BACKGROUND:Alveolar bone remodeling and sustained absorption due to tooth extraction seriously affect the implanting conditions and morphology of hard and soft tissue in implant zone. OBJECTIVE:To evaluate the effect of nano-hydroxyapatite/polycaprolactone electrospinning scaffolds to improve the osteogenic effect of bone defects around immediate implants. METHODS:Tissue-engineered bone was prepared by combining canine bone marrow mesenchymal stem cels with nano-hydroxyapatite/polycaprolactone electrospinning scaffold. Bilateral mandibular second premolars from six dogs were extracted mandibular second premolar, and an immediate implant was placed in the mesial fossa of the mandibular second premolar. Three-wal bone defects was made buccaly using titanium nails, then tissue-engineered bone and Bio-Oss bone powders were implanted bilateraly covered by colagen membranes (Bio-Gide). Imageology examination was performed to measure bone gray levels immediately, 4, 8, 12 weeks after surgery. After 12 weeks, the mandible was removed completely, toluidine blue staining was used for observation of microstructure, new bone formation, bone morphology and implant osseointegration. RESULTS AND CONCLUSION: Between the two groups, there was no difference in bone mineral density at each time point after surgery, indicating that the effects of the two materials to promote bone regeneration process are basicaly the same. After implantation, the dense lamelar bone formed in the bone defect region of tissue-engineered bone group, mature bone cels, Haversian canal, and implant osseointegration were visible. While, in the Bio-Oss group, the lamelar bone was dense, a smal amount of Bio-Oss particles distributed within new bone tissues, fewer bone cels were found, a part of Haversian canal was shown to have blood capilaries, and new bone was in close conjunction with the implant. These findings indicate that the nano-hydroxyapatite/polycaprolactone electrospinning scaffold combined with bone marrow mesenchymal stem cels and Bio-Gide colagen membrane can promote the regeneration of alveolar bone around the implant.%背景：牙齿缺失导致牙槽嵴骨质的改建和持续吸收，严重影响种植体植入的条件和种植区软硬组织的美观。目的：评价纳米羟基磷灰石/聚己内酯电纺支架促进即刻种植体周围骨缺损的成骨效果。方法：制作犬骨髓间充质干细胞复合纳米羟基磷灰石/聚己内酯电纺支架的组织工程化骨。拔除6只实验犬双侧下颌第二前磨牙，在其近中根牙槽窝处制备种植床，即刻植入种植体，在钛钉颊侧制作三壁骨缺损，两侧骨缺损处分别植入组织工程化骨与Bio-Oss小牛无机骨粉，并在材料表面覆盖Bio-Gide胶原膜。术后即刻、4周、8周、12周X射线测量种植体周围骨灰度值；12周后完整取出下颌骨，甲苯胺蓝染色观察骨缺损区的微观结构，新生骨量、形态结构及种植体-骨结合情况。结果与结论：两组间术后各时间点骨密度变化无明显差异，表明两组材料在促进骨再生过程中的成骨效果基本一致。组织工程化骨组骨缺损区内形成致密板状骨，可见成熟骨细胞，哈弗氏管，新生骨-种植体结合较紧密；Bio-Oss小牛无机骨粉组板层骨致密，新骨中有少量Bio-Oss颗粒分布，成骨细胞较组织工程化骨组少，部分哈弗管结构内可见到毛细血管，新骨与植入材料之间形成桥形连接，与种植体结合紧密。表明纳米羟基磷灰石/聚己内酯支架复合骨髓间充质干细胞、Bio-Gide胶原膜可促进种植体周围牙槽骨再生。
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