The Comparison Of The Friction Between TOMY And AO Self-ligating Brackets With Rocking Chair Curvature During Space Closing By Sliding Mechanism

Objectives：The TOMY self-ligating(TOMY SLB) brackets and AO self-ligatingbrackets(AO SLB) were investigated with scanning electron microscopy and analysed withenergy spectrum,The static frictional force between posterior segmental brackets andrectangular stainless steel archwires were tested in dry conditions,respectively by differentSLB,by different size archwire,by different rocking chair curvature.In order to guide theorthodontist on choice of the brackets and archwires.Methods：We investigated the TOMY self-ligating(TOMY SLB)brackets and AOself-ligating brackets(AO SLB)with scanning electron microscopy and analysed thechemical constituent of brackts with energy spectrum.The static frictional forces were testedin dry conditions, respectively using two kinds of self-ligating brackets of right maxillaryposterior segment including TOMY and AO self-ligating brackets, two size of rectangularstainless steel(SS) archwires including0.018inch×0.025inch and0.019inch×0.025inch，4different rocking chair curvature of0°,5°,10°,15°. The brackets and arch wires arecombined and tested in the XF-1-type friction tester for testing, record Fluke190oscilloscopes mark of friction mV-ms variation. We use graphics software Matlab2007tocompile and sort the data, then get the frictional forces for statistical analysis.Results：The scanning electron microscope on bracket surface and its spectrum analysisTOMY and AO self-ligating brackets are18-8stainless steel material, the most importantcomponents is Fe and Cr；⑴Dynamic friction in the same combination of slightly less thanthe maximum static friction⑵The frictional forces have significant differences withindifferent groups:①different rocking chair curvature (0°,5°,10°,15°) of the archwire(Pr> F <0.0001) and15°＞10°＞5°＞0°.②0.018x0.025″and0.019x0.025″(Pr> F<0.0001) and0.019″×0.025″＞0.018″×0.025″.③TOMY and AO SLBs (Pr> F <0.0001)and TOMY SLB＞AO SLB.Conclusion：The scanning electron microscope on bracket surface and its spectrumanalysis results show TOMY and AO self-ligating brackets with the same material that is18-8stainless steel, the most important component is Fe, Cr;When we close the extractionspace using sliding mechanism, the frictional forces between brackets and archwires have the following laws：①the same combination of dynamic friction is slightly less than themaximum static friction.②the frictional force of TOMY SLBs is bigger than that of AOSLBs.③the frictional force gradually increased with the enlargement of rocking chaircurvature, regardless of the AO self-locking brackets or TOMY self-locking brackets.④0.019x0.025″archwire has bigger frictional force than0.018x0.025″archwire.⑤In clinic,orthodontists should flexibly choose the optimal brakets, curvature of the rocking chair andarchwires in order to attain the ideal treatment outcomes according to these data andtreatment objectives.