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Chapter 234of polytetrafluoroethylene (PTFE), also known as Teflon, to the field of TMJ surgery by Kent(28,29) (OCEBM LOE IV, OCEBM LOE III) in 1972. The material was deemed of interest because it had a porous structure that allowed soft and hard tissue ingrowth and potentially allowed better fixation. Kent used Proplast, a mixture of carbon fibers and Teflon, which was used to coat the condylar head of a CoCr ramal prosthesis.(28,29) To further improve implant stability, the ramal component was redesigned with an L-shape 2 years after its introduction.(18,19) A second alteration to the design was made 11 years after its introduction due to a significant number of patients showing resorption of the glenoid fossa. As countermeasures, the condyle was flattened and elongated, and a fossa component was developed to be combined with the condyle.(18)Keeping this complication in mind, Spiessl(30) (OCEBM LOE IV) developed a titanium condylar prosthesis in 1976, which also was known as the AO/ASIF prosthesis (Association for Osteosynthesis (AO)/Association for the Study of Internal Fixation (ASIF)). In addition to being influenced by the Kent prosthesis, he also applied the concept of intramedullary placement, which had become a favorable means of fixation in orthopedic surgery. Further stability and fixation were provided by seven transcortical screws.(18,19) Presently, the AO/ASIF prosthesis is still available, although it is used with certain alterations. Short and longer versions have been developed in addition to a condylar head ‘add-on’ option. Despite the manufacturer stating that the short condylar implant can still be used for certain indicated pathologies(18), a total TMJ replacement system should be preferred over the use of a condylar prosthesis, as discussed later.In 1977, Silver et al.(31) (OCEBM LOE III), inspired by orthopedic prosthetic hip surgery, developed a condylar prosthesis which was fixated using both a rectangular intramedullary Vitallium pin and polymethylmethacrylate (PMMA) cement. However, due to the heat created during the polymerization process, causing risk of thermal damage to surrounding tissues, the prosthesis was abandoned.(18) Furthermore, two of the three implants that were placed showed mobility, which proved that the system was too unstable for implantation.(19) Raveh et al.(32) (OCEBM LOE IV) introduced a titanium-based system with a ball-joint Nikolas de Meurechy NW.indd 34 05-06-2024 10:14