Division of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Japan.
Division of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Japan.
J Mech Behav Biomed Mater. 2021 Aug;120:104571. doi: 10.1016/j.jmbbm.2021.104571. Epub 2021 May 21.
The loss of bone quantity and quality in postmenopausal female patients can be a problem for dental treatment. A sufficient intake of nutrients such as calcium, magnesium, and vitamins D and K is likely correlated with the mechanical properties of bone. In particular, vitamin K2, also called menaquinone (MK), inhibits bone loss in postmenopausal women. Here we demonstrate the microstructural and mechanical properties of bone recovery in ovariectomized (OVX) rats during MK-7 administration. Bilateral ovariectomy and a sham operation were performed on 14-week-old female SPF Wistar rats. MK-4 and -7 were orally administered at 30 mg/kg daily for 12 weeks. The femur was used for the 3-point bending test and microstructural analysis of the cancellous bone by micro-CT, and the mandibular cortical bone for the evaluation of mechanical properties on a nanoscale. Micro-computed tomography revealed irregular trabecular architecture, hollow marrow cavities, and sparse trabecular bone in the femurs of the OVX group. Trabecular bone structure analysis showed that the MK-7 group had greater bone volume per tissue volume (BV/TV) and a higher trabecular number than the OVX group. The bulk-scale 3-point bending test did not allow the mechanical properties between OVX and OVX/MK7 groups to be discerned, yet at the smallest level, the elastic-plastic transition point of the nanoindentation stress-strain curve of the mandibular cortical bone was higher in the MK-7 group than in the OVX group. These findings suggest that MK-7 enables bone microstructural and mechanical recovery in the OVX model.
绝经后女性患者的骨量和骨质量损失可能会给牙科治疗带来问题。充足的钙、镁、维生素 D 和 K 等营养素的摄入可能与骨的机械性能相关。特别是维生素 K2，也称为甲萘醌 (MK)，可抑制绝经后女性的骨丢失。在这里，我们展示了 MK-7 给药期间去卵巢（OVX）大鼠骨恢复的微观结构和机械性能。将 14 周龄 SPF Wistar 雌性大鼠进行双侧卵巢切除术和假手术。MK-4 和 -7 每天口服 30mg/kg，共 12 周。使用股骨进行三点弯曲试验和微 CT 对松质骨的微观结构分析，并使用纳米压痕技术对下颌皮质骨进行机械性能评估。微计算机断层扫描显示 OVX 组股骨的小梁结构不规则，骨髓腔中空，小梁骨稀疏。小梁骨结构分析表明，MK-7 组的组织体积骨体积比（BV/TV）和小梁数均高于 OVX 组。整体的三点弯曲试验无法区分 OVX 和 OVX/MK7 组之间的力学性能，但在最小的水平上，MK-7 组下颌皮质骨纳米压痕应力-应变曲线的弹塑性转变点高于 OVX 组。这些发现表明，MK-7 可使 OVX 模型的骨微观结构和机械性能得到恢复。
