title: Computational fluid dynamics analysis of the upper airway after rapid maxillary expansion: a case report.
abstract: BACKGROUND
  Assessment of the upper airway volume, morphology, and mechanics is of great importance for the orthodontic patient. We hypothesize that upper airway dimensions have significant effects on the dynamics of the airway flow and that both the dimensions and mechanics of the upper airway are greatly affected by orthodontic and orthopedic procedures such as rapid maxillary expansion (RME). The aim of the current study was to assess the effect of RME on the airway flow rate and pattern by comparing the fluid dynamics results of pre- and post-treatment finite element models.
  
  
  METHODS
  Customized pre- and post-treatment computational fluid dynamics models of the patient's upper airway were built for comparison based on three-dimensional computed tomogram. The inhalation process was simulated using a constant volume flow rate for both models, and the wall was set to be rigid and stationary. Laminar and turbulent analyses were applied.
  
  
  RESULTS
  Comparisons between before and after RME airway volume measurements showed that increases were only detected in nasal cavity volume, nasopharynx volume, and the most constricted area of the airway. Pressure, velocity, and turbulent kinetic energy decreased after dental expansion for laminar and turbulent flow. Turbulent flow shows relatively larger velocity and pressure than laminar flow.
  
  
  CONCLUSIONS
  RME showed positive effects that may help understand the key reasons behind relieving the symptom of breathing disorders in this patient. Turbulence occurs at both nasal and oropharynx areas, and it showed relatively larger pressure and velocity compared to laminar flow.
authors.affiliation: Department of Orthodontics and Oral Facial Genetics, Indiana University School Dentistry, 1121 West Michigan Street, Indianapolis, IN, 46202, USA, aghoneim@iu.edu.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ghoneima
authors.forename: Sahar
authors.initials: S
authors.lastname: AlBarakati
authors.forename: Feifei
authors.initials: F
authors.lastname: Jiang
authors.forename: Katherine
authors.initials: K
authors.lastname: Kula
authors.forename: Tamer
authors.initials: T
authors.lastname: Wasfy
mesh_terms: D000403:Airway Resistance / Q000502:physiology; D019412:Anatomy, Cross-Sectional; D002648:Child; D003198:Computer Simulation; D020342:Finite Element Analysis; D005500:Follow-Up Studies; D006801:Humans; D057446:Hydrodynamics; D007013:Hypopharynx / Q000502:physiology; D021621:Imaging, Three-Dimensional / Q000379:methods; D001239:Inhalation / Q000502:physiology; D008297:Male; D008954:Models, Biological; D009296:Nasal Cavity / Q000502:physiology*; D009305:Nasopharynx / Q000502:physiology; D009960:Oropharynx / Q000502:physiology; D016382:Orthodontic Appliance Design; D010155:Palatal Expansion Technique / Q000295:instrumentation; D010614:Pharynx / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology; D036542:Tomography, Spiral Computed / Q000379:methods