Symptoms such as fractured hips in the elderly or brittle and weak bones are caused due to fluorine deficiency in the body. Fluoride stimulates bone formation and increases bone density, however bone with excess fluoride content has an abnormal structure resulting in increased fragility. Thus fluoride therapy results in large increases in bone mineral density but the effect on fracture rates, while positive, is small.Disputes over the essentiality of fluorine date back to the 19th century, when fluorine was observed in teeth and bones. In 1973 a trial found reduced reproduction in mice fed fluorine-deficient diets, but a subsequent investigation determined that this was due to reduced iron absorption. Role of fluoride
Fluoride has proven to be an essential element with preventative and protective properties. Fluoride is capable of combating and working against tooth decay and increases resistance to the "demineralisation of tooth enamel during attack by acidic bacterias". While essential for all individuals, it is significant for children, as when ingested, the fluoride is incorporated into their developing enamel. This in turn causes their teeth to become less prone to decay. Therefore, a relationship can be formulated, in that the more fluoride entering the body, the overall decline in the rate of decay. Sources of fluoride
Fluorine is the 13th most aboundant element in the Earths crust. The ionic form of fluorine is called fluoride. Fluoride is most commonly found as inorganic or organic fluorides such as naturally occurring calcium fluoride or synthetic sodium fluoride.
Fluoride or fluorine deficiency is a disorder which may cause increased dental caries (or tooth decay, is the breakdown of dental tissues by the acidic products released by the "bacterial fermentation of dietary carbohydrates.") and possibly osteoporosis (a bone disorder which leads to a decrease in bone mass, and an increase in bone fragility),  due to a lack of fluoride in the diet. Common dietary sources of fluoride include tea, grape juice, wine, raisins, some seafoods, coffee, and tap water that has been fluoridated. The extent to which the condition truly exists, and its relationship to fluoride poisoning has given rise to some controversy. Fluorine is not considered to be an essential nutrient, but the importance of fluorides for preventing tooth decay is well-recognized, although the effect is predominantly topical. Prior to 1981, the effect of fluorides was thought to be largely systemic and preeruptive, requiring ingestion. Fluoride is considered essential in the development and maintenance of teeth by the American Dental Hygienists Association. Fluoride is also essential as it incorporates into the teeth to form and harden teeth enamels so that the teeth are more acid resistant as well as more resistant to cavity forming bacteria. Caries-inhibiting effects of fluoride were first believed to have been seen in 1902 when fluoride in high concentrations was found to stain teeth and prevent tooth decay.Fluoride salts, particularly sodium fluoride (NaF), are used in the treatment and prevention of osteoporosis.