Aim: Prospective, longitudinal, clinical long-term follow-up study of a homogeneous sample of children affected by hemifacial microsomia and treated by mandibular distraction osteogenesis.
Material: Eight patients affected by types I and II hemifacial microsomia were operated on at an average age of 5.6 years with an average follow-up of 5.8 years.
Methods: Vertical changes were measured on postero-anterior cephalometric and panoramic radiographs taken sequentially.
Results: Angular changes of the infraorbital and nasal floor planes were not significant, showing that distraction osteogenesis starting after 5 years of age did not influence the maxillary skeletal base. Occlusal (plane) cant was reduced by 7 degrees on average following distraction osteogenesis, showing good dentoalveolar plasticity. Mandibular vertical changes showed a gradual return of the asymmetry, with growth in all patients (the ratio between affected and non-affected rami returned by 77% of the correction obtained by means of distraction 5 years postoperatively).
Conclusion: Although aesthetic and psychological advantages of distraction osteogenesis are well accepted it should only be applied after careful patient selection and honest explanation of the long-term recurrence by genetically determined craniofacial growth patterns.