ABSTRACT
Objective: To investigate the effects of the KlearwayTM appliance on the upper airway in patients with obstructive sleep apnea (OSA) in the
supine position. Methods: Sixteen subjects (12 males and 4 females) were recruited on the basis of baseline
polysomnography with a documented Apnea and Hypopnea Index (AHI) >15 per hour. A second
overnight sleep study was performed for each subject with the appliance in place.
Baseline supine cephalometry was performed for each subject before the initial insertion
of the appliance, and follow-up supine cephalometry was undertaken with the appliance
in place. Results: The polysomnographic variables improved significantly, and the mean changes in overbite
and overjet were 5.15 mm and 6.26 mm after insertion of the KlearwayTM appliance. The supine sagittal cross-sectional areas of the pharynx and the tongue
significantly increased, while the linear distance from the hyoid position to the
mandibular plane or the RGN-C3 line significantly decreased after insertion of the
appliance. The ratio of the vertical pharyngeal length to the sagittal cross-sectional
area of nasopharynx or tongue decreased significantly. When the subjects were evaluated
on the basis of the after-insertion AHI, the group with good response (n = 11) was
found to be significantly younger than the group with the poor response (n = 5). Similarly,
the good responders revealed less prominent chins, larger tongue heights, and an increase
in hypopharyngeal sagittal cross-sectional area after insertion of the appliance.
There was a significant correlation between the improvement in AHI (%) and the supine
middle airway space (r = -0.52, p < 0.05). Conclusion: The mechanical effect of the KlearwayTM appliance on the upper airway and the stabilization of jaw posture may be important
determinants of the efficacy of the appliance.
KEYWORD
obstructive sleep apnea (OSA) - oral appliance (OA) - supine cephalometry