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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

Aims: Evaluate the amount of anchorage loss of the lower posterior teeth 2nd premolar and first molar when used as anchorage teeth for retraction of canine bilaterally by using lace back technique after extraction of first premolar in sever crowding cases. Materials and Methods: Two groups of brackets, one of them labial (conventional) were bonded on the labial aspect of metal teeth except 4 4 typodont by special adhesive and other groups lingual brackets also bonded in the same teeth lingual surface and two types of light or low gauge arch wire Niti , twisted multi strand for sliding the canines retraction by using elastomeric ring with ligature wire active lace back once with labial and other with lingual technique. Results: There is no significant difference between twisted multi strand wire when ligated on the teeth in both lingual technique and labial technique. Significant difference when used Niti wire on lingual technique when compared with the same type of wire when ligated on labial technique and significant difference with twisted multi strand when ligated on teeth in lingual technique. Conclusion: Anchorage loss decreases with twisted multi strand wire because the friction increased between arch wire and base of bracket in both labial and lingual technique and decreased with Niti wire specially when used in lingual techniques

Aims: To evaluate the effect of different ligature types and ligation techniques on the rate of space closure, tipping and rotation of canine after sliding. Materials and Methods: The total number of the samples were 50 sample classified under five groups according to the method and type of ligation; the first group: preformed stainless steel ligature wire (SL), the second group: preformed stainless steel kobayashi ligature wire (KL), the third group: elastomeric ligature in figure – O (EO), the fourth group: elastomeric ligature in figure – 8 (E8) and the fifth group: non-conventional Slide Leone elastomeric ligature (NE). A typodont used in this study with preadjusted Roth stainless steel brackets 0.022×0.030 inch and a stainless steel orthodontic arch wire 0.017×0.025 inch. A bite plane extension bar (BPB) and canine extension bar (CB) are constructed for the measurement of canine tipping and rotation. A 180 gm. of force applied by short continuous elastomeric power chain to retract the right canine. After immersion of the typodont in water bathe with 50-55 0C 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), the tipping and rotation were measured by taking a photograph to the typodont using digital camera, with transvers projection (for tipping) and occlusal projection (for rotation) from right side (directly toward the right canine), then the angle between (BPB) and (CB) measured directly on the photograph using Protractor. Results: A statistical analysis (descriptive statistics, ANOVA and Duncan Multiple Analysis Range Test) used in this study, for the rate of space closure the results showed that there is a significant difference between the five groups at p ≤ 0.001, the NE group had the highest amount of tooth movement while KL group had the lowest level, for the tipping; the NE group had the highest level of tipping while SL, KL and E8 groups had the lowest level with a non-significant difference between them, for the rotation; the results showed that NE group had the highest level of rotation, while KL group had the lowest level. Conclusions: The higher rate of space closure, the higher rotational degree and the higher tipping degree were associated with NE group, while KL group had shown the lowest rate of space closure and the lowest rotational degree. The lowest degree of tipping was associated with the SL, KL and E8 groups.