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Aims:The purpose of this study was to identify the cephalometric features of bimaxillary protrusion in adolescents. Materials and Methods: Ninty four students were selected aged (12-15) years from secondary schools in Mosul City.Fourty four with class I biprotrusion which were chosen to have an inte-rincisal angle less than 110o, and 50 with class I normal occlusion. Astandardized lateral cephalometric radiograph was taken for each student, sixteen variables, (9 angular and 7 linear) were used in this study. Results: Significant differences were seen in the majority of the linear and angular measure-ments used in this study, the total anterior facial height, lower anterior facial height, upper anterior den-tal height , lower anterior dental height, the angle defines the anteroposterior position of maxilla in re-lation to anterior cranial base, the angle indicates the anteroposterior position of the mandible in rela-tion to the anterior cranial base, mandibular plane angle, palatomandibular plane angle, gonial angle, the angulation of upper central incisor to anterior cranial base and the angulation of lower central inci-sor to mandibular plane were significantly higher in bimaxillary protrusion than normal occlusion in both sexes and total sample.No significant differences were seen in other measurements : upper ante-rior facial height, posterior facial height, ramus height and the angle of palatal plane inclination in rela-tion to anterior cranial base.Interincisal angle was significantly smaller in bimaxillary protrusion than normal occlusion. Conclusions: Most of the anterior facial measurements were significantly higher in bimaxillary protrusion than normal occlusion if compared to posterior facial height and ramus height due to the downward and backward rotation of the mandible in bimaxillary protrusion.

Aims: . To investigate the rates of space closure achieved by elastomeric chain and nickel titanium coil springs with the evaluation of the effects of using different bracket types on the rate of space closure during its retraction along different sizes of orthodontic arch wires using typodont simulation system (Ormco). Materials and Methods: The standardization criteria were all typodont teeth situated in well aligned position, covered and immobilized by the acrylic bite except canine, elastic chain and nickel – titanium closed coil spring exerting 180 gm of force on canine measured carefully by tension gauge. The available space was 13.5mm (the rate of space closure). Results: The present study showed that when using elastic chain as a method of canine retraction gave rise to a a significant decrease in the rate of space closure as compared with nickel – titanium closed coil spring also sliding the canine using ceramic brackets gave rise significant reduction in the rate of space closure than when using stainless steel brackets. Another finding of the present study showed that sliding the canine on large rectangular arch wire (0.019x0.025 inch) gave rise to a significant reduction in the rate of space closure when com-pared with 0.018 inch and 0.018x0.022 inch arch wires were used. Conclusions: It was concluded that the canine retraction with 0.018 inch wire on Roth stainless steel bracket by closed coil spring gave rise a large amount of space closure rate. While the opposite is true for canine retraction with 0.019x0.025 inch wire on standard ceramic bracket by elastic chain retraction method.

Aims: The present study concerned with the evaluation of the effects of using different bracket,s types (material and design), different arch wire types (shape and size) and different methods of retraction (elastic chain and closed coil spring) on the degree of tipping of canine during its retraction along an arch wire using typodont simulation system (Ormco). Materials and methods: The standardization criteria were all typodont teeth situated in well aligned position, covered and immobilized by the acryl-ic bite except canine, elastic chain and nickel – titanium closed coil spring exerting 180 gm of force on canine measured carefully by tension gauge., the angle between bite plane extension,s bar and canine,s extension bar was (90°) measured by protractor directly on photographs that were taken for typodont using digital camera from both vertical and horizontal direction. Results: The present study showed that sliding the canine on large rectangular arch wire (0.019x0.025 inch) gave rise to a significant de-crease in the degrees of tipping when compared with 0.018 inch and 0.018x0.022 inch arch wires were used. Also, sliding the canine using ceramic brackets (0.022) inch gave rise to the significant decrease in the degree of tipping than when using stainless steel brackets. Another finding of the present study showed that when using elastic chain as a method of retraction gave rise to a a significant decrease in the degree of tipping as compared with nickel – titanium closed coil spring and lastly the attachment of the method of retraction around the bracket tie wing rather than hook gave rise to the high degree of tipping . Conclusion: It was concluded that the canine retraction with 0.019x0.025 inch wire on stan-dard ceramic bracket(0.022)inch by elastic chain retraction method could be regarded as the best com-bination variables that produced less degrees of tipping While the opposite is true for canine retraction with 0.018 inch wire on Roth stain less steel bracket by closed coil spring.