Finite element evaluation of unilateral distraction splints: implications for temporomandibular joint loading...

Area of Science:

• Biomechanics
• Dental device analysis
• Finite element analysis

Background:

• Unilateral distraction splints (DSs) were historically used for temporomandibular disorder (TMD) therapy.
• Concerns exist that DSs may induce compressive forces on the temporomandibular joint (TMJ) rather than the intended distractive effects.

Purpose of the Study:

• To investigate the biomechanical behavior of two unilateral splint designs (DS7 and DS567) in a healthy TMJ model.
• To analyze the influence of ipsilateral masseter force and capsular stiffness on TMJ stress and displacement.

Main Methods:

• A finite element analysis model of a healthy TMJ was created using cone-beam computed tomography data.
• Simulated unilateral clenching under varying masseter force and capsular stiffness conditions.
• Nonlinear static analysis to calculate condylar and disc stress and displacement.

Main Results:

• Increased ipsilateral masseter force significantly elevated condylar and disc displacement.
• The DS7 design resulted in higher disc (60%) and condylar (30%) movement compared to DS567.
• Capsular stiffness had a minor effect on displacement; masseter force was the dominant loading factor.
• Both condyles exhibited superior, compressive movement; contralateral structures showed higher stress peaks.

Conclusions:

• Unilateral distraction splints primarily induce compressive, not distractive, forces on the TMJ.
• Splint geometry, specifically broader coverage, can modulate load transmission and reduce stress/displacement.
• Masseter muscle force is a critical determinant of TMJ loading during simulated clenching.