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Biomaterials in TMJ replacement693for the fossa-bearing surface. Nevertheless, these previous setbacks, in combination with the extensive expertise acquired in the field of orthopedic surgery for more than 5 decades, now provide us with the indispensable information required for the development of newer implant systems. When selecting the appropriate materials for TMJ prostheses, the following considerations should be taken in to account.BiocompatibilityA prerequisite for any successful clinical application of an implant is biocompatibility, a concept originally conceived to refer to a material’s ability to be in contact and interact with the tissues of the human body without eliciting any adverse effects at the implant site (locally) or in the patient as a whole. As such, a material and its degradation products should be non-cytotoxic—i.e., support cell survival and maintain specific cellular functions—and not cause inflammation or allergic reactions (hypersensitivity).(34,42) Advances in medical technology, such as the development of biodegradable implant materials and tissue engineering, have urged a re-evaluation of the biocompatibility edict to not only address biological safety but also the specific functionality aspect of a material. According to Williams, a biomaterial can also be expected to passively allow or actively generate the most appropriate beneficial cellular or tissue response in a given application site.(43) The relevant biological processes in TMJ TJR are osteogenesis and vascularization; as Table 1: Materials used in (previously) United States Food and Drug Administration–approved implant systems* (6,11,37,41,55–57)Biomet System Nexus CMF System TMJ Concepts SystemDesign Stock Stock CustomFossa UHMWPE Co-Cr-Mo Cp TiUHMWPECondyle Co-Cr-Mo Co-Cr-Mo Co-Cr-MoRamus Co-Cr-MoTi-coatingCo-Cr-Mo Cp Ti or Ti-6Al-4VScrews Ti-6Al-4V Co-Cr-Mo Ti-6Al-4VAl, aluminum; Co, cobalt; Cp Ti, commercially pure titanium; Cr, chromium; Mo, molybdenum; Ti, titanium; UHMWPE, ultra-high-molecular-weight polyethylene; V, vanadium *: The Nexus CMF system has recently lost its FDA-approval. Nikolas de Meurechy NW.indd 69 05-06-2024 10:14