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Chapter 5156achievable to scan the fossa after production. However, this error margin did not significantly affect the UHWMPE fossa part under investigation, as they were oversized 3D-printed and consequently milled down to the original STL file boundaries with a precision of 0.02 mm, as was also the case for the titanium condylar component. In addition, as we were not able to scan the implants prior to implantation, we were unable to predetermine reference points as to use a closed loop information system to overlap the ‘pre-implantation’ STL and ‘explanted-STL’ and instead relied on the ‘best-fit’ method using GOM Inspect (GOM GmbH). A second limitation we faced, were the fitting difficulties of the UHMWPE fossa during implantation, resulting in the trimming down of the non-loadbearing UHMWPE surfaces. While this allowed for easier implantation, this did result in problems determining the both linear and volumetric wear in one sample and volumetric wear in one additional sample. This was due to the ‘best-fit’ algorithm no longer being able to find a sufficient amount of matching surface points between the design-STL and the explanted fossa.A significant limitation we were confronted with as well, was the lack of prior research into both in vitro and in vivo wear analysis in TMJ TJR. Thus we were forced to compare our results to wear evaluation in TKR.ConclusionOur custom additively manufactured TMJ replacement system is wellsuited for implantation, with an average linear and volumetric UHMWPE wear well below the maximum allowed per year in TKR, for both the non-coated and H-DLC-coated Ti6Al4V condyles. Furthermore, the use of the H-DLC coating significantly improved the surface roughness of the condylar surface. Based on these findings, the combined use of the condylar H-DLC-coating with Vitamin E-stabilized UHMWPE should be considered the preferable TMJ implant option. Nikolas de Meurechy NW.indd 156 05-06-2024 10:14