title: Comparative effects of two oral appliances on upper airway structure in obstructive sleep apnea.
abstract: OBJECTIVE
  Oral appliances are increasingly being used for treatment of obstructive sleep apnea (OSA). Mandibular advancement splint (MAS) mechanically protrudes the mandible, while the tongue stabilizing device (TSD) protrudes and holds the tongue using suction. Although both appliances can significantly improve or ameliorate OSA, their comparative effects on upper airway structure have not been investigated.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  Sleep Investigation Unit.
  
  
  METHODS
  39 patients undergoing oral appliance treatment for OSA.
  
  
  METHODS
  OSA patients underwent magnetic resonance imaging (MRI) of the upper airway during wakefulness at baseline and with MAS and TSD in randomized order. Treatment efficacy was determined by polysomnography in a subset of 18 patients.
  
  
  RESULTS
  Upper airway lumen and surrounding soft tissue structures were segmented using image analysis software. Upper airway dimensions and soft tissue centroid movements were determined. Both appliances altered upper airway geometry, associated with movement of the parapharyngeal fat pads away from the airway. TSD increased velopharyngeal lateral diameter to a greater extent (+0.35 ± 0.07 vs. +0.18 ± 0.05 cm; P<0.001) and also increased antero-posterior diameter with anterior displacement of the tongue (0.68 ± 0.04 cm; P<0.001) and soft palate (0.12 ± 0.03 cm; P<0.001). MAS resulted in significant anterior displacement of the tongue base muscles (0.35 ± 0.04 cm). TSD responders (AHI reduction ≥50%) increased velopharyngeal volume more than non-responders (+2.65 ± 0.9 vs. -0.44 ± 0.8 cm(3); P < 0.05). Airway structures did not differ between MAS responders and non-responders.
  
  
  CONCLUSIONS
  These results indicate that the patterns and magnitude of changes in upper airway structure differ between appliances. Further studies are warranted to evaluate the clinical relevance of these changes, and whether they can be used to predict treatment outcome.
authors: Centre for Sleep Health and Research, Department of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia.
authors: Kate
authors: K
authors: Sutherland
authors: Sheryn A
authors: SA
authors: Deane
authors: Andrew S L
authors: AS
authors: Chan
authors: Richard J
authors: RJ
authors: Schwab
authors: Andrew T
authors: AT
authors: Ng
authors: M Ali
authors: MA
authors: Darendeliler
authors: Peter A
authors: PA
authors: Cistulli
mesh_terms: D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010614:Pharynx / Q000503:physiopathology; D017286:Polysomnography; D019736:Prostheses and Implants; D012137:Respiratory System / Q000503:physiopathology; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology / Q000628:therapy*; D014059:Tongue / Q000503:physiopathology; D016896:Treatment Outcome