Fitting a temporomandibular joint prosthesis to the skull

Area of Science:

• Biomedical Engineering
• Orthopedic Surgery
• Craniofacial Reconstruction

Background:

• Stock prostheses for temporomandibular joint (TMJ) reconstruction often require numerous custom parts for adequate skull fit.
• Existing methods necessitate a wide variety of differently shaped stock components, increasing complexity and cost.

Purpose of the Study:

• To evaluate the feasibility of achieving a precise fit to the skull using a novel TMJ prosthesis design composed of two connected stock parts.
• To determine if a close fit could be achieved with a limited number of components (maximum of 10).

Main Methods:

• Measurements of 20 dry skulls were taken to define optimal dimensions for prosthesis components.
• A gully-shaped fitting member, rotationally connected to a basic part, was designed for the articular eminence and lateral TMJ, respectively.
• Prototypes were fabricated and their fit was assessed by measuring the maximum gap between the fitting member and the skull.

Main Results:

• All tested skulls were successfully fitted using a set of four basic parts and three fitting members, totaling seven unique components.
• The average maximum gap between the fitting member and the skull was minimal, measuring 0.20 mm (range: 0.11-0.43 mm).

Conclusions:

• A close fit to the skull is achievable with a TMJ prosthesis constructed from two connected stock parts.
• The proposed design, utilizing a limited set of seven distinct parts, offers a viable solution for efficient TMJ reconstruction.