Introduction: Midface advancement surgery using LeFort III with external distraction osteogenesis is commonly indicated for patients diagnosed with syndromic craniosynostosis who present with severe midface hypoplasia. This study aims to investigate the long-term surgical outcomes and cephalometric changes in patients undergoing LeFort III distraction osteogenesis during middle and late childhood.

Methods: This study enrolled six consecutive patients (5 males, one female) with syndromic craniosynostosis (four Crouzon, one Apert, one Pfeiffer), who underwent LeFort III distraction osteogenesis at an average age of 10.3 ± 1.5 years. Longitudinal lateral cephalograms were collected at pre-distraction (T0), early post-distraction (T1), and skeletal maturity (T2). Cephalometric measurements and dental relationship were assessed between T0, T1, and T2.

Results: LeFort III distraction osteogenesis resulted in an anterior advancement of 19.7 ± 8.1 mm at the anterior nasal spine (ANS) and 21.7 ± 9.4 mm at the A-point immediately after the procedure (T0 to T1). These advancements led to an overcorrection of the initial facial profile characterized by midface hypoplasia, dental class III malocclusion, and anterior crossbite. Notably, no significant surgical relapse or maxillary forward growth was observed after distraction, upon reaching skeletal maturity. However, continuous mandibular growth in the anteroinferior direction was noted, resulting in a gradual phenotypic relapse toward the initial facial profile, marked by decreasing ANB, Wits relationship, and overjet. Ultimately, only one patient necessitated orthognathic surgery in adulthood due to recurrent severe overjet of -8.8 mm.

Conclusion: LeFort III distraction osteogenesis achieves overcorrection of midface hypoplasia with favorable surgical stability. Performing distraction after the age of eight years may mitigate the extent of phenotypic relapse, potentially avoiding additional skeletal interventions post-skeletal maturity.

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