Comparative Analysis Of Intrusion Force Vectors With Different Temporary Anchorage Device Placements And Heights In Orthodontic Treatment: A Three Dimensional Finite Element Analysis

Abstract

Aim and Background: This study aims to analyze the intrusion force vectors by utilizing two combinations of temporary anchorage device placements. Combination I involves two mini-screw implants placed bilaterally between the roots of maxillary first molars and second premolars. Combination II includes an additional midline mini-screw implant placed between the roots of maxillary central incisors at a height of 12 mm from the archwire. The objectives are to assess the maximum principal stress in the bone, implant, and periodontal ligament (PDL) and to determine the initial displacement patterns in vertical and antero-posterior directions under varying conditions.

Methods: Finite element analysis (FEA) was employed to simulate and evaluate the stress distribution and displacement patterns. The study considered different heights of implants (13 mm, 10 mm, and 7 mm from the archwire) and variations in the orientation of anterior retraction hooks. Two groups were analyzed: Group I with bilateral implants and Group II with an additional midline implant at 10 mm height. Each group was subdivided based on the pull direction and height of the implants and hooks.

Results: The analysis revealed that Group II implant placement generally resulted in lower stress levels in the PDL and bone compared to Group I. The 3 mm occlusal anterior retraction hook produced the highest stress in most regions. High-pull implants in Group II were most effective in causing anterior segment intrusion. Initial displacements were influenced by the implant placement combination, height, and hook orientation, with significant variations observed across different setups.

Conclusion: Combination II implant placement with a high-pull orientation and specific anterior retraction hook height can optimize stress distribution and displacement patterns, enhancing the effectiveness of orthodontic treatment. Clinical Significance: This study provides valuable insights into the optimal placement and configuration of mini-screw implants and retraction hooks. For efficient intrusion the use of a mini-screw in the midline along with posterior implant that is combination II was better than only placing 2 mini-screws in the posterior region as in combination I.