EMG Study On Facial And Head-cervical Muscles In Mandibular Deviation Patients

Objective:To investigate the influence of mandibular deviation on facial and head-cervical muscles function and the role of those muscles in abnormal development in patients with mandibular deviation by analysis the electromyographic(EMG) activities of masticatory muscles and head- cervical muscles during various mandibular movement.Methods:15 patients(male 6,famale 9;aged 18-29,the avarage is 23.3)with mandibular deviation were selected as a sample group,other 12 young healthy adults(male 6,famale 6;aged 20-25,the avarage is 21.6)with normal occlusion were selected as a control group.Using eight-channel electromyograph with surface electrode to record the EMG activities of masticatory muscles and head- cervical muscles during rest position,various mandible functional movement(including①maximum clench②open-close movement③gum chewing movement④protraction movement⑤left movement⑥right movement)and cervical,shoulders movement(①head around movement②shrug movement).Results:1.All the four muscles showed constant electromyographic activities when the mandible was in the rest position.2.The EMG activity compares between the two groups during all kinds of movement: Control group:No significant difference between the left and the right muscles during those four kind of mandibular functional movement and cervical-head movementPatient group:①the figure of paired side of muscles compared no significant difference in postural position and open-close movement,while in other position and movement the conditions is converse.②The figure of both side of MM has obvious difference during bilateral chew:the counter side is higher than the deviation side,but the figure of other muscle(TA,SCM and TR)is just converse.Overall,the difference between the both side of TA,SCM and TR is smaller than that of MM.③During cervical-head movement the figure of paired side of the four muscles has significant difference:the deviation side is higher than the counter in MM,while in TA, SCM and TR it is exactly opposite.④The muscle acitivity of TA is difference between control group and patient group in different condition:when in some condtions(rest position,protraction movement,right and left movement )that without compared Occlusal contacts,the former is higher than latter,while in other conditions(maximum clench and bilateral chew),the former is lower thanthe latter. 3 No significant difference on the symmetry between the left and the right muscles during those four kind of mandibular functional movement in control group:;But pronounced difference was found between the two groups.4.The symmetry of the paired muscles was lower in patient group than that of control group during cervical-head movement5.Head-cervical muscles burst and masticatory muscles burst presented durinmandible functional movement and cervical,shoulders movement respectively.The EMG amplitude between patient group and control group is positively correlated.There has significant differences between the two groups.Conciusions:1 It could be concluded that there has significant difference between mandibular deviation group and control group during mandibular functional movement cervical-head movement.2.Mandibular deviation has impact on the muscle coordination of different muscles and between the left and right side the same muscle.