With its unique ability to bind to enamel and smooth out micro-imperfections, Nano-hydroxyapatite actively works to repair the enamel and block the nerve passageways to relieve tooth sensitivity. Nano hydroxyapatite (n-Ha for short), was developed by NASA to repair and regenerate bone and enamel that astronauts were losing while out in space. Our teeth and bones are largely composed of a natural mineral called hydroxyapatite with our enamel composed of about 97% hydroxyapatite. Davids has incorporated the power of nano-hydroxyapatite into our Sensitive+Whitening Toothpaste to create a revolutionary advancement for those who suffer from sensitive teeth by repairing the tooth enamel to help stop tooth sensitivity.