الفهرس 
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Abstract
The current project evaluated the frictional forces of SPEED selfligating compared to a chromiumcobalt and stainless steel metal brackets using different sizes (small /large), shapes (round/rectangular/half roundhalf square) and types (St.St./Ni Ti) of archwires. Additionally, surface modified elastic ligature was compared to the traditional modules. The sample of this study was composed of 300 brackets and was divided into three main groups according to the type of bracket used. Each group was further subdivided into ten subgroups according to the type,shape and the size of archwire. Each subgroup consisted of ten brackets/archwire couples (N =10). The force of friction was measured on Material Testing System (Instron 1124, Instron Corp, MA, USA). Statistical analysis was performed using four ways ANOVA (p<0.05) to determine the effect of bracket type, archwire type, archwire size and and archwire shape on the frictional forces. Post Hoc Scheff(Ra(Be multiple comparison test (p<0.05) were performed to determine significant intragroup difference of frictional resistance of the tested groups. Finally Student ttest was done to compare the frictional forces between the two different elastic ligatures. The analysis showed that the SPEED selfligating brackets have the lowest frictional forces with all archwires tested. Also, the surface modified elastic modules showed less frictional forces than the regular modules. Ni Ti showed less frictional forces compared to St.St and there was no significant difference between the halfroundhalf square archwires.