sEMG test of masseter muscle
pain
CONTRACTION
sEMG recordings from the masseter muscles were performed with a two-channel NeuroTrac MyoPlus 2 device with NeuroTrac software (Verity Medical Ltd., Tagoat, Ireland). Clinical Mode EMG was used during the study. To obtain precise sEMG measurements, a band-stop filter was used, which guarantees that the frequencies of 50 Hz and 60 Hz (mains) will not interfere with the recording of muscle activity (measured in microvolts). Specialized filtering allows sEMG to be measured with a precision of 0.1 µV.In order to avoid magnetic interference, when collecting sEMG measurements, the device was not placed in the vicinity of cell phones (< 4 m) or other sources that might interfere with the results. Two unipolar electrodes were used for the test, which were attached at a distance of 10 mm from each other. The main principle used in all subjects was to position the electrodes over the center of muscle belly, parallel to the path of its fibers (the lower electrode was placed approx. 5 mm above the mandibular angle and the upper electrode 10 mm above it); precise placement of the electrodes was preceded by careful palpation of each muscle. The masseter muscles bioelectrical signals were acquired in an upright sitting position, with the head in a natural, postural position, hands resting on the knees and feet resting on the ground. Before the electrodes were applied, the skin was cleaned with rubbing alcohol disinfectant, following electrode manufacturers’ manual and guidelines of Seniam project (Examination of the electrical activity of the masseter muscle at rest (Rest Test): the test was performed on relaxed and relaxed patients. The dental arches remained slightly open during the examination. In order to eliminate the registration of signals related to the electrical activity of the eye circular muscle, these persons had their eyelids closed during the measurements. The patients were instructed not to swallow saliva during the examination and to place their tongue in a resting position.Study of the bioelectrical activity of the masseter muscle during maximal muscle contraction (MVC): sEMG signal was recorded in a sitting position, while clenching the teeth, using the greatest possible force, within 5 s. The computer program with which the device cooperated registers the minimum and maximum values and calculates the average values of electric potentials.The sEMG values obtained were normalized as the ratio of RLX to MVC.Activity normalized to MVC [%] = RLX [µV]/ MVC [µV] × 100% [Mean sEMG values were then calculated between the right and left masseter muscles.The G1 patients were then randomly divided into three treatment subgroups, in which physiotherapy management was implemented over a period of 10 days (excluding Saturdays and Sundays). Two subgroups received manual therapy and therapeutic exercises/massage—MTM_TE; PIR—MTPIR_TE), while the third subgroup was prescribed monotherapy—TE.In women with G1, the pain was assessed each time after therapy using the NRS scale, and the mandibular range of motion was evaluated. After the 5th and 10th therapeutic day, a follow-up sEMG examination was performed at rest and on exertion.