Abstract
The aim of this study was to assess the influence of unilateral posterior crossbite on the electrical activity of the temporal and masseter muscles in patients with subjective symptoms of temporomandibular dysfunctions (TMD). The sample consisted of 50 patients (22 female and 28 male) aged 18.4 to 26.3 years (mean 20.84, SD 1.14) with subjective symptoms of TMD and unilateral posterior crossbite malocclusion and 100 patients without subjective symptoms of TMD and malocclusion (54 female and 46 male) aged between 18.4 and 28.7 years (mean 21.42, SD 1.06). The anamnestic interviews were conducted according to a three-point anamnestic index of temporomandibular dysfunction (Ai). Electromyographical (EMG) recordings were performed using a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany). Recordings were carried out in the mandibular rest position and during maximum voluntary contraction (MVC). Analysis of the results of the EMG recordings confirmed the influence of unilateral posterior crossbite on variations in spontaneous muscle activity in the mandibular rest position and maximum voluntary contraction. In addition, there was a significant increase in the Asymmetry Index (As) and Torque Coefficient (Tc), responsible for a laterodeviating effect on the mandible caused by unbalanced right and left masseter and temporal muscles.
Highlights
Bilateral symmetry, characteristic of vertebrates, is extremely important for describing the morphology of the masticatory organ
The aim of this study was to assess the influence of unilateral posterior crossbite on the electrical activity of the temporal and masseter muscles in patients with subjective symptoms of temporomandibular dysfunctions (TMD)
There was a significant increase in the Asymmetry Index (As) and Torque Coefficient (Tc), responsible for a laterodeviating effect on the mandible caused by unbalanced right and left masseter and temporal muscles
Summary
Characteristic of vertebrates, is extremely important for describing the morphology of the masticatory organ This feature is strongly marked in the craniofacial area and is an important determinant of its correct structure. Assessment of bilateral symmetry in the craniofacial area is a fundamental component of the examination and description of people with and without disorders It must be stated, that slight facial asymmetry is acceptable, being a common and frequently observed morphological feature [1, 2]. The concept of the bilateral symmetry of the human body is connected with functional symmetry An assessment of this feature in the craniofacial area is primarily related to the function of the largest and strongest facial bone, namely, the mandible. The symmetrical function of this bone, which is the single and only movable bone of the skull, is determined by two morphologically coupled temporomandibular joints
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