Fitting a temporomandibular joint prosthesis to the skull

Fitting a temporomandibular joint (TMJ) prosthesis to the skull by using stock prostheses seems to be an appropriate method. However, fitting the skull with one stock part requires many differently shaped parts. Therefore, we fitted the skull with two connected stock parts. The aim of the study was to test whether it is possible to achieve a close fit to the skull with this design, with a maximum of 10 different parts. The articular eminence was fitted with a gully-shaped fitting member, which was rotationally connected to a basic part that fitted to the lateral side of the TMJ. The relevant dimensions of 20 dry skulls were measured and the results were used to derive the optimal dimensions of the prosthesis parts. Prototypes were subsequently fabricated. The fit of the prototypes was tested by measuring the maximum gap between fitting member and skull. All skulls could be fit with a set of four different basic parts and three different fitting members. The average maximum gap between fitting member and skull was 0.20 mm (range 0.11-0.43 mm). It was concluded that a close fit to the skull can be achieved with two connected stock parts and with a total number of seven parts.