Will a jaw surgery change my facial apperance?

Depend on type of Sx: If you have facial surgery to change the position of your jaw bones or facial cosmetic surgery then yes it will change the appearance of your face but if you have intra-oral surgery for problems involving your gums or teeth then there should be no external changes in your facial appearance. You need a consultation with a surgeon to see what type of surgery you need.

Perhaps: Sometimes of surgery will change appearance. Some not. Ask your oral surgeon.