Introduction: During Canine retraction and space consolidation, biologic tissue response and tooth movement occur only when applied forces adequately overcome the friction at bracket-wire interface. Today, many clinicians prefer to use wires of alloys such as Stainless steel, Nickeltitanium, or Beta-titanium during different phases of treatment. To deliver optimal forces for efficient and predictable tooth movement, it is necessary to have both an assessment and knowledge of forces required to overcome friction when different wire sizes and materials are used. Materials & Methods: Frictional force of Stainless steel, Nickel-titanium and Beta-titanium wires of different sizes will be tested in stainless steel pre-adjusted edgewise MBT premolar brackets. Brackets will be attached to special jig and wires will be ligated with elastomeric ligatures. Bracket movement along the wire will be implemented by an Instron universal testing machine, and frictional forces will be measured by a compression cell and recorded on an X-Y recorder. Frictional forces generate by each bracket-wire subsample will be subjected to statistical analysis. Interactive effects of wire size and alloys type on magnitude of bracket-wire friction will be assessed by two- way analysis of variance. Results &Conclusion: Sliding mechanics can best be performed using stainless steel archwire. Wire alloy could be ranked in order from lowest to highest friction: Stainless steel, Nickel-titanium and Beta-Titanium irrespective of wire and slot sizes. Frictional force increases with increase wire sizes in both 0.018 and 0.022 slot in all three kind of archwire alloys. Slotsize does not tend to have a significant effect on friction, but more importantlyrelative size of archwire within bracket slot will have a significantinfluence.
