Assimetria de razão modular mioelétrica lateral mastigatória durante a mordida máxima em mulheres com e sem disfunção temporomandibular

Abstract

Introduction: Temporomandibular disorders cover a series of conditions that affect the muscles or joints of mastication. The condition is identified as the second most frequent cause of orofacial pain in the world. In Brazil, 37.5% of the population has symptoms of temporomandibular disorder, mainly women between 18 and 45 years old, the diagnostic criteria include limitation of the range of motion of the mandible, noise or locking in the temporomandibular joint and pain intensified by the function of the mandible. Pain from temporomandibular disorders is related to the hyperactivity of the muscles involved. Objective: To analyze the presence of asymmetries between latero-lateral muscle excitation through electromyography of the anterior temporal muscle and masseter bilaterally in patients with temporomandibular disorders and healthy individuals. Method: Cross-sectional cohort study for biomechanical analysis with a sample of 102 women from the city of Governador Valadares - MG, of which 72 were diagnosed with TMD by the Research Diagnostic Criteria For Temporomandibular Disorders. Volunteers were divided into two groups: Without TMD (n=30) and TMD (n=72). An initial assessment was performed, followed by an assessment of the excitation of the masseter and anterior temporal muscles, assessed during a maximum bite effort test. Results: The differences in the asymmetry of the relationship between the masseter muscles were evaluated in a module to determine the sensitivity of binomial logistic models, based on the dominance of the TA muscle or the M muscle, in accurately predicting the presence of TMD. All assumptions were met and comparisons between groups showed significant differences for the TA muscle ratio 9p=0.007), but not for the M muscle ratio (p = 0.13). The left side was predominant over the right side in the TMD group for both TA (p = 0.02) and M (p = 0.001) muscles, while the group without TMD had a higher frequency on the right side. Binary logistic regression showed a significant model (x2 = 9.53; p = 0.002) for the TA muscle with Sn 0.843. The model for muscle M also showed significance (x2 = 8.03; p= 0.005) with = Sn = 0.837. TMD patients showed increased TA muscle proportion and left dominance asymmetry compared to healthy subjects. Both binomial logistic models, based on TA or M muscle dominance, were moderately sensitive to predict the presence of TMD. Conclusion: The electromyographic analysis for detection and characterization of mandibular muscle excitation asymmetries in patients with temporomandibular disorders allowed us to observe that the existence of an inter-subject variability is natural, but the existence of an intrasubject variability should not be observed, making it an important assessment tool.