Mesial orthodontic movement of rat molars after extraction of the adjacent first molar and

本研究旨在开发一种新型的正畸装置，该装置集成了可拆卸的超弹性镍钛合金（NiTi）闭合螺旋弹簧。使用雄性SD大鼠（5周龄）。上颌切牙被固定并用作闭合线圈矫治器的支抗。同时拔除上颌第一磨牙。在伤口愈合5天后，将激活的闭合线圈矫治器放置在固定切牙和第二磨牙之间。使用三种类型的制造的NiTi闭合螺旋弹簧来产生10- 40 gf的一定范围的力。我们首先通过将NiTi螺旋弹簧放置在该位置4天至14天的不同时间段来评估该装置的可保持性和耐久性。结果表明，大多数的镍钛螺旋弹簧在整个观察期间保持激活的位置，支持了该装置的实用性。结合微焦点X线断层扫描（μCT）和三维重建技术对动物标本的检查证实，第二和第三磨牙执行近中漂移，伴随着切缘-上颌前骨缝处的力诱导变形。这是相关的，牙槽骨建模在间隔内区域的牙齿位移过程中取得了显着进展，而身体牙齿漂移并没有伴随着任何显着的牙周膜或强直的压缩。我们还开发了实验模型，使用Alzet渗透泵系统输注双膦酸盐在牙齿移动。组织学检查显示，在其全身递送期间，药物依赖性骨细胞行为的局部变化。本正畸牙齿移动模型将用于在幅度/时间特性下牙齿位移的动力学的广泛研究，例如，连续与间歇施力。

The present study aimed to develop a new orthodontic apparatus integrating a removable super-elastic nickel-titanium (NiTi) alloy closed coil springs. Male SD rats (5 weeks old) were used. Maxillary incisors were pinned and utilized as anchorage for a closed-coil appliance. At the same time, upper first molars were extracted. After 5 days interval for wound healing, the activated closed-coil appliance was placed between the fixed incisor and the second molar. Three types of fabricated NiTi closed coil springs were used to generate certain ranges of force 10-40gf. We first assessed the retainability and durability of the apparatus by placing NiTi coil springs at the position for various periods ranging from 4 days to 14 days. The results supported the practical usefulness of the apparatus by showing that most of the NiTi coil springs under investigation remained activated at position throughout the observation periods. Examination of animal specimens in conjunction with microfocus x-ray tomography (μCT) and 3D-reconstruction technology validated that the second and third molars executed mesial drifts, accompanying the force-induced deformation at the incisal-premaxillary bony suture. It is pertinent that alveolar bone modeling in the intraseptal region progressed markedly during tooth displacement, whereas the bodily tooth drift did not accompany any marked compression of periodontal ligament or ankylosis. We also developed experimental models using an Alzet osmotic pump for systemic-infusion of bisphosphonate during tooth movement. Histologic examination revealed the local variation in agent-dependent osteoclastic cell behavior during its systemic delivery period. The present orthodontic tooth movement model will be useful in a wide range of investigation of the kinetics of tooth displacement under magnitude/temporal characteristics, e.g., continuous versus intermittent force application.