Measurement of masticatory forces in the horse

Abstract

To measure the forces of the equine chewing cycle, which comprises three distinct phases: (1) opening stroke: downward and sideward movement of the mandible; (2) closing stroke: initial occlusion of the cheek teeth; (3) power stroke: laterolateral grinding movement. No data has yet been available about the forces exerted during the distinct phases of equine chewing. However, such physical data will advance investigations in equine nutrition, dentistry, and mandibular surgery. Measuring equipment: a quartz crystal force sensor was embedded in a nylon capsule and connected to a handgrip of steel tubing containing the wiring. Animals: 12 warmblood horses (6 female, 6 male, between 5 and 27 years old). The sensor was placed on the second or third premolar teeth of the lower jaw (Triadan: 306/307, and 406/407). The data measured during mastication were transferred to a computer equipped with an analysis system. Two peaks of masticatory forces were recorded during a single chewing cycle: (1) an initial minor peak of 248±117 N, duration 0.27±0.08 sec. (2) a major peak of 875±278 N, duration 0.59±0.1 3 sec. Chewing rate: 8±1 chewing cycles per 10 sec. Maximum chewing force: 1758 N. During the measuring procedure, the horses showed regular chewing cycles. The recorded force time graphs revealed two different periods of force generation (peak 1:248 N; peak 2:875 N). This pattern reflects well the distinct phases of the chewing cycle. Peak 1 corresponds to the closing stroke; peak 2, to the power stroke.