Occlusal difficulties after simultaneous mandibular and maxillary distraction in an adult case of hemifacial microsomia.

A 23-year-old woman with hemifacial microsomia type IIB was treated by simultaneous mandibular and maxillary distraction. During the course of the distraction, cephalometric analysis showed that the maxilla was not moving downward and that the upper edge of the mandibular condyle was moving upward into the space between the condyle and the glenoid fossa. This phenomenon could lead to early consolidation of the osteotomized maxilla, resulting in malposition and occlusal difficulties. This is thought to be a problem unique to bimaxillary distraction of hemifacial microsomia type IIB with severe hypoplasia of the mandibular ramus and space between the condyle and the glenoid fossa. Surgeons should be alerted to this risk and prepared to address it when performing this procedure.