• 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)


  • Active ingredient approved as an anticaries agent, ‘Medical Hydroxyapatite’(<mHAP>), in Japan.
  • Sangi's nano-hydroxyapatite patented worldwide


  • Particle-size reduced from 3- to 2-figure nanoscale, increasing remineralizing effect
  • Growing interest worldwide in nano-hydroxyapatite
  • first European toothpastes launched
  • new dental applications developed (‘Renamel’ 2004, ‘Nanotect’ 2009)

1970s Born in Japan: A Toothpaste that Repairs Tooth Enamel

1970s Born in Japan: A Toothpaste that Repairs Tooth Enamel 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 nano-hydroxyapatite 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.

1980s Early Lab Work and Field Trials

1980s Early Lab Work and Field Trials 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 nano-hydroxyapatite 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.

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 nano-hydroxyapatite 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.

1990s Anticaries Approval: Medical Hydroxyapatite(<mHAP>®)

Following over a decade of laboratory research and field trials, Sangi's proprietary form of hydroxyapatite was approved by the Japanese government as an active anticaries ingredient in 1993.

It was officially designated ‘Medical Hydroxyapatite’ (<mHAP>) to distinguish it from other types of hydroxyapatite used in dental applications, such as dental abrasives. In contrast, Sangi's ingredient is non-abrasive, and repairs microscopic defects in surface and subsurface tooth enamel, restoring mineral density and therefore translucence to the enamel, and reversing incipient caries, the beginning of tooth decay.

1990s Anticaries Approval: Medical Hydroxyapatite(‹mHAP› ®)

Nano<mHAP> particle size distribution
(Data: Sangi Central Research Laboratory)

2000s Emerging Interest in Nano-hydroxyapatite Worldwide

Sangi's hydroxyapatite, in oral care, is used mainly in toothpaste and remineralizing chewing gum. It has been shown to occlude exposed dentinal tubules, helping reduce hypersensitivity, and is also used in enamel-restorative formulations for dental clinical use.

Other applications now under development by Sangi include a home-care anticaries system targeting oral mutans streptococci reduction developed, in conjunction with the Japanese National Institute of Infectious Diseases, and a hydroxyapatite powder jet deposition system (PJD) for restorative dental treatment applications, in conjunction with Tohoku University.

In recent years, widespread interest has arisen in the restorative applications of nano-hydroxyapatite pioneered by Sangi over the last three decades. Chemical companies BASF and Henkel, in Europe, both announced development of nanoparticle hydroxyapatite as a promising dentifrice ingredient in 2002, and Henkel launched the first European toothpaste to contain nano-hydroxyapatite some years after. Many companies have now entered the field and a wide range of hydroxyapatite toothpastes is now available.

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