Influence of experimental interfering occlusal contacts on the activity of the anterior temporal and masseter muscles during mastication.

Quantitative electromyography (EMG) was used to study, in eleven volunteers with complete, natural dentitions, the effects of an experimental intercuspal occlusal interference on the pattern of activity of the anterior temporal and masseter muscles during mastication. The results show that a small occlusal interference (about 0.5 mm) in the intercuspal position can change the co-ordination of muscular activity during mastication. In general, there was a prolonged contraction time as well as a reduction of the activity in all the investigated elevators, especially on the side of the interference. Furthermore, after 48 h several subjects preferred to chew unilaterally. After removal of the interference, the pattern of co-ordination of muscular activity returned almost to the pre-experimental pattern within 2 weeks.