Stroke: An electromyographic approach to the masseter and temporal muscles, orofacial soft tissue pressure, and occlusal force.

Stroke is a cerebrovascular disease that triggers changes in the central and peripheral nervous systems, and can compromise human body function. This cross-sectional observational study aimed to analyze the electromyographic (EMG) activity of the masseter and temporal muscles, orofacial soft tissue pressure, and strength of occlusal contacts in patients who had suffered a stroke. Twenty-four patients were divided into two groups: stroke (n = 12) and control (n = 12). The EMG of the masseter and temporal muscles was evaluated during mandibular rest, protrusion, right laterality, left laterality, and maximal voluntary contraction. The Iowa Oral Pressure Instrument (IOPI) was used to measure pressure from the tongue, lips, and buccinator muscles. A computerized system for occlusal analysis (T-Scan III) was used to measure the occlusal contact points of the right and left hemiarches (upper and lower) and the upper and lower first molars. Data were subjected to Student's t-test (p < 0.05). The stroke group had lower normalized electromyographic activity, with a significant difference in the left temporal muscle during rest (p = 0.03) when compared to the control group. There was a significant difference between the groups in tongue pressure (p = 0.004) with a lower mean value in the stroke group. There was a significant difference between the groups in the evaluation of the occlusal contact points of the first permanent molars, with a lower mean percentage in the stroke group. The results indicate that stroke negatively affects functional performance of the stomatognathic system.

Stomatognathic function in Duchenne muscular dystrophy: a case-control study.

AIM: This study aimed to analyse electromyographic activity, masticatory efficiency, muscle thickness, and bite force of individuals with Duchenne muscular dystrophy (DMD). METHOD: Forty males aged 4-15 years, 20 with DMD and 20 healthy age-, height-, and weight-matched controls, underwent electromyography and ultrasonography of temporalis, masseter, and sternocleidomastoid muscles during postural control of the jaw, mastication, and maximal molar bite force. RESULTS: The normalized electromyography signals showed higher activity in masseter and temporal muscles at rest, during protrusion, left and right laterality, and fatigue condition in the group with DMD than in the comparison group (p≤0.05). For masticatory efficiency of cycles, in analysis of non-habitual chewing of flavourless gum, and habitual chewing of peanuts and raisins, the group with DMD presented lower averages (p≤0.05). For the muscle thickness, the results showed that there was a lower muscle thickness in the group with DMD for all muscles during the rest and maximal voluntary contraction, except for masseter and sternocleidomastoid in the maximal voluntary contraction. In the maximal molar bite force, the group with DMD presented higher values for both sides than the comparison group (p≤0.05). INTERPRETATION: Patients with DMD show muscle changes related to the stomatognathic system, in their activity, bite force, and muscle thickness.