MECHANICAL ENVIRONMENT IN MANDIBULAR DISTRACTION

描述（由申请人提供）：牵张成骨（DO）是一种 以通过在愈合的截骨术上施加拉伸载荷来延长骨。虽 在下颌骨上使用了仅仅十年，这项技术已经 取代了传统的正颌手术，尤其是对儿童。 尽管DO使用机制来实现其目标， 机械环境未知。咀嚼等功能必须放在 牵引部位上的间歇性压缩或剪切应变。这些 应变，以及由牵引器具产生的拉伸应变， 对于成骨过程具有重要的生物学意义，但 从未被测量过。使用已建立的下颌骨DO模型，猪， 我们提出（目标1）阐明牵张的力学环境 在截骨术时、牵引期间和通过 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 研究矫治器大小、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 下颌骨DO治疗生长期儿童的一个主要问题是， 手术通过超负荷对下颌髁突的生长产生不利影响 颞下颌关节因此，我们建议（目标2），以确定的影响，DO对颞下颌关节 通过对髁突进行应变计测量， 颈部和相关的调查结果，以增长，作为衡量的矿物沉积 速率和骨膜变形。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， 通过影响哪些细胞被招募， 它们的繁殖以及它们最终的命运因此，我们建议（目标3） 将DO的机械历史与修复过程联系起来， 骨膜、肌肉结缔组织和血管系统的作用 重生的人这将通过脉冲标记复制的 牵张过程中的细胞，结合蛋白质表达的研究 在献祭的时候。这项提案最重要的贡献是 将是在自然条件下DO地点的菌株表征， 以及应用这些信息来理解DO如何在 细胞水平以及它如何影响下颌骨生长。

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.