Braces do not cause numbness of the face!
Something is wrong if you have numbness. Go see you orthodontist immediately and he will refer you to a specialist to diagnose what is the reason. Sound like a nerve damage and needs to diagnosed asap.

I have never had a patient complain of having a numb face after bonding brackets on. I don’t recall having had that issue when I had my braces put on either. If you are having that issue, you should talk to your orthodontist about it.
Thanks!!

Sincerely,

Robert E. Sims, D.M.D, M.S.D.