Before I answer this question, as it is not really straight forward from your question? Damage can be permanent or may grow out depending on different factors! Certain medications can cause damage, as can aesthetics as well as other drugs, trauma, disorders, illness and filing (I am sure there are more) can all cause differences in nail growth but I believe that if it is permanent or not determins whether the matrix of the nails has been damaged (place where nail cell divide and grow to form nail plate and bed).
If you can be more specific then more help may be available.