Static and dynamic loading effects on temporomandibular joint disc tractional forces.

Area of Science:

• Biomechanics
• Biomaterials Science
• Orthodontics

Background:

• Mechanical fatigue contributes to temporomandibular joint (TMJ) disc degeneration.
• Tractional forces are implicated in promoting TMJ disc degeneration.

Purpose of the Study:

• To investigate if tractional forces in the TMJ disc increase with compressive strain at the start of movement.
• To determine if tractional forces are velocity-dependent during TMJ disc movement.

Main Methods:

• Sixty-four porcine TMJ discs were subjected to a 10-N static load for 1 or 30 seconds.
• Cyclic movement was applied to the discs post-loading.
• Physical data were recorded and analyzed using ANOVA.

Main Results:

• Compressive strain and tractional forces were highest after 30 seconds of static loading and correlated significantly (R² = 0.84).
• Peak tractional forces showed a linear, positive relationship with movement velocity (R² = 0.85).
• Tractional forces were strain-related at movement onset and velocity-dependent during movement.

Conclusions:

• Tractional forces in the TMJ disc are influenced by both compressive strain and velocity of movement.
• Findings suggest a mechanism for mechanical fatigue-related degeneration of the TMJ disc.