Oral surgery. This includes: reduction of a dislocation or fracture of the jaw or facial bone; excision of a benign or malignant tumor of the jaw; and removal of impacted teeth that are fully or partially imbedded in the bone and orthognathic surgery that is needed to correct a significant functional impairment that cannot be adequately corrected with orthodontic services when the member has a serious medical (or dental) condition that requires admission to a Surgical Day Care Unit of a hospital or to an Ambulatory Surgical Facility in order for the surgery to be safely performed.