Abstract: Objective: To analyze the stress distribution at micro-implant-bone interface and the displacement of micro-implant based on different endosteal section diameters, and for choosing orthodontic anchorage micro-implant and optimize design of micro-implant. Methods: The finite element models of micro-implant with different endosteal section diameters and mandible were established by Pro/E; the elements were divided by Hypermesh and the results were calculated by Ansysl0.0. A force of 1.96 N was applied on the top of the implant parallel to the mandible surface to analyze the differences of the micro-implant displacement and that of the force on the micro-implant-bone interface. Results: With the increasing of endosteal section diameter, both the maximum Von-mises stress on micro-implant-bone interface and the maximum displacement in micro-implant decreased. The maximum Von-mises stress focused on the neck and tip of micro-implant. The Von-mises stress of micro-implant on z axis is the smallest, and the stress curved is the flattest at the endosteal section diameter of 1.5mm than that of other sizes. The tendence of the contour map area for mandible surface stress is 1.7mm>1.6 mm>1.4 mm>1.5 mm .Conclusion: The influence of the micro-implant diameter in-bone on the micro-implant is significant. The damage on the mandible and the displacement of the micro-implant are both the smallest in the 1.5mm case.

Key words: finite element analysis stress, mechanicalorthodontic anchorage procedures mandiblemicro-implant