| The term of tooth wear (TW) is used to describe the loss of hard tooth tissue caused by friction between tooth occlusal facing or tooth facing and food during masticatory movement and non-masticatory movement under no occurrence of dental caries and external injury. A small and gradually TW was a physiological process accompanied by one's all life, but severe TW could cause a series of pathological changes between tooth and dentition, occlusion and articulation, the maxillomandibular relation and masticatory muscles. TW can affect the healthy between mastication and all correlated tissue. Mandibular movement was one of important indexes to reflect the functional status of stomatognathic system, a lot of investigations found that TW affected masticatory muscle. The study on electrophysiological movement of TW could help to discover the pathologic lesion of it. At present, the research of TW out overseas or in domestic were mostly about the clinical epidemiological survey and common clinical restoration. The studies of mandibular movement and electromyography are major in diagnosis of malocclusion and TMJDS, occlusion and articulation, therapeutic criterion of malocclusion and TMIDS and in definition of maxillomandibular relation. The research on mandibular movement and electromyography of TW had not been reported. This study began with the epidemiological survey of severe TW and used K6-1 diagnostic system witch produced by Myotrontic company of USA to evaluate mandibular movement and the value of masticatory muscles underMPP and maximal clenching in ICP. These may help to analyze theregularpattems on mandibular movement and masticatory muscles of severe TW and to provide some the theoretical bases for profound study and clinical restoration of tooth losing accompanied by severe TW .All of the following results were obtained:1. In both arches, anterior teeth of elderly people exhibited greater wear than did posterior teeth. Multiple factors most frequently considered to be contributed to TW, the habitation of eating hard diet or sour diet had significant correlation with TW.2. Closing from MPP to ICP, model I (posterior teeth's occlusal surfaces are flattened, over bite is deepened) TW showed a posterial displacement, model II (posterior and anterior teeth are all flattened) > III (wear of teeh is irregular, functinal cusps are low, unfunctinal cusps are high) TW showed a lateral displacement,TW patients showed bad consistent opening-closing trajectory,the stability of ICP in TW was decreased significantly.3. The freeway space of TW increased, model I N III showed great significant, model II had a tendency to increase.4. The fast and wide opening-closing trajectory of TW showed unregulation and unsmooth. The fast and wide opening-closing velocity of model IN II increased significantly, the fast and wide opening-closing velocity of model III decreased significantly.5. The largest wide of opening movement of TW showed no great significant to compare samples.6. The horizontal displacement of anterior excursion in model I> II showed no great significant to compare samples, model III decreased, model I > III showed great significant in vertical displacement of anterior excursion.7. The horizontal displacement of lateral excursion of model I was smaller than compare samples, model II > III showed no great significant, but they had had a tendency to decrease; the vertical displacement of lateral excursion of model I, III increased significantly.8. TW patients showed hyperactivity of TAx M1VL DA in MPP than compare samples, TAx MM increased significantly, MM of model II showed lower value than model I > III, MM of model III increased significantly than model I > II.9. During maximal clenching in ICP, MM> DA decreased significantly, TA had no great significant, but had a tendency to decrease, MM was sensitive to TW, TW had greater damage to MM <. DA than to TA.All of these results indicated that it...
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