Object:The object of this study was to evaluate how friction that occurred during sliding movement of an orthodontic archwires, through the orthodontic brackets is differently affected by variant designs and ingredients of brackets and archwires and bracket-archwire angle. Methods:In order to simulate the situations which could happen during orthodontic treatment with fixed appliance, 4 types of bracket (Gemini; a stainless steel twin bracket, Mini Uni-Twin; stainless steel bracket which had a single bracket design and narrow mesial-distal width, Clarity; a metal reinforced ceramic bracket, Transcent; a ceramic bracket. ll bracket product by 3M Unitek) and 3 types of orthodontic archwire (0.016", 0.016×0.022" stainless steel, 0.016" Nitinol) were used and the bracket-archwire angles were controlled as 0°, 3°, 6°, 9°. Results:1. Gemini significantly showed the lowest static and kinetic frictions (P<0.001). The highest static and kinetic frictions were significantly showed when the bracket-archwire angle of Clarity was 0° and bracket-archwire angle of Transcent were 6° and 9°(P<0.001). 2. 0.016×0.022" stainless steel rectangular archwire significantly showed the highest static and kinetic frictions(P<0.01). The lowest static and kinetic frictions were observed when the bracket-archwire angle were 0° and 3° with 0.016" stainless steel round archwires(P<0.01) and 6° and 9° with 0.016 Nitinol(P<0.001). 3. The static and kinetic frictions were increased as the bracket-archwire angles were increased(P<0.001). Conclusions:Generally, twin brackets are thought to be more profitable than single brackets, considering frictional characters in orthodontic treatment. And using ceramic brackets with stainless steel lining when using ceramic brackets is considered for esthetic orthodontic treatment is recommended. In space closure procedures using sliding mechanics, it is recommended to perform space closure after complete alignment and leveling in order to minimize binding between bracket and archwire.