In conventional orthognathic surgery, Le Fort I osteotomy （L1）, sagittal splitting ramus osteotomy （SSRO）, and two-jaw surgery （L1+SSRO） have been used to correct severe reversed occlusion caused by maxillary hypoplasia in patients with cleft lip and palate. However, these methods produce a limited amount of movement for osteotomized jaw bone, and postoperative relapse has also been problematic. Maxillary distraction osteogenesis has attracted attention in recent years as a method that improves both the amount of jaw bone movement and postoperative relapse. We examined changes in maxillofacial condition and postoperative relapse in patients with unilateral cleft lip and palate. In addition, we compared patients who underwent L1+SSRO with those who underwent maxillary distraction osteogenesis.
Materials and methods: The subjects were 14 patients with unilateral cleft lip and palate treated in the Maxillofacial Surgery of Tokyo Medical and Dental University from 1992 through 2005. Five patients underwent L1+SSRO conventional orthognathic surgery. Nine patients underwent maxillary distraction osteogenesis （4 RED cases and 5 Zürich cases）. Their maxillofacial conditions were examined on lateral cephalograms before surgery, immediately after surgery （just after distraction was completed）, and more than 6 months after L1+SSRO surgery （more than 12 months after distraction）.
Results: Preoperatively, the SNA was less than -1 S.D. in all 14 patients （100 ％）, who all had maxillary hypoplasia. The SNB was less than -1 S.D. in 3 patients （21.4 ％）, within 1 S.D. in 10 patients （71.4 ％）, and more than 1 S.D. in 1 patients （7.1 ％）. In patients who underwent L1+SSRO, SNA averaged 72.3 ± 4.3 ° before surgery and increased to 75.2 ± 3.6 ° more than 6 months after surgery. However, no patient was included within 1 S.D. after surgery. In patients who received maxillary distraction osteogenesis, the SNA averaged 72.5 ± 5.0 ° before surgery and increased to 79.3 ± 5.1 ° more than 12 months after distraction. Five of these 9 patients were included within 1 S.D. after distraction. The mean distance of maxillary advancement was 4.8 mm in L1, 7.3 mm in the Zürich system, and 10.6 mm in the RED system. The relapse rate was 24.5 ％ of patients in L1, 12.7 ％ in the Zürich system, and 16.6 ％ in the RED system.
Conclusion: In orthognathic surgery for severe maxillary hypoplasia in patients with cleft lip and palate, maxillary distraction osteogenesis is more effective than conventional orthognathic surgery.