Class II surgical/orthodontic cases.  If the mandible is too retrognathic, surgical advancement may be in order.  Unlike class III surgical cases we do not always have to wait for growth to cease prior to pursuing the surgery.  The surgeons tell me that the mandible must be matured to the point that it does not splinter or greenstick fracture during surgery.  Prior to the surgery it is necessary for us to level the curve of Spee in the lower arch and close all lower spaces that are not planned for implants or restorations. Otherwise, maximum advancement of the mandible cannot be expressed.  Surgical advancement of the mandible will improve the airway in most retrognathic patients and may lessen the chance for obstructive sleep disorders in the future.