Demineralisation and remineralisation of dental enamel in the presence of acid and fluoride in saliva and plaque fluid.^[1]

Remineralisation of teeth (UK spelling; US Remineralization of teeth) is a process in which minerals are returned to the molecular structure of the tooth itself. Teeth are (often) porous allowing fluids and demineralisation beneath the surface of the tooth. When demineralised, these pores become larger.^[1] This process cannot replace lost tooth material: it will not fill a cavity that has developed into a hole.^[2]

Tooth decay is an infectious disease, the key feature of which is an increase within dental plaque of bacteria such as Streptococcus mutans and Lactobacillus. These produce organic acids when carbohydrates, especially sugar, are eaten.^[1] When enough acid is produced so that the pH goes below 5.5,^[3] the acid dissolves carbonated hydroxyapatite, the main component of tooth enamel, in a process known as demineralisation. After the sugar is gone, the mineral loss can be recovered—or remineralised—from ions dissolved in the saliva. Cavities result when the rate of demineralisation exceeds the rate of remineralisation and the latticework is destroyed,^[2] typically in a process that requires many months or years.^[1]

Fluoride therapy is often used to promote remineralization. This produces the stronger and more acid-resistant fluorapatite, rather than the natural hydroxylapatite. (Both are made of calcium. The fluoride takes the place of a hydroxide.)

Fluoride exerts its major effect by creating low levels of fluoride ions in saliva and plaque fluid, thus exerting a topical or surface effect. A person living in an area with fluoridated water may experience rises of fluoride concentration in saliva to about 0.04 mg/L several times during a day.^[4] Technically, this fluoride does not prevent cavities but rather controls the rate at which they develop.^[5] When fluoride ions are present in plaque fluid along with dissolved hydroxyapatite, and the pH is higher than 4.5,^[3] a fluorapatite-like remineralised veneer is formed over the remaining surface of the enamel; this veneer is much more acid-resistant than the original hydroxyapatite, and is formed more quickly than ordinary remineralised enamel would be.^[1] The cavity-prevention effect of fluoride is mostly due to these surface effects, which occur during and after tooth eruption.^[6]

Since there is no connection between the bloodstream and the enamel, swallowed calcium supplements have no effect on remineralization, nor does calcium deficiency remove enamel from the teeth.^[2] The calcium used to rebuild teeth must be dissolved in the saliva.

Some remineralisation methods may work for "white spot lesions" but not necessarily "intact tooth surfaces". ^[7]

[edit] References

[edit] See also

• Amorphous calcium phosphate
• Calcium lactate
• Calcium phosphate
• NovaMin
• Recaldent
• Tooth development
• Toothpaste
• Tooth enamel

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