Does rapid maxillary expansion improve nasal airway obstruction? A computer fluid dynamics study in patients with nasal mucosa hypertrophy and obstructive adenoids

Introduction: Rapid maxillary expansion (RME) expands the maxillary dentition laterally and improves nasal airway obstruction. However, the incidence of nasal airway obstruction improvement following RME is approximately 60%. This study aimed to clarify the beneficial effects of RME on nasal airway obstruction in specific pathologic nasal airway diseases (nasal mucosa hypertrophy and obstructed adenoids) using computer fluid dynamics (CFD).
Methods: Sixty subjects (21 boys, mean age 9.1 years) were divided into three groups according to their nasal airway condition (control, nasal mucosa hypertrophy, and obstructed adenoids), and those requiring RME had cone‐ beam computed tomography (CBCT) images taken before and after RME. CBCT data were used to evaluate the nasal airway ventilation condition (pressure) using CFD and measure the cross-sectional area (CSA) of the nasal airway.
Results: The CSA of the nasal airway significantly increased after RME in all three groups. The pressures in the control and nasal mucosa groups significantly reduced after RME but did not change significantly in the adenoid group. The incidence of improvement in nasal airway obstruction in the control, nasal mucosa, and adenoid groups was 90%, 31.6%, and 23.1%, respectively.
Conclusions: The incidence of improvement in nasal airway obstruction after RME depends on the nasal airway condition (nasal mucosa hypertrophy and obstructed adenoids). In patients with non-pathologic nasal airway conditions, the obstruction may be sufficiently improved with RME. Furthermore, RME may be effective, to some extent, in treating nasal mucosa hypertrophy. However, RME was not effective in patients with nasal airway obstruction due to obstructed adenoids.

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