Manual Therapy in Vagus Nerve Neuromodulation for the Treatment of Bruxism

Introduction: Sleep bruxism is defined as the repetitive activity of the masticatory muscles, characterized by clenching or grinding of the teeth. Studies confirm the association between sleep bruxism and episodes of masticatory muscle activity, with an increase in autonomic sympathetic activity observed during transient periods of sleep. This is associated with nocturnal awakenings, related to increased cardiac, cerebral (cortical arousal), respiratory, and muscular activity. Objectives: The main objectives are "To study the mean power frequency (MPF) of the masticatory muscles measured by surface electromyography (sEMG) in the general population (with and without bruxism according to ICSD-3 and DC/TMD criteria)"; and "to assess the effectiveness of manual therapy applied to structures adjacent to the vagus nerve based on its impact on orofacial pain and symptomatology in patients with bruxism". Material and Methods: A cross-sectional observational study and a randomized controlled experimental study were designed. The first will analyze data collected by sEMG in the masticatory muscles, at rest and during maximum clenching, comparing results between bruxists and non-bruxists. The second will analyze, compared to the control group, data collected on signs (range of motion alteration, presence of sounds), symptomatology (pain, headaches, sensation of blockage, functional limitation) caused by bruxism, sleep quality (Pittsburgh Sleep Quality Index (PSQI)), oral health-related quality of life (OHIP-14), stress and anxiety status (Perceived Stress Scale and GAD-7 (Generalized Anxiety Disorder-7), respectively), and sympathetic-vagal balance (Heart Rate Variability in its frequency and time domains) before and after a manual therapy intervention on structures adjacent to the vagus nerve pathway (head, neck, thorax, diaphragm, abdomen). The collected data will be analyzed using IBM SPSS® version 25.0.0.