[Establishment and experimental study of alveolar preservation before dental implantation in Beagle dogs].

PURPOSE: To establish the model of alveolar ridge preservation after tooth extraction for dental implant replacement, and to observe the effect of tissue engineered bone on osseointegration. METHODS: Isolated BMSCs were expanded and osteogenically induced in vitro. The tissue engineering complex was constructed with BMSCs/A-PCPC in vitro. Six extraction sockets, with three on each side, were created in the mandibles of four Beagle dogs by extracting the second, third and fourth premolars. BMSCs/A-PCPC were placed on one side of the extraction sockets, while autogenous bone, A-PCPC and nothing were placed on the other side as control. X-ray and CT scans were conducted 1day, 4 and 12 weeks after operation to detect the change of the alveolar ridge. The bone of sockets were harvested at 8-week post-implantation and subject to histological for evaluating. SPSS17.0 software package was used for data analysis. RESULTS: Radiographs demonstrated higher radiodensity in group of complex than in simple materials group, autogenous bone group after 4 weeks. Hard tissue biopsy at 12-week showed that bone activity of BMSCs/A-PCPC complex was better than the other groups. Spiral CT analysis showed that alveolar ridge of each group experienced a certain degree of absorption. At 12-week, the alveolar ridge height reduction values in A-PCPC group was smaller than in A-PCPC group, autogenous bone group and blank group (P<0.05). CONCLUSION: The BMSCs/A-PCPC complex is favorable for preservation of alveolar ridge.

[Experimental study of subcutaneous osteogenesis by bone marrow stromal cells with A-PCPC in Beagle dogs].

PURPOSE: To study the osteogenic capability of the construct combined dog's bone stromal cells with active porous calcium phosphate cement (A-PCPC) in nude mice in vivo. METHODS: Isolated bone marrow stromal cells (BMSCs) were expanded and osteogenically induced in vitro. Their osteogenic phenotype was evaluated by cytochemistry. The tissue engineering complex was constructed with BMSCs/A-PCPC in vitro. After SEM scanning, the complex of BMSCs/A-PCPC was implanted into the subcutaneous tissue of the nude mice as experimental group, and A-PCPC as control group. The engineered bone was harvested 2,4,8weeks post-implantation and processed for HE staining, then evaluated by histology and histomorphometry. RESULTS: Cytochemistry showed alkaline phosphate activity, Von Kossa staining proved the formation of mineralization nodules. Scanning electron microscopy showed the cells adhered to the inner surface of the A-PCPC. HE staining showed a small group of woven bone formation 2 weeks later in the experimental group, while the formation of bone less in the control group. Woven bone turned into trabecular bone gradually at 4 weeks in the experimental group, while the control group showed a large number of bone-like tissue. Histomorphometry showed more mature bone in the experimental group than the control group at 8 weeks. CONCLUSIONS: The A-PCPC/BMSCs composites show good osteogenetic activity and could promote mineralization of the immature bone. It can be used as the bone tissue engineering scaffolds. Supported by Innovation Fund for Science and Technology Development of Pudong New District(Grant No. PKJ2009-Y19).