A finite element analysis of en-mass retraction of maxillary anterior teeth with double keyhole loops / 实用口腔医学杂志

ABSTRACT

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.