Analyses Of Mandibular Movement Characteristics In Patients With Different Occlusion Styles

Objective:(1)Through the the average EMG value of masticatory muscles and temporomandibular joint vibration feature among individual normal occlusion,Class?,?,? malocclusion subjects in natural head position(Natural Head Position,referred NHP)and head position indicator obtained no statistical difference.Provide EMG and joints theoretical basis for the terms of natural head shotcephalograms and facial Photograms.For cephalometrics analysis and photography analysis under NHP provide a useful complement.(2)Through masticatory and neck muscles and temporomandibular joint vibration characteristics of the Class?,?division 1,? malocclusion subjects to a comparison between the Class?,?division 1,? malocclusion,and Class?,? division 1,?malocclusion and individual normal occlusion,and thus to the observation of whether occlusal abnormalities have an effect on the masticatory muscles,neck muscle and temporomandibular joint.Methods: 40 college students were chewing as subjects.Occlusal relationship were individual normal occlusion,Angle ? malocclusion,Angle class ? Divisi on 1 malocclusion,Angle ? malocclusion all 10,in the natural head position and head position indicator,every subject was measured separately the average EMG value of anterior temporalis muscles(TA),masseter muscles(MM),anterior digastic muscles(DA),sternocleidomastoid muscles(SCM)during intercuspal position(ICP),mandibular postural position(MPP),maximal voluntary clenching(MVC),swallowing,chewing gum left side,chewing gum right side and temporomandibular joint vibr ation.Finally,the corresponding datum were dealt with statistics.the corresponding parameters between different groups were compared using independent sample t-t est analysis,the group before and after comparison using Analysis of Variance a nd Welch test.Results:There are 17 males and 23 females,aged(20.3 ± 0.3)years.(1)Under the natural head position and head position indicator,there was no significant difference in the average EMG value of bilateral anterior temporalis muscles,masseter muscles,anterior digastic muscles,sternocleidomastoid muscles during intercuspal position,mandibular postural position,maximal voluntary clenching,swallowing,chewing gum left side,chewing gum right side among individual normal occlusion,Class ?,? division 1 and ? malocclusion groups.(2)There was no significant difference in temporomandibular joint vibration total integral,integral<300Hz,integral>300Hz during the natural head position and head position indicator among individual normal occlusion,Class ?,? division 1 and ?malocclusion groups.(3)Under NHP,all masticatory muscles and neck muscles under ICP and MPP was no difference.(4)Under NHP,the average EMG values of right anterior temporalis and right digastric muscles muscles of individual normal occlusion group were higher than those of Class ? malocclusion group during MVC.The average EMG values of right anterior temporalis muscles of individual normal occlusion group were higher than those of Class ? malocclusion group during left chewing gum.(5)Under NHP,the average EMG value of left anterior temporalis,right anterior temporalis,left digastric muscles and right digastric muscles of Class ? malocclusion group were higher than those of Class ? malocclusion group during MVC.The average EMG value of left anterior temporalis,left masseter mascles,right massetermascles,left digastric muscles and right digastric muscles of Class ? malocclusion group were higher than those of Class ?malocclusion group during MVC.(6)Under NHP,the average EMG value of left digastric muscles of Class ?malocclusion group were higher than those of Class ? malocclusion group during swallowing.The average EMG value of right anterior temporalis of Class ?malocclusion group were higher than those of Class ? malocclusion group during left chewing gum.(7)Under NHP,the right temporomandibular joint vibration total integral of Class?and Class ? malocclusion groups were higher than those of Class ? occlusion group.(8)Under NHP,the left and right temporomandibular joint vibration integral>300Hz of Class ?malocclusion groups were higher than those of individual normal occlusion group.The left and right temporomandibular joint vibration integral<300Hz of Class?and Class ? malocclusion groups were higher than those of Class ? malocclusion group.Conclusion:(1)The results of average EMG value of masticatory muscles and neck muscles and the results of temporomandibular joint vibration feature releave no statistical differences in two head positions.Shooting cephalometric and facial image analysis under natural head position has a certain reliability.(2)Compared with indivial natural occlusion,from masticatory muscles,neck muscles and temporomandibular joint vibration,we can suggest that malocclusion may could lead to abmormalities of muscles and joints.