[Mandibular positioning and movements relative to the pain dysfunction syndrome]

The movements and positions of the mandible are controlled by three guiding factors: tooth guidance, joint guidance, and muscle guidance. For this reason, the author proposes new, clearly delineated definitions for the terms "central occlusion", "central relation" and "muscle guidance". The unity of structure and function results from the harmony (biological equilibrium) between these three guiding factors. Deviations of the individual guiding factors (occlusal disorders, decentralized relations, malpositions and misguidances of the muscles) may be analyzed separately to begin with; thereupon, their interrelations will be elucidated. As not all of these three guiding factors are necessarily involved in an impairment (above all, the mandibular joints often show no abnormalities), and since pain is the principle sign in the clinical picture of a dysfunction of the orofacial organ, the author is of the opinion that the term "pain-dysfunction syndrome" (as coined by L. Schwarz) is more correct than such terms as "Costen's syndrome" or "myoarthropathy".