Muscle organization in individuals with and without pain and joint dysfunction.

Area of Science:

• Biomechanical Engineering
• Neuroscience
• Dental Research

Background:

• The central nervous system's control over masticatory muscles influences joint and muscle forces.
• Understanding neuromuscular organization is crucial for diagnosing and treating temporomandibular disorders (TMD).

Purpose of the Study:

• To investigate neuromuscular organization of masticatory muscles during biting in individuals with and without TMD using computer-assisted models.
• To compare muscle organization patterns between healthy individuals and those with TMD, considering pain and disc displacement.

Main Methods:

• Ninety-one participants were categorized into four groups based on pain and temporomandibular joint disc displacement.
• Electromyography and bite-force data were collected during incisor and molar biting tasks.
• Two 3D neuromuscular models (Minimization of Joint Loads and Minimization of Muscle Effort) simulated biting, with statistical analyses evaluating model fit and accuracy.

Main Results:

• The Minimization of Muscle Effort (MME) model was the best fit for left molar biting in individuals with disc displacement and for incisor biting in men.
• Individuals without TMD exhibited significantly higher symmetry in incisor biting muscle organization compared to those with TMD.
• Model accuracy was consistent across groups, with 8-15% error rates.

Conclusions:

• Computer-assisted models effectively predict human masticatory muscle organization during static biting, differentiating between individuals with and without TMD.
• Neuromuscular control strategies during biting may differ based on TMD status, gender, and biting task.
• Findings contribute to a better understanding of TMD pathophysiology and inform potential therapeutic strategies.