Some skeletally mature patients with cleft lip and palate show severe maxillary transverse contraction and posterior crossbite. This study presents the experiences with surgically assisted maxillary expansion based on the theory of distraction osteogenesis in 8 patients. The surgical technique was basically a subtotal Le Fort I osteotomy. Expansion of the maxilla was done at 0.4-1.0mm a day by using Hyrax-type and Haas-type appliances after a latency period of 4.5 days on average. The duration of consolidation period was an average of 94 days and bone formation was clearly observed in radiographic views of the maxilla following 3 months of expansion. All patients were treated successfully without any complications such as fistula formation at the palate. This procedure may be very helpful in improving a severely contracted maxillary dental arch in cleft lip and palate patients.
