Joint Disorders

Abstract

During maximum intercuspation of teeth, the disc should be centered onto the condyle, and the disc-condyle complex should be centered into the fossa. According to different authors, in such a position the condyle shows an average concentric position in the fossa with symmetric joint space widths (Pullinger et al. 1985, 1986; Ren et al. 1995; Rammelsberg et al. 2000). The posterior band of the disc should therefore sit on top of the condyle whereas the pars intermedia rests where condyle and tubercle are at their closest. If one were to imagine the condylar head profile as a clock, then the area between the posterior border and the bilaminar zone should lie at 12 o’clock (Fig. 7.1a, b). This physiological position has been named superior disc position (Tasaki et al. 1996). In gnathological terms, the term centric relation is often used when describing the position of the condyle-disc-fossa complex. It is a term which historically aroused controversy and its definition changed throughout the years. However, when the condyle-disc unit is functionally intact, any spatial location during functional movements in which condyle and disc are related as above can be defined as a centric relation. The centric relation position in the uppermost and most anterior position of the fossa is named terminal centric relation, and it is often used for prosthetic rehabilitation purposes (Tanteri et al. 2009).