Multiscale biomechanical responses of adapted bone-periodontal ligament-tooth fibrous joints.
Multiscale biomechanical responses of adapted bone-periodontal ligament-tooth fibrous joints.
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DOI：
10.1016/j.bone.2015.07.004
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发表时间：
2015-12
期刊：
影响因子：
4.1
通讯作者：
Ho SP
中科院分区：
文献类型：
--
作者：
Jang AT;Merkle AP;Fahey KP;Gansky SA;Ho SP
功能负荷减少会导致器官适应。在这项研究中，使用整体方法绘制了骨-韧带-牙齿纤维关节对减少功能负荷的时间适应。进行了系统研究，以评估定期从给予粉末食物 6 个月的大鼠（N = 60，8、12、16、20 和 24 周）中采集的标本的器官水平和组织水平适应性。通过比较关节刚度的变化与牙齿和牙槽骨槽之间功能空间的变化来评估骨-牙周韧带（PDL）-牙齿纤维关节的适应性。组织的适应包括绘制 PDL 和骨结构的变化，如通过胶原蛋白双折射、骨硬度和体积分数观察到的，与喂食硬颗粒作为常规饮食的大鼠（硬饮食，HD）相比，喂食软食物（软饮食，SD）的大鼠中观察到的 PDL 和骨结构的变化。对收获的纤维关节进行的原位生物力学测试显示，第 8 周和第 12 周时，SD 组的刚度增加 (SD:239-605 N/mm) (p<0.05)。早期发育阶段关节刚度增加是由于功能空间减少（8周时功能空间变化为-33微米，12周时功能空间变化为-30微米）以及组织质量的变化（如双折射、结构和硬度所强调的）。这些物理变化在功能良好的关节（即 12 周龄以上的啮齿动物）中没有观察到。骨生长（24周骨体积分数：Δ-0.06）和骨硬度（8周：Δ−0.04 GPa，16周：Δ−0.07 GPa，24周：Δ−0.06 GPa）的变化凸显了老年组的显着适应。 SD 组的关节对机械载荷的响应率 (N/s) 下降。研究结果表明，关节适应取决于年龄。最初的与形式相关的适应（观察到的功能空间的变化）可以挑战组织的应变适应性性质，以满足随着年龄的增长而进入成年的功能需求。骨-PDL牙齿复合体中的功能空间与组织的应变适应性性质之间的耦合效应对于适应功能需求是必要的，并且尽管存在关节功能障碍，但它在时间上是敏感的。从应用科学的角度来看，我们建议将适应记录为组织和关节的功能历史。
Reduced functional loads cause adaptations in organs. In this study, temporal adaptations of bone-ligament-tooth fibrous joints to reduced functional loads were mapped using a holistic approach. Systematic studies were performed to evaluate organ-level and tissue-level adaptations in specimens harvested periodically from rats given powder food for 6 months (N = 60 over 8,12,16,20, and 24 weeks). Bone-periodontal ligament (PDL)-tooth fibrous joint adaptation was evaluated by comparing changes in joint stiffness with changes in functional space between the tooth and alveolar bony socket. Adaptations in tissues included mapping changes in the PDL and bone architecture as observed from collagen birefringence, bone hardness and volume fraction in rats fed soft foods (soft diet, SD) compared to those fed hard pellets as a routine diet (hard diet, HD). In situ biomechanical testing on harvested fibrous joints revealed increased stiffness in SD groups (SD:239-605 N/mm) (p<0.05) at 8 and 12 weeks. Increased joint stiffness in early development phase was due to decreased functional space (at 8wks change in functional space was −33 µm, at 12wks change in functional space was −30 µm) and shifts in tissue quality as highlighted by birefringence, architecture and hardness. These physical changes were not observed in joints that were well into function, that is, in rodents older than 12 weeks of age. Significant adaptations in older groups were highlighted by shifts in bone growth (bone volume fraction 24wks: Δ-0.06) and bone hardness (8wks: Δ−0.04 GPa, 16 wks: Δ−0.07 GPa, 24wks: Δ−0.06 GPa). The response rate (N/s) of joints to mechanical loads decreased in SD groups. Results from the study showed that joint adaptation depended on age. The initial form-related adaptation (observed change in functional space) can challenge strain-adaptive nature of tissues to meet functional demands with increasing age into adulthood. The coupled effect between functional space in the bone-PDLtooth complex and strain-adaptive nature of tissues is necessary to accommodate functional demands, and is temporally sensitive despite joint malfunction. From an applied science perspective, we propose that adaptations are registered as functional history in tissues and joints.