Filler for a "cleft lip" type of scar. Can symmetry be improved? (photos)

I had a scar revision done 3 years ago from a past accident. The dermatologist performed a sort of "Z plasty" and the resulting scar left a straight line that is indented, which is what bothers me because of the way it catche slight and casts a shadow making the line look more prominent. It's somewhat red in person and a little tender at times. Would injecting filler or some implant under the scar help raise the skin surface and or lessen the indented appearance? Other options?