Spontaneous activity in dental mechanosensitive units in the dog

Abstract

The behaviour of 60 spontaneously active dental mechanosensitive units was observed in dogs anaesthetized with pentobarbitone. The units could be stimulated by applying forces to the teeth and showed a post-stimulus depression, or silent period, in the discharge of nerve impulses when these forces were removed. The duration of the silent period was found to be increased by increases in the magnitude, rate of application, rate of removal and duration of force applied to the teeth, and it was inversely related to the rate of spontaneous discharge. Spontaneously active units were simulated by subjecting non-spontaneously active units to low-grade mechanical stimulation prior to test-loading the teeth, and the simulated units were shown to have the same characteristics as the true spontaneously active units. It is suggested that the silent period may be due to hyperpolarization of the receptors following removal of the stimulus, and that the cause of spontaneous activity may be simply low-grade mechanical deformation of the receptors within the periodontal tissues.