A Comparative Assessment Of Mechanical Capabilities Between Lingual And Labial Archwires Using Three-Dimension Finite Element Method

Objective:To construct three-dimensional(3-D)finite element model of Lingual and Labial archwires with brackets using finite element method,and to analyze the different distance of brackets between Lingual and Labial archwires as well as the pattern of the influence that the archwires of different materials and sizes have on the mechanical capability of Lingual and Labial archwires based on the three-point bending principle,so as to provide theoretical reference for choosing optimal archwires in lingual and labial orthodontics.Methods:1 Construct solid model of lingual brackets with horizontal slot and labial brackets with vertical slot of the right and left upper incisors including 0.20 mm dimension ligation wires and archwires at the length of 20mm with different dimensions(0.43×0.64mm2 and 0.048×0.64mm2)by using Pro/E Wildfire4.0 software.In this study,all brackets were of 0.022-inch slot size.2.Assemble the solid models and guide them into the CADfix8.0 software to repair the models and to further mesh accurately.3.M eshing the repaired models in MSC.Marc.Mentat2005R3 software,and then setting up the 3-D finite element model of Lingual and Labial archwires with brackets.4.According to the principle of three-point bending,simulate the force load at middle point using MSC.Marc.Mentat software under different boundary and material properties.All the brackets are fixed in three dimensional directions,and the apply 2mm vertical displacement to four different distance of lingual and labial brackets which are 8mm,10mm,12mm and 14mm respectively.Record the reaction forces of the force point with different materials and dimensions of archwires,and draw the curves of load/deflection and average force histograms.Results:1.Construct 3-D finite element model of Lingual and Labial archwires with brackets by meshing reasonably and accurately,which can effectively carry out three-point bending test to research the mechanical properties of archwires.2.The load/deflection curve of lingual archwires was similar to labial archwires at the same distance of brackets under the different dimensions and materials archwires.With the increase of displacement,load force increased gradually,and the force of lingual archwire is2.30 times of the labial with 0.43×0.64mm2 dimension,while it is 1.20 times with 0.48×0.64mm.And the ratio doesn’t change with the change of archwire material.3.The force value of lingual Stainless Steel(SS)is the largest at the same load area under the same dimension but different material qualities,which is about 3.10 times of Nickel-Titanium(NiTi),and the value of Beta-titanium(TMA)is about 1.31times of NiTi.Moreover,the value of lingual archwires with 0.48×0.64mm2 dimension is 1.11 times of 0.43×0.64mm2 under the same material.4.With the increase of distance to lingual and labial brackets,both the forces of lingual archwires and of labial decreased gradually.But the lingual is larger than the labial at the same load.5.The load/deflection curves of lingual archwires with different materials and sizes are similar among different distance of brackets.The force SS generated is largest,followed by TMA and NiTi,and 0.48×0.64mm2 is larger than 0.43×0.64mm2.With the increase of distance of brackets,the force decreased gradually.From 14mm to 12mm,the force was increased to 150%,and from 14mm to 10mm,it was increased to 240%.While load area changed to 8mm,it was increased to 430%.Conclusion:1.Apply the combination of Pro/E Wildfire,MSC.Marc.Patran and MSC.Marc.Mentat to develop 3-D finite element model of Lingual and Labial archwires with brackets,which can provide a reliable study platform for the mechanical properties of the archwires in biomechanical analysis.2.With the increase of displacement,both the force values of lingual and labial archwires increased at the same distance of brackets.The force lingual archwires generated was larger than the labial,and the ratio only influenced by dimension is fixed.3.The force of lingual archwire was proportional to Young’s Modulus and dimension,and the effects the type of wire alloy affected were greater.4.With the increase of distance of brackets,the force lingual and labial archwires produced decreased gradually.But the lingual to labial ratio was constant and not affected by the distance of brackets.5.Mechanical capabilities of lingual archwires were affected by the characteristics of archwires and distance of brackets.The effect of load distance was greater,followed by the type of wire alloy and dimension,when the load point was at the middle of the near distance of brackets.While the distance of brackets were far from each other,force lingual archwire produced was mainly affected by the type of wire alloy.The dimension had least influence on the force.