LATENCY OF THE INHIBITORY REFLEX (SILENT PERIOD) IN INDIVIDUALS WITHOUT INPUT FROM PERIODONTAL RECEPTORS

Latencies of the inhibitory reflex (silent period) (SP) in jaw elevato r muscles were electromyographicaly examined in 62 subjects with natur al teeth (periodontal receptors existing) and in 30 complete denture w earers (periodontal receptors missing). SPs were eliciting during ten subsequent open-close-clench cycles (fi om the position of open mouth subject closes jaws firmly and the teeth. come into occlusal contact) for each individual. The new EMGA-1 configuration and Medwin software enabled exact measurement of such short reflex appearances. Latencies in individuals with periodontal inervation varied from 12.54-12.97 ms. In individuals without periodontal inervation latencies were signific antly longer (p<0.05) and varied from 16.46-17.27 ms, dependent on the examined muscle. Longer latencies in individuals with complete dentur es could be attributed to the time needed for the denture to shift and elecit oral mucous membrane and/or more synapses (or a longer conduct ion time) from the oral mucous receptors to the nucleus motorius n. tr igemini than from the periodontal receptors. Although complete den den ture wearers exhibit similar patterns of muscle activity to the indivi duals with natural dentition, it is obvious that reflex reaction time is longer without periodontal receptors.