Journalof Oral Rehabilitation, 1989, Volume 16, pages 249-255 • Comparative electromyographic study of elevator muscles in patients with complete dentures and natural dentition R. MIRALLES, B. BERGER, W. IDE, A. MANNS, R. BULL and A. CARVAJAL* Department of Physiology and Biophysics, Faculty of Medicine, and * Department of Prosthetics, Faculty of Odontology, University of Chile, Santiago, Chile Summary An analysis of integrated electromyographic (IEMG) activity of masseter and ante- rior temporal muscles was undertaken in fifteen patients with complete dentures and eight adult subjects with natural dentition. Bipolar surface electrodes were used for IEMG recordings during maximal voluntary clenching and saliva swallowing in the inter-cuspal position. The IEMG activity of both muscles during maximal voluntary clenching was significantly lower in patients with complete dentures than in subjects with natural dentition. During saliva swallowing the activity in both muscles was similar in both groups. This may have a great clinical significance in the maintenance of the functional state of the different structures of the stomatognathic system in complete denture wearers, since the process of swallowing is a 24-h function repeated about 600-2400 times each day. Introduction The functional state of the stomatognathic system during swallowing and maximal bite has been electromyographically studied in patients with complete dentures. Thus, Ingervall & Hedegard (1980) showed that muscle activity during maximal bite was markedly lower in patients with complete dentures than in the ones with natural dentition. Furthermore, the activity during swallowing of three test foods was also smaller in patients with complete dentures than in middle-aged and younger patients (Ingervall, 1978; Haraldson & Ingervall, 1979; Ingervall & Egermark-Eriksson, 1979). Ingervall & Hedegard (1980) pointed out that patients with complete den- tures are obviously handicapped, judging from the low activity during maximal bite and swallowing. Moreover, Tallgren et al. (1980) in an electromyographic (EMG) longitudinal study of eighteen denture wearers indicated marked alteration in EMG activity of the jaw closing muscles during maximal biting. Other researchers (Vennstrom, 1971; Haraldson, Karlsson & Carlsson, 1979; Tarbet, Silverman & Schmidt, 1981 ;Meng& Rugh, 1983; Colaizzi era/., 1984; Gibbs et al, 1986) have also reported that denture wearers were unable or hesitant to produce high levels of bite forces, compared to individuals with natural teeth. Furthermore, it has been reported that edentulous persons are oral invahds and even Correspondence: Dr Rodolfo Miralles, Department of Physiology and Biophysics, Faculty of Medicine, University of Chile, Casilla 70055, Santiago 7, Chile. , .„.. • . 249