Mandibular Advancement for Obstructive Sleep Apnea: Efficacy and the Trade-off of Expiratory Velopharyngeal...

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).

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 (SpO₂). The primary outcome was the change in upper airway obstruction severity at each VOTE anatomical site.

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 SpO₂ 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.

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.