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General discussion 33713General discussionOf the 27 different total TMJ prostheses that have been distributed in over fifteen countries in 2019, only two had an FDA approval.(1) Many of the new implant brands seem to copy the design of these two ‘tested and tried’ systems, without providing any significant clinical improvements. They also fail to be properly tested, with only 12 of them having gone through preclinical laboratory tests. None of these systems has gone through in vivo testing before being applied in humans. This is of significant importance, as in vivo wear rates might be higher compared to those measured in vitro.(2) Although several in vitro laboratory and in silico models have been developed, there remains uncertainty concerning the amount of force the TMJ is subjected to.(3,4) During mastication, both rotational and translational movements occur, which is difficult to properly mimic in a laboratory model.The aim of this thesis was threefold. Firstly, by performing several literature analyses, we aimed to determine an evidence-based proper implant design and material choice. This design was tested in silico regarding stress and strain.(5) Secondly, said design was in vivo tested by means of an animal-model experiment, to determine if the TMJR met orthopedic standards in terms of wear, adverse tissue reactions and tissue integration. Lastly, by both human application and literature analysis, we aimed to improve upon the implant replacement procedure, its revalidation and perform an, albeit short-term, functional evaluation. Implant development – Material choice When developing a new joint prosthesis several main issues must be regarded. Through literature analysis, we found that for a material to be suitable for implantation, it needs to meet several criteria. Firstly, the materials used must be biocompatible. While this may seem obvious, these materials are subjected to loading and wear, during which they must remain biocompatible. This means that the material used should be able to be in contact and interact with the human tissues without eliciting any adverse effects such as inflammation or allergic reactions.(6–9) Otherwise, such could lead to severe reactions, such as fragmentation of Nikolas de Meurechy NW.indd 337 05-06-2024 10:15