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

Area of Science:

• Biomechanics
• Dental device analysis
• Finite element modeling

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) instead of the intended distraction.

Purpose of the Study:

• To investigate the biomechanical effects 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 responses.

Main Methods:

• Finite element analysis of a TMJ model derived from cone-beam computed tomography data.
• Simulation of unilateral clenching under varying masseter force and capsular stiffness.
• Calculation of condylar and disc stress and displacement using nonlinear static analysis.

Main Results:

• Increased ipsilateral masseter force significantly elevated condylar and disc displacement.
• The DS7 design resulted in substantially higher disc (60%) and condylar (30%) movement compared to DS567.
• Capsular stiffness had a minimal effect on displacement (<2.5%).
• Both condyles exhibited superior, compressive movement; contralateral structures showed higher stress peaks.

Conclusions:

• Unilateral distraction splints predominantly induce compressive, not distractive, forces on the TMJ under simulated conditions.
• Masseter muscle force is the primary factor determining TMJ loading, with capsular stiffness playing a minor role.
• Broader splint coverage may modulate load transmission, reducing stress and displacement.