Aim: To study the therapeutic effect of the RelaxBogen device on sleep bruxism (SB) and temporomandibular dysfunction (TMD)-related symptoms and pain of myogenic origin in a trial of RelaxBogen plus stabilization splint therapy (RB-SST) versus stabilization splint therapy alone (SST). Materials and methods: A single-blind, single-center randomized controlled trial of RB-SST versus SST (control) in 32 patients with SB and TMD symptoms, who were randomly assigned to treatment with either RB-SST or SST for a comparative efficacy analysis over a treatment duration of 8 weeks. All examinations were performed according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) standards. Results: Analysis of Stelzenmüller’s Pain Location/Numeric Rating Scale Questionnaire (SL-NRS) responses and muscle palpation test findings revealed significant pain reduction in the jaw elevator muscles in the RB-SST group compared with the SST (control) group. The RB-SST patients also had less pain on mouth opening. Furthermore, the RelaxBogen device had a mitigating effect on headache in association with muscular TMD symptoms, commonly described as tension headache. Keywords: temporomandibular dysfunction, bruxism, jaw, headache, fascia, RelaxBogen, CMD, TMD, myalgia