2004 Volume 14 Issue 2 Pages 145-151
In cases of severe anterior cross bite caused by hypoplastic maxilla, most involving cleft lip and palate, maxillary advancement by distraction osteogenesis was performed with internal distraction devices that were fixed bilaterally on the zygoma after a high Le Fort I osteotomy. The lengthening devices were activated by 0.5 mm or 1.0mm per day. The length of maxilla ranged from 6.1mm to 14.0mm. Approximately 6 months after distraction osteogenesis of the maxilla, the lengthening devices were removed and mandibular setback was performed by sagittal split ramus osteotomy. CT images taken 6 months after maxillary advancement sho ed a bone-like radiopaque area in the pterygomaxillary junction in all three cleft lip and palate cases, whose lengthening speed was 0.5mm per day. Furthermore, no relapse was recognized in these three cases 1 year after maxillary advancement.
Regarding velopharyngeal function, hypernasality was recognized at 14mm of maxillary advancement in the cleft lip and palate cases, whereas, no hypernasality was found at under 10mm in the other cases. Velopharyngeal function might be preserved with in 10mm of maxillary advancement in cleft lip and palate cases. These findings are expected to be helpful in the consideration of the strategy of maxillary advancement by distraction osteogenesis.
