I've scoured the research on PRP and the results are mixed. Its pretty contentious. I have friends, other physicians, who provide it for a bunch of stuff, and TBH, they aren't convinced it does much! What it DOES do, is put a lot of money in people's pockets--its very lucrative and requires no time, energy, or real expertise. I was interested in getting injections for some injuries and they all told me not to bother. That said, I do know people who swear it did some stuff for them (shhh...I think it was placebo!).
PRP is basically your bodies own concentrated anti-inflammatory. In the context of jaw surgery, unless you used A LOT, I'm not convinced it would do much--rubber bullets are effective against a robber maybe (rotator cuff injury), but a tank (jaw surgery)?
Again, this is NOT my area of expertise but I know a bit about it and I'm not convinced yet (probably never?).