Mandibular Distraction Osteogenesis in Toddlers with Hemifacial Microsomia: A Five-Year Follow-Up of a Prospective Cohort Trial

Background: Mandibular Distraction Osteogenesis (MDO) is commonly used to treat Hemifacial Microsomia (HFM); however, its long-term efficacy, particularly on maxillary growth, remains unclear. Preliminary studies have suggested that MDO in toddlers may result in better outcomes. This five-year follow-up study evaluated the long-term effects of early MDO on maxillary growth and facial symmetry. Methods: A five-year follow-up was conducted in patients who participated in a prospective cohort study. Patients were divided into Group A (surgical age 1–3 years) and Group B (surgical age 4–6 years). The 3D CT data were analyzed. Symmetry was assessed using occlusal plane canting (∠OP) and the symmetry index (affected/unaffected side), and maxillary growth was evaluated using volume and linear measurements. Correlation analysis was performed to explore the relationship between mandibular distraction and maxillary growth. Results: 24 patients completed the 5-year follow-up, with 11 patients in Group A and 13 patients in Group B. Group A showed significant and sustained improvements in facial symmetry and maxillary compensatory growth compared to Group B. The ∠OP in Group A decreased from 4.40° preoperatively to 2.23° postoperatively, with little relapse to 2.51° at five years, while Group B showed less favorable changes. Correlation analysis confirmed a strong relationship between mandibular vertical extension and maxillary growth. Conclusion: Early MDO in toddlers with HFM was demonstrated to be safe and effective, with significant improvements in facial symmetry over a five-year follow-up period. Further studies are warranted to evaluate the longitudinal outcomes of MDO in 1- to 3-year-old HFM patients.