title: Herbst appliance effects on pharyngeal airway ventilation evaluated using computational fluid dynamics.
abstract: OBJECTIVE
  To evaluate the effect of a Herbst appliance on ventilation of the pharyngeal airway (PA) using computational fluid dynamics (CFD).
  
  
  METHODS
  Twenty-one Class II patients (10 boys; mean age, 11.7 years) who required Herbst therapy with edgewise treatment underwent cone-beam computed tomography (CBCT) before and after treatment. Nineteen Class I control patients (8 boys; mean age, 11.9 years) received edgewise treatment alone. The pressure and velocity of the PA were compared between the groups using CFD based on three-dimensional CBCT images of the PA.
  
  
  RESULTS
  The change in oropharyngeal airway velocity in the Herbst group (1.95 m/s) was significantly larger than that in the control group (0.67 m/s). Similarly, the decrease in laryngopharyngeal airway velocity in the Herbst group (1.37 m/s) was significantly larger than that in the control group (0.57 m/s).
  
  
  CONCLUSIONS
  The Herbst appliance improves ventilation of the oropharyngeal and laryngopharyngeal airways. These results may provide a useful assessment of obstructive sleep apnea treatment during growth.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Iwasaki
authors.forename: Hideo
authors.initials: H
authors.lastname: Sato
authors.forename: Hokuto
authors.initials: H
authors.lastname: Suga
authors.forename: Ayaka
authors.initials: A
authors.lastname: Minami
authors.forename: Yuushi
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Takemoto
authors.forename: Emi
authors.initials: E
authors.lastname: Inada
authors.forename: Issei
authors.initials: I
authors.lastname: Saitoh
authors.forename: Eriko
authors.initials: E
authors.lastname: Kakuno
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Kanomi
authors.forename: Youichi
authors.initials: Y
authors.lastname: Yamasaki
mesh_terms: D002648:Child; D019295:Computational Biology; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D057446:Hydrodynamics; D008297:Male; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D017289:Orthodontic Appliances, Functional; D010614:Pharynx / Q000000981:diagnostic imaging*; D012119:Respiration; D016896:Treatment Outcome
keywords: Computational fluid dynamics; Cone-beam computed tomography; Herbst appliance; Obstructive sleep apnea; Pharyngeal airway