Is there a difference in the electromyographic activity of the masticatory muscles between individuals with temporomandibular disorder and healthy controls? A systematic review with meta‐analysis

Abstract

The diagnosis of temporomandibular disorders (TMD) is complex, and it is not yet clear in the literature whether the clinical changes associated with these disorders are also reflected in the electromyographic (EMG) activity of the muscles of mastication. To determine whether there is a difference in the electromyographic activity of the masticatory muscles between individuals with TMD and healthy controls. ScienceDirect, EMBASE, MEDLINE, PEDro, SciELO, CINAHL and LILACS databases from January 2000 to February 2019. Cross-sectional studies, crossover studies and randomised controlled trials evaluating EMG activity of right and left masseter and anterior temporal muscles in patients with TMD and healthy controls. Two independent assessors extracted data from the selected articles. The risk of bias was determined using a checklist for assessing methodological quality created based on the guidelines of the Strengthening the Reporting of Observational Studies in Epidemiology and International Society of Electrophysiology and Kinesiology. Mean differences and 95% confidence intervals were calculated and combined in metaanalyses. A total of 51 267 studies were retrieved, and 12 were included in this review. Only two studies enabled the comparative analysis of the results. The different EMG signal capturing, processing and analysis methods used constitute an important limitation to the comparative analyses of the results reported in the studies selected for the present review. This systematic review did not demonstrate evidence of significant differences in the EMG activity of the masticatory muscles between individuals with TMD and healthy controls. K E Y W O R D S electromyography, mastication, systematic review, temporomandibular disorders | 673 MASSAROTO BARROS eT Al.

Is jaw muscle activity impaired in adults with persistent temporomandibular disorders? A systematic review and meta‐analysis

“…Task‐specific and muscle‐specific changes in jaw muscle activity may explain why the findings of this review differ to those by Massaroto Barros et al, 7 who found no difference in masticatory muscle activity between TMD and controls. With activity increased in some muscles during certain tasks and reduced in others, combining results of all variables could potentially result in a ‘cancelling out’ phenomenon.…”

“…This may help explain some of the conflicting findings between studies in this review, which ultimately contributed to the moderate to very low confidence ratings across several outcomes. In those studies where reported EMG values were averaged between sides a nullifying effect may have occurred, potentially reducing effect sizes and limiting statistical findings in this review and that of Massaroto Barros et al 7 …”

“…It has even been proposed and tested as a tool to help diagnose TMD and differentiate between different TMD subgroups, although this has conflicting evidence 4‐6 . A recent systematic review by Massaroto Barros et al 7 investigated muscle activity in TMD populations compared with healthy controls. Through meta‐analysis, they concluded that no significant difference in overall masticatory muscle activity was found between individuals with TMD and healthy controls; although data were not separated for individual muscles or tasks.…”

Effects of Therapeutic and Aerobic Exercise Programs on Pain, Neuromuscular Activation, and Bite Force in Patients with Temporomandibular Disorders

“…Regarding sEMG in the PR, despite the decreasing trend seen in the three groups after the exercise interventions, there were no significant differences. Studies that have compared the sEMG activity at rest between patients with TMD and healthy individuals have shown contradictory findings, with some authors identifying greater activity in individuals with TMD [55] and others not reporting significant differences [56]. The effects obtained immediately after completing the intervention program were maintained at the final follow-up.…”

Assistência ao paciente com disfunção temporomandibular na atenção primária à saúde brasileira: lacunas, desafios e possibilidades

“…O diagnóstico da DTM é essencialmente clínico, baseado em sinais e sintomas que podem ser investigados com auxílio de ferramentas específicas (índices e questionários) (Barros et al, 2020). Frequentemente, o indivíduo com DTM pode queixar-se de dor (nos músculos mastigatórios e na ATM) e cefaleia (Moura et al, 2017).…”