Obstructive sleep apnoea (OSA) is a common disorder that can present with various clinical Background -Although oral appliances are effective in some patients with ob-consequences.1 Nasal continuous positive airway pressure therapy (nCPAP) is a highly structive sleep apnoea (OSA), they are not universally effective. A novel anterior effective treatment for OSA, 2 but there can be substantial problems with patient acceptance mandibular positioner (AMP) has been developed with an adjustable hinge that and long term compliance.3 The most common surgical treatment for OSA is uvulopalatoallows progressive advancement of the mandible. The objective of this prospective pharyngoplasty (UPPP) but this approach is limited by its variable success. 4 Consequently, crossover study was to compare efficacy, side effects, patient compliance, and pref-there is a need for alternative treatments for OSA that are safe, effective, and acceptable. erence between AMP and nasal continuous positive airway pressure (nCPAP) in Oral appliances represent a relatively new approach in the management of OSA. 5 Schmidtpatients with symptomatic mild to moderate OSA.Nowara and co-workers have reported their experience with a mandibular repositioning apMethods -Twenty four patients of mean (SD) age 44.0 (10.6) years were recruited pliance in 68 patients with either snoring or OSA. 6 In the 20 patients with follow up polywith a mean (SD) body mass index of 32.0 (8.2) kg/m 2 , Epworth sleepiness score 10.7 somnography the appliance reduced the apnoea and hypopnoea index (AHI) by more than 50% (3.4), and apnoea/hypopnoea index 26.8 (11.9)/hour. There was a two week wash-and improved both arterial oxygen saturation and sleep quality. O'Sullivan and co-workers in and a two week wash-out period and two treatment periods (AMP and nCPAP) have recently shown that a mandibular advancement splint decreased AHI to <20/hour each of four months. Efficacy, side effects, compliance, and preference were evalu-in 12 of 17 patients in whom untreated AHI was 20-60 per hour, and in two of nine patients ated by a questionnaire and home sleep monitoring.in whom untreated AHI was >60/hour. 7 Eveloff and colleagues reported their results with an Results -One patient dropped out early in the study and three refused to cross over anterior mandibular positioning appliance in 19 patients with OSA. 8 Their success rate was so treatment results are presented on the remaining 20 patients. The apnoea/hypo-53% when they defined treatment response as a reduction in AHI to <10/hour with the pnoea index (AHI) was lower with nasal CPAP 4.2 (2.2)/hour than with the AMP appliance. Division of (14.5)/hour (p<0.01). Eleven of the 20There are major design differences in the

Background-The mechanisms of action of oral appliance therapy in obstructive sleep apnoea are poorly understood.Videoendoscopy of the upper airway was used during wakefulness to examine whether the changes in pharyngeal dimensions produced by a mandibular advancement oral appliance are related to the improvement in the severity of obstructive sleep apnoea. Methods-Fifteen

Oral appliances for the treatment of obstructive sleep apnea (OSA) produce either mandibular or tongue protrusion, and are thought to enlarge the upper airway (UA). We used videoendoscopy to measure UA cross-sectional area (CSA) and shape in the hypopharynx, oropharynx, and velopharynx during various stages of active mandibular and tongue protrusion during wakefulness in 10 patients with OSA and nine control subjects. Measurements were made in the supine position at end-tidal expiration, and were normalized to the CSA in the normal bite position. Airway shape was expressed as the anteroposterior/lateral (AP/L) diameter ratio. There were no differences between OSA patients and controls in the effects of mandibular and tongue protrusion on UA caliber. Both mandibular and tongue protrusion increased CSA in the hypopharynx and oropharynx (p < 0.001), whereas only tongue protrusion increased CSA in the velopharynx (p < 0.001). Tongue protrusion caused a greater increase in oropharyngeal and velopharyngeal CSA than did mandibular protrusion (p < 0.05). Mandibular protrusion caused a greater increase in CSA in the hypopharynx than in the oropharynx or velopharynx (p < 0.05). Obese patients had a larger relative increase in oropharyngeal CSA with mandibular and tongue protrusion than did subjects of normal weight. Tongue protrusion increased the AP/L diameter ratio in the oropharynx and velopharynx (p < 0.001), and mandibular protrusion did so to a lesser extent in the oropharynx (p < 0.01), resulting in a more circular airway shape. We conclude that mandibular and tongue protrusion increase the CSA and alter the shape of the UA during wakefulness.

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