Three-dimension Structural Comparison Of Arch Wire Segment Slided By Canine During Orthodontic Treatment Between Straight Arch Wire And Self-ligation Bracket Fixed Appliance Under Atomic Force Microscope

Object:To detect three-dimension structure changes of arch wire segmentslided by canine tooth bracket during orthodontic treatment with straight archwire and self-ligation bracket fixed appliance under atomic force microscope.Method:Two malocclusion patients who have been extracted four firstbicuspids and treated with fixed appliance have been recruited.One patient wastreated with Damon-Q Self-ligation bracket appliance,another with Z2straightarch wire appliance.Their upper left canine tooths were drew to contact secondbicuspid tooth on segment of0.018″×0.025″edgewised stainleess arch wireduring treatment.Three-dimension structures of four faces of edgewised archwire segment slidded by canine tooth bracket was scanned under atomic force microscope during treatment.Three-dimension parameters (Sz、Sp、Sr、St、Sdc)were obtained from scanning figure.Structural comparison of arch wire sliddedby bracket,including before and after bracket slidding in clinic groups andbetween clinic groups were done.SPSS13.0were used for statistic analysis.Results:⑴Drawing force for canine tooth moving in Damon group wasaverage120g,canine tooth moving rate was about0.96mm/month.Drawing forcein straight wire group was about150g.Moving rate was about0.72mm/month.⑵Three-dimensional surface structure of different edgiwised arch wireswhich had the same brand hadn’t significant different under scanning of atomicforce microscope.⑶Four surface of arch wire slided by canine tooth bracket in straightwire group turned to rough.Upper and lower wide surface of arch wire slided bycanine tooth bracket in Damon group turned to smooth, change of externalnarrow surface wasn’t significant.Internal narrow surface turnde to a little rough.⑷Change sum of arch wire surface wasn’t significant between arch wirearea slided by canine tooth bracket and arch wire which was before the firstmolar and after the second bicuspid and hadn’t been slided by any bracket inDamon group.Arch wire segment which was before the first molar and after thesecond bicuspid turned rough during canine tooth sliding movement. Structuraldifferent of internal narrow surface was significant in straight arch wiregroup.Internal narrow surface in arch wire segment slided by canine toothbracket turned rougher than arch wire segment being before the first molar and after the second bicuspid.Structural change of other three surface in arch wireweren’t significant during canine tooth sliding movement.They turned to samerough.⑸Arch wire segment being before molar and after second bicuspid inDamon or straight wire group all turned rough during canine tooth slidingmovement.Structural change sum of internal and exterior narrow surface hadsignificnat different.Change sum in straight arch wire was heavier than inDamon group.Difference in upper and lower wide surfaces wasn’t significantand they all turned same rough during canine tooth sliding movement.Conclusion:⑴Three-dimensional surface structure of edgewised arch wireswhich had same brand were almost the same under scanning of atomic forcemicroscope.⑵Comparing to straight arch wire group,surface structures of archwire slided by canine tooth bracket in self-ligation group were lessdamage,upper and lower wide surface become smoother.Friction force anddrawing force for canine tooth moving was less.Movement rate of canine toothwas faster.⑶Surface of edgwised stainless arch wire in fixed appliance,eventhought not slided by bracket,still turned rough.So do arch wire should beinstanced to new one in the oral environment after long time treatment.