EMG Study Of The Masticatory Muscles In Children And Adults Patients With Mandibular Deviation

Mandibular deviateon is a very common malocclusion in clinic. Patients suffer from not only craniofacial deformity but also the negative influence on psychology. Pathogenesis and pathogeny are still unclear. Recently, native and overseas researchers have done many researches on masticatory activity of the patients with the mandibular deviation by EMG. It is known that the mandibular deviation is correlated to the malfunction of craniofacial muscles. These functional diversifications can be measured by EMG Through the results of EMG in each group of normal children, normal adults, children patients and adults patients, we can study the effects of masticatory muscles on the mandibular deviation and effects for mandibular deviation on the muscle function. The difference of EMG of masticatory muscles in children and adults patients was investigated, The muscles asymmetry, activity and toque Index were analysed and the relationship of pathogenesis and development between the mandibular deviation and the related musclesfunction were discussed in this article. The results are as follows:1. The EMG of each side of masticatory muscles in children and adults were symmetry and have a good balance.2. The children patients with mandibular deviateon: In open-close activity, there were no significant difference of EMG of the masseter on both sides. However, it shows that the amplitude of EMG on opposite muscle was much higher than that on the shift side in other functional positions. The amplitude of EMG of the temporle muscle on the side of mandibular deviation is smaller than that on the other side.The opposite results were found in anterior digastric muscle. On the other hand, it shows the significant difference in main masticatory muscles on different functional occlusion.3 The asymmetry index of EMG activities in the child and adult patients with mandibular deviation were higher than that with normal occlusion in general.In child patients: the muscles were ranked in activity index order from top down as follows: the anterior temporal muscle, the anterior digastric muscle, then the masseter muscle in posture position; the masseter muscle, the anterior temporal muscle, then the anterior digastric muscle in clenching and chewing position; the anterior digastric muscle, the masseter muscle, the anterior temporal muscle in maximum open position; the anterior digastric muscle, the anterior temporal muscle, then the masseter muscle in maximum close movement position; the masseter muscle, the anterior temporal muscle, then the anterior digastric muscle in free mastication movement.In summary, there were significant muscle asymmetry index differences among the different positions of the patients with mandibular deviation. The more active the muscle was the more severe its asymmetry was as well.4. The torque index of mastication muscles:The torque index was least between the masseter muscle and the anterior temporal muscle, but in clenching and chewing position, the value raised dramatically, even by ten times higher than that in other positions. The index was medium between the anterior diagstric muscle and the anterior temporal muscle. And the highest one was between the masseter muscle and the anterior digastric muscle, which valleyed in close movement position and peaked in clenching position.5. The asymmetry index of EMG activities, the activity index and the torque index were all high, especially in the critical functional positions, such as, clenching position, free mastication ect. The muscles were ranked in EMG activities variety order from top down as follows: the masseter mascle, the anterior temporal muscle, then the anterior digastric muscle.Conclusion:1. Physiologically, the amplitude of EMG was relatively symmetric bilaterally in the children or the adults with normal occlusion.2. There was certain degree of EMG asymmetry and muscle activity variety both in the adult and the child patients with mandibular deviation. However, it was more severe in adults.3. As to the same group of masticatory muscles in the patients with...