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. 2011 May;81(3):420-5.
doi: 10.2319/071910-418.1. Epub 2011 Feb 7.

Three-dimensional morphology of root and alveolar trabecular bone during tooth movement using micro-computed tomography

Li Zhuang  1 , Yuxing Bai, Xianying Meng
Affiliations

Three-dimensional morphology of root and alveolar trabecular bone during tooth movement using micro-computed tomography

Li Zhuang et al. Angle Orthod. 2011 May.

Abstract

Objective: To investigate the effects of force magnitude on three-dimensional alveolar trabecular bone structure and root resorption.

Materials and methods: Twenty-two 11-week-old Sprague Dawley rats were randomly assigned to two groups that received a mesially directed orthodontic force to the upper right first molars at different magnitudes of force, 30 g or 100 g, for 2 weeks. The contralateral molars served as controls. The teeth and alveolar bone around the teeth were dissected from the sacrificed animals and were scanned with micro-computed tomography (CT). Structural properties of the trabecular bone and resorption crater volume on the mesial roots of the maxillary first molars were analyzed.

Results: The bone volume fraction of the 30 g group and the 100 g group increased significantly in both groups, and trabecular separation of the 100 g group decreased significantly compared with controls (P < .05). The total root resorption volume in all experimental groups and the resorption volume of the lower distal surface in the 100 g group increased significantly compared with controls (P < .01). The volume of the upper mesial root surface in the 30 g group increased significantly compared with the 100 g group and controls (P < .05).

Conclusion: The alveolar trabecular bone was denser after orthodontic force was applied for 14 days. The effects of 30 g and 100 g orthodontic forces on root resorption were different at the upper mesial and lower distal surfaces of the mesial roots of maxillary first molars.

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Figures

Figure 1
Figure 1
The NiTi coil was ligated to each of the rat's maxillary right first molars with a ligature, and the contralateral molars served as controls.
Figure 2
Figure 2
A 300 µm × 300 µm × 300 µm cube distal to the apical third of the mesial root of the maxillary right first molar was extracted from the trabecular bone for analysis. (A) Sagittal view. (B) Horizontal view.
Figure 3
Figure 3
Bone volume (BV)/total volume (TV) values among the experimental and control groups. The BV/TV values of the 100 g force (heavy) and 30 g force groups (light) were not significantly different, but both were significantly higher than control values. Data represent the mean ± standard deviation.
Figure 4
Figure 4
Trabecular separation (Tb.Sp) in the experimental and control groups. Tb.Sp in the 100 g force group (heavy) was significantly less than that of controls, but differences between the 100 g force group and the 30 g force group (light) and between the 30 g force group and controls were not significant. Data represent the mean ± standard deviation.
Figure 5
Figure 5
Three-dimensional micro-CT image of the alveolar trabecular bone. (A) Control group. (B) 30 g force group. (C) 100 g force group.
Figure 6
Figure 6
The mesial root was divided into four surfaces: A is the lower mesial surface; B the lower distal surface; C the upper mesial surface; and D the upper distal surface.
Figure 7
Figure 7
Total crater volume in the three groups. The volume was significantly greater in both the 100 g force (heavy) group and the 30 g force (light) group compared with control values, but the difference between the 100 g force group and the 30 g force group was not significant. Data represent the mean ± standard deviation. **P < .01.
Figure 8
Figure 8
Crater volume on the lower distal surface. The volume was significantly greater in the 100 g force group (heavy) than in the control group. Differences between the 100 g force group and the 30 g force group (light), and between the 30 g force group and controls, were not significant. Data represent the mean ± standard deviation. **P < .01.
Figure 9
Figure 9
Crater volumes on the upper mesial surface. The volume of the 30 g force group (light) was significantly greater than that of the 100 g force group (heavy) and the control group. Data represent the mean ± standard deviation. *P < .05. **P < .01.
Figure 10
Figure 10
Three-dimensional micro-CT image of the root. Root lacunae (arrows) are visible.
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