DEVELOPMENT OF ORTHODONTIC BONE RESPONSE MODELS

骨的形成和吸收与机械负荷有关， 个世纪目前的问题包括：绝经后骨质疏松症， 骨骼发育，矫形和牙科植入物的预后， 医源性正畸牙根吸收和长期失重。 对非骨细胞的机械影响现在也在密切关注。 审查一个共同的未知数是机械传导机制， 迫使细胞做出反应。一种研究方法使用压力分析 工具（有限元法，FEM）对加载骨进行建模。的部件 （应力、应变能……）计算的力学环境 然后，骨内的骨密度与观察到的骨密度的损失和/或增加相关。 骨头这种攻击被用于正畸的二维分析 大鼠磨牙牙槽骨反应。拟议项目旨在 扩展、完善并进一步验证该模型， 初始PDL细胞对抗肿瘤药的反应。出发点和优势 独特的正畸模型相对于矫形方法是： (1)实验力，施加与正畸精度，更多 可控和创伤比施加到长骨的力量，（2） 相同的系统（牙槽骨）可以暴露于非常不同的 载荷条件（齿倾翻、侵入、挤压、横向 平移或轴向旋转），以及（3）研究的重点包括 牙周膜，骨形成的软组织储库 前体细胞，而不仅仅是硬组织本身。这种方法， 结合组织学和工程学分析， 理念的我们确定骨形成可能与 PDL软组织内的机械环境，而 再吸收可能与骨本身内的环境有关。 解剖复杂性（五根）造成的障碍， 小尺寸的大鼠磨牙可以克服所提出的发展 新的（正畸和工程）模型的基础上更大的狗的牙齿。 因此，这个跨学科项目的目标是：（1）建立 一个更大和更简单的（相对于大鼠磨牙）狗牙齿模型， 正畸移动，（2）计算相应的力学 环境与三维有限元应力分析，和（3） 统计学上研究组分之间的关系（张力， 剪切等）机械环境和新的实验 结果要做到这一点，狗下颌第二前磨牙将倾斜 远端24小时。弹性体附着于颊侧粘接托槽 第二和第三前磨牙的舌面将提供 力PDL细胞合成DNA的分布， 将用BrdU标记物测定代谢物。我们预计 这些标记细胞的分布模式与 有限元计算某些机械部件的分布。这一点 当然，这将是关于机械刺激的有价值的信息， 可能与细胞反应有关。未来的研究需要关注 在其他（轴向旋转、平移、侵入、挤出）齿 动作这之后应该对长骨进行类似的研究 行为，包括考虑机械环境 在骨膜里

Bone formation and resorption have been linked to mechanical loads or centuries. Current concerns include: post-menopausal osteoporosis, skeletal development, prognosis for orthopedic and dental implants, iatrogenic orthodontic root resorption, and long-term weightlessness. Mechanical influences on non-bone cells are now also under close scrutiny. A common unknown is the transduction mechanism of mechanical forces into cell responses. One study approach uses a stress analysis tool (Finite Element Method, FEM) to model a loaded bone. A component (stress, strain energy ...) of the calculated mechanical environment within the bone is then associated with the observed loss and/or gain of bone. This attack was used in a two-dimensional analysis of orthodontic bone response in rat molar alveolus. The proposed project is intended to expand, refine, and further validate that model by focusing on the initial PDL cell response to orthodontics. The departures and advantages of the unique orthodontic model relative to orthopedic approaches are: (1) the experimental forces, applied with orthodontic precision, are more controllable and a traumatic than forces applied to long-bones, (2) the same system (tooth-alveolar bone) can he exposed to very different loading conditions (tooth tipping, intrusion, extrusion, lateral translation, or axial rotation), and (3) the focus of the study includes the periodontal ligament, the soft tissue reservoir of bone forming precursor cells, not only the hard tissues themselves. This approach, combining histologic and engineering analyses, has yielded novel concepts. We determined that bone formation may be linked to the mechanical environment within the soft tissues of the PDL, while resorption may be associated with the environment within the bone itself. The obstacles attributable to the anatomic complexity (five roots) and small size of the rat molar can be overcome with the proposed development of new (orthodontic and engineering) models based on larger dog teeth. Thus, the aims of this interdisciplinary project are to: (1) establish a larger and simpler (relative to rat molar) dog tooth model for orthodontic movement, (2) calculate the corresponding mechanical environment with three-dimensional FEM stress analysis, and (3) statistically investigate the relationship between components (tension, shear, etc.) of the mechanical environment and the new experimental results. To do so, dog mandibular second premolars will be tipped distally for 24 hours. Elastics attached to bonded brackets on the buccal and lingual surfaces of the second and third premolars will provide the force. The distribution of PDL cells synthesizing DNA as a result of orthodontics will be determined with BrdU labels. We expect the distribution pattern of these labelled cells to be correlated with the FEM calculated distributions of certain mechanical components. This, of course, would be valuable information about the mechanical stimulus that may be associated with cell response. Future research would need to look at other (axial rotation, translation, intrusion, extrusion) tooth movements. That should be followed by similar studies of long-bone behavior, including the consideration of the mechanical environment within the periosteum.