Soft Tissue Mechanics of the Temporomandibular Joint

Abstract

Direct measurement of temporomandibular joint (TMJ) tissue deformation requires animal experimentation. Most of the available data pertain to the mechanical strain on the bone surfaces around the joint. However, bone is rarely the first joint tissue to show injury, being affected after damage to collagenous tissues such as the disc or capsule. Capsular ligaments guide or limit movement, while the intra-articular disc may also distribute joint loads. However, these tissues are difficult to visualize dynamically and not suitable for strain gage attachment, so in vivo deformations are poorly understood. Using pigs as the best nonprimate model for human TMJ function, we implanted differential variable reluctance transducers to measure antero-posterior strain in the lateral aspect of the intra-articular disc. The results were compared to previously published data on the TMJ capsule. Passive manipulation in anesthetized animals indicated that opening, protrusion, and contralateral movements caused the disc to elongate. On the contrary, closing, retrusion and ipsilateral movements caused disc shortening. These strains are opposite to those observed in the capsule and are expected on anatomical grounds. Surprisingly, disc strain during mastication differed from that during manipulation. The disc elongated during jaw closure, more on the retruding balancing side (16% ± 1) than on the working side (8% ± 2). This anomalous behavior may reflect compressive loading, such that the disc elongates as a result of the Poisson effect rather than condylar movement. Because the capsule also elongates during the power stroke, especially on the balancing side, both disc and capsule are maximally loaded on the same side at the same moment.

Biomechanical Signals Suppress TAK1 Activation to Inhibit NF-κB Transcriptional Activation in Fibrochondrocytes

“…Chondrocytes and FCs both respond to mechanical signals in a magnitudedependent manner. The anti-inflammatory actions of mechanical signals are observed at magnitudes close to those experienced by chondrocytes during normal joint movement (16,17,19,20,34). In this report we have shown for the first time, that at low magnitudes mechanical signals down-regulate activation of TAK1, to intercept intracellular proinflammatory responses generated by several different proinflammatory insults.…”

“…During joint movement, the disc elongates in antero-posterior axis, and experiences tensile forces around 8% on the balancing side and 16% on the working side (34). We have observed that FCs when exposed to tensile forces at a magnitude of 12% elongation inhibit proinflammatory responses.…”

XROMM analysis of tooth occlusion and temporomandibular joint kinematics during feeding in juvenile miniature pigs

“…These relative positions then switch during the occlusal phase, when the contralateral/BS condyle experiences retraction and the ipsilateral/WS condyle experiences protraction. The differential translations of the contralateral/BS condyle affect soft tissue deformation and strain at the TMJ Sindelar and Herring, 2005).…”

“…The strongly curved surface of the articular eminence permits anterior movements of the condyle. Posteriorly, the postglenoid wall is absent in pigs and the space is filled with a fibrous-fatty retrodiscal pad, which is flexible enough to allow slight retraction of the mandibular condyle (Sindelar and Herring, 2005). Thus, based on both bony and soft tissue morphology, we anticipate a high degree of anteroposterior mobility for the mandibular condyles in the miniature pig.…”

Carga imediata sobre implantes osseointegráveis para ancoragem ortodôntica: estudo em minipigs

“…• Temporomandibulares (DTMs) têm sido estudadas em suínos (CHEUNG et al, 2007;HERFORD et al, 2005;NAVARRO et al, 2008;NAVARRO et al, 2008;HERRING, 2005;SINDELAR et al, 2003;THURMULLER et al, 2006;THURMULLER et al, 2002;WARD et al, 1990;ZOUHARY;FEINBERG, 2006 cúspides dos dentes inferiores são muito menos importantes, sendo a força da mastigação controlada pela musculatura (HERRING, 1995).…”