Implant fixation of novel and commercial TMJ implants

There are several diseases that can affect the human temporomandibular joint (TMJ). In recent years, new TMJ prosthetic systems have been introduced in the market and it is difficult to draw conclusions about the indications for TMJ prostheses and their success and survival rates (Mercuri et al. 2007). When surgical interventions are required, TMJ can often be repaired or reconstructed using autogenous tissues (Zanakis et al. 2009). However, certain specific TMJ conditions and pathologies can require a reconstruction with a total joint prosthesis to obtain improved treatment outcomes (Mercuri et al. 2002; Wolford et al. 2003). Alloplastic total joint prostheses offer a biomechanical behaviour rather than a biologic solution for the treatment of severe joint diseases (VanLoon et al. 1995). The prosthesis provides an effective and efficient means of dealing with joint anatomy. Two total joint prostheses are commercially available in the market. The most known model is the Christensen implant that presents a lateral plate that is fixed with screws. The 3D finite element (FE) model used in this study to simulate the mandible behaviour with this TMJ implant was carried out through previous studies (Hsu et al. 2011; Ramos et al. 2011a). We found that the fixation method is insufficient and the success depends on the positions of the screws. Manufacturers of this prosthesis have claimed good success rates and have shown clinical improvement (Driemel et al. 2009). Some studies have evaluated in vivo commercial implants (Guarda-Nardini et al. 2008) and point out good implant stability but reduced mandible mobility. Through the use of FE models we analysed two types of implant fixation means. We compared fixation using commercial screws and an internal new fixation possibility.