Comparison of load transfers in TMJ replacement using a standard and a custom-made temporal component

Area of Science:

• Biomechanical Engineering
• Craniofacial Surgery
• Biomaterials Science

Background:

• Total joint replacement (TJR) for the temporomandibular joint (TMJ) is often a final solution for mechanical deficits.
• Prosthesis design, particularly the fossa component, plays a critical role in TJR success.

Purpose of the Study:

• To investigate the influence of temporomandibular joint fossa component geometry on biomechanical load transfer.
• To analyze how different fossa geometries affect strain distribution and screw fixation.

Main Methods:

• Finite element analysis (FEA) was employed to model two fossa components: a standard Christensen and a custom-made design.
• Both models utilized identical commercial condyle geometry and screw fixation, simulating a 5 mm mouth aperture for incisive teeth loading.

Main Results:

• Fossa geometry demonstrably altered strain distribution within the condyle and fossa components.
• Maximum strain occurred near cranial screw fixation points, with variations between the Christensen and custom-made models.
• Both component types exhibited limited bone integration potential, with micromovements around 40 μm.

Conclusions:

• The geometry of the TMJ fossa component is crucial for modulating load transfer to the mandibular condyle and influencing periscrew strain.
• Fossa geometry dictates the optimal positioning of screws for secure fixation within the cranial bone.