Transparent To Keep The Temporomandibular Joint Condyle Position And Related Muscle Emg

Part1The influence of clear thermoplastic retainer on the electromyography of temporalis muscle and masseter muscleObjective: To investigate the influence of clear thermoplastic retainer on the EMG of TM,MM and to explore the role of clear thermoplastic retainer in the etiology of temporomandibular diseases.Methods: Choose people according to the standards, fabricate an acceptable clear thermoplastic retainer for everyone. Then decide the situation by preliminary experiment. The EMG of TM,MM was studied before and after clear thermoplastic retainer was wore. Analysis of variance was used to evaluate the differences.Results: The EMG activity of TM,MM, viewed in mandible posture position(MPP), was higher after clear thermoplastic retainer was wore (P＜0.05). The EMG activity of the muscles increased when the patient said [S] and [Z] after the retainer was wore (P＜0.05). The EMG activity of the muscles didn't change so much when the patient said [a] after the retainer was wore (P＞0.05).Conclusion: Clear thermoplastics retainer has effect on the EMG of TM,MM, but whether it plays a role in temporomandibular diseases need further observation. Part 2A primary study of condylar position change before and after clear thermoplastic retainer was woreObjective: The study primarily evaluates whether condylar position changed before and after clear thermoplastic retainer was wore.Method: The temporomandibular joints(TMJs) of 15 healthy people, without TMD, were viewed in MPP with TMJ lateral tomography before and after clear thermoplastic retainer was wore. Computer technique was used to evaluate tomograms: areal and linear changes of the anterior and posterior intra-articular joint spaces were measured. Analysis of variance was used to evaluate the differences.Results: After the clear thermoplastic retainer was wore, condyle moved forward. LogE (P/A) valuses were analyzed, the differences between them were found significant(p＜0.01). Two methods used to analyze the tomograms produced similar results.Conclusion: With the limitions of this study ,significant changes in the condylar position occurred after clear thermoplastic retainer was wore. Condyle moved from medial positions to anterior positions, but the changes after clear thermoplastic retainer was used for different times need further observation.