Some implications of normal tooth mobility during mastication

Abstract

The average time interval between normal chewing thrusts was assessed from seven young male subjects masticating a variety of foods. For four subjects oscilloscope records were studied from a strain gauge dynamometer placed in the first molar teeth which measured the force of the chewing thrusts. Estimates for the other three subjects were assessed from records derived from cine film of chewing sequences. The mean interval was 0.412 sec. Using this estimate the degree of recovery was studied for upper incisors and premolars in five young male subjects. Controlled thrusts of 2 kg were applied in the axial plane and 1 kg thrusts in the bucco-lingual plane. The movement of the test teeth was detected by transducers employing wire strain gauges. Two phases of recovery were noted for both planes of movement; a fast linear phase was followed by a slow gradual return which was completed in 1.5 min. The equivalent of 0.412 sec after the release of the thrusts was found to fall into the slow phase of recovery for half the teeth examined. The implications of these observations are that a tooth tends to remain in a depressed and mesially displaced position in its socket during normal chewing.