Can i ride a roller coaster after orthognathic surgery?

Eventually: But you will have to wait until everything heals and get the approval of your surgeon.

Dr. clearance first: I would hold off until you get clearance from the surgeon to do so. That is not a surgery that i would want to risk having redone/repaired.

Orthognathic concern: Depends on when done. After 3 months healing, probably no real concern assuming bones are healed which can only be determined by your surgeon's evaluation.

Roller coaster: It depends on when your surgery was and exactly what operation(s) you had. Generally, i advise no contact sports for six weeks, and certainly by three months you should be good to go on a roller coaster, but you should definitely discuss it with your surgeon first.