[A biomechanical study on the retrodiscal tissue of human temporomandibular joint].

In order to investigate the biomechanical properties and functional mechanism of the retrodiscal tissue (RT) of human temporomandibular joint (TMJ), we conducted a uniaxial tensile test on thirteen RT specimens taken from eight fresh TMJs of the human cadavers aged between 8-15 years (m = 11.8 yrs). The experimental data were analyzed in conjunction with the Quasi-Linear Viscoelastic Theory as proposed by Fung YC to characterize the time-dependent behaviour and the constitutive relationship of the RT. The results showed that the physiological biphasic zone of stress-strain curve lied within 20%-30% strain levels. The elastic modulus (MPa), tensile strength(MPa) and strain to failure(%) were high. There were significant differences in strain to yielding and energy resorption (N.mm) between lateral and medial RT. There was a good agreement between theoretical prediction value and experimental result within 6% strain level. These data suggest that there would be a higher passive deformation and lower safety storage of strength in the RT which could be related to anterior displacement of the TMJ disc and that Fung's Theory can adequately describe the stress-time behaviour and the constitutive relationship of the RT within lower strain rate.