Three dimensional finite element study of the stress induced deformation patterns during segmented canine retraction

ABSTRACT

This study makes use of the finite element method to determine the stresses induced in the periodontal ligament and hone in three dimensions when a maxillary canine was subjected to an orthodontic load of 100gm applied to the crown center in the mesiodistal direction. The 17 x 25 T loop spring was centered in position within the interbracket distance between the maxillary canine bracket and the first maxillary molar tube. The spring was constructed from two different materials TMA and Stainless Steel to compare the force system produced from each material and determine which material was more superior in clinical use in terms of optimal force magnitude per unite activation and lowest load deflection rate. The results showed that a centered T loop spring with a ratio between the activation force to the antirotation force to the antitipping force to be 100272 for either material. Maintenance of such ratio would approximate translation of the canine. The stiffness of Stainless Steel was found to be 2.4 that of TMA that indicated TMA superiority. The distribution of the stresses was shown to be nonuniform, with a maximum stress at the cervical margin then gradually decreasing toward the apex