Objective: The present study evaluated the clinical effects of Invisalign-aided molar distalization in the treatment of mild or moderate crowding in anterior teeth. Methods: Eleven adults with class Ⅱ dental malocclusion and a class Ⅰ skeletal pattern were selected as subjects. The patients’ molar occlusion did not exhibit an end-to-end relationship. Subjects were selected for straight profile, mild or moderate crowding in maxillary teeth and normal or mild crowding in mandibular teeth. Nonextraction and Invisalign-aided molar distalization were planned for treatment. Model measurement and cephalometric analysis were performed before and after treatment. A paired t test was used for the statistical analysis. Results: The crowding and class Ⅱ molar relationship were corrected in all 11 patients. The upper first molars were moved distally by 2.32 mm (t = 3.315, P < 0.01) and were inclined distally by 3.35° (t = 3.959, P < 0.01) on average. The central incisors were protruded by 1.72 ° (t = 3.274, P < 0.01) on average. The buccal movement of the upper first molars was 1.32 mm (t = 2.461, P < 0.05) on average. The above differences were statistically significant. Conclusion Upper molar distalization can be achieved using a class Ⅱ elastic-aided Invisalign technique. The end-to-end molar occlusion can be corrected, and front teeth with mild or moderate crowding can be aligned using our treatment protocol.

Objective: To explore the clinical application of cone beam CT in the diagnosis of traumatic anterior teeth before orthodontic treatment in order to reduce the risk of orthodontic treatment failure due to adhesion. Methods : 48 fixed orthodontic treatment cases with the history of anterior teeth trama were selected. The anterior teeth were examined by CBCT to exclude root and alveolar bone adhesions. Results : 3 cases of root-alveolar bone adhesion were found, and the upper anterioa teeth of the remaining 45 cases were successfully moved by orthodontic treatment. Conclusion CBCT examination is recommended to check the periodontal ligament in patients of fixed orthodontic treatment with the history of anterior teeth trauma in order to exclude the root-alveolar bone adhesion cases.

Objective To compare the temporomandibular joint changes in adolescent Class Ⅱ division 1 malocclusion patients with mandibular retrusion treated with Twin-block and Class Ⅱ elastics.Methods Sixty Class Ⅱ division 1 malocclusion patients with mandibular retrusion were divided into 3 groups (Twin-block group,Class Ⅱ elastic group and control group,20 patients in each group) randomly.Differences of condylar process morphology were compared using cone-beam CT(CBCT) before and after treatment.Results Condylar largest anteroposterior diameter and upper condylar height increased after treatment in both Twin-block groupand Class Ⅱ elastic group.The condylar largest anteroposterior diameter and upper condylar height were longer in both Twin-block group [(8.51 ± 1.48) and (7.39 ± 1.42) mm] and Class Ⅱ elastic group [(8.44± 1.03) and (7.24±0.89) mm] than those in the control group[(7.47± 1.27) and (6.47 ± 1.56) mm] (P＜0.05).No significant difference was found in other measurements (P＞0.05).Conclusions Condylar largest anteroposterior diameter and upper condylar height in Class Ⅱ division 1 malocclusion patients increased after treatment using Twin-block and Class Ⅱ elastics.There was no significant difference between two groups.