Maxillomandibular and occlusal relationships in preadolescent patients with syndromic craniosynostosis treated by LeFort III distraction osteogenesis: 10-year surgical and phenotypic stability.

INTRODUCTION: LeFort III distraction osteogenesis may be indicated in the treatment of syndromic craniosynostosis with severe midface retrusion. This study investigates long-term changes in patients undergoing distraction as children, and compares outcomes to an unaffected, untreated control. METHODS: Fifteen patients (9 males, 6 females) with syndromic craniosynostosis treated by LeFort III distraction at an average age of 4.9 +/- 1.5 years were identified. Lateral cephalograms at predistraction, immediate, 1-, 5-, and 10-year postdistraction were superimposed using the best-fit of cranial base details. An untreated, unaffected matched control was obtained from the American Association of Orthodontists Foundation Legacy Collection. Differences in landmark location and cephalometric relationships were assessed between time points and between treatment and control groups. RESULTS: LeFort III distraction produced an average advancement of 14.86 +/- 5.14 mm at A-point and 10.54 +/- 3.78 mm at orbitale. This advancement produced overcorrection of anteroposterior occlusal relationships and phenotypic correction of midface position. Surgical stability over a 10-year follow-up was excellent. Posttreatment growth was characterized by absent anteroposterior maxillary growth, preservation of dentoalveolar development and maxillary remodeling, and delayed mandibular growth. Subsequent growth resulted in a long-term phenotypic relapse of pretreatment Class III maxillomandibular relationship and negative overjet. CONCLUSIONS: LeFort III distraction osteogenesis produces stable advancement of the midface. Overcorrection is required for long-term phenotypic stability because of deficient postdistraction sagittal midface growth. Late mandibular growth contributes to underestimation of the amount of distraction required to produce long-term phenotypic correction.