Temporomandibular joint (TMJ) disorder relates to the biomechanical irregularity of the structual joint components, and the behavior of soft tissue components is considered as a key to understand the biomechanical condition in the TMJ. The configuration of joint components, however, deeply depends on individual patient. In this study, the attention has been focused on the stress and displacement of irregular TMJs with anterior disc displacement (ADD). Using biplane MRI, typical ADD-TMJs of patients have been modeled individually. The stress distribution in ADD-TMJs has been compared with that in normal-TMJs. The parameter study with the elastic modulus has been carried out and revealed that the stress distribution in the TMJ is very dependent on the connective tissue modulus as well as disc modulus in the case of ADD-TMJ, and that the disc displacement due to jaw opening movement depends on disc modulus in normal subjects but depends on retrodiscal connective tissue in ADD subjects.
