i agree that your teeth may heal over time if you constantly keep the damaged tooth clean. keeping the tooth clean is the key though. im not sure why.........maybe its because when you keep your teeth clean and you keep applying pressure on your teeth when chewing, the teeth actually grow just a bit over time and the damaged spot ends up growing closed. maybe it also has to do with fluoride in the water we use to rinse teeth, etc. the flouride maybe continues to keep coating the damaged tooth every time we rinse and it forms a protective coating on the tooth and the cleaner we keep the tooth, the thicker the coating becomes.
about the store bought toothpaste? my dentist told me last year that i have been brushing my teeth too vigorously and that my gums were receding because of it. he told me that when you are using toothpaste that you should NEVER brush your teeth vigorously because the "detergent" in the toothpaste just eats away at your gums. so i'd have to say i also agree with you that "natural" toothpaste would probably be the safer and healthier of the two.