Should I use dermal fillers for a lower abdomen scar? (Photo)

From the picture it looks hypertrophic - stretched out.  It is most likely in a high tensile area and has thus stretched.  If it is a little sunken then some fat can be injected beneath the skin.
It is also more obvious due to the deficient hair.
It can be excised and revised.  If the skin edges are opposed neatly then the surrounding hair will conceal it rather well and you may not need any filling.

You could use filler to help this and I would recommend combining with PRP to help. However, this would take quite a bit of filler and would only last 6-8 months typically. I would definitely consider scar revision through excising (cutting out) the scar tissue and allowing it to heal again. 

The combination of sublative radiofrequency and filler would be a good solution.  This will remodel the scar after four to five treatments and then fill the volume defect.  Choose a cosmetic dermatologist with a variety of treatment options.  All the best, Alexis Parker MD

Hi Dear
I would recommend a good examination because if the scar formation is because of tethering. Then one can open the scar tissue manually or with laser. Other wise filler might be good idea if you don't want any scar revision.
Thank you
Ramtin Massoudi, MD