Hydroxyapatite is the same material that makes up 97% of our natural tooth material. NASA figured out how to create hydroxyapatite in a lab to give to Americhan astronauts to remineralize their teeth in space, and this same technolgy is now available in Davids nano hydroxyapatite toothpaste.
Instead of using potassium nitrate found in most sensitive toothpaste to numb the tooth nerves, Davidsuses Nano Hydroxyapatite to repair the enamel and block the passageways to the nerves.
300X magnification of actual human tooth material prior to brushing with Davids Sensitive+Whitening w/nano-hydroxyapatite toothpaste.
(from actual test results provided by Intertek)
300X magnification of actual tooth material showing remineralization and tubules occluded (passageways to the nerves repaired) to relieve sensitivity.
(from actual test results provided by Intertek)