Tensile properties of the porcine temporomandibular joint disc

Despite the significant morbidity associated with the temporomandibular joint (TMJ), little is known about the pathophysiology of this complex joint. TMJ disc degeneration plays a central role in the progression of TMJ disorders, and therefore disc regeneration would be a crucial treatment modality. Unfortunately, scarce information about the structural and functional characteristics of the TMJ disc is available. The current study aims to provide a standard for the biomechanical behavior of the TMJ disc for future tissue engineering studies. The disc was loaded under uniaxial tension in two directions, mediolateral and anteroposterior, and in three locations per direction. In the mediolateral direction, the posterior band was 2.5 times stiffer, 2.4 times tougher (energy to maximum stress), and 2.2 times stronger than the anterior band, which was in turn 16 times stiffer and 5.7 times stronger than the intermediate zone. In the anteroposterior direction, the central and medial regions were 74% and 35% stiffer and 56% and 59% stronger than the lateral region, respectively, although similar to each other in strength and stiffness. There was no significant difference in toughness between regions in the anteroposterior direction. These results correlated qualitatively with collagen fiber orientation and fiber size obtained using polarized light microscopy.