Analysis of nasal airway symmetry and upper airway changes after rapid maxillary expansion

The objectives of this study were to assess the changes in right vs left nasal cavity volumes and minimum cross-sectional width, nasopharyngeal, and oropharyngeal volumes of the upper airway in response to rapid maxillary expansion (RME). Pretreatment and posttreatment cone-beam computed tomography scans of 28 patients with a mean age of 9.86 ± 2.43 years and 20 age- and sex-matched controls were digitized and linear, angular, and volumetric measurements were obtained. Nasopharyngeal volume, right, and left nasal cavity volumes, and minimum cross-sectional widths increased significantly 2 years post RME (P 0.05), whereas the oropharyngeal volume increase for both groups was comparable (P = 0.92). In the experimental group, the right and left nasal cavity volumes were not significantly different at baseline or posttreatment. However, the change that occurred was significantly larger for the left nasal cavity. This change for the control group was more significant for the right nasal cavity. Maxillary right and left molar inclinations were positively correlated to the nasal cavity volume, showing that the more buccally inclined the maxillary molars were, the smaller the nasal cavity volume. Nasopharyngeal and right and left nasal cavity volumes and minimum cross-sectional widths increase significantly after RME in young children. Expansion decreases the degree of difference in volume between the right and left nasal cavities. The buccal inclination of maxillary molars is correlated with nasal cavity volume. •Maxillary expansion reduces the volume difference between the nasal cavities long term.•Two years posttreatment, significant increases in nasal volume were found.•Minimum cross-sectional width and nasopharyngeal volume also increased.•The increase in oropharyngeal volume did not differ significantly from the control group.•Increased inclination of maxillary molars was correlated with smaller nasal cavity volume.