Orthodontic mini-implant design using the FE and Taguchi method

Objective: The mini-implant design factors used as an anchor for orthodontic tooth movement are the main issue that influences the biomechanical aspects. The aim of this study was to determine the relative contribution of changes in eight engineering design factors on the bone mechanical response of a mini-implant.

Methods: The Taguchi L18 orthogonal array was used to reduce the number configurations for eight design factors assigned two/three levels. Eighteen finite-element (FE) models, according to the L18 orthogonal array, including the bone/implant interface osteointegration, implant material, implant length, outer diameter, screw thread geometry, depth of threads, head diameter and implant exposed length were constructed to perform the simulations. The Taguchi method was employed to identify the significance of each design factor in controlling the bone strain. ANOVA was used to test for the relative importance of the investigated factors and main effects for each level of the eight investigated factors in terms of the bone strain values.

Results: The results indicated that the implant material (62%) and implant exposed length (24%) were the major factors affecting the strain value in the alveolar bone. However, the corresponding bone strain values did not exhibit obvious differences (<2%) for other physiological and engineering design factors, especially for the bone/implant interface condition.

Conclusions: The combined use of FE analysis and the Taguchi method facilitated effective evaluation of the mechanical characteristics of a mini-implant design. The choice of titanium implant and burying the implant into the bone are recommended and thread geometry of mini-implant and osteointegration exist minimal effects and imply immediate load on the mini-implant is preferred in orthodontic treatment.