Hydroxyapatite is a naturally occurring mineral form of Calcium Phosphate which is found in the human body: in bones, tooth enamel, and dentin (the boney structure of the tooth). In fact, it comprises nearly 97% of tooth enamel and 70% of dentin. It plays a crucial role in maintaining the structure of bones and teeth. As an alternative to fluoride, it remineralizes enamel, reduces tooth sensitivity, and strengthens teeth against decay.
Hydroxyapatite can be obtained in several ways. It can be extracted from bony substances, namely by grinding bones into a fine powder, or it can be synthesized in a laboratory. In searching for the best, most effective and cleanest option for our tooth powder we discovered that not all hydroxyapatite is created equal.
When it comes to this mineral, size matters! If the particle size is too large, as in more than 1.3 microns, it is not able to enter into the dentin tubules, which when exposed, leads to tooth sensitivity. Also, if used in tooth powder, these larger sized particles can create a gritty sensation after brushing. Furthermore, larger sized particles have a more difficult time aggregating into crystals, which is an essential step in tooth remineralization.
What’s more, not only is size an important factor, but also shape (also known as morphology). Hydroxyapatite particles can be needle shaped, rod shaped, or spheroid. This morphological distinction is of primary importance when the particle size is in the 60-100 nanometer range. This form of hydroxyapatite is known as nano-HAP, or nano-hydroxy. The morphological condition of HAP particles is a matter of some contention within the scientific community.
However, the general consensus is that rod-shaped HAP particles are considered superior to the other two shapes. The reason for this is that rod shaped particles, with an aspect ratio of no more than 1:3 are better able to aggregate into crystals and assist in the remineralization process. Spheroid shapes do not “stack” as well, and therefore appear less likely to create dense clusters of crystals which function to repair enamel, and fill holes within the dentin tubules. Furthermore, ‘needle shaped’ nano-HAP crystals have become a cause for concern among some researchers, who claim that they pose a danger to some cells of the human body.
For this reason, the European Union has banned the use of needle shaped nano-hydroxyapatite in oral care products, and allows only the rod shaped nano particles to be used by the personal hygiene industry in Europe.
One other consideration that is worth noting here is the manufacturing process for hydroxyapatite. In order to obtain ultra small particles, in the nanometer range, most laboratories heat inorganic calcium and phosphorous to over 1000 degrees in order to synthesize particles that meet the size requirements for nano-HAP. This was of some concern to us, at REAL products and so we spent a long time considering all of our options, while still striving to obtain the best quality HAP for our tooth powder.
As it turns out, we found just one lab, in Europe, which holds the only license for rod shaped nano-HAP for use in oral care products within the European Union, which uses a patented process for synthesizing nano-hydroxyapatite at room temperature, using only inorganic calcium and phosphorous salts as the base ingredient. This aqueous suspension of nano-hydroxyapatite has then slowly dehydrated to create the powder we use in our own formulation.
We considered every option, in our own research, and finally concluded that this option was the best fit for our product, and our values.
