A comparison of habitual jaw movements and articulator function

Inherent in adjustable articulators are errors related either to recordings from the patient or to adjustments to the instrument, or both. Furthermore, the validity of the geometric concepts on which the design of these instruments is based, stressing the dominant role of the temporomandibular joints in mandibular movements, is open to question. Microchip technology now makes it possible to view jaw movements in three dimensions while impeding physiological activity minimally. Using a kinesiograph, young dentate Swedish and Chinese adults were examined on two occasions, and the magnitude and direction of some jaw movements were recorded. The results showed that voluntary opening and closing excursions of the mandible frequently followed disparate paths and that closure from the rest position to occlusion was three-dimensional, a lateral component of movement being usual. Retruded contact position was both uncomfortable and unstable. These findings suggest that current procedures for designing and refining occlusal schemes on articulators are invalid.