Purpose: Mandibular advancement devices (MADs) are effective alternatives for obstructive sleep apnea (OSA), yet robust predictors of response are lacking, and the phenomenon of device-induced expiratory velopharyngeal obstruction (EVO) remains overlooked. This study conducted an exploratory clinical simulation to compare the efficacy and airway dynamics of a custom-fitted, maximally protrusive advanced MAD simulator versus a conventional edge-to-edge oral appliance (OA) during drug-induced sleep endoscopy (DISE). Patients and Methods: In this prospective observational study, 75 adults with OSA underwent target-controlled infusion DISE. Upper airway obstruction (VOTE classification) and EVO were assessed in supine and head-rotated positions under three conditions: baseline, conventional OA, and advanced MAD simulator. A monitored subset (n=18) underwent simultaneous home sleep apnea testing to quantify apnea–hypopnea index (AHI) and lowest oxygen saturation (SpO 2 ). The primary outcome was the change in upper airway obstruction severity at each VOTE anatomical site. Results: Compared to the conventional OA, the advanced MAD simulator resolved complete velum obstruction in 34.8% of cases (supine, P = 0.015) and achieved 80.0% resolution for epiglottic obstruction during head rotation ( P < 0.001). Velum responders in the supine position were younger and had a lower body mass index (BMI) and lower baseline AHI compared to non-responders ( P < 0.05). In the monitored subset, the advanced simulator reduced AHI and improved lowest SpO 2 compared to the conventional OA ( P < 0.05). The incidence of EVO was higher with the advanced device (64.0% vs 41.3% in supine, P < 0.001), showing no significant association with tongue pressure. Conclusion: While the advanced MAD simulator effectively resolves inspiratory obstruction at the velum and epiglottis, it significantly increases EVO. This exploratory simulation highlights a critical mechanical trade-off between inspiratory patency and expiratory resistance. These hypothesis-generating results warrant further longitudinal research to determine the net clinical impact on long-term treatment adherence and sleep quality. Keywords: endoscopy, orthodontic appliances, obstructive sleep apnea, expiratory velopharyngeal obstruction
Lo et al. (Mon,) studied this question.