Is it possible to remove / repair "dents" in the front portion of my head left from bad hair transplants? I am not looking to have another hair transplant, just a normal looking scalp through repair.
Unfortunately, damage done to the scalp during hair transplant surgery such as pitting or cobblestoning cannot be undone. However, hair transplant repair options exist that might improve your appearance by camouflaging any "pitting" (which you referred to as dents) or old hair plugs. Hair transplant repair is typically performed by camouflaging old work with follicular unit grafts creating a more natural looking appearance. In more extreme cases, old hair plugs may be removed and redistributed as smaller grafts.
In my opinion, consult with a world class hair restoration physician about your options that might help improve your appearance and hide old hair transplant work.