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Chapter 244Ivory was first used as TMJ implant material by Gluck, yet its use was not exclusive to the TMJ. Ivory was also favored by many plastic surgeons after Joseph first used the material as nasal dorsum for rhinoplasty in 1918. Implantation continued until the middle of the 20th century; when a 40% rejection rate was observed, resulting in the material being abanded.(62–65) Pichler also described the need for explantation of the ivory condylar prosthesis by Köning due to loss of stability.(6) Despite these findings, Baw developed a femoral prosthesis that made use of an ivory head. He chose the material because of properties such as the friction coefficient, which was close to that of cartilage if the ivory was well polished, as well as strength, being nearly as strong as Vitallium when statically compressed. He placed more than 100 ivory hip replacements with a reported success rate of 88%.(66) A third material worth mentioning is tantalum. Although the material was recently reintroduced in the field of knee and hip arthroplasty, it was first used in neurosurgery for cranioplasty, after Burke(67) and Pudenz(68) demonstrated that the material had high corrosion resistance.(69) Furthermore, Pudenz(68) noticed the formation of a tissue capsule around the material, which made surgeons believe that the implant was better fixed. Not much later, the material was used as an interpositional foil in the TMJ by Eggers(16) and Goodsell.(17) However, as it was very expensive to make, and was reported to fragment and result in inflammation, the use of tantalum was halted.(18,69)Subsequent generation of materialsSilicone elastomersThe polydimethylsiloxane silicone elastomer Silastic was first produced by Dow Corning in 1948. After Wesolowski et al.(70) concluded that the material was biologically inert when used as joint replacement material in 1966, it quickly gained attention in the medical world because it was easily carved, did not allow tissue ingrowth, was flexible and was easily available.(71) The popularity of the elastomer followed in part after a misinterpretation of Brown’s research by Braley.(72) While Brown et al.(73) concluded that the material was capable of preventing recurring ankylosis of the joint, as they noticed that a fibrous capsule had formed Nikolas de Meurechy NW.indd 44 05-06-2024 10:14