Case Report
Kaan Orhan, Ozlem Ucok, Cag
Abstract
The objectives of this study were to figure out the prevalence of sideways disc displacement of the temporomandibular joint (TMJ) in symptom-free volunteers and to compare signal intensity ratios of masticator muscles in normal joints and in sideways disc displacements. The study was based on bilateral Magnetic Resonance Images (MRI) of 112 joints in 56 symptomfree volunteers. Sideways displacements were identified as medial disc displacement (MDD) and lateral disc displacement (LDD). The signal intensity ratios (SIR) of masticator muscles for both normal joints and pure sideways displacements were measured with elliptic ROI on T1 and T2 weighted MRIs. Of the 112 TMJ images, one showed LDD and two showed MDD. The signal intensity ratios increased for pterygoid lateral and temporal muscles in sideways disc displacements. The results of this study suggest that the temporal muscle fibres are also inserting into the TMJ disc like the pterygoid muscle. Therefore, sideways disc displacements have direct effect on pterygoid lateral and temporal muscles.