The hero strikes me more as just a self-righteous idiot, the prince is certainly an asshole and the saintess is possibly evil depending on how this plays out.
If it's just a pulling, it's really nothing to be scared of. When i've had teeth pulled, I just closed my eyes and tried to relax. The part that hurt the most was the injections before they started.
Hienz isn't one of the MC's classmates, the only 1 of hem to be reincarnated so far was Kanata. Hienz is just a self-righteous moron with a hero and guilt complex who has convinced himself he is doing right while just coasting along.