Stress-field translation in the healthy human temporomandibular joint (original) (raw)
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Movements of the Temporomandibular Joint Disk
Seminars in Orthodontics, 2012
The etiology of temporomandibular joint (TMJ) disorders, including osteoarthritis, is largely unexplained. TMJ disk integrity is crucial, as its failure appears to precede degeneration of the joint. During mandibular function, the TMJ disk undergoes displacements and deformations, generating strains and stresses. Dynamic stereometry, a combination of imaging and jaw tracking, yields a noninvasive, 3-dimensional, and dynamic representation of the relationship between the articular surfaces of the human TMJ. The aim of this study was to refine this method to depict also movement and deformation of the TMJ disk during jaw opening/closing. Data collected in 4 asymptomatic subjects (2 male and 2 female subjects, aged between 24 and 32 years) indicated large disk displacements and deformations that can load TMJ soft tissues during opening and closing of the jaw. Such displacements and deformations can trigger disk damage during dysfunctional loading and/or compromised state of TMJ tissues. These displacements and deformations can also be used for numerical joint modeling.
Prediction of volumetric strain in the human temporomandibular joint cartilage during jaw movement
Journal of Anatomy, 2006
Human temporomandibular joint loading causes pressurization and flow of interstitial fluid in its cartilaginous structures. This largely determines its load-bearing and maintenance capacity. It was hypothesized that during cyclical jaw movements normal pressure distribution dynamics would enable fluid to reach all necessary cartilage regions. This was tested qualitatively by analysis of local volumetric strain dynamics during jaw open-close movements predicted by a dynamic model of the human masticatory system. Finite-element analysis was performed in separate regions of the articular cartilage layers and articular disc. Heterogeneous patterns of dilatation and compression were predicted. Compression was found to be more dominant during jaw closing than opening. The pressure gradient in the superior layer of the articular disc was more mediolaterally orientated than in its inferior layer. The findings suggest that, where necessary, regionally the cartilage can imbibe fluid to protect the subchondral bone from impact loads effectively. In the disc itself presumably all areas receive regular refreshment of interstitial fluid.
Diagnostic group differences in temporomandibular joint energy densities
Orthodontics & craniofacial research, 2015
Cartilage fatigue, due to mechanical work, may account for precocious development of degenerative joint disease in the temporomandibular joint (TMJ). This study compared energy densities (mJ/mm³) in TMJs of three diagnostic groups. Sixty-eight subjects (44 women, 24 men) gave informed consent. Diagnostic criteria for temporomandibular disorders (DC/TMD) and imaging were used to group subjects according to presence of jaw muscle or joint pain (+P) and bilateral disk displacement (+DD). Subjects (+P+DD, n = 16; -P+DD, n = 16; and -P-DD, n = 36) provided cone-beam computed tomography and magnetic resonance images, and jaw-tracking data. Numerical modeling was used to determine TMJ loads (Fnormal ). Dynamic stereometry was used to characterize individual-specific data of stress-field dynamics during 10 symmetrical jaw-closing cycles. These data were used to estimate tractional forces (Ftraction ). Energy densities were then calculated as W/Q (W = work done or mechanical energy input=tra...
Journal of Anatomy, 2007
The temporomandibular joint plays a crucial role in human mastication acting as a guide of jaw movements. During these movements, the joint is subjected to loads which cause stresses and deformations in its cartilaginous structures. A perfect balance between the two sides of the joint is essential to maintain the physiological stress level within the tissues. Therefore, it has been suggested that a derangement of the joint is a contributing factor in the development of mandibular asymmetry, especially if problems of the temporomandibular joint start in childhood or adolescence. To analyze the movement of the mandible and the stresses undergone by the discs, two finite element models of the human temporomandibular joint including the masticatory system were developed, one corresponding to a healthy joint and the other with a unilateral anterior disc displacement with their movement controlled by muscle activation. A fibre-reinforced porohyperelastic model was used to simulate the behaviour of the articular discs. The stress distribution was analyzed in both models during free opening and closing, and during the introduction of a resistant force between incisors or molars. It was found that a slight unilateral anterior disc displacement does not lead to mandibular asymmetry but to a slight decrease of the maximum gape. With the introduction of a restriction between incisors, the maximum stresses moved to the anterior band in contrast to what happened if the restriction was imposed between molars where maximum stresses were located more posteriorly. Finally, the presence of a unilateral displacement of the disc involved a strong change in the overall behaviour of the joint including also the healthy side, where the maximum stresses moved to the posterior part.
Radiologia Brasileira
Objective: To assess changes in the articular surfaces of the temporomandibular joint (TMJ) and in condylar translation, as detected by magnetic resonance imaging (MRI), determining whether such changes correlate with disc displacement. Materials and Methods: We retrospectively analyzed the MRI scans of 2076 TMJs of 1038 patients with symptoms of temporomandibular disorder. We attempted to determine whether articular disc deformity and changes in condylar translation, as well as changes in the articular surfaces of the condyle, glenoid fossa, and articular eminence, correlated with disc displacement. Results: Disc displacement with reduction was associated with changes in the shape of the articular eminence. Disc displacement without reduction was most strongly associated with disc deformity, condylar degeneration, glenoid fossa degeneration, and effusion. Neither decreases nor increases in condylar translation were associated with disc deformity, degenerative bone changes, or disc ...
Tensile stress patterns predicted in the articular disc of the human temporomandibular joint
Journal of Anatomy, 2009
The direction of the first principal stress in the articular disc of the temporomandibular joint was predicted with a biomechanical model of the human masticatory system. The results were compared with the orientation of its collagen fibers. Furthermore, the effect of an active pull of the superior lateral pterygoid muscle, which is directly attached to the articular disc, was studied. It was hypothesized that the markedly antero-posterior direction of the collagen fibers would be reflected in the direction of the tensile stresses in the disc and that active pull of the superior lateral pterygoid muscle would augment these tensions. It was found that the tensile patterns were extremely dependent on the stage of movement and on the mandibular position. They differed between the superior and inferior layers of the disc. The hypothesis could only be confirmed for the anterior and middle portions of the disc. The predicted tensile principal stresses in the posterior part of the disc alternated between antero-posterior and medio-lateral directions.