To evaluate the changes of morphology in the pharyngeal airway after incisor retraction in bimaxillary protrusion growing patients with maximum anchorage by three-dimensional?3D?registration and evaluation.

Study Design

Cone beam computed tomography (CBCT) scans of 32 growing patients with bimaxillary protrusion and 32 age- and gender- matched controls were reconstructed. A student t-test was used to compare morphological changes of pharyngeal airway between two groups.

Result

After treatment, both groups showed a general enlargement in pharyngeal airway dimensions. There showed no statistical differences in the change of pharyngeal volume, CSA, LAT/AP and GH between the two groups. However, the experiments showed a significant decrease in the ration of palatopharynx area (PPA) to glossopharynx area (GPA) compared with the control group. A significant correlation was observed among the PPA/GPA?the incisor retraction amount and the hyoid backward amount.

Conclusion

Growing bimaxillary protrusion patients with maximum anchorage showed a potential trend of slower growing speed of palatopharynx than glossopharynx, which may be caused by the backward of the hyoid and retraction of the central incisor