Scars may result from injury, trauma, surgery, severe inflammation (such as from nodulocystic acne) or infection (e.g. chicken pox scars). No scar, once fully formed, can be totally erased. But there are a couple of different treatments that I have found extremely effective for improving them.
One technique, known as scarabrasion, is particularly effective for treating relatively fresh scars, i.e. those that have resulted from any of the above processes within the previous three months. Manual dermasanding, which uses what amounts to sterilized, high grade sandpaper, to abrade the surface of the young scar and the surrounding skin (under local anesthesia), when performed within this critical period, may significantly improve the appearance of the scar, and in some instances almost erase it.
For older scars, i.e. those well beyond this critical three month period, I have found medical microneedling to be quite useful. In this procedure, which is performed under local, a roller device containing many fine, almost microneedles, is rolled back and forth over the scar to break it up and to promote the sythesis of fresh, non-scar collagen. Several treatments, spaced at six week intervals, are often required, to significantly improve and fade the scar.