There are many problems associated with model surgery and splint fabrication, and they can directly affect the results of surgery. An erroneous diagnostic wax bite can lead to improper positioning of the upper jaw during bimaxillary surgery. In addition, postoperative malocclusions that are out of orthodontic range often are initiated perioperatively by insufficient surgical control over interdigitation, overjet, overbite, and control of the midlines. The objectives of this study were to investigate whether wax bites can be used effectively in patients undergoing bimaxillary operations. In 5 (10%) of 50 patients, the wax bite did not fit properly. Based on these preliminary results, we believe it would be prudent to build safety measures into the treatment of patients who require bimaxillary surgery. If the wax bite does not fit properly at the beginning of surgery, navigation tools could be used to overcome inaccuracies resulting from the wax bite.