Dimensional changes in lateral pterygoid muscles and disc position during mandibular movement using magnetic resonance imaging
Keywords:Magnetic Resonance Imaging, Temporomandibular Joint, Pterygoid Muscles.
AbstractThe lateral pterygoid muscle (LPM) has been the focus of numerous studies attempting to elucidate its possible role in temporomandibular disorders (TMDs). Disc displacement is widely accepted as a fi nding characteristic of this clinical condition. However, few studies have investigated the association between disc position and morphological alterations of the LPM. Objectives: to investigate the relationship between articular disc position and area measurements of the superior head (SH) and inferior head (IH) of the LPM using magnetic resonance (MR) imaging. Methods: The sample comprised 148 temporomandibular joints (TMJs) of 74 patients with complaints of pain and/or dysfunction in the TMJ area. Sagittal plane images were used for assessments of disc position and for tracings. Tracings of the areas of the heads were performed under 4 mandibular positions (at rest, and openings of 10 mm, 20 mm, and 30 mm) with the aid of image processing software. Data acquired was subjected to statistical analysis. Results: Statistical tests revealed changes in LPM head areas during mandibular opening movement, showing a reduction in total IH area and more heterogeneous changes in SH area. Relevance: The IH mean area was reduced in the positions assessed and showed no correlation with disc displacement. For the SH, reduced mean area was associated with anterior disc displacements without reduction, while increased mean areas were correlated with anterior disc displacement with reduction.
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