The Analysis Of Occlusal Measured By T-Scan Ⅱ System And EMG Activity Of Masticatory Muscles During Occlusal Reconstruction

Objective: To investigate the changes in occlusion and EMG activity of masticatory muscles during occlusal reconstruction in patients with decreased vertical dimensions by using the T-Scan II system and EMG system.Methods: Ten patients with dentition defect and decreased vertical dimensions which was caused by severe dental attrition were restored by removable acrylic occlusal splints at increased vertical dimensions first. then after one month permanent occlusal rehabilitation were conducted according to this occlusal vertical dimension. After one month patients were counter-cheched. The occlusal and EMG activity of masticatory muscles were compared among the stages of pre-treatment,one month after temporarily restored and one month after permanently restored to analyze the clinical effect of the occlusal reconstruction.Results:1 Results of clinical symptom:After occlusal reconstruction the function of swallow,chew, pronunciation is better than that of pre-treatment.The TMD symptom is improved. 2 Results of T-Scan system:(1) Occlusal force: After occlusal reconstruction the force of occlusion increased obviously.(P<0.01)(2) Centrol occlusion force: After treatment, the centrol occlusion force tend to be centrol. The balance of occlusion is improved.(P<0.01)3 Rusults of EMG system:(1) The EMG at rest position: After temporary and permanent restoration, the EMG amplitudes of masseter and anterior temporal muscles at rest position decreased.(p<0.05)(2) The EMG at maximum clenching position: After temporary restoration the EMG amplitudes had no more change. After permanent rehabilitation, the EMG amplitudes increased obviously .(P<0.05)(2) The balance of EMG : After permanent rehabilitation,the balance of masticatory muscles increased obviously .(P<0.05)Conclusions:1.After reconstruction the occlusal force and balance increased obviously.2.Raising the vertical dimension and undertaking occlusal rehabilitation can increase decrease the EMG activity of masticatory muscles at rest position,and increase the balance and contract strength of these muscles during maximal clenching.3. After reconstruction, The TMD symptom is improved. The coordination of occlusion,muscles and temporomandibular joint is recovered.