Ghayor Chafik, Bhattacharya Indranil, Guerrero Julien, Özcan Mutlu, Weber Franz E
Center of Dental Medicine, Oral Biotechnology & Bioengineering, University of Zurich, Plattenstrasse 11, 8032 Zurich, Switzerland.
Center of Dental Medicine, Division of Dental Biomaterials, Clinic for Reconstructive Dentistry, University of Zurich, Plattenstrasse 11, 8032 Zurich, Switzerland.
Materials (Basel). 2022 Feb 15;15(4):1433. doi: 10.3390/ma15041433.
Additive manufacturing enables the realization of the macro- and microarchitecture of bone substitutes. The macroarchitecture is determined by the bone defect and its shape makes the implant patient specific. The preset distribution of the 3D-printed material in the macroarchitecture defines the microarchitecture. At the lower scale, the nanoarchitecture of 3D-printed scaffolds is dependent on the post-processing methodology such as the sintering temperature. However, the role of microarchitecture and nanoarchitecture of scaffolds for osteoconduction is still elusive. To address these aspects in more detail, we produced lithography-based osteoconductive scaffolds from hydroxyapatite (HA) of identical macro- and microarchitecture and varied their nanoarchitecture, such as microporosity, by increasing the maximum sintering temperatures from 1100 to 1400 °C. The different scaffold types were characterized for microporosity, compression strength, and nanoarchitecture. The in vivo results, based on a rabbit calvarial defect model showed that bony ingrowth, as a measure of osteoconduction, was independent from scaffold's microporosity. The same applies to in vitro osteoclastic resorbability, since on all tested scaffold types, osteoclasts formed on their surfaces and resorption pits upon exposure to mature osteoclasts were visible. Thus, for wide-open porous HA-based scaffolds, a low degree of microporosity and high mechanical strength yield optimal osteoconduction and creeping substitution. Based on our study, non-unions, the major complication during demanding bone regeneration procedures, could be prevented.
增材制造能够实现骨替代物的宏观和微观结构。宏观结构由骨缺损决定，其形状使植入物具有患者特异性。3D打印材料在宏观结构中的预设分布定义了微观结构。在较小尺度上，3D打印支架的纳米结构取决于后处理方法，如烧结温度。然而，支架的微观结构和纳米结构对骨传导的作用仍不明确。为了更详细地探讨这些方面，我们用相同宏观和微观结构的羟基磷灰石（HA）制作了基于光刻的骨传导支架，并通过将最高烧结温度从1100℃提高到1400℃来改变其纳米结构，如微孔率。对不同类型的支架进行了微孔率、抗压强度和纳米结构的表征。基于兔颅骨缺损模型的体内结果表明，作为骨传导指标的骨向内生长与支架的微孔率无关。体外破骨细胞可吸收性也是如此，因为在所有测试的支架类型上，其表面都形成了破骨细胞，并且在暴露于成熟破骨细胞后可见吸收凹坑。因此，对于开放多孔的HA基支架，低程度的微孔率和高机械强度可产生最佳的骨传导和渐进性替代。基于我们的研究，可以预防骨不连，这是复杂骨再生过程中的主要并发症。
