Reducing Obstructive Sleep Apnea After Hypoglossal Nerve Stimulation Through Mandibular Advancement

Inclusion Criteria: * Age ≥ 18 years. * Ability to read, write, speak, and understand English. * Failure of hypoglossal nerve stimulation (HGNS) therapy, defined as intolerance to HGNS or insufficient AHI reduction based on modified Sher criteria while using HGNS. * Ability to insert and remove the mandibular advancement device (MAD) independently. * Ability to complete all study assessments and evaluations, including home sleep apnea tests (HSAT). * Ability to abstain from any other treatment for obstructive sleep apnea (OSA) during the entire study duration. * Access to an internet-connected device (phone, tablet, or laptop) with a camera. Exclusion Criteria: * Age over 70 years. * Inability to use a mandibular advancement device (MAD), defined as having fewer than 9 healthy teeth per dental arch. * Prior intolerance to MAD therapy. * Previous participation in a trial involving the use of oral appliances. * Chronic nasal obstruction. * Dependence on or frequent use of medications that alter consciousness, respiration, or alertness. * Insomnia and/or use of medications to treat insomnia. * Sleep disorders such as narcolepsy, insomnia, restless leg syndrome, or other disorders affecting sleep, and/or use of medications to treat such disorders. * Substance abuse. * Unstable psychiatric disorders. * Current use of a GLP-1 receptor agonist (e.g., Zepbound, Wegovy, Ozempic, Mounjaro) with ongoing, active weight loss at the time of enrollment, or recent dose escalation within the prior 8 weeks.