earticle

영어

Temporomandibular joint (TMJ) disorder leads to pain and limited opening range. TMJ disorder are caused by occlusal problem, bad habit, and muscular overactivity. The TMJ works bilaterally to create jaw motion; however, it moves asymmetrically during a production exercise. And most people move mandible toward their preferred side during a production exercise. In general, Masseter, main muscle used for chewing exercise, frequently results in TMJ disorder when biomechanical and physiological imbalance occurs. Therefore, the purpose of this study is to investigate the difference of TMJ movement range and the effect of masseter asymmetry on the TMJ pain in patients with and without TMJ pain. 30 subjects was recruited for this study, with 15 subjects with TMJ pain as the experimental group and 15 subjects with no TMJ pain as the control groups. Using Image J program, ranges of maximal mouth opening and mouth opening taken under only mandibular rotation were measured, and the thickness of masseter in the TMJ in resting condition was measured with the ultrasonography. The results of this study showed that there was a significant difference in the ratio of ranges of he maximum mouth opening and mouth opening taken under the mandibular rotation only(p<.05). However, no significant difference was found in the masseter’s thickness (p>.05). In this study, the results showed that the pain in the TMJ was not related to the asymmetry of the masseter’s thickness, and that the reduction of maximum opening and mandibular rotation were closely related to the pain. Therefore, training to use TMJ of both sides when chewing food may be helpful to prevent TMJ disorders. In addition, we recommend interventions to improve bad habits. Further studies qill bw continued in this field.