Does functional appliance treatment truly improve stability of mandibular vertical distraction osteogenesis in hemifacial microsomia?

Aim: After mandibular unilateral distraction osteogenesis (DO) a gradual reappearance of the vertical asymmetry during growth is observed. A pre- and post-surgical functional-orthodontic treatment was added to our distraction protocol in the attempt to increase long-term stability. In order to evaluate the actual efficacy of such a combined treatment, two samples of children affected by hemifacial microsomia were compared long-term. Material: Ten children were treated by a combined orthodontic–distraction treatment, seven by distraction only. Method: Only the vertical changes in the mandible and maxilla in the panoramic and postero-anterior cephalometric X-rays were measured. Results: All of the patients showed a gradual return of the asymmetry with growth. Occlusal plane correction and, to a much lesser extent, mandibular vertical ramus height correction were better maintained over 5 years post-DO in the orthopaedic group. Conclusion: Although orthopaedic treatment allows for a more stable occlusal plane and for a slower return of the mandibular vertical asymmetry, it has mainly a dento-alveolar effect. Therefore, the decision of applying an orthopaedic treatment associated with distraction, should be taken by surgeon and orthodontist together, considering both the advantages and the disadvantages of this treatment.