If you are planning to use a derma roller on your scalp you will need to combine it with a topical hair growth treatment like minoxidil for the results.
Needles create microchannels in the scalp skin which enhance the absorption and penetration of minoxidil.
Personally I use the derma roller on my face and I huve noticed a clear improvement in skin regeneration. The mini injuries created by the needles seem to stimulate collagen production my skin feels firmer and more toned after consistent use.