Long-term changes in pharyngeal airway morphology after mandibular setback surgery.

Long-term changes in pharyngeal airway morphology were evaluated after mandibular setback surgery in 10 women who were diagnosed as having skeletal mandibular prognathism and underwent mandibular setback surgery by bilateral sagittal split ramus osteotomy (SSRO) and orthodontic multi-bracket treatment. The subjects were assessed before treatment (T1), 3-6 months after SSRO (T2), and 2 or more years after SSRO (T3). From T1 to T2, the pharyngeal airway constricted significantly. On the other hand, from T2 to T3, the lower facial morphology showed no significant changes. The pharyngeal airway morphology showed significant changes in soft-palate length and posterior reference line to point of posterior tongue, indicating a tendency for relapse. These results suggest that, although the lower facial morphology and the pharyngeal airway morphology showed marked changes after SSRO, the pharyngeal airway morphology exhibited gradual physiologic readaptation. However, because the lower facial morphology after surgery was retained and stable for a long period, it was considered normal for the pharyngeal airway morphology to adapt after surgery to the improved hard tissue relationship.