Effects Of Orthodontic Treatment On Temporomandibular Joint And Mandibular Position In Young Adults With Mandibular Deviation

Objective: The purpose of this study was to analyze the symmetry of the mandibular and investigate the effects of orthodontic treatment on temporomandibular joint and mandibular position in young adults with mandibular deviation and to approach the mechanism and feasibility of orthodontic treatment in young adults with mandibular deviation.Methods: 1. The first part is the analysis of the symmetry of the mandibular in young adults with mandibular deviation. Sixteen young adults with mandibular deviation were included as the experimental group and another sixteen normal ones as the control group. The height of the condylar process and ascending branch was measured and compared in Digital Panoramic Radiograph.2. The second part is the investigation of the effects of orthodontic treatment on temporomandibular joint and mandibular position in young adults with mandibular deviation. The subject was the experimental group in the first part. The TMJ transcranial projection films and Posterior-anterior films were taken before and after treatment to evaluate the change of the temporomandibular joint and mandibular position. 3. Cephalometric analysis was carried out with computer. All data were analysed with SPSS 11.0.Results: the results of the first part:1. There was significant difference in the height of the condylar process and ascending branch in the experimental group.2. Significant difference was found in the Asymmetry Index of the condylar process and ascending branch between the two groups.the results of the second part:1. There was significant difference in the linear ratio and area proportion before treatment, but no significant difference was found after treatment.2. No significant change was found in the condylar process of the deviated side. The condylar process was in the center of the cavity. After orthodontic treatment, the linear measurement and area of anterior space in the opposite side of TMJ increased by 0.13mm and 0.30mm~2; while the posterior space decreased by 0.16mm and 0.38 mm~2, linear ratio decreased from 9.37 % to 2.99 %, and area proportion decreased from 1.19 to 1.09. All the changes were statistical significantly. Anterior space became equal to the posterior space after treatment.3. There was significant difference in the distance from the condylar process and the gonion to the admedian before treatment, but no significant difference was found after treatment.4. After orthodontic treatment, the condylar process of the deviated side shift to the admedian, while the condylar process of the opposite side shift away from the admedian. The distance between gonion and the admedian in the deviated side decreased by 1.58mm, while in the opposite side increased by 1.57mm. The distance between genion and the admedian decreased by 2.16mm. Mandibular shift from the deviated side to the opposite side.Conclusion: 1. Bony asymmetry could be found in young adults with mandibular deviation. The height of the condylar process and ascending branch of the deviated side was larger than that of the opposite side.2. After orthodontic therapy, the condylar process of the opposite side moved posteriorly to the nomal concentric position, which was helpful in alleviating temporomandibular disorders symptom in young adults with mandibular deviation.3. After orthodontic therapy, mandibular revolved to the normal position, as a result, the symmetry of prosopo was obviously improved.