Li Zhuang1, Yuxing Bai, Xianying Meng. 1. Department of Orthodontics, School of Stomatology, Capital Medical University, Beijing, China.
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.
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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