Comparative Effects of Two Oral Appliances on Upper Airway Structure in Obstructive Sleep Apnea

“Good article just published in the latest edition of Sleep. It compares a MAS device with a TSD – the results are interesting where both appliances worked, at least in the responders, but the imaging showed some differences. This data reinforces the need for tongue position and management with OAT like The Moses appliance does”


Kate Sutherland, PhD1,2; Sheryn A. Deane, MDSc3; Andrew S.L. Chan, MD, PhD1,2,4; Richard J. Schwab, MD5; Andrew T. Ng, MD, PhD4; M. Ali Darendeliler, PhD3; Peter A. Cistulli, MD, PhD1,2,4

1Centre for Sleep Health and Research, Department of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia; 2Woolcock Institute of Medical Research, University of Sydney, NSW, Australia; 3Department of Orthodontics, Faculty of Dentistry, University of Sydney, Sydney Dental Hospital, NSW, Australia; 4Department of Respiratory and Sleep Medicine, St George Hospital, University of New South Wales, NSW, Australia; 5University of Pennsylvania, Philadelphia, PA

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.


Cohort study.


Sleep Investigation Unit.


39 patients undergoing oral appliance treatment for OSA.


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 in a subset of 18 patients.

Measurements and 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 cm3; P < 0.05). Airway structures did not differ between MAS responders and non-responders.


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.


Full text with images:


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