Research on 3-D FEM of the three types anchorage micro-implants

Objective: To investigate the stress around different types of anchorage micro-implants , thus selecting the appropriate micro-implant for orthodontic anchorage. Methods: Three-dimensional finite element method (FEM) was used to analyze the stress around three types of micro-implants after 400-gram horizontal force loaded. Type 1 is cylinder-shaped micro-implant, triangle threads, with superperiosteal step (shoulder); Type2 is cylinder-shaped micro-implant, triangle threads, without superperiosteal step;Tpye 3 is cylinder-shaped micro-implant, trapezoid threads , with superperiosteal step. Results: 1) The von mises stress of Type 1 is notably higher than that of Type2. 2) The von mises stress of Type 3 is indistinctively lower than that of Type 1. Conclusion: The superperiosteal step can obviously decrease the stress around the micro-implant and the type of threads cannot influent the stress markedly.