A FEM study about the initial stress distribution on canine altered by the application point of preangulated TMA T-loop spring

Kim, Jung Min; Cha, Kyung Suk; Lee, Jin Woo

Abstract

The purpose of this study was to find the difference of stress distribution on canine altered by the application point of preangulated T-loop spring T-loop spring. For this study, the finite element models of upper left canine, upper left second premolar and upper left first molar were made. Also, the finite element models of 0.017X0.025 inch preangulated, preactivated T-loop spring and 0.018X0.025 inch stainless steel wire were made. Three types of T-loop spring were made : the middle of activated T-loop is positioned in accordance with the middle position of distance of bracket position of both the canine and first molar, 2mm anterior, 2mm posterior. We compared the forces and the distribution of stress that were generated by the difference of position of T-loop spring. The results were as follows. 1. All of the 3 types of T-loop spring showed the similar retraction forces. 2. All showed the similar amount & pattern of stress distribution. 3. The centers of rotation of canine in 3 types of T-loop spring were same and were positioned between C and D plane. 4. The canine showed the intrusive force by 2mm anterior positioned T-loop spring, but the extrusive force by 2mm posterior positioned T-loop spring. Neverthless, because of the small amount of the forces, the effect of vertical force was not significant.