I Am Loosing The Top Layer Of My Tongue Skin....don't

I am loosing the top layer of my tongue skin....don't know what its called....They say its the part of the tongue that allows you to taste....I have a bare spot on both sides of my tongue size of a quarter and a nickel....and one very small area in the far back that is starting to disappear as well....my dentist noticed it at my last check-up and said it's not cancer but has not seen this before.