Might be post-inflammatory hypopigmentation instead of a scar
So you have had 3 really nice answers by plastic surgeons on this subject. The first 2 questions are how long has it been there and what caused it? Is it in fact a scar or post-inflammatory hypopigmentation? You might try some of the topical immunomodualtors -- Elidel or Protopic -- to see if they can stimulate the pigment that might be dormant. Or you might try an excimer laser which can re-pigment hypopigmented scars or concerns. In fact, both the non-ablative and ablative fractional devices can re-pigment scars. So cutting a white scar causes another scar. I would try other things first to see if surgery is really needed. We have come a long way in this area -- so be careful, or you will have an even larger scar.
Scar on lip.
See a very experienced surgeon for a scar revision. You will always have a scar but I think it can be made much better.
Lip scar revision
Thank you for the question and pictures.
A scar excision can be performed in the office under local anesthetic. This should make the scar thin and barely noticeable.
I hope this helps.
How to treat white scar on lower lip?
White scars are very difficult to make darker. It is sometimes possible to tattoo a white scar to make it darker, but I think a simple scar revision on your lower lip would be your best treatment option. The white part would be removed so that it is no longer there. This would be a procedure that could be done in the office.