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·World’s first   *enamel-restorative
*hydroxyapatite toothpaste
(‘Apadent’ 1980)
·Field trials among Japanese schoolchildren:
36-56% new caries reduction over 3 years
(‘Apagard’ 1985)

·Active ingredient approved as an anticaries agent, ‘Medical Hydroxyapatite(<mHAP> ), in Japan.
Sangi's nanohydroxyapatite patented worldwide

·Particle-size reduced from 3- to 2-figure nanoscale, increasing remineralizing effect
·Growing interest worldwide in nanohydroxyapatite
*first European toothpastes launched
*new dental applications now under study
(‘Renamel’ 2004, ‘Nanotect’ 2009)

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 hydroxyapatite 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 synthetic hydroxyapatite as a means of restoring this. Sangi conceived the idea of enamel-restorative toothpaste using the same substance as our teeth in 1978, and launched the world's first nanoparticle hydroxyapatite enamel-restorative 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 the past 30 years, with over 90 million tubes sold.

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 nanohydroxyapatite ingredient. Most were 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 almost 700 Japanese primary schoolchildren. Researchers from Tokyo Medical and Dental University and Gifu Dental University (now Asahi University) found children using Sangi's nanoparticle 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 this ingredient. In some groups, the difference was as great as 36-56% reduction in new tooth decay. (See, data from Kani et al, Effect to Apatite-Containing Dentifrices on Dental Caries in School Children (1989)).

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 nanohydroxyapatite <nHAP> 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.

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

During this period, Sangi obtained widespread patents on its nanohydroxyapatite dental technology. It has continued to work on upgrading and extending the applications of this technology and in 2003, succeeded in reducing the average size of its nanoparticles from 3-figure to 2-figure nanometer size, further increasing their enamel-restorative capability. (1 nanometer = one millionth of a millimeter)

2000s Emerging Interest in Nanohydroxyapatite Worldwide

Sangi's hydroxyapatite is used in 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 (3DS), in conjunction with the Japanese National Institute of Infectious Diseases, and a hydroxyapatite powder jet deposition system (PJD) for treating tooth decay, in conjunction with Tohoku University.

In recent years, widespread interest has arisen in the restorative applications of nanohydroxyapatite pioneered by Sangi over the last three decades. Chemical companies BASF and Henkel both announced development of nanoparticle hydroxyapatite as a promising dentifrice ingredient in 2002, and Henkel launched the first European toothpaste to contain nanohydroxyapatite some years after. At least two companies have now followed suit, and others can be expected to follow.