Fluorine dental enamel

Fluorine (F) is the second most active chemical element after astatine. It was isolated in 1886 by Henri Moisson in Paris (BriH 1995), and five years later, F. Erhardt in Germany recommended that pregnant women and children should take fluorine pastilles at second dentition. Moreover, F. Erhardt was the first to observe that fluorine fortified dogs dental enamel (Anke 1991). However surprising it is, now as before, the plastic role of fluorine is beyond doubt. Nevertheless, in spite of the availability of a wide class of flu-orous compounds with a pronounced physiological activity, some of the aspects of its biological effects are still not clear. 

Lindh, U. and Tveit, A.-B. (1980) Proton microprobe determination of fluorine depth distributions and surface multielement characterisation of dental enamel. J. radioanal. Chem., 59, 167-191. 

The presence of fluorine as a soluble fluoride in drinking water to the extent of 2 ppm may cause mottled enamel in teeth, when used by children acquiring permanent teeth in smaller amounts, however, fluorides are added to water supplies to prevent dental cavities. 

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. 

Fluorine is an essential element involved in several enzymatic reactions in various organs, it is present as a trace element in bone mineral, dentine and tooth enamel and is considered as one of the most efficient elements for the prophylaxis and treatment of dental caries. In addition to their direct effect on cell biology, fluoride ions can also modify the physico-chemical properties of materials (solubility, structure and microstructure, surface properties), resulting in indirect biological effects. The biological and physico-chemical roles of fluoride ions are the main reasons for their incorporation in biomaterials, with a pre-eminence for the biological role and often both in conjunction. This chapter focuses on fluoridated bioceramics and related materials, including cements. The specific role of fluorinated polymers and molecules will not be reviewed here. 

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). 

Fluorine is widely distributed in Nature, representing about 0.065% of the earth s crust, making it the 13th most abundant element. It is more abundant than chlorine and much more abundant than common metals such as zinc and copper. Fluorine occurs in many minerals in which fluoride ion replaces hydroxide. The conversion of hydroxyapatite to flu-oroapatite strengthens tooth enamel. However, this would result in an increased brittleness in bones. An untested theory is that the widespread use of fluoride in drinking water, which had remarkable benefits in preventing dental caries in the 1960s, may be the cause of the rise in osteoporosis in the elderly population. 

Fig. 16 3 Geographic location of mottled enamel in the US (1941) (Figure is a reproduction of Fig. 2 from Dean HT, Kitchin P, Moulton FR (eds) Fluorine and dental health. American Association of the Advancement of Science Publication No 19 Washington DC 1942 AAAS 1942, pp. 6-11)...

There are a certain number of options to control and reduce dental caries, the biggest problem in tooth care. The use of fluoride salts is one of the most effective methods to prevent or slow down demineralization that causes tooth decay [16,17]. The action of fluoride can be explained by its antimicrobial action, its interaction with enamel to form a fluorinated hydroxyapatite compound (hydroxyfluorapa-tite or fluorapatite Ca5(P04)3F) by substitution of an hydroxyl ion in hydroxyapatite Ca5(P04)3(0H), which is more resistant to add than enamel on its own, and its repairing effect by formation of calcium and phosphate, which ranineralize the tiny lesions in which caries begin. 

Long before the present interest in fluorine in relation to the prevention of dental caries the view was held that it was an essential element in animal nutrition especially concerned in the formation of the enamel of teeth. This view no doubt arose from its constant presence in the bones and teeth, as well as in other organs and tissues, notably the thyroid and epidermal... 

Whether fluorine is an essential human nutrient is unknown. Fluorine is of importance to human health because of its influence on the incidence of dental caries. It has been shown that the incidence of caries is low in children who have received water containing fluorine in amounts of 1 to 1.5 p.p.m. during the period of calcification and maturation of teeth. A high incidence of dental caries has been observed in children who have received water containing less than 1 p.p.m. of fluorine. When water contains more than 2.5 p.p.m. of fluorine, mottling of the enamel of the teeth is observed. In a number of communities in the United States, addition of fluorine to the water supply (1 p.p.m.) has resulted in a decrease in caries incidence. Topical application of fluorine to teeth has also been found beneficial. 

Although fluoride is very toxic at high concentrations, fluorine is a trace element naturally present in the diet which is essential for the formation of healthy bones and teeth, and resistance to dental caries is substantially reduced in children whose intake is inadequate at the stage of enamel formation. Much of the fluoride ingested by humans dependent on water from wells must orginally have been obtained from the water supply. It has been established that the optimal level of fluoride in drinking water, for the prevention of dental caries, is about 1 ppm. 

---