Fluorapatite occurs naturally in the form of crystals. In the human body, it is mainly found in the teeth and bones. The inorganic crystalline compound makes tooth enamel more resistant to acids and thus can prevent tooth decay from occurring. If there is enough fluorapatite in the bones, there is a lower risk of developing osteoporosis in old age.
What is fluorapatite?
Naturally occurring fluorapatite is a mineral that belongs to the class of phosphates, arsenates and vanadates (anhydrous phosphates with foreign anions). If it is treated with UV light or heated, it starts to glow. It is also soluble in nitric and hydrochloric acids. The molecular formula of fluorapatite is Ca5(PO4)3F. In the human body, it is found in the osteoclasts of bones and in dental bone and enamel. The higher its content of fluorapatite, the more resistant the enamel is to acids. Fluorapatite, on the other hand, is more resistant than hydroxyapatite, which is also found in tooth enamel. This property is exploited in caries prophylaxis. Around 90 percent of the fluoride present in the human body is found in the bones. Of this, approximately 2.5 percent is fluorapatite.
Function, effect and tasks
Fluorapatite makes tooth enamel more resistant to acids. They are formed by bacteria or ingested through daily food. The harmful compounds dissolve minerals from the enamel and sometimes even from the underlying dentin, causing the formation of holes (caries). Fluorapatite formation with the help of dental fluoridation can effectively prevent caries. In case of already existing caries, it remineralizes the damaged teeth. Since the daily food intake does not contain enough fluoride – experts estimate the fluoride content in it at 0.2 to 0.5 mg – the user should consume additional fluoride every day if he wants to prevent caries. The daily use of fluoride-containing toothpaste and mouthwash is suitable for this purpose. Once a week, he should apply a fluoride-containing tooth gel. The treatment of the tooth enamel with fluoride-containing varnish is carried out exclusively in the dentist’s office. It is important that the user does not exceed the maximum daily dose. It is 0.05 mg per kilogram of body weight per day (adults) and 0.1 mg/kg of body weight per day for children. The German Society for Dental, Oral and Maxillofacial Medicine (DGZMK) recommends that young children brush their teeth once a day with a small amount of children’s toothpaste from the time their teeth erupt. It has a lower fluoride content than adult toothpaste. From the age of 2, teeth should be brushed with it twice a day. From the start of school, the child can then use normal fluoride toothpaste. The additional use of fluoride gels, solutions and varnishes is only necessary in case of increased caries risk. Fluoride tablets should only be given to older children and then only sucked. Recent research shows that hydroxyl-containing toothpastes are even more effective than fluoride toothpaste: the fluoride forms fluorapatite only on the tooth surface, while the hydroxylapatite remineralizes even the bottom of caries cavities.
Formation, occurrence, properties and optimal values
Fluorapatite is formed when tooth enamel is treated with fluoride-containing substances. In this process, the fluorine ions added replace the OH group of hydroxyapatite. The most resistant mineral found in tooth enamel is the fluoride fluorapatite. It forms an extremely thin protective layer on the tooth surface, but must be formed anew every day throughout life in order to be able to protect the tooth sufficiently. Since fluorapatite is only formed by the external treatment of the tooth with fluoride-containing agents (fluoridation), dentists recommend that this substance be added locally on a daily basis. This can be done, for example, by sucking fluoride tablets and using fluoride-containing toothpaste.
Diseases and disorders
As long as the maximum daily dose is not exceeded when using fluoride-containing agents, there is no risk to the user’s health. When used topically only, the risk of accidental overdose is lower than when used systemically (swallowing the preparation). Excessive doses of fluoride can lead to dental fluorosis (over-calcification of the tooth enamel) in children. It is clearly recognizable by permanent, brownish discolored areas on the teeth.Although dental fluorosis is harmless, it can place a heavy psychological burden on the child patient because of its unattractive appearance. It should also be taken as an indication that the rest of the body may also have been damaged by excessive fluoride intake. Because fluoride compounds are mildly toxic, irreversible damage can occur, especially with prolonged overdose. For example, excessive concentrations in children can cause impairment of their cognitive abilities. It can also cause permanent damage to the kidneys, glands, brain and bones. In fluorosis, bones are so hardened that they become brittle with even minor injuries. In addition, the spine, bones and joints stiffen even more. Excessive doses of fluoride can lead to thyroid and nerve damage, reduced fertility in males, type-2 diabetes, and vasoconstriction (proven in animal studies). In case of acute fluoride poisoning, the patient should immediately consult his doctor, because the substance forms the highly toxic hydrogen fluoride in the stomach. It attacks the stomach and intestinal mucosa. Symptoms of such poisoning are abdominal pain, nausea and vomiting. Systemic fluoride intake via fluoride-containing table salt and fluoride-containing foodstuffs causes the bone substance to become harder (osteoporosis prophylaxis). Fluoride is absorbed in the small intestine and absorbed into the bloodstream.
