Electromyography and asymmetry index of masticatory muscles in undergraduate students with temporomandibular disorders

Abstract

Aim:To compare the electromyographic activity and the asymmetry index among degrees of severity of temporomandibular disorders (TMD). Methods: Surface electromyography (EMG) of the right and left masseter and temporalis muscles was performed in 126 undergraduate students at rest and at maximal voluntary contraction. Three measurements were performed for five seconds of maximal contraction and mandibular rest. The degree of temporomandibular dysfunction was identified according to the Fonseca anamnestic index. The analysis of the asymmetry index for two pairs of muscles during maximal voluntary contraction was based on the asymmetry index proposed by Naeije, McCarrol and Weijs (1989). Results: 48.41% of the sample had mild TMD, followed by volunteers without TMD (26.98%), moderate TMD (19.05%) and severe (5.56%). The survey results show absence of correlation between the Fonseca anamnestic index and electromyographic activity at rest and at maximal voluntary contraction in undergraduate students in both muscles (p>0.05) and the asymmetry index did not differ between the analyzed groups. Conclusions: For the population of undergraduate students, there is no evidence that the presence and severity of TMD influence the EMG activity of masseter and temporalis muscles and the muscle asymmetry index at rest and maximal voluntary contraction.

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

“…Ten studies had good methodological quality, and two had low quality (Table ). Only four studies assessed the quality of the EMG signal (baseline and noise). Care taken to avoid sources of bias (blinding) and the limitations of the study based on potential sources of bias were not described in any of the articles.…”

“…Two studies used the questionnaire proposed by Fonseca et al as the criterion for the inclusion of the participants, eight used the Research Diagnostic Criteria for Temporomandibular Disorders (DC/TMD), one used the Helkimo questionnaire, and one employed a method developed by the authors of the study.…”

“…Nine studies used only the amplitude of the EMG signal for the analysis of the data, one used only the frequency of the EMG signal, and two used both amplitude and frequency.…”

“…The normalisation of the amplitude of the EMG signal was achieved using maximum voluntary contraction (MVC) with material placed between the teeth in ten studies . Normalisation of the data was not performed in one study .…”

“…Three readings were performed, with a rest period between readings ranging from one to three minutes. The material placed between the teeth during the MVC readings was cotton with a thickness of 10 mm or folded strips of parafilm …”