0 mg/L of water as fluoride or 1.5 to 2.2 mg/L as NaF (2). NaF is also appHed topically to teeth as a 2% solution (see Dentifrices). Other uses are as a flux for deoxidiziag (degassiag) rimmed steel (qv), and ia the resmelting of aluminum. NaF is also used ia the manufacture of vitreous enamels, ia pickling stainless steel, ia wood preservation compounds, caseia glues, ia the manufacture of coated papers, ia heat-treating salts, and as a component of laundry sours. 

Eluoride added to a compatible dentifrice base at a level of 1000 ppm has been clinically proven to reduce the incidence of dental caries by about 25% on average, even in areas where the water supply is fluoridated (4). Elevation to 1500 ppm increases the protection. Sources of fluoride approved for use in dentifrices are sodium fluoride [7681-49-4] (0.22%), sodium monofluorophosphate (0.76%), and stannous fluoride [7783-47-3] (0.41%). The Eood and Dmg Administration regulates fluoridated dentifrices as dmgs and has estabUshed parameters for safe and effective products. CompatibiUty of the fluoride with the abrasive is an important requirement. 

The incidence of dental caries has decreased dramatically in recent years. It has fallen to such an extent as to reduce the need for professional dental health services related to caries significantly. The cause is not clear, but water fluoridation, addition of fluoride to toothpaste, and other modes of fluoride adrninistration are generally conceded to be important contributors to the phenomenon and the American Dental Association recommends use of a fluoride toothpaste for all patients (10). 

F H. T. Dean et al. put the correlation between decreased incidence of dental caries and the presence of fluoride ions in drinking water on a quantitative basis... 

NaF for water fluoridation, wood preservatives, the formulation of insecticides and fungicides, and use as a fluxing agent. It is also used to remove HF from gaseous Fz in the manufacture and purification of Fz-SnFz in toothpastes to prevent dental caries,... 

Dissolved mineral salts The principal ions found in water are calcium, magnesium, sodium, bicarbonate, sulphate, chloride and nitrate. A few parts per million of iron or manganese may sometimes be present and there may be traces of potassium salts, whose behaviour is very similar to that of sodium salts. From the corrosion point of view the small quantities of other acid radicals present, e.g. nitrite, phosphate, iodide, bromide and fluoride, have little significance. Larger concentrations of some of these ions, notably nitrite and phosphate, may act as corrosion inhibitors, but the small quantities present in natural waters will have little effect. Some of the minor constituents have other beneficial or harmful effects, e.g. there is an optimum concentration of fluoride for control of dental caries and very low iodide or high nitrate concentrations are objectionable on medical grounds. 

A town adds 2.0 ppm of F ion to fluoridate its water supply (fluoridation of water reduces the incidence of dental caries). If the concentration of Ca2+ in the water is 3.5 X 10-4 M, will a precipitate of CaF2 form when the water is fluoridated ... 

Most foods and drinking waters contain enough fluoride to result in the incorporation of significant amounts of fluoride into this mineral whereby the solubility decreases. Therefore, the system hydroxyapatite-fluorapatite is primarily of importance for the prevention of dental caries. However, in this context its theoretical treatment is important for geochemists who may be confronted with so-called subregular solid solutions. 

Fluoride is the salt, such as sodium fluoride, of the element fluorine. It is readily absorbed by the intestine and is incorporated into bone or tooth enamel. When incorporated into teeth, fluoride strengthens the outer layers of enamel, thus reducing dental caries. It is generally accepted that addition of fluoride to the drinking water (approximately 1 ppm) is beneficial for the reduction in childhood dental caries. 

Fluoridation of drinking water has been shown to be highly effective in reducing the incidence of childhood dental caries [128,129], Earlier results were better,... 

A major benefit of water fluoridation to children is that it reduces disparities between socio-economic groups [133,134], Children in lower socio-economic groups tend to suffer more severely from dental caries, and though the reasons for this are not clear, the result has been confirmed in many parts of the world. Children in these groups therefore benefit enormously from fluoridation of the water supply and in areas where the water supply is fluoridated, the differences in dental caries experience between the social classes are much less than in non-fluoridated areas [135],... 

The effect of fluoridation on adult dental health is harder to quantify. There are several reasons for this. Adults vary in the extent to which they may have been exposed to fluoride while growing up, and they may experience tooth loss for reasons other than dental caries, for example, trauma or periodontal disease. However, despite these difficulties, what evidence there is points to fluoride being beneficial for adult healthcare [136,137], and for older adults in particular, conditions such as root caries has been demonstrated quite clearly to be less prevalent in regions where the drinking water is fluoridated [138,139], The overall conclusion from all of these studies is that the whole population benefits from fluoridation in terms of improvements to their overall dental health. 

H.T. Dean, F.A. Arnold Jr., E. Elvove, Additional studies of the relation of fluoride domestic waters to dental caries experience in 4,425 white children aged 12-14 years of 13 cities in 4 states, Public Health Rep. 65 (1942) 1403-1408. 

F.A. Arnold Jr., H.T. Dean, J. Knutson, Effect of fluoridated public water supplies on dental caries incidence. Results of the seventh year of study at Grand Rapids, Muskegon, Mich., Public Health Rep. 68 (1953) 141-148. 

S.A. Ekiund, B.A. Burt, A.I. Ismail, J.J. Calderone, High fluoride drinking water, fluorosis, and dental caries in adults, J. Am. Dent. Assoc. 114 (1987) 324-328. 

D.M. O Mullane, J. Clarkson, T. Holland, S. O Hickey, H. Whelton, Effectiveness of water fluoridation in the prevention of dental caries in Irish children, Commun. Dent. Health 5 (1988) 331-344. 

Because of the low natural levels of fluoride in some water supplies and correspondingly high levels of dental caries, many authorities worldwide have permitted, or instigated, fluoridation of water supplies, although this has met some opposition, partly because of the potential health or dental effects including fluorosis. In order to prevent dental caries, fluoride is deliberately added to salt or milk in some countries. 

Due to ubiquitous exposure to fluoride sources other than drinking water, it is not possible to draw firm conclusions regarding the independent effects of fluoride in drinking water on dental caries and its prevention. It has been estimated that moderate dental fluorosis occurs in 1-2% of the population exposed to fluoride at 1 mg/L in drinking water and in about 10% of the population at 2 mg/L moderate/severe fluorosis occurs in variable percentages ranging up to 33% of the population exposed to fluoride at 2.4-4.1 mg/L [52]. 

The Standing Committee on the Scientific Evaluation of Dietary Reference Intakes [8] in 1997 defined the Al for fluoride, stating Based on the extensively documented relationship between caries experience and both concentration of fluoride in water and fluoride intake, the Al for fluoride from all sources is set at 0.05 mg/day/kg body weight. This intake range is recommended for ages above 6 months because it confers a high level of protection against dental caries and is associated with no known unwanted health effects . 

F.J. McClure, Ingestion of fluoride and dental caries, quantitative relations based on food and water requirements of children one to twelve years old. Am. J. Dis. Child. 66 (1943) 362-369. 

Fluorine in Plants and Animals, In 1802 Domenico Pini Morichini discovered the presence of fluorine in fossil ivory (157). He later detected it in the enamel of the teeth, and Berzelius soon confirmed the discovery and showed that fluorine is also a normal constituent of bone (158,159, 165). The presence of excessive amounts of fluoride in drinking water causes the well-known mottling of the enamel of children s teeth (160), but small amounts of fluoride protect the teeth from dental caries (161). 

Fluoride therapy and fluoridation of drinking water has played a significant role in deccreasing the dental caries. The incidence of dental caries can be significantly decreased by adding fluorides into the drinking water supply. Fluorides prevent decalcification of the structure of tooth by inhibiting bacterial enzymes which produce lactic acid. Fluorides also increase the tooth resistance to acid decalcification. 

Fluorides can be used prophylactically as well as therapeutically. Prophylactically, fluoride (in the form of sodium fluoride) can be used in drinking water and one part of fluoride to one million part of drinking water is sufficient for reducing the incidence of dental caries by 50%. Therapeutically, 2% sodium fluoride solution is applied locally to the teeth after... 

Fluoride is well established as effective for the prophylaxis of dental caries and has been under investigation for the treatment of osteoporosis. Both therapeutic applications originated from epidemiologic observations that subjects living in areas with naturally fluoridated water (1-2 ppm) had less dental caries and fewer vertebral compression fractures than subjects living in nonfluoridated water areas. Fluoride is accumulated by bones and teeth, where it may stabilize the... 

Fluoride in drinking water appears to be most effective in preventing dental caries if consumed before the eruption of the permanent teeth. The optimum concentration in drinking water supplies is 0.5-1 ppm. Topical application is most effective if done just as the teeth erupt. There is little further benefit to giving fluoride after the permanent teeth are fully formed. Excess fluoride in drinking water leads to mottling of the enamel proportionate to the concentration above 1 ppm. 

Early dental caries (incipient lesions) are non-cavitated and limited to the outer enamel surface. Clinically, these lesions are identified as visible white spots when the tooth is air-dried (Fig. 11.1). The incipient lesion is known as a subsurface lesion since the surface appears intact. However, histological investigations have shown that below the surface, there are zones that vary in porosity (voids from mineral loss) as well as biochemical composition (e.g. fluoride, water and carbonate content) [29]. The enamel caries can vary from a depth of 100-250 J.m (for incipient caries) to entirely through the enamel ( 1.5mm deep), at which point the cavitated lesion has extended into the underlying dentin [35]. The diagnostic challenge remains early caries detection and the focus has been on caries lesions that form on the tooth crown affecting the enamel. The remainder of the discussion will therefore concentrate on enamel caries. 

Fluoride (F ) is a halogen ion that occurs in many potable and wastewaters. It may also occur in soils, sediments, hazardous waste, aerosol, and gas. While a low concentration of fluoride (below 1 ppm at controlled level in drinking water) is beneficial for reducing dental caries, a higher content is harmful. Fluoride in water may be determined by one of the following methods ... 

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