Biomechanical calculation of human TM joint loading with jaw opening

Area of Science:

• Biomechanics
• Dental Mechanics
• Orthodontics

Background:

• The stomatognathic system involves complex muscle forces and joint interactions.
• Understanding temporomandibular joint (TMJ) loading is crucial for diagnosing and treating jaw-related disorders.

Purpose of the Study:

• To predict total temporomandibular joint (TMJ) loading during various jaw opening levels using a 3D mathematical model.
• To analyze the nature and magnitude of joint reaction forces under different physiological and pathological conditions.

Main Methods:

• A three-dimensional, static mathematical model of the stomatognathic system was developed.
• Muscle forces were simulated using contractile and elastic components, assuming static equilibrium of the mandible.
• Joint reaction forces were constrained to act on the condyle's center.

Main Results:

• All simulated jaw opening conditions resulted in compressive forces between the TMJ condyle and articular eminence.
• Compressive force magnitude increased from 2.7 N to 27.6 N as jaw opening progressed from 10 mm to 40 mm.
• Simulating trismus (increased jaw closing activation) significantly elevated joint reaction forces at 20 mm opening (7.7 N to 64.9 N with 20% closer activation).

Conclusions:

• Temporomandibular joint (TMJ) tissues experience low levels of compression at jaw openings up to 40 mm under normal function.
• The mathematical model provides valuable insights into TMJ biomechanics and the impact of conditions like trismus.
• Further research can refine these models to better predict TMJ behavior and inform clinical interventions.