ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the effect of distraction osteogenesis for severe micrognathia by comparing the pre- and post-operative profile and mentolabial relationship.</p><p><b>METHODS</b>16 cases underwent temporal-mandibular joint plasty and temporal fasciomuscular flap transfer. The mandibular distraction began at the 5th postoperative day at a rate of 0.8 mm a day, two times a day. Bony and soft tissue cephalometry were performed before and after operation. T-test was used to study the change after distraction osteogenesis.</p><p><b>RESULTS</b>There were significant differences in facial convexity, lower facial height, lower lip length, inter-labial distance, the ratio of lip to mental, the distance from lip to esthetic plane, the depth of mentolabial crease and the thickness of mental soft tissue.</p><p><b>CONCLUSIONS</b>Mandibular distraction osteogenesis can markedly improve the soft tissue profile of the middle and lower face for severe micrognathia.</p>