Page 41 - Demo

Historical evolution of the TMJ prosthesis392condylar head was designed to have the same geometry as the UHMWPE fossa to maximize contact while reducing the amount of wear.(18) Techmedica ceased production in 1993 after the FDA ordered a stop to the manufacturing of all TMJ prosthesis that were developed after 1976, as a direct effect of complications seen with the Vitek-Kent TMJ system. In 1997, TMJ Concepts took over manufacturing, after marketing was once more allowed by the FDA in 1996.(40) In 1999, the system received full FDA approval.(18) Mercuri et al.(39,41) and Wolford et al.(42) conducted several multi-center follow-up studies, evaluating patients treated between 1989 and 1993, with a TMJ concepts TJR device. The first study was conducted 1 year after implantation and the most recent study was published in 2015. All studies had similar conclusions, stating a significant decrease in pain, and a significant increase in mandibular function, mouth opening and quality of life. Furthermore, no failures were seen during long-term follow-up, although it should be noted that only 56 out of 111 patients were included in the most recent study.(39,41,42) In 1992, Bütow et al. started developing a titanium/titanium nitride TMJ (TTN-TMJ), which was released in 1994. Both the condylar surface and fossa were treated with nitride to harden the material and create better wear properties.(18) Bütow et al.(43) (OCEBM LOE IV) released a clinical review of their system in 2001, evaluating 27 patients. It is unclear if the system was used afterwards. A year after the TTN-TMJ system was released, Hoffman and Pappas released a CAD/CAM system that resembled both the TMJ Concepts and TTN-TMJ system. While the fossa consisted of titanium mesh with a UHMWPE articulating surface, the condylar component was composed entirely of titanium, with the articulating surface coated with nitride. Unique to this system was the possibility of replacing the UHMWPE surface in case of deterioration, by sliding the UHMWPE block out of the titanium base. Furthermore, the system required fewer screws compared to other systems due to the use of micro-locking screws.(44) Tsang et al.(44) (OCEBM LOE IV) conducted a retrospective study in 2008 evaluating 113 implants placed between 1995 and 2006, and stated that the system produced good results. However, the Hoffman-Pappas TMJ system did not receive FDA approval and production was halted.Nikolas de Meurechy NW.indd 39 05-06-2024 10:14