Background: Mandibular advancement devices (MADs) are an effective treatment for patients with sleep-related breathing disorders, with variable response. Increasingly more research points to the predictive value of Drug-Induced Sleep Endoscopy (DISE) in patient selection. This study aims to analyze the changes in upper airway collapsibility using a titratable MAD simulator during DISE. Methods: This study included 104 patients with simple snoring and obstructive sleep apnea (OSA). The VOTE scale was used to assess the presence of collapses during the DISE both without and with the MAD simulator. Results: In snorers, there was a decrease in collapses at the level of the soft palate and oropharynx when the advancement was achieved. Patients with mild OSA also showed a decrease in collapses at the base of the tongue. Patients with moderate/severe OSA exhibited significant amelioration at all levels. The levels at which there were residual collapses despite the maneuver were, in order, the velopharynx, oropharynx, epiglottis, and tongue. Conclusions: The MAD simulator reduces collapsibility at all levels and in all severity groups. Residual collapses suitable for combined treatments were able to be identified. This highlights the need for individualized patient selection, as upper airway collapsibility exhibits variable improvement or worsening with the MAD simulator regardless of the severity of the condition.

Objective: Accurate measurement of orofacial muscle strength is essential for phenotyping patients with obstructive sleep apnea (OSA), and particularly those with hypotonic phenotypes. High costs associated with gold standard devices such as the Iowa Oral Performance Instrument (IOPI^®) limit their clinical use. This study aims to validate the Sandway^® manometer, a low-cost alternative to the IOPI^®, by comparing its performance against the IOPI^® and the Tongue Digital Spoon (TDS) in both laboratory and clinical settings. Methods: We conducted a two-phase study. In the laboratory phase, pressure readings from the IOPI^® and Sandway^® devices were compared using standardized force application methods. In the clinical phase, 60 patients with moderate-to-severe untreated OSA underwent orofacial strength evaluation using IOPI^®, Sandway^®, and TDS devices. Intraclass Correlation Coefficient (ICC), Bland–Altman analysis, and Pearson correlation were used to assess reliability and agreement. Results: The Sandway^® showed excellent reliability for anterior tongue and lip strength measures (ICC = 0.978). Bland–Altman plots revealed minimal bias and narrow limits of agreement compared to the IOPI^®, indicating strong agreement for both tongue and lip measurements. A high correlation was also observed between Sandway^® and TDS results (r = 0.863, p < 0.001), supporting secondary validation. Conclusions: The Sandway^® manometer demonstrates high reliability and strong agreement with gold standard instruments, representing a valid, accessible alternative for objective assessment of orofacial muscle strength in clinical practice.