拔牙后牙槽窝软硬组织的充分保留以及拔牙窝内新生骨的质量对种植修复后良好功能和美观的重建非常重要。位点保存的理想支架既要维持软硬组织形态，又要有效促进牙槽窝内的骨再生。本项目旨在以复合超顺磁性氧化铁（SPIO）纳米颗粒的根形支架用于位点保存。SPIO既可促进成骨，又可使支架在MRI下显影。首先将表面处理后的SPIO均匀分散在生物可降解聚合物中进行低温三维打印得到个体化磁性根形支架。研究支架孔隙和SPIO添加量对支架性能的影响。对支架进行形貌表征、机械性能和降解性能等检测，并进行细胞实验和动物实验，检测支架的细胞毒性，对细胞黏附、增殖和分化的影响，对细胞成骨和成血管相关蛋白mRNA表达的影响；将支架植入动物拔牙创，通过micro CT和组织学手段，评价新生骨的质量和位点保存效果，并利用MRI检测支架在体内的降解。研究结果有望为位点保存支架的制备提供新思路，也为无创性监测支架降解提供一种新方法。

The functional and aesthetic reconstruction after dental implantation depends on the preservation of alveolar ridge dimensions and bone regeneration in the defect. Ideal scaffolds for alveolar ridge preservation (ARP) should retain the dimensions, while enhance the bone regeneration at the same time. This project focuses on developing customized tooth root shape scaffolds by three-dimensional (3D) printing for ARP. Superparamagnetic iron oxide (SPIO) nanoparticles were added to the scaffolds to enhance the osteogenesis. And the composite scaffolds containing SPIO can be imaged by magnetic resonance imaging (MRI). To fabricate the scaffolds, coated SPIO was dispersed uniformly in the solution of biodegradable polymers. The scaffolds are 3D printed by the blends of the two. Its architecture follows digital model whose outer shape is exactly like the tooth root to be extracted, with specially designed inner structure. The effects of pore size and SPIO content to the as fabricated scaffolds were explored. Characterization including scanning electron microscope (SEM) observation, mechanical test, and in vitro degradation properties are investigated. Cell experiments are adopted to evaluate the effects on cytotoxicity, cell adhesion, proliferation and differentiation. And the mRNA levels of proteins related to osteogenesis and angiogenesis are measured. In vivo tests on animal models are characterized by micro CT and histomorphology to evaluate the quality and quantity of new bone formation. Also, dimensional preservation of alveolar ridge is evaluated. Furthermore, MRI is used to track the scaffolds degradation in vivo. The results would offer new sights in designing biomaterials for ARP, and provide new methods to characterize the degradation of scaffolds in vivo.