Prevalence and clinical signs of degenerative temporomandibular joint changes validated by magnetic resonance imaging in a non-patient group

The aim of this study is to investigate associations between degenerative bony changes of the temporomandibular joint (TMJ) evaluated by magnetic resonance imaging (MRI) and signs and symptoms of temporomandibular disorders (TMD) in a non-patient group. A total of 307 subjects (140 males and 167 females) were selected from the cross-sectional epidemiological study "Study of Health in Pomerania" (SHIP) for this evaluation. A clinical functional examination of the masticatory muscles and the TMJs was performed as well as an MRI examination of the TMJs. Another 77 subjects (25%) exhibited degenerative changes of one or both TMJs in the MRI. Clinical analysis revealed pain on palpation of the masticatory muscles in 113 subjects. Some 39 subjects had pain during palpation of the TMJs. There were significant associations between the MRI confirmed diagnosis of osteoarthrosis and some clinical signs (joint noises, joint palpation pain, reduced mouth opening) and symptoms (reported pain in the jaw and masticatory muscles) of TMD as well as further MRI diagnoses (disc displacement with and without reduction, fibrosis of the posterior ligament). Although there were some associations, clinical examination alone is not sufficient for diagnosing degenerative joint diseases. MRI is a necessary diagnostic adjunct for estimating the prevalence of TMD subgroups in non-patient populations.     

Cytopathologic diagnosis on joint lavage fluid for patients with temporomandibular joint disorders

Temporomandibular joint (TMJ) disorders (TMD) are usually diagnosed based on the patient's clinical findings and the results of image investigations; however, understanding of the inflammatory process in TMJ is difficult. In addition, many of the TMJ disease types share common principal symptoms. Therefore, TMJ diseases in the early stage can be misdiagnosed with TMD. It is hypothesized that cytopathologic examination of the joint lavage fluids is useful in interpreting the TMD‐associated inflammatory process from a cellular aspect. The aim of this study was to assess the TMJ lavage fluid cytopathologically in TMD patients. Thirty‐nine patients, clinically diagnosed as TMD, were included in the present study. Clinical symptoms of the patients were recorded. Forty‐four samples of TMJ lavage fluid were collected and paraffin‐embedded cell sections were made by cell block tissue array method. Cytologic conditions in upper articular cavity of TMJ were cytopathologically diagnosed and were compared with the clinical symptoms of each patient. Cell components were detected in 22 of the 44 analyzed joint lavage fluids. There was a correlation between cytopathologic findings and clinical symptoms. Variety of cytopathology and inflammatory conditions in patients with similar clinical symptoms were also found. The results suggested that cytopathologic examination of the joint lavage fluids from TMD patients is helpful for gaining an understanding of the inner local conditions of TMJ at the cellular level. Diagn. Cytopathol. 2014;42:30–36. © 2013 Wiley Periodicals, Inc.     

An anatomical study of the muscles that attach to the articular disc of the temporomandibular joint

The masticatory muscles are generally described as the muscles that originate from the cranium and insert on the mandible. Some of the masticatory muscles also insert into the articular disc of the temporomandibular joint. Although there are numerous reports of studies on the attachment of the fibers to the disc, most reports discuss only one muscle. We have shown that the masticatory muscles are not simply a group of clearly independent muscles, but that these muscles contain various transitional muscle bundles among the major muscles. From this point of view, we carried out minute dissection of the collective muscles and muscle bundles surrounding the temporomandibular joint. We dissected 40 head halves of 20 Japanese cadavers (10 males, 10 females: average 79.6 yr). After complete removal of the bony elements, the structures surrounding the temporomandibular joint were investigated en‐block. In all specimens, the superior surface of the upper head of lateral pterygoid and the midmedial muscle bundle were attached to the disc. In some specimens, the discotemporal bundle, zygomaticomandibularis, and masseter were attached to the anterior surface of the disc. The total vector of these muscles pulls the disc anteriorly. In contrast, the vector of the muscles to the condylar processes of the mandible pulls the mandible medially. From these observations, it seems that the fibers, which attach to the disc act to steady the disc against the masticatory movement. Clin. Anat. 22:932–940, 2009. © 2009 Wiley‐Liss, Inc.     

Role of magnetic resonance imaging in the clinical diagnosis of the temporomandibular joint

Temporomandibular joint (TMJ) abnormalities cannot be reliably assessed by a clinical examination. Magnetic resonance imaging (MRI) may depict joint abnormalities not seen with any other imaging method and thus is the best method to make a diagnostic assessment of the TMJ status. In patients with temporomandibular joint disorder (TMD) referred for diagnostic imaging the predominant TMJ finding is internal derangement related to disc displacement. This finding is significantly more frequent than in asymptomatic volunteers, and occurs in up to 80% of patients consecutively referred for TMJ imaging. Moreover, certain types of disc displacement seem to occur almost exclusively in TMD patients, namely complete disc displacements that do not reduce on mouth opening. Other intra-articular abnormalities may additionally be associated with the disc displacement, predominantly joint effusion (which means more fluid than seen in any asymptomatic volunteer) and mandibular condyle marrow abnormalities (which are not seen in volunteers). These conditions seem to be closely related. Nearly 15% of TMD patients consecutively referred for TMJ MRI will have joint effusion, of whom about 30% will show bone marrow abnormalities. In a surgically selected material of joints with histologically documented bone marrow abnormalities nearly 40% showed joint effusion. Disc displacement is mostly bilateral, but joint effusion seems to be unilateral or with a lesser amount of fluid in the contralateral joint. Abnormal bone marrow is also mostly unilateral. Many patients have unilateral pain or more pain on one side. In a regression analysis the self-reported in-patient TMJ pain side difference was positively dependent on TMJ effusion and condyle marrow abnormalities, but negatively dependent on cortical bone abnormalities. Of the joints with effusion only one fourth showed osteoarthritis. Thus, there seems to be a subgroup of TMD patients showing more severe intra-articular pathology than disc displacement alone, and mostly without osteoarthritis. It should, however, be emphasized that patients with TMJ effusion and/or abnormal bone marrow in the mandibular condyle seem to constitute only a minor portion (less than one fourth) of consecutive TMD patients referred for diagnostic TMJ imaging. The majority of patients have internal derangement related to disc displacement, but without accompanying joint abnormalities. In patients with rheumatoid arthritis and other arthritides TMJ involvement may mimick the more common TMDs. Using MRI it is possible, in most cases, to distinguish these patients from those without synovial proliferation.     

Temporomandibular Joint: Disorders,Treatments, and Biomechanics

Temporomandibular joint (TMJ) is a complex, sensitive, and highly mobile joint. Millions of people suffer from temporomandibular disorders (TMD) in USA alone. The TMD treatment options need to be looked at more fully to assess possible improvement of the available options and introduction of novel techniques. As reconstruction with either partial or total joint prosthesis is the potential treatment option in certain TMD conditions, it is essential to study outcomes of the FDA approved TMJ implants in a controlled comparative manner. Evaluating the kinetics and kinematics of the TMJ enables the understanding of structure and function of normal and diseased TMJ to predict changes due to alterations, and to propose more efficient methods of treatment. Although many researchers have conducted biomechanical analysis of the TMJ, many of the methods have certain limitations. Therefore, a more comprehensive analysis is necessary for better understanding of different movements and resulting forces and stresses in the joint components. This article provides the results of a state-of-the-art investigation of the TMJ anatomy, TMD, treatment options, a review of the FDA approved TMJ prosthetic devices, and the TMJ biomechanics.     

颞下颌关节音分析的临床应用研究

目的：探讨以TMJ音分析作为TMJ损伤及病变临床诊断和病理研究方法的可行性。材料和方法：利用线性谱分析和非线性分形分析两种方法对健康人和TMD患者的TMJ音进行分析。结论：结果表明，两种方法均能正确识别健康人和TMD患者的TMJ音，但谱分析法仍需依靠医生的临床经验。     

颞下颌关节三维动态磁共振成像研究及生物力学分析

目的通过在多层面二维动态MR成像上获取颞下颌关节组织的运动数据,构建颞下颌关节的三维动态模型,并进行初步生物力学分析。方法 MRI检查采用GE Signa 1.5T TwinSpeed超导型磁共振扫描仪。选取2例无症状男性志愿者行颞下颌关节MRI检查,将图像数据导入Mimics软件,构建颞下颌关节的三维模型,动态分析张口幅度和关节盘横径的量化关系。结果建立的颞下颌关节三维动态模型清晰显示三维动态盘髁关系及关节盘在动态过程中的形态变化;志愿者1张口/关节盘横径拟合直线为:y=-0.03x+14.44,相关系数R2=0.591,志愿者2相关拟合直线为:y=-0.061x+13.48,相关系数R2=0.306,志愿者张口位置与关节盘横径变化具有直线趋势,关节盘横径随着张口幅度的加大而呈现减小的趋势,颞下颌关节盘对于髁突的包绕程度与张口幅度呈反比。颞下颌关节盘纵径厚度在张口活动中后带外份及中带内份的变化幅度最大。结论通过颞下颌关节二维动态MR成像数据可构建三维动态模型立体动态地观察颞下颌关节运动,可直观、准确显示颞下颌关节盘髁关系,可作为颞下颌关节二维静态MR成像的有益补充,弥补常规MRI检查的局限。     

Comparison of reference points in different methods of temporomandibular joint imaging

PurposeConventional radiography is a well-established method for imaging of the temporomandibular joint (TMJ) structures. However, the dental computer tomography becomes more important for the visualization of teeth in the jaw-bone. The applicability of dental computer tomography for the visualization of the TMJ it not yet been proven. The aim of the study was to identify TMJ structures using reference points with the magnetic resonance imaging (MRI) and the computed tomography (CT).MethodsIn order to compare the visualization and measurement of the TMJ a total of eight human cadaver heads was examined with CT and MRI and analysed using reference points.ResultsIn both imaging techniques the selected reference points and distances are well definable and allow objective evaluation of anatomical structures. The CT images display a clearly better contrast to noise ratio than the MR images. The distance measurement of different width and length showed significant correlation of both images techniques.ConclusionsIn TMJ diagnostics, maximum information could be obtained using both imaging techniques together due to synergistic effects.     

Modeling the biomechanics of articular eminence function in anthropoid primates

One of the most prominent features of the cranial component of the temporomandibular joint (TMJ) is the articular eminence (AE). This bar of bone is the primary surface upon which the condyle translates and rotates during movements of the mandible, and is therefore the primary point at which forces are transmitted from the mandible to the cranium during loading of the masticatory apparatus. The shape of the AE is highly variable across primates, and the raised eminence of humans has often been considered a defining feature of the human TMJ, yet few data exist to address whether this variation is functionally significant. This study used a broad interspecific sample of anthropoid primates to elaborate upon and test the predictions of a previously proposed model of AE function. This model suggests that AE inclination acts to resist non-normal forces at the TMJ, thereby maximizing bite forces (BFs). AE inclination was predicted to covary with two specific features of the masticatory apparatus: height of the TMJ above the occlusal plane; and inclination of the masticatory muscles. A correlate of this model is that taxa utilizing more resistant food objects should also exhibit relatively more inclined AEs. Results of the correlation analyses found that AE inclination is strongly correlated with height of the TMJ above the occlusal plane, but less so with inclination of the masticatory muscles. Furthermore, pairwise comparisons of closely related taxa with documented dietary differences found that the AE is consistently more inclined in taxa that utilize more resistant food items. These data preliminarily suggest that variation in AE morphology across anthropoid primates is functionally related to maximizing BFs, and add to the growing dataset of masticatory morphologies linked to feeding behavior.     

颞下颌关节可复性盘前移患者的MR表现

目的:研究颞下颌关节可复性盘前移（ADDWR）患者的磁共振（MR）成像表现。方法:纳入颞下颌关节ADDWR患者55例作为观察组,另纳入30例牙齿排列整齐的健康志愿者作为对照组。所有研究对象均接受MR成像检查,记录颞下颌关节ADDWR患者关节盘前移程度,比较不同严重程度患者关节盘形态和关节渗出情况。结果:55例颞下颌关节ADDWR患者中,轻症35例,重症20例。对照组、轻症组及重症组关节盘形态分型比较,差异有统计学意义（P<0.05）。3组对象颞下颌关节渗出情况比较,差异有统计学意义（P<0.05）。不同程度关节渗出患者视觉模拟评分法（VAS）评分差异有统计学意义（P<0.05）。3组对象关节盘长度差异有统计学意义（P<0.05）。轻度组关节盘前移度较重症组显著减轻,差异有统计学意义（P<0.05）。结论:MR有助于颞下颌关节ADDWR患者病情判断,可为临床治疗提供依据。     

Skeletal pattern in subjects with temporomandibular joint disorders

Introduction

To establish the skeletal pattern in subjects with malocclusions and temporomandibular disorders (TMD); to assess the relationship between craniofacial skeletal structures and TMD in subjects with malocclusions.

Material and methods

Sixty-four subjects with malocclusions, over 18 years of age, were included in the study. Temporomandibular disorders were clinically assessed according to the Helkimo Anamnestic Index. Subjects underwent a lateral cephalogram. Subjects were grouped according to the sagittal skeletal pattern (ANB angle) into class I, II and III. Parametric Student tests with equal or unequal variations were used (variations were previously tested with Levene test).

Results

Twenty-four patients with TMD (experimental sample); 40 patients without TMD (control group); interincisal angle was higher in class I and II (p < 0.05) experimental subjects; overjet was larger in experimental subjects; midline shift and Wits appraisal were broader in the experimental group in all three classes. In class III subjects, the SNB angle was higher in the experimental group (p = 0.01). Joint noises followed by reduced mandible mobility, muscular pain and temporomandibular joint (TMJ) pain were the most frequent symptoms in subjects with TMD and malocclusions.

Conclusions

Temporomandibular joint status is an important factor to consider when planning orthodontic treatment in patients with severe malocclusions; midline shift, large overjet and deep overbite have been associated with signs and symptoms of TMD.     

Comparison of conventional MRI and 3D reconstruction model for evaluation of temporomandibular joint

The aim of this work was to define the diagnostic value of a method for 3D reconstruction of MRI images for the assessment of temporomandibular joint. Sixty subjects, 42 diagnosed with unilateral temporomandibular disorders (TMD) with disc displacement and 18 without signs or symptoms of TMD (control group) were included. All subjects had both temporomandibular joints scanned by MRI. Three-dimensional imaging reconstructions of temporomandibular joint were generated by segmentation software, allowing visualization of the components of temporomandibular joint (articular disc, condyle and temporal bone) on arbitrary planes. Disc displacement was observed in 83% of 3D reconstruction and 81% of conventional MRI. The agreement between 3D diagnosis and MRI findings was significant and high. The present analysis suggested that 3D reconstruction is a useful and accurate method for the assessment of the temporomandibular joint in TMD ID.     

上颌扩弓对颞下颌关节应力影响的有限元分析

目的 通过三维有限元法对比扩弓前和放置扩弓器时颞下颌关节(temporomandibular joint, TMJ)内部各组织应力分布情况。方法 根据1名上颌牙弓狭窄患者CBCT影像资料,构建扩弓前和包含扩弓器的TMJ三维有限元模型,对模型加载相同的肌力和边界约束,观察TMJ髁突、关节盘、关节窝的等效应力、最大主应力和最小主应力。结果 扩弓前TMJ等效应力主要分布在下颌支前缘、髁突前斜面、关节盘中间带和后带以及关节窝顶部。放置扩弓器时,TMJ应力分布特征与扩弓前基本一致,应力虽然明显增加,但应力分布区域更加均匀;髁突和关节盘应力向前、向外侧移动,髁突后斜面表现出更加均匀的最大主应力分布范围。结论 上颌扩弓器产生的矫形力能够使TMJ应力增加,诱导髁突发生组织改建,协调髁突和关节盘的关系。临床上对于牙弓狭窄的患者应该采用合适的手段进行扩弓矫治。     

Stress distribution in the temporo-mandibular joint discs during jaw closing: a high-resolution three-dimensional finite-element model analysis

Purpose

This study aims at analysing the stresses distribution in the temporomandibular joint (TMJ) using a complete high-resolution finite element model (FE Model). This model is used here to analyse the stresses distribution in the discs during a closing jaw cycle. In the end, this model enables the prediction of the stress evolution in the TMJ disc submitted to various loadings induced by mandibular trauma, surgery or parafunction.

Materials and methods

The geometric data for the model were obtained from MRI and CT scans images of a healthy male patient. Surface and volume meshes were successively obtained using a 3D image segmentation software (AMIRA^?). Bone components of skull and mandible, both of joint discs, temporomandibular capsules and ligaments and dental arches were meshed as separate bodies. The volume meshes were transferred to the FE analysis software (FORGE^?). Material properties were assigned for each region. Boundary conditions for closing jaw simulations were represented by different load directions of jaws muscles. The von Mises stresses distribution in both joint discs during closing conditions was analyzed.

Results

The pattern of von Mises stresses in the TMJ discs is non-symmetric and changed continuously during jaw movement. Maximal stress is reached on the surface disc in areas in contact with others bodies.

Conclusions

The three-dimension finite element model of masticatory system will make it possible to simulate different conditions that appear to be important in the cascade of events leading to joint damage.     

Tumoral calcium pyrophosphate dihydrate crystal deposition disease of the temporomandibular joint: identification on crystallography

This paper reports a case of calcium pyrophosphate dihydrate (CPPD) crystal deposition in the temporomandibular joint (TMJ) of a 59-year-old man with the chief complaint of severe pain in the left TMJ. On CT a radiopaque area was seen around the condylar process of the left TMJ with irregular destructive bony changes. A provisional diagnosis of crystalline-induced arthritis was made on histopathology of a biopsy specimen. Electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and X-ray diffraction showed both CPPD and hydroxyapatite (HA) in the crystalline materials. Identification of these two types of crystal in crystal deposition disease of TMJ, using crystallography, is discussed.     

颞下颌关节骨骼肌肉系统三维有限元模型的构建

目的探讨基于影像学与解剖学构建颞下颌关节(temporomandibular joint,TMJ)骨骼肌肉系统三维有限元模型的可行性,为TMJ生物力学研究提供建模的新思路。方法采集第2代中国虚拟人男性第23号头颅CT图像、咀嚼肌及TMJ关节盘MRI图像,以DICOM格式导入Mimics软件进行三维重建,再通过Geomagic Studio软件配准模型、优化模型及构建关节软骨和关节囊,最后由ANSYS软件定义各组织的材料属性,建立TMJ骨骼肌肉系统的三维有限元模型。结果建立了一个包含关节盘、关节软骨、关节囊、上颌骨(包括颧骨及鼻骨)、下颌骨、颞骨(包括部分顶骨)、蝶骨、上牙列、下牙列、颞肌、咬肌、翼内肌、翼外肌、颞下颌韧带、蝶下颌韧带及茎突下颌韧带的TMJ骨骼肌肉系统的三维有限元模型。结论根据CT、MRI图像和解剖学,利用Mimics、Geomagic Studio及ANSYS可以精确、可行地构建TMJ骨骼肌肉系统的三维有限元模型。模型更加真实还原TMJ的生物力学环境,为TMJ生物力学研究提供新的建模方法,为临床上TMJ疾病的可视化治疗提供仿真平台。     

工程化颞下颌关节盘组织的细胞源问题:现状与展望

目的是为学者探索适当的颞下颌关节盘组织工程种子细胞提供参考。目前颞下颌关节盘组织工程正处于起步阶段,而细胞来源是制约关节盘组织工程发展的主要因素之一,本文概述了关节盘细胞、软骨细胞、皮肤成纤维细胞、骨髓基质干细胞、脂肪干细胞和胚胎干细胞等6种细胞作为关节盘组织工程细胞源的可行性,以便寻找一种合适的细胞源。     

Alterations in intermediate filaments expression in disc cells from the rat temporomandibular joint following exposure to continuous compressive force

The articular disc in the temporomandibular joint (TMJ) that serves in load relief and stabilizing in jaw movements is a dense collagenous tissue consisting of extracellular matrices and disc cells. The various morphological configurations of the disc cells have given us diverse names, such as fibroblasts, chondrocyte-like cells and fibrochondrocytes; however, the characteristics of these cells have remained to be elucidated in detail. The disc cells have been reported to exhibit heterogeneous immunoreaction patterns for intermediate filaments including glial fibrillary acidic protein (GFAP), nestin and vimentin in the adult rat TMJ. Because these intermediate filaments accumulate in the disc cells as tooth eruption proceeds during postnatal development, it might be surmised that the expression of these intermediate filaments in the disc cells closely relates to mechanical stress. The present study was therefore undertaken to examine the effect of a continuous compressive force on the immunoexpression of these intermediate filaments and an additional intermediate filament - muscle-specific desmin - in the disc cells of the TMJ disc using a rat experimental model. The rats wore an appliance that exerts a continuous compressive load on the TMJ. The experimental period with the appliance was 5 days as determined by previous studies, after which some experimental animals were allowed to survive another 5 days after removal of the appliance. Histological observations demonstrated that the compressive force provoked a remarkable acellular region and a decrease in the thickness of the condylar cartilage of the mandible, and a sparse collagen fiber distribution in the articular disc. The articular disc showed a significant increase in the number of desmin-positive cells as compared with the controls. In contrast, immunopositive cells for GFAP, nestin and vimentin remained unchanged in number as well as intensity. At 5 days after removal of the appliance, both the disc and cartilage exhibited immunohistological and histological features in a recovery process. These findings indicate that the mature articular cells are capable of producing desmin instead of the other intermediate filaments against mechanical stress. The desmin-positive disc cells lacked α-smooth muscle actin (α-SMA) in this study, even though desmin usually co-exists with α-SMA in the vascular smooth muscle cells or pericytes. Because the precursor of a pericyte has such an immunoexpression pattern during angiogenesis, there is a further possibility that the formation of new vessels commenced in response to the extraordinary compressive force.     

颞下颌关节被动运动时的轴心

采用5具尸体头颅,取其半侧,切除皮肤和肌肉,先保留韧带,再除去韧带,分别拍摄从咬(牙合)位至大张口位共8个位置的X光片。以探讨颢下颌关节在被动运动时的轴心位置。在除去韧带的情况下,髁突绕本身的轴作中心定轴转动,该中心位于髁嵴下方6毫米处,运动发生在髁突与关节盘之间。在保留韧带的情况下,下颌张口运动也是定轴转动,轴心位于髁嵴下方约12毫米处的Q点,髁突绕偏心的Q点转动,同时带动关节盘一起向前下滑动。     

Temporomandibular joint formation and condyle growth require Indian hedgehog signaling.

The temporomandibular joint (TMJ) is essential for jaw function, but the mechanisms regulating its development remain poorly understood. Because Indian hedgehog (Ihh) regulates trunk and limb skeletogenesis, we studied its possible roles in TMJ development. In wild-type mouse embryos, Ihh expression was already strong in condylar cartilage by embryonic day (E) 15.5, and expression of Ihh receptors and effector genes (Gli1, Gli2, Gli3, and PTHrP) indicated that Ihh range of action normally reached apical condylar tissue layers, including polymorphic chondroprogenitor layer and articular disc primordia. In Ihh(-/-) embryos, TMJ development was severely compromised. Condylar cartilage growth, polymorphic cell proliferation, and PTHrP expression were all inhibited, and growth plate organization and chondrocyte gene expression patterns were abnormal. These severe defects were partially corrected in double Ihh(-/-)/Gli3(-/-) mutants, signifying that Ihh action is normally modulated and delimited by Gli3 and Gli3(R) in particular. Both single and double mutants, however, failed to form an articular disc primordium, normally appreciable as an independent condensation between condylar apex and neighboring developing temporal bone in wild-type. This failure persisted at later stages, leading to complete absence of a normal functional disc and lubricin-expressing joint cavities. In summary, Ihh is very important for TMJ development, where it appears to regulate growth and elongation events, condylar cartilage phenotype, and chondroprogenitor cell function. Absence of articular disc and joint cavities in single and double mutants points to irreplaceable Ihh roles in formation of those critical TMJ components.