Temporomandibular Joint Components Research Articles

BMPRIA mediated signaling is essential for temporomandibular joint development in mice.

The central importance of BMP signaling in the development and homeostasis of synovial joint of appendicular skeleton has been well documented, but its role in the development of temporomandibular joint (TMJ), also classified as a synovial joint, remains completely unknown. In this study, we investigated the function of BMPRIA mediated signaling in TMJ development in mice by transgenic loss-of- and gain-of-function approaches. We found that BMPRIA is expressed in the cranial neural crest (CNC)-derived developing condyle and glenoid fossa, major components of TMJ, as well as the interzone mesenchymal cells. Wnt1-Cre mediated tissue specific inactivation of BmprIa in CNC lineage led to defective TMJ development, including failure of articular disc separation from a hypoplastic condyle, persistence of interzone cells, and failed formation of a functional fibrocartilage layer on the articular surface of the glenoid fossa and condyle, which could be at least partially attributed to the down-regulation of Ihh in the developing condyle and inhibition of apoptosis in the interzone. On the other hand, augmented BMPRIA signaling by Wnt1-Cre driven expression of a constitutively active form of BmprIa (caBmprIa) inhibited osteogenesis of the glenoid fossa and converted the condylar primordium from secondary cartilage to primary cartilage associated with ectopic activation of Smad-dependent pathway but inhibition of JNK pathway, leading to TMJ agenesis. Our results present unambiguous evidence for an essential role of finely tuned BMPRIA mediated signaling in TMJ development.

Internal Derangement of Temporomandibular Joint - A Review

Temporomandibular joint (TMJ) is a complex, sensitive, and highly mobile joint. Temporomandibular disorders (TMD) are a class of degenerative musculoskeletal conditions associated with morphologic and functional deformities that affect up to 25% of the population. The most frequent structural (as opposed to muscular) cause of TMD are Internal derangement , which involves progressive slipping a displacement of component of temporo mandibular joint called articular disc.The disc is a piece of cartilage located between the condyle (ball) and fossa (socket)of the joint.The disc can degenerate , becoming misshapes or even torn. Because the deranged joint willcontinue to try to function in an impaired manner, so that internal derangement disorder often get progressively worse with time. In the mechanically demanding and biochemically active environment of the TMJ, therapeutic conservative and surgical approaches that can restore joint functionality while responding to changes in the joint have become a necessity.

Stress analysis in human temporomandibular joint affected by anterior disc displacement during prolonged clenching

Parafunctional habits, such as prolonged clenching and bruxism, have been associated with dysfunctional overloading in the temporomandibular joint (TMJ). In this study, stress distributions in the TMJ were analysed during prolonged clenching, using three-dimensional finite element (FE) models of the TMJ with and without disc displacement. The aim of this study was to investigate stress distribution of the cartilaginous tissues in the TMJ with and without disc displacement. Finite element models were developed on the basis of magnetic resonance images from two subjects with and without anterior disc displacement. Condylar movements recorded during a 5-min clenching were used as the loading condition for stress analysis. In the asymptomatic model, the highest von Mises stresses were located in the lateral area (4·91 MPa) of the disc surfaces, and after 5-min clenching, the higher stresses were still located at the lateral area (3·65 MPa). In all the cartilaginous tissues, 30-50% of stress reduction occurred during 5-min clenching. In contrast, the von Mises stress in the cartilaginous tissues of the symptomatic model with disc displacement was markedly lower, compared with the asymptomatic model. However, in the condylar cartilage, stress relaxation during clenching was not recognised. Furthermore, relatively high stresses were observed in the retrodiscal tissues throughout clenching. The present results indicate that disc position could be involved in the stress distribution of the TMJ components during prolonged clenching.

Three-dimensional finite element analysis of cartilaginous tissues in human temporomandibular joint during prolonged clenching

Objective Bruxism, the parafunctional habit of nocturnal grinding of the teeth and clenching, is associated with the onset of joint degeneration. Especially prolonged clenching is suggested to cause functional overloading in the temporomandibular joint (TMJ). In this study, the distributions of stresses in the cartilaginous TMJ disc and articular cartilage, were analysed during prolonged clenching. The purpose of this study was to examine if joint degradation due to prolonged clenching can be attributed to changes in stress concentration in the cartilaginous tissues. Design Finite element model was developed on the basis of magnetic resonance images from a healthy volunteer. Condylar movements recorded during prolonged clenching were used as the loading condition for stress analysis. Results At the onset of clenching (time = 0 s), the highest von Mises stresses were located in the middle and posterior areas (6.18 MPa) of the inferior disc surface facing the condylar cartilage. The largest magnitude of the minimum principal stress (−6.72 MPa) was found in the condylar cartilage. The stress concentrations were relieved towards the superior disc surface facing the temporal cartilage. On the surfaces of the temporal cartilage, relatively lower stresses were found. After 5-min clenching, both stress values induced in the TMJ components were reduced to 50–80% of the stress values at the onset of clenching, although the concomitant strains increased slightly during this period. Conclusions It is suggested that both the condylar and temporal cartilage layers along with the TMJ disc, play an important role in stress distribution and transmission during prolonged clenching due to tissue expansion. Furthermore, our study suggests that a development of stress concentrations in the TMJ during prolonged clenching and risk factors for the initiation of TMJ degeneration could not be confirmed.

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.

Anatomy of the Temporomandibular Joint

The temporomandibular joint (TMJ), also known as the mandibular joint, is an ellipsoid variety of the right and left synovial joints forming a bicondylar articulation. The common features of the synovial joints exhibited by this joint include a fibrous capsule, a disk, synovial membrane, fluid, and tough adjacent ligaments. Not only is the mandible a single bone but the cranium is also mechanically a single stable component; therefore, the correct terminology for the joint is the craniomandibular articulation. The term temporomandibular joint is misleading and seems to only refer to one side when referring to joint function. Magnetic resonance imaging has been shown to accurately delineate the structures of the TMJ and is the best technique to correlate and compare the TMJ components such as bone, disk, fluid, capsule, and ligaments with autopsy specimens.

Factors affecting the variation in the adult temporomandibular joint of archaeological human populations

To elucidate factors that may affect the variation in the bony components of temporomandibular joint (TMJ), a preliminary study was conducted on the temporal articular surface of the TMJ of 30 skulls from Iron Age and medieval populations from Lithuania and a mixed Neolithic and Bronze Age population from the Central Elbe-Saale region (CESR). Using three-dimensional (3D) photos of the skulls, length and width measurements of the TMJ were obtained and compared with external skull measurements. Distinct, random variation between the TMJ values from opposite sides of the cranium were identified as fluctuating asymmetry. ANOVA results suggest significant differences in the length of the TMJ between the population of the CESR and the two Lithuanian populations, but not between the two Lithuanian populations. Environmental factors, including geography, may be responsible for the variation in the TMJ form.

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.

Movement of temporomandibular joint tissues during mastication and passive manipulation in miniature pigs

Movement is an important aspect of the biomechanics of the temporomandibular joint (TMJ). To track the relative movements of TMJ components, radio-opaque markers were implanted in the left squamosal bone, mandible and retrodiscal tissue of miniature pigs. Medial–lateral (ML) and dorsal–ventral (DV) fluoroscopic records were made 8–10 weeks later during chewing and passive manipulation. Marker movements were digitized from the videotapes. During passive manipulation, the deformation of the lateral capsule was also measured with a differential variable-reluctance transducer. The results provide new details about porcine chewing pattern, which is distinguished by a regularly alternating chewing side. During masticatory opening, the mandible had a centre of rotation (CR) well inferior to the condyle and close to the angle. In contrast, the passive opening movement showed a higher CR location close to the condylar neck, indicating a different motion from masticatory opening. The retrodiscal tissue followed the movements of the mandibular condyle during both mastication and passive manipulation. The lateral capsule elongated during ipsilateral shifts and retrusion, implying a possible role in limiting such movements. These movement characteristics provide a useful reference for studies on the TMJ using pigs.

Ｓｔｕｃｋ ｄｉｓｃを示したクローズドロック患者における治療奏効例のＭＲＩによる評価

The purpose of this study was to evaluate morphological changes in temporomandibular joint components by magnetic resonance imaging (MRI, 1.5 Tesla) before and after treatment for closed lock with a stuck disc.A total of 25 joints (25 patients) that were successfully treated and showed marked improvement in range of motion and articular pain after treatment were studied. Each joint was evaluated on the basis of pretreatment and posttreatment MRI findings, including disc mobility, condylar translation, disc reduction, disc shape, degree of disc displacement, bone changes of the condyle, and signal intensity of the posterior disc attachment.Posttreatment MRI revealed that all joints had mobile discs, and the range of the condylar translation had increased. Deformity of the disc and condyle had progressed remarkably. The posterior disc attachment showed low signal intensity.These results suggest that improved disc mobility is indispensable for successful treatment. The results also reveal that the disc, condyle, and posterior attachment showed various changes caused by remodeling.

Influences of occlusal and skeletal discrepancies on biomechanical environment in the TMJ during maximum clenching: an analytic approach with the finite element method

The purpose of this study was to investigate the influences of occlusal and skeletal discrepancies on temporomandibular joint (TMJ) stresses during maximum clenching. A three‐dimensional (3‐D) finite element model of the mandible including the TMJ was developed as a standard model. Furthermore, nine modified models were established; one dentoalveolar open bite model and eight skeletal open bite models with varying gonial angles or mandibular plane angles (FMAs). For the dentoalveolar open bite model, the TMJ stresses were larger than those for the standard model, although the distribution pattern was not essentially varied. In the skeletal open bite model with greater gonial angle or FMA, the TMJ stresses were significantly larger than those in the dentoalveolar open bite model. In conclusion, the TMJ stress was affected by occlusal and/or skeletal discrepancies, if coexisted in particular, indicating the association with degenerative changes of the TMJ components.

Influences of occlusal and skeletal discrepancies on biomechanical environment in the TMJ during maximum clenching: an analytic approach with the finite element method.

The purpose of this study was to investigate the influences of occlusal and skeletal discrepancies on temporomandibular joint (TMJ) stresses during maximum clenching. A three-dimensional (3-D) finite element model of the mandible including the TMJ was developed as a standard model. Furthermore, nine modified models were established; one dentoalveolar open bite model and eight skeletal open bite models with varying gonial angles or mandibular plane angles (FMAs). For the dentoalveolar open bite model, the TMJ stresses were larger than those for the standard model, although the distribution pattern was not essentially varied. In the skeletal open bite model with greater gonial angle or FMA, the TMJ stresses were significantly larger than those in the dentoalveolar open bite model. In conclusion, the TMJ stress was affected by occlusal and/or skeletal discrepancies, if coexisted in particular, indicating the association with degenerative changes of the TMJ components.

Morphological and positional assessments of TMJ components and lateral pterygoid muscle in relation to symptoms and occlusion of patients with temporomandibular disorders

Disc displacement is accepted as one of major findings in temporomandibular disorders (TMD). However, the associations of disc positions with morphological and positional changes of temporomandibular joint (TMJ) components and lateral pterygoid (LP), TMD clinical symptoms, and occlusion have rarely been discussed quantitatively. In this study, the morphological and positional changes of TMJ components and LP were assessed by means of magnetic resonance imaging (MRI) and tomography of the TMJ in 41 TMD and nine control (CN) subjects. Disc positions in TMD subjects were divided into normal position (NP) and anterior displacement with and without reduction (ADR+ and ADR-, respectively). From MRI scans and tomograms, the morphological and positional changes of TMJ components and LP were measured and compared among CN, NP, ADR+ and ADR- groups. Correlations between these measurements and the scored clinical symptoms and occlusal factors were analysed in TMD subjects. The results indicated that: (1) TMJ osseous structures and LP showed no significant difference among CN and the three TMD groups, except for a posterior seat of condyle and shorter/steeper condylar movement during jaw opening; (2) disc length and inclination were significantly shorter and steeper, respectively, in ADR+ and ADR-; (3) disc positions were not specified by clinical symptoms and occlusal factors, except for the dominant TMJ sounds in ADR+; (4) an uncoordinated movement of the condyle/disc complex was found in ADR+ and/or ADR-; (5) TMJ osseous structures and the disc were weakly associated with clinical symptoms and occlusal factors. However, the LP showed negative associations with palpable pain for both the TMJ and jaw muscles and the static occlusal factors. These findings suggest that TMJ internal derangements are more related to the positional changes or spatial relationships of TMJ components but less to the individual morphologies of TMJ osseous structures, disc and LP, as well as specific clinical symptoms and occlusal factors, which might be in disagreement with a large body of previous statements.

Morphological and positional assessments of TMJ components and lateral pterygoid muscle in relation to symptoms and occlusion of patients with temporomandibular disorders

Disc displacement is accepted as one of major findings in temporomandibular disorders (TMD). However, the associations of disc positions with morphological and positional changes of temporomandibular joint (TMJ) components and lateral pterygoid (LP), TMD clinical symptoms, and occlusion have rarely been discussed quantitatively. In this study, the morphological and positional changes of TMJ components and LP were assessed by means of magnetic resonance imaging (MRI) and tomography of the TMJ in 41 TMD and nine control (CN) subjects. Disc positions in TMD subjects were divided into normal position (NP) and anterior displacement with and without reduction (ADR+ and ADR−, respectively). From MRI scans and tomograms, the morphological and positional changes of TMJ components and LP were measured and compared among CN, NP, ADR+ and ADR− groups. Correlations between these measurements and the scored clinical symptoms and occlusal factors were analysed in TMD subjects. The results indicated that: (1) TMJ osseous structures and LP showed no significant difference among CN and the three TMD groups, except for a posterior seat of condyle and shorter/steeper condylar movement during jaw opening; (2) disc length and inclination were significantly shorter and steeper, respectively, in ADR+ and ADR−; (3) disc positions were not specified by clinical symptoms and occlusal factors, except for the dominant TMJ sounds in ADR+; (4) an uncoordinated movement of the condyle/disc complex was found in ADR+ and/or ADR−; (5) TMJ osseous structures and the disc were weakly associated with clinical symptoms and occlusal factors. However, the LP showed negative associations with palpable pain for both the TMJ and jaw muscles and the static occlusal factors. These findings suggest that TMJ internal derangements are more related to the positional changes or spatial relationships of TMJ components but less to the individual morphologies of TMJ osseous structures, disc and LP, as well as specific clinical symptoms and occlusal factors, which might be in disagreement with a large body of previous statements.

Thickness of the articular soft tissue of the temporal component in temporomandibular joints with and without disk displacement

Objective. The purpose of this investigation was to test the hypothesis that temporomandibular joint disk displacement is associated with significant functional adaptive changes of the articular soft tissue of the articular eminence. Study Design. Thirteen temporomandibular joint autopsy specimens with normal superior disk position and 12 with complete anterior disk displacement were cryosectioned, and sections were stained and photographed. At a magnification of ×20 the soft tissue was measured (1) at the inflection point, (2) on the posterior slope, (3) at the apex, and (4) on the anterior slope of the articular eminence. Results. Displacement of a deformed or nondeformed temporomandibular joint disk without perforation of the posterior disk attachment was associated with significantly increased thickness of the articulating soft tissue at the apex and on the posterior and anterior slopes of the articulating eminence. When disk displacement was associated with a perforation of the posterior disk attachment, the soft tissue was not significantly thicker than in joints with normal superior disk position. Conclusions. Increase in articulating soft tissue thickness is interpreted as an adaptive mechanism to maintain the condyle path and withstand excessive loading at interposition of the temporomandibular joint components. When the plasticity of the tissues is surpassed, the adaptation will be thwarted and replaced by tissue breakdown. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:20-26)

Stress analysis of the human temporomandibular joint

Stress analysis of the human temporomandibular joint (TMJ) consisting of mandibular disc, condyle and fossa–eminence complex during normal sagittal jaw closure was performed using non-linear finite element analysis (FEA). The geometry of the TMJ was obtained from magnetic resonance imaging (MRI). The tissue proportion was measured from a cadaver TMJ. Contact surfaces were defined to represent the interaction between the mandibular disc and the condyle, and between the mandibular disc and the fossa–eminence complex so that finite sliding was allowed between contact bodies. Stresses in the TMJ components (disc, condyle and fossa–eminence complex), and forces in capsular ligaments were obtained. The results demonstrated that, with the given condylar displacement, the stress in the condyle was dominantly compressive and in the fossa–eminence complex was dominantly tensile. The cancellous bone was shielded by the shell shaped cortical bone from the external loading. The results illustrate the stress distributions in the TMJ during a normal jaw closure.

溶連菌感染症による多発性関節炎に継発した顎関節強直症の１例

We report a case of bilateral ankylosis of the temporomandibular joint (TMJ) that occurred after streptococcal infection. The patient was a 30-year-old man, whose initial symptoms were fever and polyarthritis including the TMJ. He was treated by his orthopedist for a diagnosis of streptococcal infection, and chronic polyarthralgia resolved. However, 3 and a half years later, he visited our clinic because of difficulty in mouth opening. The clinical course and radiographic findings indicated a diagnosis of bilateral TMJ ankylosis caused by poststreptococcal arthritis. We subsequently performed TMJ mobilization.Histological examination of the left condyle showed that the articular cartilage was edematous with multiple sites of cystic absorption and that the fibrotic bone marrow involved osteoblast-like cells. Examination of the right condyle showed a thick layer of fibrocartilage and extensive proliferation of granulation tissue involving elastic fibers and necrotic bone cartilage. IL-6 and TNF a were detected in concentrations of 0.406 pg/mg and 0.103 pg/mg by ELISA in the specimen of the right condyle.These findings suggest that TMJ ankylosis in this patient was caused by injury of bone and chondrocartridge matrices affected by poststreptococcal arthritis. The destruction of TMJ components might have been induced by inflammatory cytokines.

Rheumatoid Arthritis: Evaluation of Temporomandibular Joint Abnormalities with MR Imaging

It is well known that the temporomandibular joint (TMJ), as well as other joints, may be affected in patients with rheumatoid arthritis (RA). Conventional radiographic methods can be used in the assessment of bone damage but its usefulness is limited as the soft tissue involvement cannot be demonstrated. Many reports have shown the potential of magnetic resonance imaging in the evaluation of different TMJ components, all of which are often compromised in rheumatic disease; moreover MR imaging is superior for depicting advanced stages of rheumatic disease with various degrees of disc destruction. The purpose of this study was to evaluate the role of MR imaging in the assessment of RA. MR imaging of the TMJ was performed on 14 patients (11 women and 3 men, aged 36–79 years, mean 57.5) with diagnosed RA in stages 2 and 3 according to Steinbroker criteria. Both TMJs were evaluated in ten patients. A total of 24 TMJs were studied in this group of patients. Informed consent was obtained in each case. The goal of MR is not only to facilitate a diagnosis of rheumatoid arthritis, which may be done using laboratory and clinical parameters, but to assess the extent of the early soft-tissue and bone manifestations of the inflammatory process and to identify the stage of the disease.

Stress distribution in the temporomandibular joint produced by orthopedic chincup forces applied in varying directions: A three-dimensional analytic approach with the finite element method

Stress distribution in the temporomandibular joint (TMJ) during chincup therapy was investigated by means of a three-dimensional finite element model of the mandible, including the TMJ. An orthopedic chincup force of 400 gf (3.92 N) was applied at the pogonion of the mandible in the directions ranging from −50° to 40°, relative to the line connecting the pogonion and condyle. Compressive stresses, widely distributed on the condyle and glenoid fossa and in the articular disk, were larger in the posterior area than in the anterior and middle regions, when the force direction was from −50° to 0°, whereas the forces applied in the remaining directions produced relatively uniform stress distributions. An interesting finding was that tensile stresses were induced in the anterior region of the articular disk, irrespective of force direction, although the remaining areas experienced compressive stresses. It is shown that changes in stresses in the TMJ are highly pertinent to the direction of chincup forces. When the directional angle was around −50°, the variation in stresses in the TMJ was greatest. As the angle was changed to 30° or 40°, the stresses approached a certain level of compressive stress, which indicated the force direction as an optimal application of orthopedic chincup force in terms of biomechanically balanced stress distribution for the TMJ components. (Am J Orthod Dentofac Orthop 1996;110:502-7.)

Study on porcine proteoglycans relevant to structure and function of temporomandibular joint

The purpose of this study was to characterize the biochemical and immunological properties of the temporomandibular joint (TMJ). Proteoglycans (PGs) were extracted from the porcine TMJ retrodiscal tissue (RT) and superficial fibrous layer of condyle (SLC). The proportion of Glycosaminoglycans (GAGs) with TMJ disc. RT and SLC resembled that of disc and RT GAGs, but SLC GAGs were different from others. TMJ disc had a higher Dermatan sulfate/Chondroitin sulfate ratio than that of RT. and TMJ disc had stronger tensional load resistance than that of RT. Immunologically, a high molecular weight PG resembled Aggrecan and two low molecular weight PGs resembled Decorin and Biglycan. Total RNA was isolated from SLC, and RT-PCR was performed. These products were sequenced, and these sequences were compared to the sequences of porcine Aggrecan, human Decorin and Biglycan. These results suggested that TMJ had Decorin, Biglycan, and Aggrecan. The difference of PG quantity in each region seemed to be associated with the pathological conditions found on each component of TMJ.