Computerized kinesiography in the study of mastication in dentate subjects.

M astication is a feature of mammalian evolution. Whereas in earlier species primitive teeth were present that served to grip and puncture the skin of living prey, which was then swallowed whole, it was in mammals that the teeth were first used for trituration of the food to facilitate salivation and digestion. In an attempt to achieve a better understanding of the chewing mechanism, research has been directed at identifying the nature of jaw movement together with observations of the associated neuromuscular control. Beck and Morrison’ reported the development of the mandibular replicator with extraoral frameworks that attached to the teeth of both jaws. The replicator carried sensors located in three widely separated points and monitored the spa&l movement of the mandible. Although a number of researchers have used this or a similar apparatus to reveal valuable information concerning border movements and condylar shift, the nature of the equipment so intrudes on the subject’s level of consciousness as to render it unsuitable to record the movements that occur in normal function. Although tracing the movement of a single point on the mandible has limitations on the interpretation of jaw movement, it has the merit of requiring less obtrusive markers. The earliest recorded studies of single-point movement are attributed to Luce2 who in 1889 used still photography to record the path of movement of a light source attached externally to the mandible. Hildebrand,3 reporting his cinephotographic and cineradiographic experiments on masticatory movement, included a review of the literature in 1931. Ahlgren’ and others have since used a similar technique necessitating immobilization of the subject’s head to ensure that the recorded movements were those of the mandible alone. A common fault of post experiments has been that the subjects of the study have been required to chew only on one side of the jaw. Although it may be necessary to analyze the pattern of jaw movements during enforced unilateral chewing to classify chewing strokes, any