• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.5
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• pp.457-462
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• 2005

The aim of this study is to evaluate the relative signal intensity of TMJ retrodiscal tissue in T2-weighted MRI as diagnostic marker of temporomandibular disorder(TMD). 58 temporomandibular joints from 29 TMD patients (14 men & 15 women) were evaluated. The relative signal intensity of retrodiscal tissue in T2-weighted MRI was referenced to brain gray matter same size of the region of interest(ROI). The collected data was compared to disc positions (normal, anterior disc displacement with reduction, anterior disc displacement without reduction), the presence of joint effusion. The relative signal intensity of retrodiscal tissue was significantly increased when the disc was displaced without reduction. And the relative signal intensity of retrodiscal tissue was significantly increased when joint effusion was present. The results suggest that evaluating the relative signal intensity of TMJ retrodiscal tissue using a T2-weighted MRI is valuable as a non-invasive tool for diagnosing the procession of TMD.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.4
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• pp.330-335
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• 2002

The study was performed to investigate the comparison of relative signal intensity of normal- and abnormal-side retrodiscal tissue, and relationship between clinical examination, joint effusion and relative signal intensity of retrodiscal tissue in patients with unilateral TMJ internal derangement. The study group comprised 19 females and 9 males, with a mean age of 29 years. After measurements of the signal intensity were made on the MR imager for the T2 weighted images on retrodiscal tissue and brain gray matter, we calculated relative value and tried to find relationship between clinical examination, joint effusion and relative signal intensity on normal- and abnormal-side. The results are as follows. 1. The gray matter is an appropriate reference point. 2. The relative signal intensity is high significantly in abnormal-side retrodiscal tissue compared with normal-side retrodiscal tissue. 3. The relative signal intensity is high significantly in painful joints compared with nonpainful joints and in joints with joint effusion compared with joints without joint effusion. 4. The relative signal intensity in normal joints, joints with reduction and joints without reduction is increased in order significantly.

• Journal of Oral Medicine and Pain
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• v.36 no.3
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• pp.177-185
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• 2011

Aims: The purpose of this study was to evaluate the relationship between temporomandibular joint pain and the relative signal intensity (RSI) of retrodiscal tissue on T1-, and T2-weighted MRI images. Materials and Methods: This study was based on 122 TMJs of 61 patients who complain of TMJ pain in only one side but were revealed to have disc displacement in both TMJs according to MRI findings. The signal intensities of regions of interest (ROIs) in retrodiscal tissues were measured using T1-, and T2-weighted MRI images. The RSIs of retrodiscal tissues were referenced to the signal intensities of the ROIs of brain gray matter. The relationships between the RSI of retrodiscal tissue and joint pain, joint effusion, condylar degenerative change, and degree of disc displacement were examined. In addition, the relationships between joint pain and joint effusion, condylar degenerative change, and degree of disc displacement were examined. Results: On T1-weighted MR images, the painful TMJs showed significantly higher retrodiscal tissue RSI than non-painful TMJs. In addition, there is an association between joint pain and the degree of disc displacement. However, on T2-weighted MR images, the RSIs of retrodiscal tissues didn't show any significant differences with regard to joint pain, joint effusion, condylar degenerative change, and degree of disc displacement. Conclusions: The signal intensity of retrodiscal tissue can be used as a diagnostic marker for painful TMJ. However, the overall results suggest the signal intensity of retrodiscal tissue has a limited diagnostic significance in determining the pathologic status of TMJ.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.3
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• pp.211-216
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• 2007

Temporomandibular joint disorders (TMD) often show muscular disorder, internal derangement and degenerative change of articular surface of the condyle. It is important to choose adequate diagnostic method for obtaining data for the diagnosis and treatment. Magnetic Resonance Imaging (MRI) has some advantages, because it shows good resolution image for the soft tissue and it is not invasive to the human body. We have performed serial research about the retrodiscal tissue of the TMJ according to the progress of the disease, using T2 weighted image, since 2002. In this study, we applicated resized observation area to compare signal intensity between the retrodiscal tissue of the TMJ and cerebral gray matter, using T2 weighted image.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.5
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• pp.399-408
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• 2005

In the progression of the Temporomandibular Joint Disorder(TMD), not only deformation and perforation of disc occur. But also fibrotic adhesion and inflammatory changes to the retrodiscal tissue can be seen in addition to the condylar degenerative change (e.g. osteoarthritis). However, the correct diagnosis,?planning for appropriate treatment, and prediction of prognosis are limited, because there are no means to stage the progression of the disorder. In this study relative signal intensity of retrodiscal tissue in MRI and the synovial fluid concentration of matrix metalloproteinase-2 (MMP-2), MMP-9, and Interleukin-6(IL-6) in the 23 temporomandibular joints(TMJ), from 17 patients with TMD were evaluated as a possible diagnostic marker. The relative signal intensity of retrodiscal tissue was referenced to brain gray matter with same region of interest(ROI) size. The concentrations of MMP-2, MMP-9, and IL-6 were evaluated by Enzyme Linked Immunosorbent Assay (ELISA). The collected data were compared with condylar degenerative change, joint effusion and disc position observed in MRI. The relative signal intensity of the retrodiscal tissue was increased significantly when degenerative changes were present. In addition, there was significantly high signal intensity in the presence of a disc displaced without reduction. The concentration of IL-6 was significantly increased when condylar degenerative change was no observed. And there were no changes in the levels of IL-6 according to disc position and joint effusion measurement. Moreover, there were no significant relevance between the concentration of total MMP-2 and active MMP-9 in synovial fluid, relative to degenerative changes in the mandibular condyle, to joint effusion, and to disc position observed on MRI images. In conclusion, the relative signal intensity of the retrodiscal tissue can be regarded as a mean of diagnosing the procession of TMD in a non-invasive manner. But more additional studies are required for the levels of MMP-2. MMP-9, and IL-6 to determine their potentials as a diagnostic marker for TMD.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.4
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• pp.212-218
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• 2003

Matrix metalloproteinases (MMPs) play an important role in the normal morphogenesis, maintenance, and repair of matrix and also have important functions in pathologic conditions characterized by excessive degradation of extracellular matrix, such as rheumatoid arthritis, osteoarthritis, periodontitis and in tumor invasion and metastasis. In this study, expression of MMP-1 and -2 mRNA in retrodiscal tissue of the temporomandibular joint (TMJ) was examined and compared with magnetic resonance imaging (MRI) and surgical findings. MMP mRNAs in the retrodiscal tissue samples were detected by reverse transcription - polymerase chain reaction. TMJ internal derangement (ID) was categorized as normal disc position, disc displacement with reduction, early stage of disc displacement without reduction (DDsR) and late stage of DDsR. TMJ osteoarthrosis (OA) was classified with normal, mild and advanced OA. The amount of synovial fluid collection was divided into not detected, small, large and extremely large amount on MR T2-weighted imaging. Perforation and adhesion were examined during open surgery of the TMJ. Six out of 37 samples were excluded because of little amount of extracted total mRNA. MMP-2 mRNA was detected whole joints, and so the MMP-2 mRNA seems to be expressed normally in retrodiscal tissue. However, MMP-1 mRNA was expressed in 8 of 31 joints. Frequencies of MMP-1 mRNA expression according to the TMJ IDs, amount of synovial fluid and surgical findings made no significant difference. MMP-1 mRNA was detected more frequently in OA groups (7/16 joints, 43.8%) than in normal bony structure group (1/15 joints, 6.7%). Expression of MMP-1 mRNA in retrodiscal tissue might be related with OA of the TMJ.

• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.645-660
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• 1993

In this study, effects of incision of retrodiscal tissue and unilateral occlusal reduction on temporomandibular joint of rabbit were investigated. Twenty-seven adult New Zealand White Rabbits, weighing over 3.5kg, were utilized in this study. Temporomandibular joint surgery was performed in left temporomandibular joint of 24 rabbits to displace disc anteriorly through incising the retrodiscal tissue 1-2mm posterior to the disc. They were divided into two groups : twelve were left untreated after surgery, occlusal reduction was performed on left posterior teeth every 2 weeks in the other twelve rabbits, The remaining three served as the control group. The sample were sacrificed by 8, 12, and 16 weeks after surgery. Histologic examinations were performed after sacrificing them. The results were as follows : 1. Histologic findings which were manifested by flat articular fossa, broad articular surface, generalized recession of articular cartilage and sclerosis of subchondral bone were observed. These findings were similar to internal derangement. 2. In the rabbits untreated after surgery, thin cartilagenous layer and necrotic tissue were observed in 8 weeks group, calcifying cartilagenous layer was observed in 12 weeks group, and cartilagenous layer on anterior portion was observed in 16 weeks group. So, it showed gradual healing pattern into the normal tissue except displaced disc. 3. Occlusal trauma after surgery resulted in generalized recession of upper and lower articular surface. Necrosis and vertical split on condylar process of mandible were observed in 8 weeks group. Osteoclasts, exposure of subchondral bone due to erosion on upper and lower articular surface, and degenerative changes on retrodiscal tissue were observed in 16 weeks group. So, it showed continuous prowess pattern of osteoarthrosis.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.6
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• pp.403-410
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• 2009

Those composing temporomandibular joint (TMJ) complex such as the temporal bone, the disc and the mandibular condyle perform their own functions with organic relation. The retrodiscal tissue is the main area of pain induction and contributes to compositional change of synovial fluid. If displacement of the disc lasts long time, not only adaptive changes, but also destructive or degenerative changes may happen. It was reported that these changes and symptoms appear mostly to female rather than male and especially, in the case of patients suffering from TMJ disorder, a large quantity of female sex hormone is found in the joint synovium. And that may play a role in bone resorption and inflammation. Also, the frequency and the intensity of pain perception for female is reported to be much more than for male. In this study, we investigated the expression extents of estrogen receptors (ER) and progesteron receptors (PR) in retrodiscal tissue with immunohistochemistry among the patients received TMJ surgery and compared with MRI findings and surgical findings. We report the relations between the expression of ER in retrodiscal tissue and the pathological change in TMJ, such as inflammation, internal derangement and osteoarthritis.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.24.1-24.7
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• 2016

Background: This study aimed to evaluate the structural changes of temporomandibular joint immediately after condylar fractures with magnetic resonance imaging (MRI). Method: We evaluated 34 subjects of condylar fractures with MRI. The position, shape, and signal intensity of the condyle, disc, and retrodiscal tissue were analyzed with MR images. Results: Immediately after trauma, the disc was displaced with the fractured segment in almost all cases. And, the changes of signal intensity at the retrodiscal tissue were found but less related to the degree of fracture displacement. And, the high signals were observed almost at all fractured joint spaces and even at some contralateral joints. Conclusions: The displaced disc as well as the increased signal intensity of the joint space, condylar head, and retrodiscal tissue demands more attention to prevent the possible sequela of joint.

• The korean journal of orthodontics
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• v.22 no.2 s.37
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• pp.345-372
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• 1992

The purpose of this experiment was to study the effects of changes of mandibular position on temporomandibular joint in internal derangement patients Twenty-four female New Zealand White Rabbits, weighing over 3.5kg, were utilized in this study . Bilateral temporomandibular joint surgery was performed in twenty-one of the rabbits to displace disc anteriorly through incising the retrodiscal tissue 1-2mm posterior to the disc, thus inducing internal derangement. They were divided into three groups nine were left untreated after surgery, six were fitted with functional protrusive appliances 4 weeks after surgery, and six wore collar appliances to apply 4 ounces of mandibular refractive force per side 4 weeks after surgery. The remaining three served as the control group. Histologic examinations were performed after sacrificing them by threes at 4-week intervals. The results were as follows. 1. Histologic findings similar to internal derangement were observed in the rabbits whose retrodiscal tissues had been incised. 2. In the rabbits untreated after surgery, articular surface on condylar process and articular eminence showed severe erosion and deformation, and displaced disc manifested changes in both shape and internal architecture. 3. Functional protrusion after surgery resulted in progressive remodeling on postero-superior portion of condyle and glenoid fossa, while it also brought about erosion on articular eminence and anterior portion of condyle. 4. Mandibular retraction after surgery resulted in compression of retrodiscal tissue and regressive remodeling of posterior portion of condyle.