Retraction Using Continuous Loop, Sliding Mechanics And Miniimplant Anchorage

Objective: The aims of the study were to compare the loss of anchorage in sliding and continuous loop mechanics as well as changes in orientation of occlusal plane with mini implants using FEM study. Method: CT scan of the maxillary teeth and adjacent region of the subject was taken and 3D geometric model of maxillary right first molar to left first molar teeth with periodontal ligament, cortical and cancellous bone and brackets were generated using Hypermesh software. Three Finite element models of maxilla were prepared for retraction using sliding and loop mechanics and implant supported retraction. In first and third models 0.019×0.025” Stainless steel arch wires were used. 0.017×0.025” TMA arch wire with omega loop between canines and second premolars was used in the second model for loop mechanics. In the third model 2 Titanium implants were placed between second premolar and first molar. Retraction force of 150 g was applied in all 3 models. α and β bends were given in loop mechanics. Result: 1) There was a definite anchor loss in sliding mechanics compared to loop mechanics during retraction. (-2.025mm in loop mechanics and -2.618mm in sliding mechanics). 2) The tipping of the anterior segment is less in loop mechanics compared to sliding mechanics. 3) There was a definite bite deepening effect while using posterior mini implants alone for retraction due to rotation of anterior segment. (3.79⁰). Conclusion: Thus it was concluded from the study that loop mechanics was superior to sliding mechanics in terms anchorage control and reducing the tipping and subsequent anterior teeth extrusion.