Revisiting mandibular biomechanics: A tensegrity perspective on jaw motion axes and ligamentous control

Temporomandibular biomechanics, the study of the mechanical interactions between the temporomandibular joint (TMJ), muscles, ligaments, and bone during jaw motion, is essential for understanding oral functions like mastication, speech, and swallowing. Understanding of these interactions also plays a crucial role in diagnosing jaw function and planning personalized prosthodontic treatment. Despite its significance, a universally applicable model for TMJ biomechanics remains elusive. To elucidate the complex movements of the mandible, including the shifting of the instantaneous center of rotation, this report explores the dynamic mechanisms governing mandibular movement, focusing on anatomical structures and diverse kinematic axes, including the least motion axis. We propose a novel kinematic model integrating bell-crank, slider-crank, and third-class lever mechanisms within a tensegrity framework. This framework incorporates the tensegrity principle and utilizes the least motion axis. Our biotensegrity model illuminates the significant role of mandibular ligaments in establishing the mandibular rest position. By leveraging the unique property of tensegrity structures-their ability to adapt their mechanical response to varying loads as if their center of gravity were being adjusted-our model offers a biomechanical explanation for multiple mandibular motion axes, distinct from the TMJ. This enables us to effectively model complex jaw movements oversimplified by conventional approaches, potentially advancing understanding of TMJ biomechanics.