Remineralisation of teeth

Carbonated hydroxyapatite enamel crystal is demineralised by acid in plaque and becomes partly dissolved crystal. This in turn is remineralised by fluoride in plaque to become a fluorapatite-like coating on remineralised crystal.
Example: Demineralisation and remineralisation of dental enamel in the presence of acid and fluoride in saliva and plaque fluid.[1]

Remineralisation is a natural process and does not have to involve fluoride.

Remineralisation of teeth is defined as the process whereby calcium and phosphate ions supplied from external sources are supplied to the tooth in order to promote ion deposition in demineralized enamel. The process of demineralization begins at the crystal surface found inside the enamel or dentine and may progress into cavitation unless halted by remineralisation. The remineralized crystals found on the tooth surface are acid resistant and are therefore less soluble than the original mineral. [2]


Tooth decay process

The process of dental caries occurs when the acid-producing bacteria found in the biofilm on the teeth feed on the fermentable carbohydrates and produce organic acids as by-products. [3] The acids diffuse into the tooth surface and dissolve the carbonated hydroxyapatite mineral that consecutively forms a caries lesion. When foods or drinks containing sugars enter the mouth, the bacteria within the plaque rapidly convert the sugars into acid. The plaque can hold the acid in contact with the tooth surface for up to 2 hours before it is neutralised by saliva. During the time that the plaque is acidic, some of the calcium and phosphate minerals are dissolved out of the enamel into the plaque and once the plaque acid has been neutralised the minerals can return to the enamel surface. However the capacity for remineralisation is limited and if sugars enter the mouth too frequently a net loss of mineral from the enamel surface results in a cavity through which bacteria can penetrate and infect the inner structure of the tooth. [4]

Although a key feature of tooth decay is an increase within dental plaque of bacteria such as Streptococcus mutans and Lactobacillus, it is not considered as an infectious disease.[5] Tooth decay can be managed by modifying behaviour to controlling its causative factors, i.e. reducing the frequency of fermentable carbohydrates from food. This will reduce the chance of the dental biofilm developing to a cariogenic biofilm. The bacteria in a cariogenic biofilm produce organic acids when carbohydrates, especially sugar, are eaten.[1] When enough acid is produced so that the pH goes below 5.5,[6] 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,[7] typically in a process that requires many months or years.[1]


Fluoride therapy

Fluoride is a mineral found naturally in rock, air, soil, plants and water and it assists by:

Fluoride therapy is often used to promote remineralisation. This produces the stronger and more acid-resistant[8] fluorapatite, rather than the natural hydroxyapatite. Both materials are made of calcium. In fluorapatite, fluoride takes the place of a hydroxide. [9]

Tooth Remineralisation treatments

Besides professional dental care, there are other ways for promoting tooth remineralisation:-

Saliva

Saliva, being the watery substance that constantly circulates the oral cavity, is capable of impacting both the remineralisation and demineralisation processes. It is secreted through the major salivary glands including the parotid, submandibular, sublingual and Von Ebner's glands as well as the hundreds of minor salivary glands that are located throughout the oral cavity.[10]

As saliva is rich in calcium and phosphate ions, It can act as a natural buffer to neutralise acid and allow demineralised tooth tissues to be remineralised.[11]

Xylitol

Xylitol is a natural sweetener that inibits acid production by oral bacteria and promotes remineralisation of the teeth. It can be found in various products which includes chewing gums.

Effect of fluoride

Fluoride creates low levels of fluoride ions in saliva and plaque fluid and thus exerts 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.[12] Technically, this fluoride does not prevent cavities but rather controls the rate at which they develop making them take a lot longer and making them easier to prevent via normal brushing as it will take a higher amount of acid, usually built up over a number of days, to destroy the created fluorapatite.[13] When fluoride ions are present in plaque fluid along with dissolved hydroxyapatite, and the pH is higher than 4.5,[6] 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 partly due to these surface effects, which occur during and after tooth eruption.[14]

Fluoride interferes with the process of tooth decay as fluoride intake during the period of enamel development for up to 7 years of age; the fluoride alters the structure of the developing enamel making it more resistant to acid attack. In children and adults when teeth are subjected to the alternating stages of demineralisation and remineralisation, the presence of fluoride intake encourages remineralisation and ensures that the enamel crystals that are laid down are of improved quality. [15]

Some remineralisation methods may work for "white spot lesions" but not necessarily "intact tooth surfaces".[16]

Fluoride products

There are many fluoride products available to aid in remineralisation of teeth.

Fluoride is commonly found in toothpastes. Fluoride can be delivered to many parts of the oral cavity during brushing, including the tooth surface, saliva, soft tissues and remaining plaque biofilm. [11]

Water fluoridation

Community water fluoridation is the addition of fluoride in the drinking water with the aim of reducing tooth decay by adjusting the natural fluoride concentration of water to that recommended for improving oral health. The NHMRC released the public statement of efficacy and safety of fluoridation 2007 to set the recommended water fluoridation to the target range of 0.6 to 1.1 mg/L, depending on climate, to balance reduction of dental caries (tooth decay) and occurrence of dental fluorosis (mottling of teeth). Moreover the public statement states that the fluoridation of drinking water is an effective way to ensure the community is exposed to fluoride and can benefit from its preventative role in tooth decay, regardless of age, gender or socioeconomic status. [17]

See also

References

  1. 1 2 3 4 Featherstone, J. D. B. (2008). "Dental caries: A dynamic disease process". Australian Dental Journal 53 (3): 286–291. doi:10.1111/j.1834-7819.2008.00064.x. PMID 18782377.
  2. ↑ N.J. Cochrane F. Cai N.L. Huq M.F. Burrow E.C. Reynolds "New Approaches to Enhanced Remineralization of Tooth Enamel", Journal of dental research, May 9, 2010. retrieved on 2016-04-20.
  3. ↑ Professor Michael A Lennon. "The Cochrane review of water fluoridation", Community dental health, 2015. retrieved on 2016-05-3.
  4. ↑ Dr RS Levine. "The British Fluoridation Society", A guide to the action of fluoride in the prevention of dental decay, 2016. retrieved on 2016-05-3.
  5. ↑ Fejerskov O, Nyvad B, Kidd EA: Pathology of dental caries; in Fejerskov O, Kidd EAM (eds): Dental caries: The disease and its clinical management. Oxford, Blackwell Munksgaard, 2008, vol 2, pp 20-48.
  6. 1 2 Cury, J. A.; Tenuta, L. M. A. (2008). "How to Maintain a Cariostatic Fluoride Concentration in the Oral Environment". Advances in Dental Research 20 (1): 13–16. doi:10.1177/154407370802000104. PMID 18694871.
  7. ↑ "Remineralization strategies". Registered Dental Hygienist (RDH) Magazine. 2006-07-18.
  8. ↑ "How does fluoride protect my teeth and make them strong?". UCSB ScienceLine. 2013-04-23.
  9. ↑ Better health channel. "Dental care - fluoride", April 2012. retrieved on 2016-04-15.
  10. ↑ Nanci, A., & Ten Cate, A. (2008). Ten Cate's oral histology. St. Louis, Mo.: Mosby Elsevier.
  11. 1 2 Li, Xiaoke; Wang, Jinfang; Joiner, Andrew; Chang, Jiang. "The remineralisation of enamel: a review of the literature". Journal of Dentistry 42: S12–S20. doi:10.1016/s0300-5712(14)50003-6.
  12. ↑ Pizzo, G.; Piscopo, M. R.; Pizzo, I.; Giuliana, G. (2007). "Community Water Fluoridation and Caries Prevention: A Critical Review" (PDF). Clinical Oral Investigations 11 (3): 189–193. doi:10.1007/s00784-007-0111-6. PMID 17333303.
  13. ↑ Aoba, T.; Fejerskov, O. (2002). "Dental Fluorosis: Chemistry and Biology". Critical Reviews in Oral Biology & Medicine 13 (2): 155–70. doi:10.1177/154411130201300206. PMID 12097358.
  14. ↑ Hellwig, E.; Lennon, Á. M. (2004). "Systemic versus Topical Fluoride". Caries Research 38 (3): 258–262. doi:10.1159/000077764. PMID 15153698.
  15. ↑ Dr RS Levine. "The British Fluoridation Society", A guide to the action of fluoride in the prevention of dental decay, 2016. retrieved on 2016-05-3.
  16. ↑ Iijima, Y. (2008). "Early detection of white spot lesions with digital camera and remineralization therapy". Australian Dental Journal 53 (3): 274–280. doi:10.1111/j.1834-7819.2008.00062.x. PMID 18782375.
  17. ↑ National health and medical research council. "Health effects of water fluoridation", 2016-04-06. retrieved on 2016-04-11.

Further reading

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