The authors studied the effect of midface distraction on maxillary skeletal position and clinical appearance in patients with Crouzon, Pfeiffer, and Apert syndromes, and examined the stability of these changes at 1 year after distraction.Methods:
Fifteen consecutive patients (six male and nine female; average age, 5.9 years) underwent Le Fort III osteotomy with midface advancement using a rigid external distraction device. Six patients had Crouzon, five had Pfeiffer, and four had Apert syndrome. Midface advancement was initiated at the level of the occlusal splint and at the zygomatic/maxillary anchor screws. The device was activated 11 mm on average, at a rate of 1 mm per day. Twenty anatomical landmarks were identified and digitized at three time intervals, and displacement of each landmark was compared with its pretreatment position.Results:
By the time of device removal, point A had advanced sagittally along the x axis 15.85 mm and moved downward 1.06 mm along the y axis; the orbitale was moved sagittally along the x axis 12.72 mm and downward 1.99 mm along the y axis. Maximum mean advancement (17.16 mm) was observed at the upper incisal edge. Maxillary and mandibular skeletal discrepancy was significantly decreased, with the ANB angle changing from −5.87 to +13.17 degrees. At 1 year after distraction, point A had advanced an additional 0.81 mm, and the orbitale and upper incisal edge had moved posteriorly 0.07 mm and 1.34 mm, respectively.Conclusion:
Significant midface advancement can be achieved and maintained with rigid external distraction of the Le Fort III osteotomy segment (up to 24 mm), with excellent stability of the advanced midfacial skeleton.