Maxillary movement in distraction osteogenesis using internal devices in cleft palate patients. 
The purpose of this cephalometric study was to compare the actual movement with the planned movement of the maxilla by using internal maxillary distraction in cleft lip and palate patients.  Twelve patients, including eight with unilateral and four with bilateral cleft lip and palate, underwent maxillary advancement with internal maxillary distractors.  Lateral cephalometric radiographs obtained preoperatively, predistraction, and postdistraction were used for analysis.  The movement of the maxilla, angular change of the internal devices and rotation of the mandible were measured at each stage, and the planned vector of advancement predicted from the placement vector of the distractors was compared with the actual vector.  Internal maxillary distractors were rotated in a clockwise direction during the distraction period.  The angular change of the distractors was 7.7°.  The amount of actual advancement at anterior nasal spine with distraction was 6.3 mm, which represented about 70% of the distance of activation of distraction.  The actual advanced vector at anterior nasal spine was 9.7° smaller than the planned vector.  The mandible underwent a clockwise rotation of 3.5°.  In the internal distraction technique, the maxilla was advanced inferiorly to the planned vector and with a slight clockwise rotation.  These results are useful for surgical planning when using internal distractors.