Vol.:(0123456789) 1 3 Oral Radiology https://doi.org/10.1007/s11282-018-0345-9 ORIGINAL ARTICLE Ultrasonographic evaluation of masseter muscle thickness in patients with disk displacement with reduction Ahmet Taylan Çebi 1 Received: 24 May 2018 / Accepted: 10 August 2018 © Japanese Society for Oral and Maxillofacial Radiology and Springer Nature Singapore Pte Ltd. 2018 Abstract Objectives This study was performed to ultrasonographically assess the masseter muscle thicknesses of individuals with disk displacement with reduction. Methods The thickness of the masseter muscle in 100 patients (28 male, 72 female; average age 34 years) who presented with one-sided temporomandibular joint pain and a clicking sound and were diagnosed with disk displacement with reduc- tion was measured in relaxation and at maximum contraction using ultrasonography. Results In the contracted position, the difference in the masseter muscle thickness between the healthy side and the side with disk displacement with reduction was statistically significant (p < 0.05). However, no statistically significant difference was found between the two sides in the relaxed position. Conclusions Obvious ultrasonographic changes of the masseter muscle were found in patients with temporomandibular disk displacement with reduction, and these changes might be related to unilateral chewing. Individuals with anterior disc displacement probably chew unilaterally because of pain and clicking. Keywords Temporomandibular joint disorders · Temporomandibular joint · Masseter muscle · Muscular atrophy · Ultrasonography Introduction The temporomandibular joint (TMJ) is among the most com- plex joints in the human body. The TMJ is a diarthrodial joint formed by the squamous part of the temporal bone and the mandibular condyle [1]. The term “temporomandibular disorder” (TMD) is used to describe a range of clinical prob- lems involving the TMJ, masticatory muscles, and relevant structures [2]. TMDs are characterized by clinical findings such as pain, joint sounds, and irregular and deviated jaw function. Several methods are used for TMD diagnosis. To ensure an accurate diagnosis, it is important that clinical and radi- ological examinations are used together [2]. The Helkimo index, craniomandibular index, Research Diagnostic Criteria for TMDs (RDC/TMD), and many structured examination forms have been used for clinical examination of patients with TMD [2–4]. The diagnostic criteria for TMDs (DC/ TMD) include key criteria and new disorders for the most common TMD diagnoses [4, 5]. Magnetic resonance imaging (MRI), cone beam com- puted tomography, computed tomography, and arthrogra- phy have been used for radiological examinations of patients with TMD. Because the signal intensity of bone, masticatory muscles, cartilage, articular discs, and synovial fluid differs, the structure of the TMJ region can be clearly displayed [6]. The most frequently observed TMD is disk displacement. Disk displacement occurs when the disk goes out of its ana- tomical position. Most disk displacements occur in the ante- rior direction. However, disk displacements can also occur in other directions [7–9]. This study was presented as an oral presentation at the 24th International Congress of the Turkish Association of Oral and Maxillofacial Surgery, held in Bodrum, Muğla, Turkey from 23 to 27 May 2017. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11282-018-0345-9) contains supplementary material, which is available to authorized users. * Ahmet Taylan Çebi ahmettaylancebi@karabuk.edu.tr 1 Department of Oral and Maxillofacial Surgery, Faculty Of Dentistry, Karabuk University, Balıklar Kayası Street, 78050 Karabuk, Turkey