A Study Of Friction Between Different Wire-bracket Combinations Inartificial Saliva

Objective:To compare the frictional force between different brackets and metal archwiresunder artificial saliva condition.Provide reference to choose wire-bracketcombinations in clinical.Method:The kinetic friction of different combinations of five kinds of brackets and threedifferent wires(0.019×0.025inch stainless steel archwire,0.018×0.025inch stainlesssteel archwire,0.018inch stainless steel archwire) were used Instron universal testingmachine under artificial saliva condition.Observation of the microstructure of thebracket slots were conducted with stereo microscope and scanning electronmicroscope(SEM) before and after sliding along the archwires.Result:1、 In the three different wire groups,imported metal brackets generatedsignificantly lower frictional forces than other four kinds of brackets（P＜0.05).2、In the three different wire groups,domestic polycrystalline brackets showedthe significantly highest friction than other brackets（P＜0.05).3、In the three different wire groups,imported and domestic monocrystallinebrackets had no significant differences with the three different wires（P＞0.05).4、In the five kinds of brackets groups,The friction of0.018inch stainless steelarchwire were generally lower than0.019×0.025and0.018×0.025inch stainless steelarchwire（P＜0.05),but no significant differences were found between0.019×0.025and0.018×0.025inch stainless steel archwire（P＞0.05).5、It can be observed from SEM:Imported and domestic metal brackets hadsimilar surface morphology. Their surface had some irregular shallow pits;butdomestic metal bracket’s pits were bigger and deeper.Imported monocrystallinebracket slot had shallow cellular;Domestic monocrystalline bracket slot showedrough surface.Domestic polycrystalline bracket slot had cloddy crystal particles ofvarying sizes.After sliding along the archwires,the surface of domestic polycrystalline and imported monocrystalline bracket slots can find metallic residues;two kinds ofmetal bracket slots showed no scratch or residue;domestic monocrystalline bracketslot became more rougher.Conclusion:1、Imported metal brackets had the lowest friction combined with0.019×0.025、0.018×0.025and0.018inch stainless steel archwires,whereas the domesticpolycrystalline brackets yielded the highest.Imported and domestic monocrystallinebrackets showed similar frictional force.2、The friction of0.018inch stainless steel archwires were generally lower than0.019×0.025and0.018×0.025inch stainless steel archwires,but0.019×0.025and0.018×0.025inch stainless steel archwires were similar.