Scraggly whiskers, scars on face

My Australian Shepherd / Beagle mix is about 7 months old now, and about 4 months into recovery from red mange. When I found him, he had lost most of his fur, and his face was SOOOO scratched up.

Now, his body looks good, and his face looks good unless you know what to look for. If you look closely, you can see that his whiskers are straight and firm like they should be; they're weak, they either hang down or are a little curly, and they don't feel as thick as they should. And even though his face looks normal at first glance, if you look at a picture then you can see a lot of area where the skin shows through. My guess is that these are scars from the deeper cuts from before.

These issues don't seem to be bothering him at all, they just make him not as attractive as he could be. Is there anything I can do (like, a topical solution or vitamin, or cleaning technique) to help strengthen his whiskers, and to help promote fur growth in those scarred areas?