0480 Effects of a Novel Oral Orthotic on Palatoglossal Muscle Tone as a Method for Maintaining Upper Airway Patency

Abstract Introduction The palatoglossal muscle, which is the only tongue muscle innervated by the vagus nerve, maintains oropharyngeal airway patency. Mandibular advancement devices demonstrate increased airway caliber through anterior tongue repositioning, yet the impact of occlusal modification on palatoglossal tone has not been well characterized. An increase in its resting tone may reduce airway collapsibility and potentially provide a non-invasive mechanism of vagal stimulation. This study evaluated whether a novel unilateral bite-block oral orthotic (UBB) increases resting palatoglossal muscle tone by altering vertical dimension and occlusal contact, by affecting neuromuscular feedback and palatoglossal electromyography (EMG) activity. Methods Nineteen healthy adults underwent intraoral surface EMG (sEMG) using the BioEMG III system and a custom 3-D printed palatoglossal surface electrode contoured to the palatoglossal fold and secured intraorally with cyanoacrylate adhesive. For each participant, the UBB was inserted on a side opposite to the electrode lead to avoid wire interference. Each participant completed five baseline pre-UBB and five post-UBB recordings during relaxed nasal breathing in the supine position. EMG amplitudes were compared with nonparametric Wilcoxon Signed-Rank and Sign Tests in Python and SPSS. Results Mean resting EMG amplitude increased from 20.77±20.280 μV (pre-UBB) to 34.70±32.859 μV post-UBB (90.5% increase), with 16 of 19 participants showed higher post-UBB activity. Both the Wilcoxon signed-rank test (Z=-3.30, p<.001, large effect size r=.76) and two-tailed Sign Test (p=.004) showed significant increased resting EMG amplitude from pre-UBB to post-UBB conditions. Conclusion The UBB significantly increased palatoglossal resting tone. This increase suggests a neuromuscular facilitation effect, potentially mediated by an increase in oral cavity dimensions that direct the tongue superiorly and anteriorly. This would require the palatoglossal muscle to lift and elevate the posterior portion of the tongue. The UBB does not block anterior tongue movement nor prevent a more superior position, and the genioglossus muscle can reposition the tongue anteriorly concurrent to the elevated posterior portion controlled by palatoglossal muscles. This lessens the airway blocking potential of the tongue and may reduce sleep-disordered breathing. These findings support further UBB evaluation as a non-invasive vagus-nerve stimulator capable of enhancing upper-airway muscle stability during sleep and potentially treating sleep-related breathing disorders. Support (if any) Vivos Therapeutics, Inc.