[Electromyographic study of mastication as a function of the denture in humans].

A study of mastication was conducted using global electromyography of the masseter and anterior temporal muscles. Thirty subjects were studied and distributed between two groups. A control group of 5 patients had a complete natural dentition. A group of 25 patients presented important bimaxillary tooth-loss and wore dentures. They performed masticatory cycles with and without their dentures. The masticatory efficiency of the edentulous patients was very low when compared to the control group. The use of the dentures moderately improved function. The durations of activity of the temporal muscles were slightly lengthened (but not significantly) in the edentulous patients and the denture wearers compared to control patients. The cyclic pattern of the mastication tracings persisted. On the contrary, the durations of activity of the masseters muscles were strikingly lengthened until total disappearance of the resting phases. The cyclic pattern of the mastication tracings in controls disappeared in edentulous patients and denture wearers. In the latter, the tracings were less irregular than in the edentulous patients. In conclusion, the electrical activity of temporal muscles were slightly affected by the absence and replacement of teeth, whereas the electrical activity of the masseter muscles was markedly altered.