Papers by Author: L.Y. Sun

Abstract: The study is aimed at to explore the construction of bone graft with calcium phosphate ceramics implanted in subcutaneous fat, and provide applying technique for the in vivo bone tissue engineering. Forty-eight calcium phosphate ceramics (Ca-P ceramics) columns with Φ 5×8 mm were prepared, and eight dogs were used in this experiment. Six samples were implanted in each dog. Three in dorsal muscles while the others in subcutaneous fat. The specimens were harvested at 4, 6, 12 and 24 weeks post operation, for gross observation, SPECT and histological studies. The osseous or osteoid tissue formation at different times in the two non-osseous sites was compared and the new bone grafts in subcutaneous fat and intramuscular implantations were evaluated. The results demonstrated that the bone graft could be constructed not only in muscle but also in subcutaneous fat. Compared to that in muscle, constructing bone graft in subcutaneous fat could have brighter prospect to clinical application.

Abstract: The purpose of this study is to explore the osteoinductivity of the composite materials (calcium phosphate ceramics/PLA or collagen composites) with similar physical character of osteoinductive calcium phosphate ceramics and the influence of the chemical composition of the composite materials on osteoinductivity, and also to provide an experimental evidence for optimizing the design of the composite materials. Two kinds of composite materials were prepared. One (BCP/PLA) is fabricated with different ratio of BCP (biphasic calcium phosphate) ceramics powder and PDLLA powder through the particulateleaching technique. The other (BCP/collagen) is that BCP ceramics sintered at 1250oC and modified with collagen. The porous materials cylinders with Φ 5×8 mm were prepared. SEM was used to observe the microstructure and physical morphology of the composite materials. The two groups of composite materials cylinders were implanted in the dorsal muscles of four dogs. Six samples of each group were implanted in each dog respectively. The specimens were harvested at 2, 4, 12 and 24 weeks post operation, and thin decalcified sections were prepared for light microscopy (LM) analysis to evaluate their osteoinductivity and compare the capability of osteoinduction. The fibro-tissue and bone-like tissue were observed in the two composites, but no obvious bone formation was found in the tested periods. The results indicated that the composite materials could modify the mechanical property of ceramics. However, if the composite materials were biodegraded soon, new bone could not form into the scaffold, and the calcium phosphate should be the major component of osteoinductive materials.

Abstract: The aim of this study is to evaluate treatment effects of novel GBR membranes (PDLLA membranes) applied to bony defects around dental implants on new bone regeneration alone or in combination with bioceramic bone graft (BIO-OSS®) on the mongrel dog model in comparison with collagen membrane (BIO-GIDE®) and therefore to assess the clinical values of the novel GBR membranes and bioceramic bone graft material in dental implantology. 6 implants were placed in bilateral mandibular of each mongrel dog after preparation of mid- crestal defects. The defects on one side were covered with PDLLA membranes alone or with bone graft, while the contra-lateral sides received collagen membranes alone or with bone graft. These animals were sacrificed at 2, 4, 8,12 weeks post the GBR-operation. And gross sample examination, standardized radiographs, 99mTc-MDP SPECT and histomorphometric analysis were taken. All examinations showed similar amounts of newly formed bone beneath both types of barriers. The PDLLA or collagen membrane with bone graft groups showed better results than the membrane used alone groups. The results indicated that PDLLA membranes especially with bioceramic bone graft presented an improved response in dealing with bony defects around implants.

Abstract: The purpose of this study was to explore the feasibility of repairing massive bone defect with in vivo tissue engineering(TE) bone, and to provide experimental evidence for the application of in vivo TE bone into clinic in the future. Six calcium phosphate ceramics (Ca-P ceramics) columns were prepared, and then immersed in dynamic revised simulated body fluid (RSBF). 72 hours later, the bone-like apatite was formed on the surface and pore walls of ceramics. Three dogs were used in this study. Two ceramic columns were implanted bilaterally in the femoral muscles of each dog to construct living bone graft of in vivo TE bone. 6 weeks after implantation, they were transplanted to the box-like bone defects sites created in bilateral mandible of the same animals. The dogs were sacrificed at 8, 12 week after operation respectively. Samples were harvested for gross observation, X-ray examination, tetracycline fluorescence labeling, SPECT and histological observation. These results demonstrated that as a living bone graft, in vivo TE bone participated in the bone metabolism of host, and integrated with the host bone. It is feasible to reconstruct box-like bone defect of mandible with the in vivo TE bone.