Even though conventionally prepared octacalcium phosphate and collagen composite (OCP/Col) has exhibited excellent bone regeneration and has recently been commercialized for treating bone defects, reproducible appositional bone formation with OCP/Col has never been achieved. The present study investigated whether appositional bone formation could be achieved by altering the density of OCP/Col and applying liquid nitrogen during the preparation of OCP/Col. The prepared OCP/Col disks had eight variations and were divided into categories according to four different type of densities (1.0, 1.3, 1.7, and 2.0) of OCP/Col and two different pre‐freezing conditions of gas phase (G group: −80°C) and liquid phase (L group: −196°C). These disks were implanted into subperiosteal pockets in rodent calvaria, five samples per each eight variations. Radiomorphometric analysis was conducted at 4 and 12 weeks after implantation, and histological analysis was conducted at 12 weeks after implantation. OCP/Col samples in the L group tended to retain their height and shape and had enhanced appositional bone formation, whereas OCP/Col samples in the G group tended to lose their height and shape and had limited appositional bone formation. The appositional bone formation increased along with growing density of OCP/Col, and L2.0 demonstrated higher appositional bone formation than other samples. These results suggest that the pre‐freezing conditions and densities of OCP/Col affect the appositional bone formation.

中文翻译：

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磷酸八钙和胶原复合物的预冷冻条件对可重复的同位骨形成的影响。

尽管常规制备的磷酸八钙和胶原复合物 (OCP/Col) 已表现出优异的骨再生能力，并且最近已商业化用于治疗骨缺损，但从未实现过可再生的 OCP/Col 同位骨形成。本研究调查了是否可以通过改变 OCP/Col 的密度和在制备 OCP/Col 过程中应用液氮来实现同位骨形成。制备的 OCP/Col 盘有八种变化，并根据 OCP/Col 的四种不同类型的密度（1.0、1.3、1.7 和 2.0）和两种不同的气相预冷冻条件（G 组：- 80°C）和液相（L组：-196°C）。这些圆盘被植入啮齿动物颅骨的骨膜下袋中，每八个变异五个样本。在植入后 4 周和 12 周进行放射形态学分析，在植入后 12 周进行组织学分析。L 组的 OCP/Col 样品倾向于保持其高度和形状，并具有增强的同位骨形成，而 G 组中的 OCP/Col 样品倾向于失去其高度和形状，并且具有有限的同位骨形成。同位骨形成随着OCP/Col密度的增加而增加，并且L2.0表现出比其他样品更高的同位骨形成。这些结果表明，OCP/Col 的预冷冻条件和密度会影响同位骨的形成。L 组的 OCP/Col 样品倾向于保持其高度和形状，并具有增强的同位骨形成，而 G 组中的 OCP/Col 样品倾向于失去其高度和形状，并且具有有限的同位骨形成。同位骨形成随着OCP/Col密度的增加而增加，并且L2.0表现出比其他样品更高的同位骨形成。这些结果表明，OCP/Col 的预冷冻条件和密度会影响同位骨的形成。L 组的 OCP/Col 样品倾向于保持其高度和形状，并具有增强的同位骨形成，而 G 组中的 OCP/Col 样品倾向于失去其高度和形状，并且具有有限的同位骨形成。同位骨形成随着OCP/Col密度的增加而增加，L2.0表现出比其他样品更高的同位骨形成。这些结果表明，OCP/Col 的预冷冻条件和密度会影响同位骨的形成。