[Cone-beam computed tomography evaluation of upper airway change in skeletal Class III patients after orthodontic-mandibular setback surgery].

Objective: To evaluate the short-term and long-term effects of pharyngeal airway in mandibular prognathism patients after the combined orthodontic and orthognathic treatment.

Methods: The sample included 28 skeletal Class III patients (13 males, 15 females) who had undergone mandibular setback surgery and orthodontic treatment. Cone-beam CT was taken one week before treatment (T0), 6 months (T1) and 3 years after surgery (T2). Raw data were reconstructed into three-dimensional model. Sagittal and transversal measurements, cross sectional areas, partial and total volumes were computed.

Results: Six months after surgery, oropharyngeal volume [(9 021 ± 4 263) mm³], hypopharyngeal volume [(9 236 ± 5 963) mm³] and total volume [(28 619 ± 9 854) mm³] decreased significantly (P < 0.05). Three years after surgery, only sagittal diameters [(15.9 ± 3.5) mm] and cross sectional areas [(996 ± 398) mm²] in the first cervical vertebra plane came back to the original levels (P > 0.05).

Conclusions: The pharyngeal airway space decreased after orthodontic-orthognathic therapy in the short term and it increased in some areas in the long term.