Ultrasonographic evaluation of masseter, trapezius and sternocleidomastoid muscles in patients with internal derangement in the temporomandibular joint

The aim of this thesis is to evaluate the thickness, echogenicity and fractal dimensions of the masseter, trapezius and sternocleidomastoid (SCM) muscles on ultrasonography (USG) images of patients with internal derangement in the temporomandibular joint (TMJ) and compare them with healthy individuals. The study included 60 individuals who underwent USG for various reasons and who were evaluated with magnetic resonance imaging (MRI) of the TMJ region. Using MRI images, patients were divided into three groups as disc displacement with reduction (DD), disc displacement without reduction (DD) and healthy. The thickness, echogenicity and fractal dimensions of the masseter, trapezius and SCM muscles were evaluated bilaterally on USG images. The comparison between patients and control groups was analyzed with Independent Samples T-test and between DD with reduction, DD without reduction and control groups was analyzed with One-Way ANOVA tests (p≤0.05). Muscle thickness was higher in the control group compared to the patient group for all evaluated muscles and statistically significant difference was observed for masseter muscle (p=0.001). When the internal structure of the muscle was examined, Type I echogenicity, where echogenic bands were evident, was more common in the control group, and Type II echogenicity, where echo-intensity decreased, the number of echogenic bands decreased, and visibility disappeared, was more common in the patient group. In the control group, fractal dimensions were higher for all muscles and statistically siginificance was found for masseter muscle (p=0.019). TMJ internal derangement causes a decrease in muscle thickness, atrophy in size, and deterioration in echogenicity. To support the results of this study, new prospective studies are needed in which the onset time of the disease and duration of the disease are known and clinical data are correlated with imaging techniques. KEYWORDS: Temporomandibular joint disorders, Echogenicity, Ultrasonography, Magnetic resonance imaging, Fractal dimension