Hydroxyapatite is a major component of the human body, comprising 60% of bone, 97% of tooth enamel and 70% of dentin. Saliva is also rich in the components of hydroxyapatite, which it supplies to the teeth to replace mineral dissolved by plaque acids, the first step towards tooth decay.By restoring lost mineral, saliva acts to protect against decay in a natural healing process known as ‘remineralization.’ Sangi’s Medical Hydroxyapatite supports this natural healing function,

Because it is extremely biocompatible, hydroxyapatite is used in a wide range of medical and dental applications, such as artificial tooth and bone, tissue repair, and coatings to improve the biocompatibility of orthopedic implants. It is also a protein-binding agent, used in chromatography and bacterial culture. In dental applications, hydroxyapatite is sometimes used as an abrasive,depending on its manufactured properties and particle size. However Sangi’s nanohydroxyapatite is a non-abrasive, enamel-restorative mineral, closely resembling the natural hydroxyapatite of the teeth, and approved in Japan for its anticaries properties.

The influence of fluoride in reducing dental caries has been clearly demonstrated. Its use in drinking water and oral care products dates back over 70 years. Fluoridation has been called the single most effective public health measure to prevent new tooth decay, and early U.S. studies showed it reduced caries among schoolchildren by as much as 35-60%. However excess fluoride can lead to problems such as dental or skeletal fluorosis, and the amount permitted in oral care products and community water systems is controlled.

In contrast, nano Medical Hydroxyapatite, used as a remineralizing agent in toothpaste in Japan for the last three decades, was shown in field trials leading to its approval as an active anticaries ingredient to cause a similar reduction in new caries among schoolchildren to that seen with fluoridation in the U.S., namely 36-56%.(Fig 1.T.KANI et al Effect to Apatite-containing Dentifricres on Dental Caries in school Children) 

A recent in situ study conducted among healthy adults in the U.S. found that Sangi’s Medical Hydroxyapatite toothpaste not only inhibited development of caries but was not significantly different from fluoride in its ability to remineralize early caries lesions. (Amaechi et al, Remineralization of Early Caries Lesions by Nanohydroxyapatite Dentifrice). This supported the findings of earlier in vitro studies in Hong Kong which showed no significant difference in remineralizing effect between fluoride- and Medical Hydroxyapatite (‹mHAP ›)-containing toothpastes. (NM King et al, Remineralization by Nanohydroxyapatite-containing Dentifirice)

Moreover, hydroxyapatite has been shown to be safe – even edible – and can be swallowed by children without concern, as it has no known toxic or harmful impact. 

Fluoride is an element (F-), supplied in the form of compounds such as sodium fluoride (NaF) or sodium monofluorophosphate (NaMFP). It does not replace mineral itself, but strengthens teeth against decay by promoting the uptake of calcium and phosphate from saliva and other sources into the enamel (remineralization). In doing so, it forms a new substance, fluoridated apatite, on the tooth surface, more resistant to plaque acids than the enamel’s original carbonated hydroxyapatite.
Fluoride is also said to impede bacterial metabolism, helping to lower the level of cariogenic bacteria in the mouth.

In contrast, nano Medical Hydroxyapatite is a crystalline calcium phosphate substance almost identical to the natural hydroxyapatite of our teeth. Supplied in the form of nanoparticles, it directly replaces lost mineral to restore subsurface demineralized areas of tooth enamel (incipient caries) and fill microscopic fissures on the enamel surface. Its nanoparticles also bind protein such as oral bacteria and plaque fragments during brushing, facilitating their removal from the mouth.
Unlike fluoride, nano Medical Hydroxyapatite adds nothing ‘new’ to the enamel, and is less resistant to acid attack than fluoridated apatite, though more resistant than carbonated apatite. But Medical Hydroxyapatite achieves the same degree of remineralization as fluoride, as seen above, and penetrates to the very bottom of demineralized lesions, whereas fluoride tends to create a dense zone of fluoridated apatite at the top.
And by restoring the enamel’s mineral density and surface smoothness, Medical Hydroxyapatite increases resistance to bacterial attachment and therefore plaque development and tooth decay, at the same time enhancing the translucency, gloss and whiteness of the teeth.

MEDICAL HYDROXYAPATITE

 

PRODUCT HISTORY

1980S

• World’s first *enamel-restorative
  

  *nanoparticle
  *hydroxyapatite toothpaste
  (‘Apadent’ 1980)

• Field trials among Japanese schoolchildren:
  36-56% reduction new caries in over 3 years
  

  (‘Apagard’ 1985)

1990S

• Active ingredient approved as an anticaries agent, ‘Medical Hydroxyapatite’(‹mHAP› ), in Japan.
  
• Sangi's nanohydroxyapatite patented worldwide

2000S

• Particle-size reduced from 3- to 2-figure nanoscale, increasing remineralizing effect
• Growing interest worldwide in nanohydroxyapatite
  

  *first European toothpastes launched
  *new dental applications developed
  (‘Renamel’ 2004, ‘Nanotect’ 2009)

  
  
• Medical Hydroxyapatite movie (produced in 2004)

Japanese company Sangi first became interested in hydroxyapatite – the substance of our teeth and bone – after acquiring a dental materials patent from the U.S. National Aeronautics and Space Authority (NASA) in the 1970s. Astronauts lose mineral from their teeth and bone in a gravity-free environment, and NASA proposed synthesizing hydroxyapatite as a means of restoring this.

Sangi conceived the idea of enamel-restorative toothpaste using hydroxyapatite – the same substance as our teeth – in 1978, and launched the world's first nanohydroxyapatite toothpaste (‘Apadent’), using Sangi's own technology, in 1980. Sangi's enamel-restorative toothpastes now stretch to a wide range of brands (chiefly ‘Apagard,’ launched in 1985), and have been used extensively in Japan for their anticaries and whiteness-enhancing properties for over 30 years, with over 120 million tubes sold.

Throughout the 1980s, both in its own research and third-party studies commissioned at Japanese universities, Sangi accumulated data supporting the enamel-restorative properties of its proprietary nanohydroxyapatite ingredient. Most were reported in Japanese, but studies in English include those by Kani et al, The Effect of Apatite-Containing Dentifrices on Artificial Caries Lesions (1988) and Ohashi et al, Remineralization of Artificial Caries Lesions by Hydroxyapatite (1991), both of which were commissioned by Sangi and used Sangi's material. (See Research Papers).

Field trials were also conducted in separate locations involving over 1000 Japanese primary schoolchildren. Researchers from Tokyo Medical and Dental University and Gifu Dental University (now Asahi University) found children using Sangi's nanohydroxyapatite toothpaste at school under supervision once a day over a period of years developed significantly less caries than those using an identical toothpaste not containing hydroxyapatite. In some groups, the difference was as great as 36-56% reduction in new tooth decay.