MECHANICAL ENVIRONMENT IN MANDIBULAR DISTRACTION

描述(申请人提供)：牵张成骨(DO)是一种 通过在愈合的截骨术上施加拉伸载荷来拉长骨骼。虽然这样做了 仅在下颌骨上使用了十年，这项技术已经 取代更传统的正颌手术，特别是对儿童。 尽管DO使用机械来实现其目标，但实际 机械环境未知。咀嚼等功能必须放置在 牵张部位出现间歇性压缩或剪切应变。这些 应变，以及牵张装置产生的拉伸应变， 对成骨过程具有关键的生物学意义，但具有 从未被测量过。利用一个成熟的下颌骨DO模型，猪， 我们建议(目标1)澄清分心的机械环境。 截骨时、牵张期间和固定期间的位置，由 使用应变计、数字超声波直接测量应变 和差动可变磁阻传感器。这些研究将 调查矫治器的大小、稳定性和放置位置的影响 作为特定肌肉和咬合负荷的作用。此外，我们将解决 下颌DO治疗发育期儿童的一个主要问题是， 手术过载会对下颌骨的生长发育产生不利影响 TMJ。因此，我们建议(目标2)确定DO对TMJ的影响 应用应变片测量髁突的力学和生长 并将这些发现与生长有关，通过矿物质定位来衡量 骨膜变形率和骨膜变形率。DO的机械环境，特别是 牵张部位的稳定性，可能会影响愈合过程和 最终结果通过影响哪些细胞被招募，其速度 它们的扩散，以及它们的最终命运。因此，我们建议(目标3) 通过评估DO的机械历史与维修过程相关联 骨膜、肌肉结缔组织和血管系统的作用 为再生干杯。这将通过复制的脉冲标记来完成 牵张过程中的细胞，结合蛋白质表达的研究 在牺牲的时候。这项提议最重要的贡献是 将是在自然条件下DO部位的菌株的特征， 以及应用这些信息来理解DO如何在 细胞水平及其对下颌骨生长的影响。

DESCRIPTION (provided by applicant): Distraction osteogenesis (DO) is a means to elongate bone by placing tensile loads on a healing osteotomy. Although DO has been used on the mandible for only a decade, the technique is already supplanting more traditional orthognathic procedures, especially for children. Despite the fact that DO uses mechanics to accomplish its goals, the actual mechanical environment is unknown. Functions such as mastication must place intermittent compressive or shearing strains on the distraction site. These strains, as well as the tensile strains produced by the distraction appliance, are of critical biological significance for the osteogenic process, but have never been measured. Using a well-established model for mandibular DO, the pig, we propose (Aim 1) to clarify the mechanical environment of the distraction site at the time of osteotomy, during distraction, and during consolidation by making direct measurements of strain using strain gages, digital ultrasonics and differential variable reluctance transducers. These studies will investigate the influence of appliance size, stability, and placement as well as the action of specific muscles and occlusal loads. Further, we will address a major concern of treating growing children by mandibular DO, whether the procedure adversely affects growth at the mandibular condylar by overloading the TMJ. Thus, we propose (Aim 2) to ascertain the impact of DO on TMJ mechanics and growth by performing strain gage measurements on the condylar neck and relating the findings to growth, as measured by mineral apposition rate and periosteal deformation. The mechanical environment of DO, particularly the stability of the distraction site, may affect the course of healing and the final result by influencing which cells are recruited, the rapidity with which they proliferate, and their eventual fate. Therefore, we propose (Aim 3) to relate the mechanical history of DO to the repair process by assessing the contributions of the periosteum, muscle connective tissue, and vascular system to the regenerate. This will be accomplished by pulse labeling of replicating cells during distraction, combined with an investigation of protein expression at the time of sacrifice. The most important contributions of this proposal will be the characterization of strain at the DO site under natural conditions, and the application of that information to understanding of how DO works on a cellular level and how it affects mandibular growth.