Systematic Review and Meta-Analysis of Electromyography Potential to Discriminate Muscular or Articular Temporomandibular Disorders and Healthy Patients

Background/Objectives: New devices such as surface electromyography (sEMG) have been proposed to support traditional gnathological examination and diagnostic protocols. The aim of this study is to investigate whether sEMG can be considered a diagnostic instrument to discriminate between healthy subjects and patients with temporomandibular disorders (TMDs) of an articular or muscular nature. Methods: A systematic review was conducted according to PRISMA guidelines using literature searches of MEDLINE (via PubMed), Scopus, and Web of Science. Inclusion criteria: recent clinical studies (≤10 years) in English or Italian, involving electromyography in TMD diagnosis, with a control group of healthy patients. Data considered to be homogenous were subjected to meta-analysis (95% confidence interval [CI]; α = 0.05). Hedge g was calculated because all variables were continuous. Articles meeting the inclusion criteria were checked for further consideration, and relevant data were collected into two tables. In total, 18 studies were included after full-text reading. Meta-analyses were carried out for the static impact index (IMP), percentage overlapping coefficient (POC), and torque coefficient, and dynamic Symmetrical Mastication Index (SMI). Results: Patients with TMD had lower values in all parameters except IMP. sEMG registered a reduction in masseter activity, lower chewing efficiency, and an increase in fatigue during contractions in TMD patients. Conclusions: sEMG is not reliable to distinguish healthy from TMD patients, but despite the limitations related to the high variability in the studies (type of electromyography, static or dynamic tests, and population characteristics), the sEMG results are reliable considering the POC and SMI parameters, encouraging more in-depth studies for a predictable clinical practice. Patients with TMD had lower values in the dynamic index SMI and in static indexes POC and torque coefficient, except IMP. EMG might performs better if employed in muscle forms.