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Background: Sliding mechanics is widely used during orthodontic treatment. One of the disadvantages of thismechanics is the friction generated at the bracket/archwire interface, which may reduce the amount of desiredorthodontic movement obtained. The aim of the present in vitro study was to evaluate and compare the staticfrictional forces produced by two passive self-ligating brackets stainless-steel and hybrid and two conventionalbrackets stainless-steel and monocrystal ligated with stainless-steel ligature wire at two degrees of torque(zero andtwenty) under dry condition.Materials and method: One hundred and sixty brackets were used in this study divided into four groups each groupconsisted of forty brackets these are: Two self-ligating (stainless-steel and Hybrid) while the two conventional typesare the (stainless-steel and monocrystal).twenty of each group examined with 0.016"x0.022"archwire, ten at 0˚ torqueand ten at 20˚ torque while the other twenty of each group examined with 0.019"x0.025", ten at 0˚ torque and ten at20˚ torque.Results: There was a significant different between all groups except in case when self-ligating brackets (both types)ligated to both wires at 0˚torque there was no significant difference.Conclusions: The self- ligating brackets produce significantly lower static friction than the conventional types at bothdegrees of torque. There was no significant different between both self-ligating brackets at0˚torque while at 20˚torque the stainless- steel self –ligating produce lower static friction than the clear self-ligating type

static --- friction --- self-ligating --- conventional --- torque