Change in the posterior airway after mandibular distraction osteogenesis in patients with ankylosis of the temporomandibular joint: a retrospective study.

Mandibular distraction osteogenesis (DO) has been shown to lead to considerable improvement in obstruction of the posterior airway space in patients with ankylosis of the temporomandibular joint (TMJ), and our objective was to find out if we could confirm these findings. Seventeen patients had spiral computed tomographic (CT) scans before and after DO. After treatment, the overall posterior airway space was enlarged in all three sections of the airway (oropharyngeal, glossopharyngeal, and laryngeal). We then compared rates of change in the airway among the sections using 2-dimensional and 3-dimensional assessments, and found that the rate of change in 3-dimensional assessment of volume was significantly higher than that in the 2-dimensional (62% compared with 34%). We also found that the higher 3-dimensional rate of change came from changes in the oropharyngeal and glossopharyngeal sections, while there was no significant difference between the 2- and 3-dimensional rates of change in the laryngeal section. Because the laryngeal section had the most robust enlargement after DO in both the overall area of the posterior airway space (increased by 54%) and volume (increased by 73%), we concluded that 3-dimensional assessments were more sensitive to smaller changes in the airway space during the operation. This suggests that 3-dimensional assessments are preferable in the prediction and evaluation of the effects of DO on the posterior airway space.