Are they just hyperpigmentation marks? Try the Alpha Hydrox 12% AHA Souffle. It faded my red marks very fast.
If they are indents, it takes a long time to make them disappear. The best I've used are Silkia camellia oil and Epidermx microdermabrasion. I had 5 dents on my forehead that were about 2mm deep. After a little over a year's use of these stuff I can barely see them any more. I have another 3 immediately above my upper lip and they have gotten a lot smoother looking, though not as great as those on the forehead.