I had the same surgery three years ago (aged 19). I had an underbite of about 8 mm which doesn't sound much but rendered me incapable of chewing/biting into food properly and I felt I couldn't ever smile, which affected me socially. I had braces put in when I turned 16 and then had two wisdom teeth removed when I was 18 which would have hindered the surgery.

The surgery was done in about 12 hours and I spent 3 days in the hospital recovering, off my tits on morphine and I remember nothing of those three days, other than having a great time. The surgery basically involved cutting a small segment out of my lower jaw on both sides, moving it slightly back and bolting it in place, and doing the same on the top jaw, but moving it back. I was sent home and lived off liquids for 6 weeks before moving onto soft foods. Those 6 weeks were pure hell, though. I woke up every morning for the first two/three weeks in pure agony, as my jaw had effectively been broken in 4 places. Again, thanks to opioids, those days all sort of blended in to one and after a few weeks my enormous swollen cheeks had subsided and I look relatively normal.

My chin was numb for about 6 months and a small segment of my lower lip still hasn't regained full feeling and tingles from time to time. I also get toothache in my upper jaw sporadically which I imagine has to do with the surgery.

My confidence levels skyrocketed once I could smile properly and I had the braces finally taken off 6 months after the surgery. It has subtly but noticeably changed my face's shape for the better.

The whole experience (drugs, braces and surgery) didn't cost me a penny as it was all done on the NHS.