Maxillary Advancement and Impaction Increase the Size of the Nasal Airway Anterior to the Piriform Aperture, but Not Posterior to it

The exact nasal changes caused by several types of maxillofacial surgery are not yet thoroughly understood. The aim of the present study was to determine the exact nasal airway changes caused by maxillary advancement and impaction. In a retrospective hospital-based case-control study, we evaluated cone-beam computed tomography scans in subjects with skeletal class III malocclusion undergoing maxillary advancement and impaction (cases) and in subjects undergoing removal of maxillary cysts in close proximity to the nasal floor (controls), before and after surgery. In cases and controls, we compared the sizes of several cross-sectional areas (CT-CSA) anterior and posterior to the piriform aperture before surgery with those after surgery. We examined the reproducibility of the examined CT-CSA in controls using the Bland-Altman method of agreement. In 17 cases, maxillary advancement and impaction resulted in significantly larger CT-CSA around the external nasal valve (both P≤0.002), but did not change the CT-CSA posterior to the piriform aperture significantly (all P>0.08). In 17 controls, maxillary cyst removal changed significantly neither the CT-CSA anterior (all P>0.06) nor the CT-CSA posterior to the piriform aperture (all P>0.2). Reproducibility of the CT-CSA anterior and posterior to the piriform aperture was excellent. In controls, CT-CSA values 1 year after surgery were similar (0.94-0.99 times higher) to those obtained before surgery. Orthognathic surgeons should be aware that maxillary advancement and impaction would probably not change the nasal airway posterior to the piriform aperture.