RESUMO
Objective To measure the dynamic and static frictional resistances between different self-ligating orthodontic brackets and different combination of tandem archwires.Methods On standard model the upper right quadrant Damon Q self-ligating brackets was pasted as team A,3M Smart clip self-ligating brackets as team B and Forestadent Quick 3.0 self-ligating brackets as team C respectively.Nickel-titanium archwires of 0.012 inch and 0.016 inch and two nickel-titanium archwires of 0.014 inch were applied to simulate sliding in the brackets and measure the friction changes in brackets and archwires,so as to explore the frictional resistance between different combination of the tandem archwires and different self-ligating brackets.Results When using the combination of two 0.014-inch nickel-titanium tandem archwires,the static frictional resistances was significantly different (P＜ 0.05):team A ＜team B ＜team C while the kinetic frictional resistance was also significantly different (P＜0.05):team A ＜team B ＜team C,When using the combination of 0.012-inch and 0.016-inch nickel-titanium tandem archwires,the static frictional resistances was significantly different (P＜0.05):team A＜team B＜team C,while the kinetic frictional resistance was also significantly different (P＜0.05):team A＜team B＜team C.Gonclusion There are different frictional resistance in different kind of self-ligating brackets and different combination of the tandem archwires.The combination of two 0.014-inch nickel-titanium tandem archwire applied to Forestadent Quick 3.0 self-ligating brackets has the biggest frictional resistance while the combination of 0.012-inch and 0.016-inch nickel-titanium tandem archwire applied to the Damon Q self-ligating brackets has the lowest frictional resistance,which enables the teeth to move at the fastest speed and facilitates the following use of the edgewires.