A comparative analysis of aerodynamic and anatomic characteristics of upper airway before and after mini-implant–assisted rapid maxillary expansion

Abstract

The objective of this research was to observe changes in aerodynamics and anatomic characteristics of the upper airway after mini-implants assisted rapid maxillary expansion and to evaluate the correlation between the 2 changes of the upper airway in young adults. Thirty consecutive patients (mean age, 23.82±3.90years; median, 24.5years; 9 males, 21 females) were involved. Cone-beam computed tomography was taken before activation and over 3months. Three-dimensional models of the upper airway were reconstructed on the basis of cone-beam computed tomography. The anatomic characteristics of the upper airway, including volume, area, transverse, and sagittal diameter, were measured. The aerodynamic characteristics of the upper airway were calculated on the basis of 3-dimensional models using computational fluid dynamics. The correlation between the changes in aerodynamics and anatomic characteristics of the upper airway was explored. The enlargements of the volume of the total pharynx, nasopharynx, and oropharynx were found (9.99%, 20.7%, and 8.84%, respectively). The minimum cross-sectional area increased significantly (13.6%). The airway resistance (R) and maximum velocity (Vmax) decreased significantly in both the inspiration and expiration phase (inspiration: R, -26.8%, Vmax, -15.7%; expiration: R, -24.7%, Vmax, -16.5%). The minimum wall shear stress reduced significantly only in the inspiration phase (-26.3%). The correlations between decreased R and increased volume and minimum cross-sectional area were observed. Mini-implants assisted rapid maxillary expansion is an effective device for improving anatomic characteristics represented by the total volume of the upper airway and minimum cross-sectional area, which contributed to the respiratory function depending on the favorable changes of aerodynamic characteristics including resistance, velocity, and minimum wall shear stress.