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. 2013 Oct;43(5):218-24.
doi: 10.4041/kjod.2013.43.5.218. Epub 2013 Oct 25.

Effect of bite force on orthodontic mini-implants in the molar region: Finite element analysis

Hyeon-Jung Lee  1 , Kyung-Sook Lee, Min-Ji Kim, Youn-Sic Chun
Affiliations

Effect of bite force on orthodontic mini-implants in the molar region: Finite element analysis

Hyeon-Jung Lee et al. Korean J Orthod. 2013 Oct.

Abstract

Objective: To examine the effect of bite force on the displacement and stress distribution of orthodontic mini-implants (OMIs) in the molar region according to placement site, insertion angle, and loading direction.

Methods: Five finite element models were created using micro-computed tomography (microCT) images of the maxilla and mandible. OMIs were placed at one maxillary and two mandibular positions: between the maxillary second premolar and first molar, between the mandibular second premolar and first molar, and between the mandibular first and second molars. The OMIs were inserted at angles of 45° and 90° to the buccal surface of the cortical bone. A bite force of 25 kg was applied to the 10 occlusal contact points of the second premolar, first molar, and second molar. The loading directions were 0°, 5°, and 10° to the long axis of the tooth.

Results: With regard to placement site, the displacement and stress were greatest for the OMI placed between the mandibular first molar and second molar, and smallest for the OMI placed between the maxillary second premolar and first molar. In the mandibular molar region, the angled OMI showed slightly less displacement than the OMI placed at 90°. The maximum Von Mises stress increased with the inclination of the loading direction.

Conclusions: These results suggest that placement of OMIs between the second premolar and first molar at 45° to the cortical bone reduces the effect of bite force on OMIs.

Keywords: Bite force; Finite element analysis; Orthodontic mini-implant; Stability.

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Conflict of interest statement

The authors report no commercial, proprietary, or financial interest in the products or companies described in this article.

Figures

Figure 1
Figure 1
The five finite element models. A, Orthodontic mini-implant (OMI) placed between the maxillary second premolar and first molar at 45°; B, OMI placed between the mandibular second premolar and first molar at 45°; C, OMI placed between the mandibular second premolar and first molar at 90°; D, OMI placed between the mandibular first and second molars at 45°; E, OMI placed between the mandibular first and second molars at 90°.
Figure 2
Figure 2
The 10 occlusal contact points used in the current study. A, Maxilla; B, mandible.
Figure 3
Figure 3
The eight reference nodes of the orthodontic mini-implant.
Figure 4
Figure 4
Displacements (A) and Von Mises stress distributions (B) of orthodontic mini-implants (OMIs) in models A, B, and D. The X-axis indicates sequential points along the OMI from the tip to the head. A, Positive Y-axis values indicate occlusal movement of the OMI, and negative Y-axis values indicate apical movement.
Figure 5
Figure 5
Displacements (A) and Von Mises stress distributions (B) of orthodontic mini-implants (OMIs) in models B, C, D, and E. The X-axis indicates sequential points along the OMI from the tip to the head. A, Positive Y-axis values indicate occlusal movements of the OMI, and negative Y-axis values indicate apical movements.
Figure 6
Figure 6
Maximum Von Mises stress of the orthodontic mini-implants in the five models according to different loading directions.
See this image and copyright information in PMC

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