Fluorine in bones

In 1857 Jerome Nickles demonstrated the presence of fluorine in the blood of many mammals and birds. In disagreement with Berzelius, he regarded the fluorine in bones as an essential ingredient. Fluorine, said Nickl s, exists in the bile, in the albumen of the egg, in gelatine, in mine, in saliva, in hair in a word, the animal organism is penetrated by fluorine, and it may be expected to be found in all the liquids which impregnate it (163). 

J. Middleton, On the fluorine in bones, its source and its application to the determination of the geological age of fossil bones, Geol. Soc. Lond. Proc. 4 (1944)... 

Among the D vitamins, multiple fluonne substituents in the side chain of 25-hydroxy-D3 (4) markedly increases bone resorptive activity [21, 22] The enhanced activity may be due to blockade of degradation caused by the presence of fluorine in specific positions. 

Fluorine as the anion F(I) is found in bone and tooth. Enhanced levels are toxic. 

Once fluoride ions react with bone, they are not easily dissolved out or exchanged by other elements. If bone is buried for long periods of time, the relative amount of fluorine in the bone gradually increases as a function of time the "fluoridation" process continues until the maximum amount of fluorine (necessary to convert all the hydroxyapatite to fluorapatite) is reached. The total concentration of fluor in carbonated fluorapatite can reach levels as high as above 3%. There is ample room, therefore, for an increase in the relative amount of fluorine in buried bone. Determining the relative amount of fluorine in buried bone may thus serve as a tool for dating bone. 

Fluoride ions may be relatively abundant in groundwater at one location and practically absent in that at another site hence the rate of fluoridation of the bone (the rate of increase in the relative amount of fluorine in the bone) varies from site to site. For instance, bones buried for a short time at a site in which the groundwater is rich in fluoride may acquire much more fluorine than bones buried for a very long time at a place where there is little fluoride in the groundwater. Therefore, fluorine analysis does not provide a tool for estimating the absolute age of buried bone, but only for dating bones at the same site, comparative to each other. The relative amount of fluoride in buried bone at a particular site thus provides a clue as to the length of time the bone has been buried. 

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). 

The availability of a chemical to the cells is affected by where it is stored. First, lipophilic chemicals tend to get absorbed by and retained in fat cells, from which they are released slowly back into the bloodstream. Second, some chemicals are strongly bound to plasma proteins and are released to the cells more slowly over time. For example, acetaminophen (Tylenol ) does not bind strongly to plasma proteins, while diazepam (Valium ) does. Thus, diazepam will persist in the body for longer periods of time than will acetaminophen. Finally, some elements, such as fluorine, lead, and strontium, are bound up in bone for long periods of time. As bone slowly renews itself or is broken down under special circumstances such as pregnancy, the chemicals are released and can affect the mother and fetus. 

Carnot, A., Researches on Fluorine in Modern Bone and in Fossil Bone, ... 

Hard bone tissue contains Ca, P04, OH, small amounts of carbonate, magnesium and sodium and trace elements of fluorine, chlorine and sulphur. That is why the Ca/P value in bone is not 1.67. Substitution of strange ions results in a change in the crystal structure. Consequently it is impossible to imitate the mineral part of bone exactly. 

Many investigations about fluorine uptake are reported in literature. The goal of these examinations is to unravel the exposure duration of different materials to various environmental conditions. Here, the application of ion beam analysis in studies on terrestrial contamination of meteorites from Antarctica and diffusion profiles in bones from archaeological burial sites is presented. 

The process of mathematical fitting is error-prone, and especially two different issues have to be considered, the first one dealing with the boundary conditions of the fitting procedure itself A pure diffusion process is considered here as the only transport mechanism for fluorine in the sample. A constant value for the diffusion constant D, invariant soil temperatures and a constant supply of fluorine (e.g. a constant soil humidity) are assumed, the latter effect theoretically resulting in a constant surface fluorine concentration for samples collected at the same burial site. In mathematical terms, Dt is influenced by the spatial resolution of the scanning beam, the definition of the exact position of the bone surface, which usually coincides with the maximum fluorine concentration, and by the original fluorine concentration in the bulk of the object, which in most cases is still detectable. A detailed description on... 

G.E. Coote, Fluorine as an indicator of changes in bones and teeth, Trace elements in New Zealand environmental, human and animal, Proc. New Zealand Trace Elements Group Conf., 1989, pp. 183-188. 

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