I had something like that. When you get older your teeth flesh (is it called gums?) will track back. Than the part of your teeth can become unprotected.
(on the right you see it, flesh getting back).
What helped with me is a good toothpaste. Not the cheap shit but someting like Elmex sensitive or ther toothpaste for sensitive teeth.
Now i use this on advice of the dentist to strenghten the teeth.
And yes, it helped. So you could try it. Ask wich helps best for sensitive teeth.