An electromyographic study of masticatory muscle activity at increased occlusal vertical dimension in complete denture wearers.

I t is a common clinical experience that patients wearing complete dentures at an increased occlusal vertical dimension (OVD) will suffer discomfort and complain that the dentures feel “too big.” At one time this discomfort was said to be an attempt of the muscles of mastication to return the mandible to its predetermined rest position.’ However, the concept that mandibular rest position is stable throughout life is no longer accepted,“5 but that the mandible can adapt to a rest position at an OVD Provided by the dentures.6 The idea now proposed is that at an increased OVD there is increased muscle activity during function, instead of an attempt to return the mandible to a rest position. This investigation tested this idea by recording the quantitative level of muscle activity occurring during function at increased OVD. The activity levels were recorded on an electromyograph (EMG), and a summation integrator was used to permit accurate measurement of the recorded activity.