Tractional Forces, Work and Energy Densities in the Human TMJ

Area of Science:

• Biomechanics
• Biomedical Engineering
• Orthodontics

Background:

• The mechanical factors influencing temporomandibular joint (TMJ) degenerative disease remain poorly understood.
• Understanding these mechanics is crucial for developing effective treatments for TMJ disorders.

Purpose of the Study:

• To develop an empirical model linking cartilage mechanics and tractional forces in the TMJ.
• To utilize this model to estimate TMJ work and energy densities in humans.

Main Methods:

• An empirical model was derived from static and dynamic loading of porcine TMJ discs.
• Dynamic stereometry measured stress-field velocities and cartilage thickness in human subjects.
• The model estimated tractional forces, work done, and energy densities in healthy and displaced TMJs.

Main Results:

• Mechanical work was significantly higher (20x) in TMJs with disc displacement compared to healthy TMJs.
• TMJs with disc displacement exhibited 350% more mechanical work and 180% higher energy densities in women versus men.
• A power analysis suggested 40 participants per gender are needed to detect a 50% difference in energy densities.

Conclusions:

• Empirical modeling provides insights into TMJ mechanics and degenerative disease.
• Increased mechanical work and energy density are key features of TMJ disc displacement, particularly in women.
• Further research with larger cohorts is warranted to confirm gender-based differences in TMJ biomechanics.