Abstract
This study aimed to determine the effect of newly introduced 0.020” slot size brackets on di-mensional positions and space closure ratio of mandibular canine. Material and Methods: The study includes six groups according to slot sizes (0.018”, 0.020” and 0.022”) and materials of canine retrac-tion (elastomeric power chain and closed coil spring). A 200 gm of retraction force was used on 0.017” X 0.025” stainless steel wire ligated to brackets by elastomeric ligatures along 13 mm available space. After immersion of the typodont in water bath with (50-55) C for 5 minutes, the rate of space closure were measured in millimeter using vernier (from the distal wings of canine bracket and the mesial wings of the second premolar), In both vertical and horizontal directions, digital images were taken by camera and the angle between canine extension bar )C B) and bite plane extension bar (BPB) was measured by protractor to determine tipping and rotation. Results: The results showed that 0.022” slot bracket groups had highest amount of rate of space clo-sure tipping and rotation, while 0.020” slot brackets groups had higher space closure rate than 0.018” slot brackets groups. Conclusions: bracket slot 0.022” groups showed higher tipping, rotation and space closure rate, while 0.020” slot brackets groups had higher rate of space closure with same or bet-ter rotation and tipping control in comparison with 0.018” slot bracket groups
