A novel 3D-printed, patient-specific alloplastic temporomandibular joint replacement allowing enthesis reconstruction: A finite element analysis

This study aims to evaluate the mechanical performance of a unique, state-of-the-art, patient-specific alloplastic total replacement system for the temporomandibular joint that allows for enthesis reconstruction developed by CADskills BV (Ghent, Belgium), and its influence on the remaining adjacent healthy tissue, by looking into the magnitude and location of the stresses and micromotions. Because the reattachment of the lateral pterygoid muscle is unique, having never before been used in temporomandibular joint prostheses, the loading patterns and performance may be completely different from existing devices and their analyses. Therefore, multiple finite element models were created to compare existing devices, prosthetic models of the CADskills device, and healthy situations. These were used to investigate the influence of such patient-specific prostheses through the evaluation of micromotion, loading on the opposite joint, strain on the healthy bone and condyle, and stress shielding.

The results showed that the temporomandibular joint prostheses were subject to stress considerably below their yield strength, except for the polyethylene of the fossa component, which might undergo abrasion under extreme muscular loads (larger than loads occurring during the activities of daily living). Additionally, the implant was shown to have little influence on stresses in the bone compared to a healthy model. Furthermore, the dynamic model shows how the load upon and stresses in the healthy joint increase when maximum muscle activation takes place with the mouth open.