Zhenrui Xu1, Lixing Zhao1, Yeke Wu1, Xing Wei1, Jue Wang1, Na Tang1, Tian Tang1, Zhihe Zhao2. 1. Department of Orthodontics, State Key Laboratory of Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, China. 2. Department of Orthodontics, State Key Laboratory of Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, China. Electronic address: zhzhao@scu.edu.cn.
Abstract
OBJECTIVES: The aim of this study was to evaluate the osseointegration of loaded orthodontic microscrews at different cortical bone thickness (CBT) sites. STUDY DESIGN: Forty-eight microscrews were inserted bilaterally in the tibias of 12 beagles, and divided into thick and thin CBT group. After 1, 3, 5, and 7 weeks, the dogs were killed and bone-screw specimens prepared for polyfluorochrome sequential labeling, microscopic computerized tomography (μCT) analysis, and biomechanical pull-out testing. RESULTS: All μCT parameters were increased in the thin CBT group, and decreased in the thick CBT group with time passed. Fmax of microscrews in thick CBT sites reached a peak in week 1, but dropped to lowest levels in week 3. Remodeling, apposition, and measured deposition areas of 3 labels were significantly higher in the thin CBT group than in the thick CBT group (P < .05). CONCLUSIONS: Relatively larger CBT is of benefit for primary stability at early time points, whereas thinner CBT is more appropriate for achieving long-term stability with prolonged time.
OBJECTIVES: The aim of this study was to evaluate the osseointegration of loaded orthodontic microscrews at different cortical bone thickness (CBT) sites. STUDY DESIGN: Forty-eight microscrews were inserted bilaterally in the tibias of 12 beagles, and divided into thick and thin CBT group. After 1, 3, 5, and 7 weeks, the dogs were killed and bone-screw specimens prepared for polyfluorochrome sequential labeling, microscopic computerized tomography (μCT) analysis, and biomechanical pull-out testing. RESULTS: All μCT parameters were increased in the thin CBT group, and decreased in the thick CBT group with time passed. Fmax of microscrews in thick CBT sites reached a peak in week 1, but dropped to lowest levels in week 3. Remodeling, apposition, and measured deposition areas of 3 labels were significantly higher in the thin CBT group than in the thick CBT group (P < .05). CONCLUSIONS: Relatively larger CBT is of benefit for primary stability at early time points, whereas thinner CBT is more appropriate for achieving long-term stability with prolonged time.