Hydroxyapatite in a toothpaste. Remineralization of teeth

The main substance of our teeth is hydroxyapatite (97 % of enamel and 70 % of dentin), a calcium phosphate compound. Hydroxyapatite to support a naturally occurring function – the restorative role of saliva – in the mouth. This ingredient is safe and highly biocompatible. Hydroxyapatite (mHAP) particles penetrate below the surface of the enamel, providing replacement calcium and phosphate ions to areas from which minerals have dissolved, thereby remineralizing the demineralized enamel and restoring its integrity and translucent gloss.

Demineralization and remineralization of tooth enamel take place constantly. The tooth surface is easily colonized by bacteria to form dental plaque, especially in minute fissures or spaces between the teeth where a toothbrush cannot reach. Enamel is made up of closely packed hydroxyapatite rods, separated by tiny channels about 50 nanometers wide. Acids produced by plaque bacteria seep into these channels and can dissolve the rods, causing the enamel to become demineralized.
  Saliva plays a protective role, by neutralizing acids caused by plaque bacteria, and by providing calcium and phosphate ions – the building blocks of hydroxyapatite – which diffuse back into the enamel to restore lost mineral, so that the enamel becomes remineralized.
  If demineralization and remineralization balance each other at the tooth surface, no net loss of mineral occurs. But conditions such as excess plaque, inadequate saliva flow, or heavy intake of acidic foods and beverages can tip the balance in favor or demineralization, so that a cavity – dental caries – may result. However in its early stages, if sufficient mineral is provided, demineralization (incipient caries or ‘white spot’ lesions) can be reversed.

Three functions of hydroxyapatite as an active anticaries ingredient:

  Filling of Microscopic Surface Fissures

 Hydroxyapatite also acts as a filler, repairing minute pits and fissures in the enamel surface. This function, also enhanced by its nano size, results in smoother, glossier enamel, with fewer sites likely to harbor plaque and stains. mHAP helps to remove bacteria and biofilm, thereby protecting against tooth decay.1 Removes white spots and incipient caries and restores enamel almost to its original form.2 

 mHAP nanoparticles supplement the supply of mineral from saliva, remineralizing subsurface demineralized areas of the enamel (‘white spot’ lesions or incipient caries), and restoring mineral density and translucency to enhance the whiteness of the teeth.

Filling of Microscopic Surface Fissures

Antimicrobial properties

 Hydroxyapatite has a strong propensity to bind with protein, and adheres to bacteria and plaque fragments during brushing, facilitating their removal on rinsing from the mouth. This feature is enhanced by mHAP’s nanoparticle size, which increases the surface area to which proteins attach. Hydroxyapatite shows superior bacterial absorption compared to other forms of hydroxyapatite3 and has a strong selectivity for cariogenic streptococcus mutans.

Antimicrobial properties

Tooth sensitivity

 Hydroxyapatite nanoparticles occlude and offer a protective coating beyond comparison over exposed dentinal tubules, providing quick and effective relief from refractory tooth hypersensitivity. Coats and fills exposed dentin and dentinal tubules protecting against dentinal hypersensitivity.4 

 Recommended Hydroxyapatite in toothpastes Dentissimo Complete Care and Dentissimo PRO-whitening.

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Sources:1. NISHIMURA et al, Demineralized Enamel Surface Microstructure after Brushing Using Toothpaste Containing Medical Hydroxyapatite under FE-SEM Observation, The Journal of Japanese Stomatological Society, 48(3), 199-210, 1999. 2. ARAKAWA et al, Reduction of Oral Mutans streptococci by Small-Crystals, 82nd General Session & Exhibition of the IADR, March 10-13, 2004.  3 ARAKAWA et al, Reduction of Oral Mutans Streptococci by Small Crystal Hydroxyapatite, Journal of Dental Research Vol. 81, A200-1478, San Diego Abstracts, 2002. 4. KONDO et al, Study of