mederma can only help make the scar softer. the only way to fill a pitted scar is to have collagen or one of the many variances to it as a skin filler injected below the surface of the mole.
not sure why you would need to keep it dry
To treat pitted scars skin specialists first reduce underlying fibrous adhesions and later either perform a dermal filler or stimulate new collagen growth with Non Ablative Laser Rejuvenation.
There are other options available, and you could discuss them in detail with your doctor.
Let us know about how you are doing and if you need any other information.