Distalization of maxillary molars for Class Ⅱ malocclusion with Chinese Ni-Ti coil-springs appliance

Objective ： To evaluate the effects of the Chinese Ni Ti coil-springs appliance on distalization of maxillary molars and the reciprocal effects on the anchorage teeth. Methods：Twenty-four adolescent pa tients（12 boys,12 girls） with Class Ⅱ malocclusion were selected and the coil-springs appliance was used during the treatment. Pre and postdistalization lateral cephalometric radiographs were analyzed and compared. Results： The average time for the correction of Class Ⅱ molar relationship was 4.6 months. And the mean distance of molar distalization was 4.4 mm. The Chinese Ni-Ti coil springs also demostrated less tipping and better bodily movement of maxillary molars. Conclusion ： This study suggests that the Chinese Ni-Ti coil springs appliance distalizes the upper molar significantly, while there is no remarkable loss of anchorage because of patients＇ wearing headgear with J hooks at night and Class Ⅱ elastics in the day time.