A Comparative Assessment Of Extrusion Or Intrusion Capabilities Between Three Kinds Of Lingual And Labial Brackets With Different Slot Using Three-dimension Finite Element

Objective:Analyze the difference of extrusion and intrusion performance between three kinds of brackets as well as the influence of lingual or labial,horizontal or vertical slot,canine’s distal tilt and arch wires with different materials and sizes through three-dimension finite element,to provide theoretical reference for clinical.Methods:1.Construction models of brackets from the left maxillary canine to the right canine of Discovery○R,Incognito?,Kurz^7th by Pro/E.Wildfire5.0,and models of lingual and labial wires with different size and material.There have five different sizes of labial wires,which size was 0.012inch,0.014inch,0.016inch,0.016×0.025icnh,0.017×0.025inch and0.025×0.016inch,0.017×0.025inch.There have four kinds of round wires of lingual wires,which size were 0.012inch,0.014inch and 0.016inch.There have two kinds of horizontal lingual rectangular wires,which size was0.025×0.016inch and 0.025×0.017inch,and two kinds of zonal lingual rectangular wires,which size were 0.016×0.025inch and 0.017×0.025inch.The material of those wires were set as eta-titanium（TMA）,Nickel-Titanium（NiTi）,Stainless Steel（SS）,Australian wire（AUSS）.The diameter of ligature wire was0.2mm.2.Those models were imported into MSC.Patran software to be meshed and solved.3.Then those completed models were imported into MSC.Marc.Mentat2005R3 software,to limited rotation and displacement of the three-dimensional direction,and load the specified force.Recording each model’s displacement contours and loading values,drawing each model’s time/loading graph and a bar graph the maximum loading moment.The Part one wish to research the extrusion capabilities of three kinds of brackets when leveling,the Part two wish to research the extrusion capabilities of three kinds of brackets when using rectangular arch wire,the Part three wish to discuss the intrusion capabilities of three kinds of brackets when the canine teeth is distal tilting.Results:1.Part one:（1）The time/loading curve of three kinds of brackets were found to be similar:the load presents 0 in a short period of time,then the load increased as the load time increased,that to say the load increased to the peak when times come to 1s,but their increased ratio present the same that was Kurz^7th’s>Discovery○R’s>Incognito?’s.when assembled with same wire,the length of platform stage of three brackets were different,Incognito?’s>Discovery○R’s>Kurz^7th’s in order.And when the wire’s size increase,the length of platform stage of three brackets became shorten.（2）.When the wire’s size increase only,the max loading increased as the wire’s size increased,when the size from 0.012inch comes to 0.014inch,the max loading increased 2.1-2.3 times,when the size turn to 0.016inch,the max load increased1.6-1.7 times.（3）.when the material changes,the max loading of AUSS>TMA>NiTi,the ratio was 2.8:1.3:1。（4）.when assembled with same wire,the max loading of Kurz^7th was 3 times more than Discovery○R’s,1.5times more than Incognito?’s,but the max loading of the model of Incognito?which assembled 0.016inch wire was approach to Discovery○R’s.2.Part two:（1）.The time/loading curve of three kinds of brackets were found to be similar:the load increased as the load time increased,that to say the load increased to the peak when the left incisor move 1mm along X axis,but their increased ratio present the same that was Kurz^7th’s>Discovery○R’s>Incognito?’s.（2）.When the wire’s size increase only,the max loading increased as the wire’s size increased,when the size from 0.016inch comes to0.016×0.025inch inch,the max loading of Discovery○R’s increased 11.5 times,the max loading of Kurz^7th’s increased 18.9 times,the max loading of Incognito?’s increased 26.4 times.when the size turn to 0.017×0.025inch,the max loading of models of horizontal slot brackets increased 1.3 times,while models of vertical slot increased little（3）.when the material changes,the max loading of model were similarity,SS>TMA>NiTi,the ratio was about3.2:1.3:1。（4）.when assembled with same wire,the max loading of Kurz^7th was about 3.7 times more than Discovery○R’s,1.5-1.9 times more than Incognito?’s.3.Part three:（1）.The lateral incisor of Kurz^7th models have a extrude-crowned movement,but all the models of Incognito?did not.（2）.In the models of Discovery○R and Kurz^7th,the displacement of lateral incisor increased as the distal-tilting of the canine teeth,but no one of Incognito^TM’s model happend（3）.When the wire’s size increased only,it has a little influence to the extrude-crowned movement of lateral incisor,but lateral incisor flared as the size.（4）.when assembled with same wire,and the same distal tilting of the canine teeth,Discovery○R have a more effective work to extrude-crowned,but it can make lateral incisor becomes to medal-tilting,whiles Kurz^7th’s tilt to distal.（5）.The loading of incisor in all the models were 0.Conclusion:1.The lode of the three kinds of brackets were,Kurz^7th>Incognito?>Discovery○R,lingual or labial,horizontal or vertical slot,all have an influence to extrusion or intrusion capabilities between three kinds of brackets,but the mainly factors was the length between two brackets.2.The lode of the three kinds of bracket increased as the inch of wire and young’s modulus.3.In the models of Discovery○R and Kurz^7th,the displacement of lateral incisor increased as the distal tilt of the canine teeth,but none of Incognito?’s.Because Incognito?’s slot face to vertical dimension and be short of a slot well;The angle of distal tilt of the canine teeth plays a main role in the extrude-crowned movement of lateral incisor,while the size of wire plays a minor.