TENS/EMG-guided myocentric mandibular positioning: a systematic review and evidence map

Introduction and aims: Jaw registration protocols using TENS and/or EMG have been proposed to identify a physiologically relaxed mandibular position. Occlusal splints, neuromuscular orthoses, and mouthguards fabricated in this position have been proposed to improve masticatory muscle function, body posture, athletic performance, and temporomandibular disorder (TMD) symptoms, but the evidence is limited and heterogeneous. This review aimed to systematically map and appraise the evidence on neuromuscular/myocentric mandibular positioning (TENS- and EMG-guided jaw posture) and its associations with (1) masticatory and postural muscle activity, (2) posture/locomotor symmetry, and (3) TMD-related symptoms and athletic performance. Methods: This systematic review followed PRISMA 2020 guidelines and was registered in PROSPERO (Registration ID: CRD420251125459). A PICOS framework was used to define eligibility criteria. Human studies assessing neuromuscular/myocentric mandibular position or appliances (neuromuscular orthoses, myocentric splints, neuromuscular mouthguards) and comparing them with conventional occlusion (centric relation, centric occlusion, habitual occlusion, or standard custom-made mouthguards) were included. Primary outcomes were EMG activity, postural/balance measures, and TMD symptoms; secondary outcomes were strength and performance measures. Risk of bias was assessed with RoB 2 for randomized/crossover trials and ROBINS-I for non-randomized studies. Due to clinical and methodological heterogeneity, a narrative synthesis was conducted, and the certainty of the evidence was assessed using the GRADE approach. Results: = 313). In healthy/athletic samples, myocentric positioning or appliances were associated with short-term changes in masticatory EMG and small, task-specific differences in balance, running symmetry, and explosive performance outcomes. In the single TMD cohort study, symptom improvement and changes in EMG patterns were reported after 3 months of neuromuscular orthosis wear, but causal inference is limited by a non-randomized pre-post design and potential confounding. Certainty ranged from low to moderate across domains. Conclusions: Evidence is sparse and methodologically limited; current findings are hypothesis-generating and do not justify routine clinical or performance claims. Clinical relevance: Neuromuscular/myocentric approaches may be considered in selected cases as an adjunct within DC/TMD-aligned care pathways, but current evidence is insufficient to support routine adoption or performance-related claims. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD420251125459, PROSPERO CRD420251125459.