Airflow analysis of pediatric upper airway following maxillary expansion using computational fluid dynamics

Purpose: The objective of this study is to numerically analyze and visualize changes in airflow characteristics due to maxillary expansion in pediatric patients using computational fluid dynamics (CFD).Materials and Methods: CBCT data from pediatric patients with an apnea-hypopnea index of over 1, habitual mouth breathing, and a constricted maxilla were used. For orthodontic treatment, maxillary expansion was conducted, and CBCT scans were taken before and after expansion. 3D models of the nasal airway, created from CBCT data, were converted into smoothed, mesh-divided models. CFD analysis was conducted and various parameters which can be used to evaluate flow obstruction, including pressure, velocity, and wall shear stress, were analyzed.Results: In the patient with rapid expansion, constriction sites with high pressure, velocity, and wall shear stress distribution were identified in the anterior and posterior regions of the nasal cavity, while in the slow expansion patient, these high pressure, velocity, and wall shear stress distributed constriction sites were found in the anterior and mid-inferior regions of the nasal cavity. In both patients, after expansion, the flow-related variables that were highly distributed prior to expansion decreased, and their maximum values were also reduced.Conclusion: CFD analysis enabled the identification of constriction sites within upper airway before undergoing expansion, and improvement in airflow was confirmed after both rapid and slow maxillary expansion in pediatric patients. CFD analysis on patient-specific upper airway models is expected to aid in precisely identifying the problematic areas of respiratory obstruction, thereby assisting in the selection of personalized treatment methods.