engleski

Electromiographic Silent Period of Jaw Elevator Muscles and its Role in Dentistry

Silent period (SP) is an inhibitory reflex in jaw elevator muscles, which can be elicited by stimulation of various receptors in oral and perioral cavity during the muscle contraction.. It was tought that SP elicited by menton tap is prolonged in myofascial pain syndrom (MPS), but recent studies have proved that the force of the stimulus, a level of previous muscle activity and the reticular formation excitement change the SP duration, not the MPS. The present study was made with the idea that occlusal interference changes the duration of periodontaly evoked SP. Thirty five healthy individuals with normal occlusion and all the teeth participated in the study. Simultaneous EMG (from both temporal and masseter muscles) and audio registration (microfones attached over the zygomatic bone) were made by the EMGA-1 device during 10 open-close-clench cycles. SP-s so obtained were single and short duration (19-20 ms) in all muscles. In an experimental procedure artificial occlusal interference of self-curing acrilyc resin was applied to the lower first premolar. Different silent period emerged: single prolonged, double and triple SPs or SPs with relative inhibition of motoneurons. In cases of more than one SP, complete duration of silent period complex was measured (CDSPC) which was approx. 60 ms and was significantly longer than normal SP (p<0.01). On the basis of the obtained results it was concluded that the shape and the duration of silent period could be used in the clinical practice for the diagnosis of occlusal interference.

silent period; normal occlusion; elevator muscles; EMGA-1 device; OCC cycle

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