Biomechanical response of retrodiscal tissue in the temporomandibular joint under compression.

PURPOSE The present study was conducted to investigate the biomechanical response of bovine retrodiscal tissue of the temporomandibular joint (TMJ) in compression. PATIENTS AND METHODS Using 10 retrodiscal tissues obtained from 10 cattle, the viscoelastic response of the retrodiscal tissue was evaluated by means of stress-strain analyses. These compressive strains were produced at a high strain rate and were kept constant during 5 minutes for stress-relaxation. RESULTS Although the stress-strain relationship in the retrodiscal tissue was essentially nonlinear represented by a quadratic or power function of strain, a linear model could reasonably represent its elastic property. In this case, the instantaneous and relaxed moduli were 1.54 and 0.21 MPa, respectively. The stress-relaxation curve showed a marked drop in load during the initial 10 seconds, and the stress reached a steady nonzero level. Furthermore, when using Kelvin's model, a satisfactory agreement can be obtained between the experimental and theoretical stress-relaxation curves. CONCLUSION It is concluded that bovine retrodiscal tissue has a great capacity for energy dissipation during stress-relaxation, although it has little or no function to pull the articular disc back.