Mri-Based Analysis Of Stress Trajectories In The Articular Disc During Jaw Opening

The aim of this study was to evaluate the stress characteristics in the temporomandibular joint disc of a patient with temporomandibular joint disorder during jaw opening and to further understand the biomechanical basis for temporomandibular joint disorders. A two-dimensional finite element model of a symptomatic articular disc was developed based on magnetic resonance imaging data from a subject with temporomandibular joint disorder. Hyperelastic constitutive laws were applied to the anterior and posterior bands and the intermediate zone of the disc. The finite element analysis of the disc deformation applied displacement loading based on the contours of the disc at different degrees of jaw opening. Stress and strain trajectories of the disc were calculated. The intermediate zone of the symptomatic disc was mainly under compression during jaw opening, while the anterior and posterior bands were being stretched. The maximum and minimum principal stresses were concentrated on the boundaries of the posterior band. In addition, relatively high shear stress was concentrated on the inferior boundary of the posterior band and the superior boundary of the middle-posterior band. The stress in the symptomatic disc increased linearly with the degree of jaw opening, especially in the posterior band. Deformation of the disc in the symptomatic joint caused high stress in the posterior band, which is also the most likely zone to suffer injury. It is suggested that the patient avoids wide jaw opening since it may cause excessive stress to the disc.