双钥匙曲整体内收上前牙的三维有限元研究

目的：探讨双钥匙曲整体内收上前牙的过程中不同的加力方式对上颌前牙生物力学效应的影响。方法：采用 CBCT采集患者上颌骨以及上牙列数据信息，利用 Mimics 软件进行三维重建，建立双钥匙曲整体内收上前牙的三维有限元模型；在ANSYS 软件中分别分析①末端回弯、②结扎丝加力以及③结扎丝加力联合双钥匙曲顶部连扎3种工况下上颌前牙的初始位移。结果：从工况1到工况3，矢状方向上：中切牙冠根位移差值由4．19E －03 mm 变为－8．85E －03 mm，表现为舌侧倾斜移动到整体移动后转变为唇侧倾斜移动。而侧切牙冠根位移差由7．99E －03 mm 减小到5．84E －04 mm，尖牙由9．47E －03 mm 变为8．54E －03 mm，显示侧切牙和尖牙由倾斜移动向整体移动转变；垂直方向上：切牙由伸长移动趋势变为压低，而尖牙的压低量也逐渐变大。结论：不同的加力方式上颌前牙的移动趋势不同，结扎丝加力和顶部连扎使前牙趋向于整体移动。

A finite element analysis of en-mass retraction of maxillary anterior teeth with double keyhole loops

Objective:To evaluate the biomechanical effects of en-mass retraction of maxillary anterior with double keyhole loops in different kinds of loading methods on maxillary anterior teeth.Methods:Three 3D finite element models of the maxillary with double keyhole loops were constructed using MIMICS software with CT data of a male patient who had maxillary first premolars extracted.The orthoclontic force was loaded by ① back winding of the archwire end,② archwire strengthening and ③ archwire strengthening com-bined with successive ligation on the top of the doube keyhole loops,respectively.The initial displacement of maxillary anterior teeth in different loading conditions was analysed with the help of ANSYS software.Results:From the loading condition 1 to 3,on the sagit-tal direction,the displacement difference of crown and root of the maxillary central incisor was reduced from 4.19E -03 mm to -8. 85E -03 mm,which means that the lingual crown tipping movement gradually turn into bodily movement and then to labial tipping crown movement.Meanwhile the displacement of lateral incisor decreased from 7.99E -03 mm to 5.84E -04 mm and that of canine decreased from 9.47E -03 mm to 8.54E -03 mm.Vertical movement of incisors became intrusion from extrusion and intrusion move-ment of canines become more significantly.Conclusion:Torque control of anterior teeth is different in three loading conditions,load-ing by ligation and successive ligation on the top of the double keyhole loops may make the anterior tooth movement as a whole.