Nano-hydroxyapatite: What do I need to know?

Recently there has been a lot of interest in nano-hydroxyapatite as a remineralizing ingredient in oral health care products. Teeth are made up primarily of the hydroxyapatite mineral in small nano-particles that average about 20 nm. These microcrystals are the basic building blocks that in turn become enamel rods which make up the anatomy of enamel. Additionally, saliva is supersaturated with nano-hydroxyapatite crystallites about 20 nm in size and spherical in shape. These super-mineralized structures, teeth, are bathed and protected 24/7 in a supersaturated solution of the mineral they are made up of. This is how the body maintains teeth. So, it makes sense to use this physiologic principle and copy it to provide remineralization of teeth. This is a biomimetic approach.

In 1993 the first oral care product containing nano-hydroxyapatite was released in Japan. Since that time there has been growing interest in this material. At the same time there is a growing concern in the public about the use of fluoride, with a portion of the population now averse to any fluoride therapies. These materials have been repeatedly studied and compared to understand the differences. Many studies have been published in the interim and most of those studies conclude that not surprisingly, nano-hydroxyapatite is as effective as fluoride as a remineralizing agent.

While older studies examined the results from 10% nano-hydroxyapatite and one study concluded that it may be the best concentration for remineralization, a newer study found no significant difference between 2, 5 and 10% solutions. And the most current literature indicates size and shape matter, with 20 nm average particle size and spherical shape providing the best outcomes. In addition to remineralization, nano-hydroxyapatite has most recently also been demonstrated to reduce dentin hypersensitivity and also whiten teeth.

But there is also a concern with nano-hydroxyapatite. Last year, the European Union banned all nano-hydroxyapatite particles in oral health care products over a concern of the flood of inexpensive needle-shaped materials being introduced into the market. These needle shaped crystallites may penetrate soft tissue, collect in organs and travel throughout the body. They then modified the ban to allow nano-hydroxyapatite particles that are rod-shaped. nanoXIM by FLUIDINOVA is now the only nano-hydroxyapatite globally recognized and approved for oral care by the European Scientific Committee on Consumer Safety.

While the FDA has not examined this issue yet, it makes good sense to know what is in the nano-hydroxyapatite oral health care products you are recommending to your patients. CariFree introduced nano-hydroxyapatite into our oral health care products in 2012, and have used a proprietary concentration of nanoXIM crystallites from the beginning.

The interest in nano-hydroxyapatite in oral health care products will continue to grow, and with good reason.

V. Kim Kutsch, DMD