KKA in the real world I work for a doctor; and I'm going to school now to become an RN.... My doctor is a family one and when I saw that new ad for ACT Mouthwash I asked him; because like yourself I heard once lost it's lost for good. The good doctor said that we can try as we might; but there's no going back once a tooth starts to get damaged, that's why if we get cavities (because lack of enamel) we just fill them.... If we "cleaned it out," a section of tooth wouldn't grow....
I guess in a bow teeth don't grow anymore so if your enamel is gone, that's it.
But there are ways to prevent them from getting damaged further and that's what the ACT Mouthwash is for....
Hoping this helps
Lady K
PS I work for a doctor not a dentist mind ya