Biomechanical properties and collagen fiber orientation of temporomandibular joint discs in dogs: 2. Tensile mechanical properties of the discs.

The tensile properties of TMJ discs in dogs were investigated using soft-tissue tensile and stress-relaxation tests. The data obtained suggested that (1) the mediolateral tensile stiffness (199.7 and 234.0 MPa), tensile strength (46.73 and 69.99 MPa), and equilibrium moduli (30.0 and 30.1 MPa) of anterior and posterior bands of the disc, respectively, were much greater than those of the middle part (46.6, 14.71, and 18.4 MPa, respectively); (2) the difference in fracture strain of various parts was not significant; (3) the physiologic strain region of the discs was about 4%; and (4) the properties of low stress/relaxation rate and nonlinear relationship of the instantaneous elastic response to various strains may represent lower permeability of TMJ discs.