SANGI first encountered hydroxyapatite on acquiring a patent from the US National Space and Aeronautics Authority (NASA) in the 1970s. NASA was seeking ways to replace mineral lost from the teeth and bones of astronauts in a gravity-free environment. It proposed using a precursor substance, brushite, to create new hydroxyapatite, the mineral of the teeth. SANGI took this idea one step further and proposed supplying hydroxyapatite itself, directly in toothpaste, to replenish tooth mineral with everyday use .
Hydroxyapatite was hard to obtain, so SANGI hired its first young scientists and synthesis of this remarkable substance began. Researchers from Japan's Tokyo Medical and Dental University, Hokkaido University and Gifu (now Asahi) University carried out in vitro remineralization and early plaque control testing, and a toothpaste manufacturer (SANGI's manufacturer to this day, Nippon Zettoc Co., Ltd.) succeeded with some difficulty in incorporating it in toothpaste. The manufacturers found SANGI's ingredient behaved quite differently from other calcium phosphates they had previously worked with. The result was the world's first hydroxyapatite-containing toothpaste APADENT, launched in 1980, followed by a second brand, APAGARD, in 1985.
納米技術 - SANGI的專利 <mHAP>成分的研發