We’d love to say indefinitely, as long as you continue the treatment. It strongly depends on your diet and pH level of your saliva. Your teeth demineralise daily, especially when consuming acidic foods and drinks (e.g.Cola, lemon juice, etc.)
Nano Hydroxyapatite is shown to reduce sensitivity by occluding the open Dentin tubules. This prevents hot, cold, acidic food from coming into direct contact with the nerve endings in your teeth. It’s not just another desensitising solution like for example potassium nitrate that constantly numbs the nerve to avoid pain. So if you stop treatment with potassium nitrate toothpaste your teeth become sensitive again. Nano HAp restores the damaged enamel, so the dentin isn’t exposed anymore.