Abstract: Objective To evaluate the therapeutic effects of midface distraction osteogenesis in the treatment of midface hypoplasia by 3D reconstruction and measurement. Methods From 2005 to 2010, 11 cases with severe midface hypoplasia were treated with Le Fort Ⅲ osteotomy and distraction osteogenesis. The change of upper airway, eyeball position, occlusion and midface position were all measured by 3D reconstruction and measurement pre- and postoperatively. Results After Le Fort Ⅲ osteotomy and distraction osteogenesis, airway obstruction was effectively relieved and facial appearance was im-proved significantly. The upper airway volume was increased to (9.13±6.94) cm3 on average, and airway obstruction was effec-tively relieved comparing with preoperative values (P<0.01). The degree of exophthalmos was about (21.23±3.3) mm before operation, and (11.4±3.5) mm after operation. The proptosis was improved significantly (P<0.01). The ANB was (7.16±3.41) ° after operation, and SNA was (83.06 ±5.85) ° after operation. The occlusion was corrected. The midface was ante-displaced about (20.27±8.04) mm on average, and the new bone formation was observed by CT scanning after 5.4 months ’ follow-up. Conclusion Le Fort Ⅲ osteotomy and distraction osteogenesis in treating midface hypoplasia can improve the function of upper airway and the appearance of midface. 3D reconstructive and measurement is an ideal evaluation method.

Key words: Distraction osteogenesis, Midface hypoplasia, Three dimensional reconstruction, Computer-aided measurement