Emergence agitation is a major concern in patients undergoing orthognathic surgery. The patients may experience the sense of suffocation during emergence due to nasotracheal intubation and orofacial edema. Postoperative pain is also associated with emergence agitation. Although there is a lot of studies about emergence agitation in children, there is a few in adults, furthermore, no data about comparison of emergence agitation between sevoflurane and desflurane anesthesia in adults. Therefore, the investigators would like to compare the incidence and severity of emergence agitation between sevoflurane and desflurane anesthesia in adults after orthognathic surgery.