I've only just heard about it. Apparently our enamel is over 90% hydroxyapatite. Hydroxyapatite is said to be as efficient (maybe more) as flouride in preventing cavities, and re-mineralizing teeth. Since HA is naturally occurring in tooth enamel, it's much better at filling in gaps that may occur in our enamel. You can look into it, I'm not sure I've done a good job at explaining it. Research says that 10% nano HA is most effective. "Nano" because it's more accessible for use, and healing than just HA. It sounds extremely interesting, and I am thinking about trying it.