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Objective To evaluate the clinical effects of anterior teeth repair of three different restorations made of Co-Cr alloy,Ag-Pd alloy and all-ceramic crowns.Methods 90 cases who needed the both maxillary and mandibular anterior teeth restarations were selected and treated respectively with Co-Cr alloy porcelain fused to metal crowns (PFM)(60 teeth),Ag-Pd alloy PFM (46 teeth)and IPS e.max Press Porcelain full crown (38 teeth).Gingival index was observed before restoration and in 6 and 12 months after restoration.Meanwhile,clinical indicators of two restorations were evaluated as cervical margin's coloration,margin fitness degree,color of restorations,fracture of restorations and contour of restorations,etc.Results The healthy condition of gingiva in groups of Ag-Pd alloy PFM and IPS e.max Press Porcelain full crown were superior to the group of Co-Cr alloy PFM (P＜0.05).There was no cervical margin's coloration in groug of all-ceramic PFM.The color and contour of this group was superior to the group of Co-Cr alloy PFM (P ＜0.05).The significant difference between group of Co Cr alloy and group of Ag-Pd alloy was cervical margin's coloration and marginal density of the restoration (P＜0.05).Conclusions The clinical effects of both groups of Ag-Pd alloy PFM and IPS e.max Press Porcelain full crown is superior to the group of Co-Cr alloy PFM.The IPS e.max Press Porcelain full crown group works best.
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BACKGROUND:Due to good function and aesthetic effect, implant dentures become prevalent in osteoporotic patients with missing teeth. However, whether osteoporosis is a contraindication of dentures as wel as effects of osteoporosis on the bone-implant integration have been not ful y understood. OBJECTIVE:To compare the levels of alkaline phosphatase, bone mineral density and implant stability in patients with osteoporosis and non-osteoporosis, and to explore whether the osteoporotic patients can achieve good prognosis. METHODS:Forty patients undergoing implant dentures in the Department of Prosthodontics, the First Affiliated Hospital of Xinjiang Medical University since February 2015 were enrol ed, and al otted to experimental (osteoporosis) and control (non-osteoporosis) groups (n=20 per group). RESULTS AND CONCLUSION:The levels of salivary alkaline phosphatase, bone mineral density and initial implant stability in the experiment and control groups both were lower than those before surgery. There were significant differences in the implant stability quotient at 1 and 3 months and immediately after implantation between groups. These results indicate that osteoporotic patients undergoing implant surgery can achieve a good prognosis that is similar with non-osteoporosis ones.
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Objective To study the expression of inflammatory factors in the saliva and the stability of implants after implant denture repair in pa-tients with dysplasia of the dentition defect ,and to analyze the prognosis of patients with lipid metabolic disorder. Methods The dentition defect patients with lipid metabolism disorder were selected as the experimental group. Patients with lipid defect were selected as the control group. Saliva was collected before implantation,1 month and 3 months after implantation. ELISA method was used to detect IL-6,IL-1βand TNF-α. Osstell ISQTM radio frequency analyzer was used to detect the stability of the implants and the periodontal status was detected by Florida probe. Re-sults There were no significant differences in the depth of implant probing(PD),bleeding index(BI)and ISQ between the two groups by radio frequency analyzer(all P>0.05). The levels of IL-6,IL-1βand TNF-αin the pre-implantation,1 month and 3 months after implantation were sig-nificantly higher than those in the control group(all P0.05). Conclusion The patients with dyslipidemia after implantation have good implant stability as those with normal blood lipid ,and the patients with dyslipidemia can also obtain good prognosis.
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BACKGROUND: Hydroxyapatite/β-tricalcium phosphate biphasic ceramic bone has good cel compatibility, but its mechanical properties are poor. OBJECTIVE: To construct chitosan/ or calcium alginate/biphasic ceramic bone scaffolds and to detect their mechanical properties and cytocompatibility. METHODS: Different concentrations of chitosan (2%, 4%, 7%, 10%) or calcium alginate (3%, 4%, 5%, 7%) were mixed with biphasic ceramic bone to prepare chitosan/biphasic ceramic bone scaffold and calcium alginate/biphasic ceramic bone scaffold. Their morphology and structure, coagulation time, anti-dissolution properties, shear force, compressive strength and cel compatibility were detected. RESULTS AND CONCLUSION: (1) Coagulation time: with the concentration increase, the initial and final setting time of these two kinds of composite scaffolds were prolonged to some extent. (2) Scanning electron microscopy: these two kinds of composite scaffolds showed porous microstructures with different pore sizes. (3) Anti-dissolution properties: the calcium alginate/biphasic ceramic bone scaffold (3%, 4%, 5%, 7%) and chitosan/biphasic ceramic bone scaffold (7%, 10%) had good anti-dissolution properties in the liquid. (4) Mechanical strength: with the concentration increase, the shear force and compressive strength of the calcium alginate/biphasic ceramic bone scaffold were reduced. (5) Cel compatibility: the cytotoxicity of chitosan/ or calcium alginate/biphasic ceramic bone scaffolds was graded as 0-1 or 2-3, respectively. These results show that the chitosan/biphasic ceramic bone scaffold has better mechanical properties and cel compatibility than the calcium alginate/biphasic ceramic bone scaffold.
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BACKGROUND: The conical telescopic crown denture has a better long-term effect on dentition defects of few remaining teeth than the traditional removable denture. However, there are few studies to analyze the application of these two kinds of repair methods using the finite element method. OBJECTIVE: To compare the stress distribution of the isolated abutment tooth repaired using the conical telescopic crown denture and traditional removable denture. METHODS: Two-dimensional images of the mandible and dentition in healthy adults were scanned by CT. Three-dimensional finite element models of conical telescopic crown denture and traditional removable denture were established in the mandible only with the bilateral canines. Under the same vertical and oblique loadings, the maximum equivalent stress of the abutment, periodontal membrane or edentulous alveolar ridge was compared between two repair methods. RESULTS AND CONCLUSION: Under the vertical and oblique loadings, the total stress of abutment and periodontal membrane in the traditional removable denture was higher than that in the conical telescopic crown denture and the stress in the corresponding ring was concentrated obviously; the total stress of edentulous alveolar ridge in the conical telescopic crown denture was slightly larger than that in the traditional removable denture, but the stress was wel -distributed and concentrated in a smal area. Under the oblique loading, the total stress of abutment, periodontal membrane and edentulous alveolar ridge was higher than that under the vertical loading in these two dentures, and the stress was concentrated in the periodontal membrane of lingual neck, but the total stress in the traditional removable denture was larger, with a wider concentration range. These findings indicate that the stress on the supporting tissue of conical telescopic crown denture is more evenly distributed within a smal er range than that of traditional removable denture, and the former is more fit for the health of abutment, periodontal tissues and edentulous alveolar ridge.
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BACKGROUND:With the promotion of 3D printing technology, 3D printing scaffolds for bone tissue engineering have become the new ideas for jaw bone repair. OBJECTIVE:To compare the physical and biological properties of sheep vertebral bone meal/polyvinyl alcohol (PVA) scaffold, nano-hydroxyapatite (nHA)/PVA scaffold, and sheep vertebral bone meal/PVA nonporous bone plate. METHODS:3D printing technology was used to print sheep vertebral bone meal/PVA scaffold, nHA/PVA scaffold, and sheep vertebral bone meal/PVA nonporous bone plate. Porosity, morphology, water absorption rate and mechanical properties of different scaffolds were detected. Three kinds of scaffolds were al used to culture bone marrow mesenchymal stem cel s, and cel proliferation ability was detected using cel counting kit-8 at 1, 4, 7 days of culture. RESULTS AND CONCLUSION:Under scanning electron microscope, the sheep vertebral bone meal/PVA scaffold and nHA/PVA scaffold exhibited regular and interconnected pores with good continuity and clear network structure;the sheep vertebral bone meal/PVA nonporous bone plate had no obvious pores;however, it had dense and evenly distributed micropores with different sizes on its surface. The porosity of nHA/PVA scaffold was lower than that of the sheep vertebral bone meal/PVA scaffold (P<0.05). The water absorption rate was highest for the nHA/PVA scaffold fol owed by the sheep vertebral bone meal/PVA scaffold and the sheep vertebral bone meal/PVA nonporous bone plate (P<0.05). In contrast, the scaffold toughness was highest for the sheep vertebral bone meal/PVA nonporous bone plate, fol owed by the sheep vertebral bone meal/PVA scaffold and nHA/PVA scaffold. In addition, the cel proliferation activity of cel s cultured on the sheep vertebral bone meal/PVA scaffold was significantly higher than that cultured on the other two kinds of scaffolds. Taken together, the 3D printing sheep vertebral bone/PVA scaffold has good physical and chemical performance.
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BACKGROUND:Currently, there are many studies on colapsed repair, but a systematic and horizontal comparison is not reported yet. OBJECTIVE: To compare the effect of conventional resin adhesive, resin adhesive+silane coupling agent and adjacent surface open part of the crown on colapsed repair through clinical trial and in vitro experiment. METHODS: (1) Clinical trial: 90 patients with porcelain colapse were randomized into three groups, and respectively treated with conventional resin adhesive, resin adhesive+silane coupling agent and adjacent surface open part of the crown. Success rate was measured and compared among three groups at 1 year after repair. (2) In vitro test: Twenty test specimens were equaly divided into two groups, and treated with conventional resin adhesive and resin adhesive+silane coupling agent, respectively. Then, shear strength was detected in the two groups. Twenty double-crown specimens were equaly divided into four groups. The first three groups were treated with sand blasting, silane coupling agent and their combination treatment, respectively; the rest group had no treatment (control group). After repair, the tensile strength of each specimen was detected.RESULTS AND CONCLUSION:The success rate of colapsed repair was 37% for conventional resin adhesive, 90% for resin adhesive+silane coupling agent and 100% for adjacent surface open part of the crown. The shear strength was (13.978±0.343) MPa for the conventional resin adhesive and (10.058±0.64) MPa for resin adhesive+silane coupling agent, and there was a significant difference between two methods (P < 0.01). The tensile strength was (0.68±0.04) kN in the control group, (1.00±0.02) kN in the sand blasting group, (1.31±0.08) kN in silane coupling agent group, and (1.09±0.04) kN in the combination group, and there was a significant differences between groups (P < 0.01). Experimental results show that the silane coupling agent+resin adhesive treatment and adjacent surface open part of the crown are superior to conventional resin adhesive.
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BACKGROUND:There are less reports on how to successfuly build the internal spatial configuration of tissue-engineered tooth scaffolds. OBJECTIVE:To find a way to establish a series of three-dimensional digital modes for tissue-engineered tooth scaffold, such as CAD spatial configuration and Standard Template Library (STL) files. METHODS:In order to get three-dimensional printing format of STL files, MICRO CT data of DICOM format were input into MIMICS and GEOMAGIC softwares, creating the outline of STL files. Then CATIA V5R17 software was used to create the three-dimensional digital mode of tissue-engineered tooth. Then, the overal model of the internal scaffold was obtained by arraying at the proper coordinates. Various overal scaffold configurations could be built rapidly by varying monomer configuration. The STL files of CAD model of three-dimensional printing tissue-engineered tooth were obtained by assembling the tooth outline mode and the internal scaffold. RESULTS AND CONCLUSION: The CAD model was constructed successfuly, and this model could be directly used for three-dimensional printing rapid prototyping system to produce tissue-engineered tooth scaffolds. These findings indicate that the three-dimensional digital mode based on reverse engineering and positive engineering can be established, which can be used to quickly build a variety of internal spatial configurations of scaffold materials required for tissue-engineered teeth.
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BACKGROUND:Porcelain jacket crowns have achieved good results in the repair of porcelain ceramic crown and bridge colapse. OBJECTIVE:To test the bond strength of single porcelain jacket crown, thus determining the feasibility of clinical application of repairing colapsed crown and fixed bridge by porcelain jacket crown, and meanwhile to discuss the influence between blastsanding and silane coupling agent treatment on the metal bonding strength in the repair of porcelain fracture. METHODS: The porcelain jacket crown was cast in the same shape from disk-shaped waxpatterns. Twenty specimens were chosen without blowholes and casting defects and they were al routinely burnished and cleaned in an ultrasonic bath and dried using an oil-free air stream stand-by. Then we randomly divided the specimens into four groups: specimens were treated with nothing (control), sandblast, silane coupling agent and sandblast+silane coupling agent, respectively. Each of the specimen was bonded with Poly-F Plus. AG-10TA universal testing machine was used to test the tensile strength. RESULTS AND CONCLUSION:The tensile bond strength of control, sandblast, silane coupling agent and sandblast+silane coupling agent groups respectively were (0.68 0.04), (1.00 0.02), (1.31 0.08), and (1.09 0.04) kN. There were significant differences between groups (P < 0.01). In the control group, the metal surface was smooth, showing some irregular smal superficial veins. In the sandblast group, the metal surface showed irregular scaly protrusions conducive penetrate adhesives. In the silane coupling group, the metal surface manifested a honeycomb structure in favor of chimeric adhesives. The sandblast+silane coupling agent group showed some metal projections ranging in size, on the rough metal surface, which was conducive to bond. Porcelain jacket crown applied to repair colapsed crown and fixed bridge is feasible. Sandblasting and silane coupling agent can improve bond strength of porcelain jacket crown. The bond strength of metal specimens treated with silane coupling agent is the best folowed by the sandblasting+silane coupling agent.
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METHODS:Lentiviral vectors carrying bFGF and BMP-2 were constructed to transfect sheep bone marrow mesenchymal stem cells. cells were divided into four groups:bFGF group, BMP-2 group, co-transfection group BACKGROUND:Basic fibroblast growth factor (bFGF) can promote the proliferation of bone marrow stromal cells, and bone morphogenetic protein-2 (BMP-2) has an important significance in the induction of new bone formation. OBJECTIVE:To analyze the effects of bFGF, BMP-2 and their co-transfection on the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells and to compare the relative expressions of col agen I, osteocalcin and osteopontin before and after celltransfection, thereby providing theoretical implications for seed cells in the construction of tissue-engineered bone. and control group. The RNA was extracted using real-time quantitative PCR to detect mRNA levels of col agen I, osteocalcin, and osteopontin. RESULTS AND CONCLUSION:Significant difference in non-specific osteogenic gene expressions was found among the four groups (P0.05). In vitro experiments showed that the relative expression of col agen I, osteocalcin and osteopontin were higher in the co-transfection group, indicating the cells from the co-transfection group have strongest osteogenic capacity that are suitable for seed cells for bone tissue engineering.
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BACKGROUND:Some studies have indicated that different genes in tooth germ tissue play a role at different time, contributing to tooth germ development. OBJECTIVE:To observe the expressions of dentin matrix protein 1, enamel protein, col agen I and homeobox gene 1 at different stage of in vitro culture of tooth germ cells. METHODS:RNA from tooth germ cells was extracted at days 1, 3, 6 of in vitro culture. After reverse transcription, real-time quantitative PCR detection was adopted to measure relative expression of dentin matrix protein 1, enamel protein, col agen I and homeobox gene 1 mRNA. RESULTS AND CONCLUSION:Dentin matrix protein 1, enamel protein, and col agen I mRNA expressions increased with culture time, and reached the peak at day 3 (P<0.05), whereas homeobox gene 1 mRNA decreased with culture time (P<0.05).
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BACKGROUND:Xenogeneic bone has a natural porous structure that is similar to human bone. In the treatment of bone defects, the porous structure is helpful to guide bone regeneration, but different degrees of immune responses wil be caused during the implantation process. OBJECTIVE:To prepare a freeze-dried antigen-extracted sheep cancelous bone scaffold and to evaluate its biocompatibility. METHODS: The sheep vertebral cancelous bone was colected to prepare two kinds of antigen-extracted heterologous bone scaffolds that were treated with chemical methods as chemical group and treated with chemical methods+cryopreservation at a-80℃ refrigerator for 4 weeks+drying in vacuum apparatus+60 RESULTS AND CONCLUSION:Freeze-dried bone had no cytotoxicity, no acute toxicity and heat reaction, and was negative for the intracutaneous stimulation test. The scaffold in the chemical group had cytotoxicity and mild irradiation as freeze-dried bone group. (1)Cytotoxicity test: Bone marrow mesenchymal stem cels isolated from sheep were cultured in extracts of the chemical group, free-dried bone group and Dulbecco’s modified Eagle’s medium/Ham’s nutrient mixture F-12. (2) Heat reaction and acute toxicity tests: Extracts from the chemical group, freeze-dried bone group and normal saline were respectively injected into the ear vein of rabbits. (3) Intracutaneous stimulation test: Extracts from the chemical group, freeze-dried bone group and normal saline were respectively injected subcutaneously into the back of rabbits. Co acute toxicity reaction, sent heat source and had mild irritation. Results show that after freeze drying processing, the sheep vertebral cancelous bone has good biocompatibility, can meet the requirements of bone tissue engineering, but the bone that through chemical processing exhibits a relatively poor biocompatibility that cannot achieve the safety standard of biological scaffold materials.
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BACKGROUND:Xenogeneic bone structure and biological characteristics are similar to human bone tissue, and the xenogeneic bone has a decreased antigenicity after physicochemical treatment, with a natural porous structure and rich source, and can be kept for a long time, which is considered to be an effective way to solve the shortage of the autogenous bone and al ograft bone. OBJECTIVE:To compare the physical and chemical properties of xenogenic bone materials prepared by two different methods. METHODS:Sheep cancellous bone treated with chemical method was placed into the muffle furnace at 1 000 ℃for 2 hours to prepare calcined bone. Another cancellous bone was placed into an 80 ℃ refrigerator for 4 weeks and then placed into a vacuum instrument to prepare freeze-dried bone. Cancellous bone rinsed with ultra-pure water served as controls. RESULTS AND CONCLUSION: Three groups of samples retained three-dimensional porous structure which similar with human bone tissue under microscopic observation. The framework was stil intact, with a smal pore of 55-650μm and high porosity of 65%-80%. For the calcined bone, the toughness was decreased and the brittleness increased significantly, but the freeze-dried bone had a little changes in the mechanical properties. Through diffraction analysis, hydroxyapatite was the main composition of the three groups. However, there was a smal amount ofβ-tricalcium phosphate in the calcined bone. Spectrum analysis confirmed that calcium and phosphorus content in these three groups were al close to the human body. The results suggest the cancellous bone treated with these two methods is similar to human bone structure, and the major elements are close to the body. In addition, the cancellous bone after processing has enough smal pore and higher porosity. However, calcination process has a more influence on the mechanical property of scaffold materials, and the freeze-dried bone has a little change but the antigen cannot be completely removed that can reach the basic requirements.
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BACKGROUND:Different methods to remove immunogenicity have different effects on the spatial microstructure of antigen-extracted heterologous bone. OBJECTIVE:To compare the microstructure of the antigen-extracted heterologous bone via different methods to provide experimental data for tissue engineering industrialization. METHODS:Fresh cancellous bones extracted from adult sheep vertebrae were prepared into cylinders. Their long axis direction was the same with orientation of the trabeculae. After vibration washing and different-frequency ultrasound rinsing, the cylinder samples were randomly divided into three groups:in physical calcined group, the samples were defatted, decellularized and deproteinized sequential y using methanol/chloroform and hydrogen peroxide, then bathed in sodium pyrophosphate and directly calcined at 1 000 ℃ for 3 hours;in chemical group, the samples were defatted, decellularized and deproteinized sequential y using methanol/chloroform and hydrogen peroxide;in control group, the samples were dried natural y at room temperature. Microstructure of the samples in each group was analyzed and compared through determination of porosity, scanning electron microscopy observation, X-ray diffraction analysis, X-ray atomic spectroscopy elemental analysis microscopic spatial structure. RESULTS AND CONCLUSION:The physical calcined and chemical groups maintained natural network pore system to different extents. The size of the large pore was 50-600μm and that of the smal one was about 2μm. The porosity was 55%to 70%. Hydroxyapatite was the main component of the physical calcined group which was determined by X-ray diffraction, and a smal amount of theβ-Tricalcium phosphate was also determined. In the chemical group, the main component was only hydroxyapatite. The three-dimensional spatial structures of the deproteinized cancellous bones were not damaged greatly, and they had a natural pore network system. Antigen component of xenogeneic cancellous bone can be more thoroughly removed by physical calcination step. The scaffold material made by antigen-extracted heterologous bone may satisfy the demands for bone tissue-engineering scaffolds.
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BACKGROUND:Fol owing physicochemical treatment and high-temperature calcinations, heterogeneous biological bone becomes a ceramic-like heterologous bone forming a similar structure to the human bone that is a natural network pore structure, which is conducive to seed cel adhesion and proliferation. OBJECTIVE:To observe the feasibility of constructing tissue-engineered bone through combination of sintered bone and bone marrow mesenchymal stem cel s to repair alveolar defects. METHODS:Sheep bone marrow mesenchymal stem cel s as seed cel s were combined with the high temperature sintered bone as scaffold materials to construct tissue-engineered bone. Under general anesthesia, sheep bilateral mandibular first premolars were removed in batches, the alveolar ridge space between the distal root and mesial root of the second premolar to form a bone defect area of 5 mm×5 mm×5 mm. Twelve experimental sheep were equal y randomized into tissue-engineered bone group and sintered bone group, which were implanted with tissue-engineered bone and sintered bone, respectively, at the left surgical area of the mandible. The right surgical area was considered as blank control group. RESULTS AND CONCLUSION:After high-temperature calcinations, the sintered bone was chalk in color, exhibiting a porous structure as the natural cancel ous bone. The porosity was (66.10±1.32)%, and the pore size was between 137.44μm and 538.72μm. After 24 hours of bone marrow mesenchymal stem cel s inoculated to the sintered bone, a large number of cel s are visible adherent to the scaffold;up to day 7, extracel ular matrix was secreted and there was no clear boundary between the cel s and the matrix. X-ray films showed that the tissue-engineered bone and pure sintered bone implants were embedded in the surgical area, and there was a low-density shadow at the edge of the sintered bone. Hematoxylin-eosin staining showed bone trabecular formation at the experimental side, but no obvious bone formation at the control ed side. Tissue-engineered bone prepared by bone marrow mesenchymal stem cel s and sintered bone can better repair sheep alveolar bone defects, which is an ideal seed cel and scaffold material for smal range bone defects.
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BACKGROUND: Due to dentition defect, dentition loss, periodontal disease, trauma and tumor, many patients have to face insufficient buccal-lingual mandibular width. At present, there is no consistent conclusion in suitable peri-implant buccal-lingual mandibular width. OBJECTIVE: To investigate the stress of implant-bone interface with three-dimensional finite element method, in order to evaluate buccal-lingual mandibular width suitable for implants. METHODS: Classes Ⅰ and Ⅲ mandible implant models (the buccal-lingual width of implant neck region was 1, 1.5, 2, 2.5, 3 and 3.5 mm) were loaded with 200 N forces vertical y and at 60° oblique. Then, the stress and strain in the implant-bone interfacial were analyzed. RESULTS AND CONCLUSION: Almost 2 mm or more than 2 mm of mandible bone width could result in good stress distribution in implant-bone interface. The stress distribution of oblique loading was much greater than that of vertical loading. Proper quantity of peri-implant mandibular width is good for stress distribution in implant-bone interface. In the clinical treatment, the oblique loading should be avoided or reduced.
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BACKGROUND:The form and structure of antigen-extracted xenogeneic cancel ous bone through series of physical and chemical treatment are similar to human tissue. OBJECTIVE:To detect the biocompatibility of antigen-extracted xenogeneic cancel ous bone matrix prepared by three different ways. METHODS:The antigen-extracted xenogeneic cancel ous bone scaffold materials which were prepared through physical, chemical and physical-chemical combined methods and hydroxy apatite biological ceramic materials were implanted into the dorsum subcutaneous tissue. Histological observation was done at 4, 8 and 12 weeks after surgery. The antigen-extracted xenogeneic cancel ous bone scaffold materials which were prepared through physical, chemical and physical-chemical combined methods respectively was used to culture sheep bone marrow mesenchymal stem cells for 7 days. Cel adhesion, growth, proliferation and stroma secretion were observed. RESULTS AND CONCLUSION:At 4 weeks after surgery, a strong inflammatory reaction was detected around materials in four groups. At 12 weeks, the xenogeneic bone materials prepared through physical and physical-chemical combined methods and hydroxy apatite biological ceramic materials internal pore and surrounding tissue inflammation disappeared basical y, with the presence of thimbleful inflammation cells. The material degradation was more than at 8 weeks. The xenogeneic bone materials prepared through chemical methods material internal pore and surrounding tissue inflammation stil existed, suggesting that the xenogeneic bone materials prepared through physical and physical-chemical combined methods exhibited good histocompatibility. A smal amount of orderly osteoblasts existed around hydroxy apatite biological ceramic materials and physical-chemical prepared materials, with a smal amount of bone. These suggested that there was a tendency for ectopic bone formation. The xenogeneic cancel ous bone materials prepared through physical or physical-chemical combined methods have better cytocompatibility. However, scaffold materials prepared through chemical method have poor cytocompatibility and they are not qualified for the safety standards of biological materials.
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BACKGROUND:Many in vivo and in vitro experiments indicate that implantation of exogenous basic fibroblast growth factor can significantly promote the process of bone formation, but the in vivo degradation of exogenous basic fibroblast growth factor affects the therapeutic efficacy. OBJECTIVE:To observe the effects of basic fibroblast growth factor-transfected mesenchymal stem cells which transfected using molecular biology techniques combined with al ogeneic bone in the repair of critical-size bone defects in sheep. METHODS:Al ogeneic bone with basic fibroblast growth factor-transfected bone marrow mesenchymal stem cells, bone marrow mesenchymal stem cells combined with al ogeneic bone material stents, al ograft bone material,β-tricalcium calcium material were respectively implanted into critical-size bone defects in sheep. After 4, 8 and 12 weeks, histological and immunohistochemical staining was performed. RESULTS AND CONCLUSION:At 12 weeks after implantation of al ogeneic bone with basic fibroblast growth factor-transfected bone marrow mesenchymal stem cells as tissue engineering bone, there were many cartilage-like structures in the operative binding region and a large amount of osteoblast-like cells in the center of operative region, and there was more material degradation in the entire operative area as compared with other groups;there were fibrous connective tissues ful of the pores, and osteoclast-like cells were commonly seen around the implant material;bone sialoprotein and col agen type Ⅰ expression were strongly positive. In the other three groups, although the cartilage-like structure appeared in the binding region, dead bone structure was found in the central area, and bone sialoprotein and type Ⅰ col agen expression was weak. These findings indicate that al ogeneic bone with basic fibroblast growth factor-transfected bone marrow mesenchymal stem cells can basical y repair critical-size bone defects in sheep.
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The conduction of performance appraisal in the hospital is of great significance to the perfection of the appraisal system and the improvement of the managerial efficiency of the hospital. The authors suggest that in the process of establishing an appraisal system of hospital performance, it is necessary to use for reference enterprises' experience in performance appraisal and the theories of performance management. Firstly, single-faceted pursuit of economic benefits should be avoided, the establishment of an external hospital appraisal system and the establishment of an internal hospital appraisal system should be combined, and attention should be paid to the overall application of performance appraisal in performance management. Secondly, in light of their own experience in hospital management, the authors put forward the suggestion of establishing a performance appraisal system of three levels: the hospital , the department and the post. They also argue that attention should be given to the selection of comprehensive appraisal methods, continuous communication about performance, and readjustment in a timely manner.