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Chapter 250From condylar to total TMJ replacementWhile the interpositional and fossa prostheses were developed to treat ankylotic joints, the condylar and TJR prostheses aimed to restore mandibular function and form. Over time alloplastic TJR devices have become the gold standard treatment for irreparably damaged TMJs in adults and they have recently gained appreciation in older children.(102) At first, most devices were of solitary focus, consisting of either a fossa or a ramal prosthesis. However, as it became clear that the solitary use of a condylar prosthesis led to resorption of the glenoid fossa, certainly in absence of an interpositional disc, total TMJ systems were developed.(18,19,103) In order to achieve good primary stability, reduce micromotions and allow good osseointegration, several techniques, such as the use of porous implants, PMMA cement, and intramedullary pins were conceived, yet none proved ideal.(18,19,49,51), A recent, more successful, option is the use of radiological imaging and CAD/CAM design. As the implant is developed to fit the patient’s specific anatomy, optimal primary stability can be achieved. Current literature reviews have indicated that the use of patient-specific implants improves long-term outcomes over stock devices, with an increased quality of life.(49) As such, it is safe to assume that further individualization of TJR systems will be a driving force for future TMJ implants. Future considerationsWhen evaluating the development of the alloplastic TMJ prosthesis, it is clear that its history was mainly a process of trial and error and that it has clearly been influenced by the development of new materials over time; such developments have often attracted the interest of the medical field. Principles in design as well as many materials were first tested in the field of orthopedic surgery, after which they found their way into the field of TMJ surgery. While some of these innovations proved suitable, such as the use of titanium or the metal-on-UHMWPE design, this was not always the case. The use of unsuitable materials such as Silastic and Teflon, as well as unsuitable design principles such as metal-on-metal systems or PMMA Nikolas de Meurechy NW.indd 50 05-06-2024 10:14