Finite element simulation and statistical investigation of an orthodontic mini-implant’s stability in a novel screw design

Abstract

One of the essential aspects of the mini-implant’s successful application is its stability after being installed in the bone. The stability of the mini-implant affected the most by its geometry. In the present research, the effect of the geometry-related parameters of the mini-implant on its lateral displacement is investigated by Finite Element (FE) modeling using ABAQUS software. The parameters studied include length, diameter, pitch, and depth of the screw threads; besides, length and angle of the conical section. The Taguchi method was used to prevent many experiments. The mesh convergence tests and experimental tests confirmed the FE model quantitatively and qualitatively. Mean of means and variance analysis determined the parameters significance and their contribution on the stability. The screw diameter and length have the most contribution to mini-implant’ displacement. The effect of screw pitch was less than that for length and diameter. The conical section improved the initial stability by creating compressive stress and additional friction in its surrounding bone. No significant effects on the stability of the mini-implant have been observed for the non-threaded part. By examining the effect of thread depth on its stability by defining the ratio of thread depth to the internal diameter and to maintain the strength of the screw the optimal value for internal to external ratio is set at about 0.7.

How Does Orthodontic Mini-Implant Thread Minidesign Influence the Stability?—Systematic Review with Meta-Analysis

“…Referring to studies included only in the systematic review, Topcuoglu et al found that a smaller thread pitch is correlated with higher removal torque values [25]. A smaller thread pitch prevents lateral displacement when orthodontic force is exerted [30]. The same was indicated by Budsabong et al in their in-vitro study [43].…”

“…From the quality analysis performed, it can be concluded that 1 animal study [25] and 2 finite element analyses are at high risk of bias [27,29], and most of the in-vitro studies are at medium bias risk. Two finite element analyses and two in-vitro studies should be considered at low risk [28,30,35,39].…”

Optimization Analysis of Two-Factor Continuous Variable between Thread Depth and Pitch of Microimplant under Toque Force

“…Based on 3D FEA, the stress generated was analyzed and the changes in the implant's surrounding bone under orthodontic load could be identified. Similarly, FEA was applied in learning the design parameters of microimplant, such as diameter, length, shape, and size [ 10 , 13 – 17 ]. Shen et al [ 11 ] applied a 2 N of mesial-distal horizontal direction load, which was parallel to the maxillary buccal surface, to simulate the horizontal retraction of the anterior teeth in clinical practice.…”