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17 September 2013, Volume 17 Issue 38 Previous Issue    Next Issue

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Physicochemical property and safety of nanometer human demineralized bone matrix composite Fang Lei, Chen Xiong-sheng, Huang Kai, Zhou Sheng-yuan, Zhu Wei, Wang Hui, Shao Jiang, 2013, 17 (38):  6701-6860.  doi: 10.3969/j.issn.2095-4344.2013.38.001 Abstract ( 336 )   PDF (2626KB) ( 434 )   Save BACKGROUND: Demineralized bone matrix and bone morphogenetic protein have been shown to have good bone induction, but less studies concerned nanometer demineralized bone matrix. Its physical and chemical properties and biological security are not yet clear. OBJECTIVE: On the basis of preparing the nanometer human demineralized bone matrix in previous experiment, we mixed the recombinant human bone morphogenetic protein-2 together to obtain the new bone graft substitute and to research its physical and chemical properties and biological security. METHODS: The human demineralized bone matrixes were prepared by the method of modified Urist and nano-processed then mixed with the bone morphogenetic protein-2 in specific proportions in order to be lyophilized to complete the following experiments. (1) Pyrogen experiment: the material extracts were injected in the rabbits by ear intravenous. (2) Toxicity experiments: material extracts and saline were separately injected via the tail vein of mice in vivo. (3) Implantation experiments: experimental materials and β-tricalcium phosphate were implanted into rabbits on both sides of the hindlimb muscle. RESULTS AND CONCLUSION: After lyophilized shaping, the nanometer demineralized bone matrix material had dense surface and it’s pore diameter was 100-400 μm. The pore distribution was less uniform and the porosity was of less than 30%. The main elements were carbon, oxygen and nitrogen. Nanometer human demineralized bone matrix with recombinant human bone morphogenetic protein-2 did not have pyrogen effect and the rabbits’ body temperature had no significant fluctuations after injection. The acute systemic toxicity test results showed that the nanometer human demineralized bone matrix with recombinant human bone morphogenetic protein-2 complied with the relevant provisions of the State, without obvious toxic reaction. The inflammatory response of nanometer human demineralized bone matrix with recombinant human bone morphogenetic protein-2 was significantly lighter than the reaction of β-tricalcium phosphate. The results showed that the nanometer human demineralized bone matrix with recombinant human bone morphogenetic protein-2 is a nanometer allogeneic bone graft substitutes with nontoxicity, good biocompatibility, high bioavailability, and less inflammatory reaction. Figures and Tables | References | Related Articles | Metrics

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Mechanical and biodegradable properties of absorbable hydroxyapatite/ poly-DL-lactide screws Fu Rong, You Xiao-bo, Zhong Zhen-dong, Li Yan 2013, 17 (38):  6709-6716.  doi: 10.3969/j.issn.2095-4344.2013.38.002 Abstract ( 474 )   PDF (959KB) ( 562 )   Save BACKGROUND: Through compounding hydroxyapatite and poly-DL-lactide, the mechanical properties, physical and chemical properties of the implants can be enhanced. OBJECTIVE: To detect the effect of hydroxyapatite/poly-DL-lactide composite internal fixation screws in canine femoral condyle cancellous bone fracture repair. METHODS: Forty-two beagle dogs were operated to bilateral femoral condyle fracture models. The left side was fixed using hydroxyapatite/poly-DL-lactide screws as experimental group; while the right side was fixed with pure poly-DL-lactide screws as control group. After 2, 4, 8, 12, 24, 36 and 48 weeks, conditions of fracture were observed using X-ray, femoral and screw specimens were observed histopathologically, and the bending strength and the average molecular weight were detected. The biological absorption rate, intensity decay rate and biodegradation rate were calculated. RESULTS AND CONCLUSION: After 2-48 weeks, bilateral fractures were fixed well and new bone grew well, but the biological absorption rate of the screws in the experimental group was lower than that in the control group (P ≤0.01). In the first 2, 4 weeks, the bending strength of the experimental screws was higher than that of the control screw (P ≤0.05), but the biodegradable speed was slower in the former one (P ≤ 0.05 or P ≤ 0.01). The pathological changes were similar in the two groups. After 48 weeks, the fractures were healed and bone tissue reconstruction was completed. Compared with the pure poly-DL-lactide screws, the hydroxyapatite/poly-DL-lactide composite internal fixation screws have better fixation effects, biocompatibility, mechanical properties and biodegradability. Figures and Tables | References | Related Articles | Metrics

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Fiber post-core restoration for incisor crown defects: Finite element analysis of stress Jie En-si, Shi Li 2013, 17 (38):  6717-6724.  doi: 10.3969/j.issn.2095-4344.2013.38.003 Abstract ( 379 )   PDF (841KB) ( 433 )   Save BACKGROUND: The combination of fiber post and resin core for restorations of mesial or distal defects of the maxillary central incisor can restore the elastic modulus close to the nature dentin, and achieve good aesthetic effects. However, when a complete dentin collar cannot be prepared due to a large number of dental tissue defects, the post and core are easy to be lost or fractured after defect repair using the combination of fiber post and resin core. OBJECTIVE: To compare the stress distribution after nickel-chromium cast post and core, gold-palladium cast post and core, and fiber post and resin core were used for restorations of mesial or distal defects of the maxillary central incisors using three-dimensional finite element analysis. METHODS: An intact adult maxillary central incisor that meets the average dental anatomical value in China was selected and scanned using a dental cone-beam CT. Then, three-dimensional tooth-fiber post and core (nickel-chromium cast post and core or gold-palladium cast post and core)-all-ceramic crown models of mesial or  distal defects of the maxillary central incisors and part loss of dentin collar were established using ABAQUS analysis. After repair with nickel-chromium cast post and core, gold-palladium cast post and core, and fiber post and resin core, stress distribution in the loaded state was compared using the ABAQUS three-dimensional finite element analysis. RESULTS AND CONCLUSION: The stress peak at the adhesive and cast layers in the fiber post and resin core group was significantly lower than that in the nickel-chromium cast post and core or gold-palladium cast post and core group. It indicated that the tooth root was easy to be fractured after mesial or distal defects of the maxillary central incisors with partial loss of dentin collar were restored with nickel-chromium cast post and core, gold-palladium cast post and core. In addition, the stress peaks at the dentin layer were consistent for fiber post and core, nickel-chromium cast post and core, and gold-palladium cast post and core. These findings indicate that the combination of fiber post and resin core is better for restorations of mesial or distal defects of the maxillary central incisors. Figures and Tables | References | Related Articles | Metrics

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Morphological changes of the smear layer after caries removal using different methods: An observation under scanning electron microscope Fang Ling, Zhu Yan-li 2013, 17 (38):  6725-6732.  doi: 10.3969/j.issn.2095-4344.2013.38.004 Abstract ( 615 )   PDF (870KB) ( 515 )   Save BACKGROUND: The methods to remove the smear layer mainly include mechanical, Carisolv chemomechanical, laser, ozone methods and so on. But studies after caries removal are limited. At present, there is no research for the observation of the smear layer after caries removal using Er:YAG laser, Carisolv chemomechanical and traditional dental turbine. OBJECTIVE: To observe the morphologic changes of the dentin smear layer after treated with the three methods of Er:YAG laser, Carisolv chemomechanical and traditional high speed dental turbine under a scanning electron microscope. METHODS: Thirty newly removed premolars or molars with moderate caries were divided into three groups, 10 teeth in each group. The bottom surface of the tooth cavity was observed with the naked eyes after caries removal with Er:YAG laser, Carisolv chemomechanical and traditional dental turbine, respectively. Then, the surface was observed using the scanning electron microscope (magnification ×1 000 and ×2 000). RESULTS AND CONCLUSION: The texture of the tooth cavity was hard in the three groups. After caries removal, the dentin surface of Er:YAG laser group was rough and uneven, and showed a peak-like shape; The dentin surface of Carisolv chemomechanical group was dark and the bottom was flat; The dentin surface of traditional dental turbine group was smooth and bright, and there was an obvious cutting trace. It was found that the surface of Er:YAG laser group did not have the smear layer, and the dentinal tubule was clearly visible. The most dentinal tubules were visible in the Carisolv chemomechanical group, and the surface was covered with a less smear layer. The surface of the traditional dental turbine group was covered with a thick smear layer, and the dentinal tubule was unseen. The differences in dentin smear layer cleanliness were significant between the three groups. These result indicate that Er:YAG laser can effectively remove the smear layer, which is better than Carisolv chemomechanical method and traditional dental turbine. Traditional dental turbine group is the worst among the three methods. Figures and Tables | References | Related Articles | Metrics

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Effects of different resin cements on the coronal microleakage and bonding strength of fiber posts Gao Shi-jun, Zong Wan-qiao, Wang Dong-xia, Hou Yu-ze, Xiao Yuan-yuan, Xue Gang, Huang Yan-jun, Jiang Jia-zhen 2013, 17 (38):  6733-6739.  doi: 10.3969/j.issn.2095-4344.2013.38.005 Abstract ( 393 )   PDF (767KB) ( 391 )   Save BACKGROUND: At present, there are still differences in the studies of total-etch, self-etch and self-bonding resin cement effect on the coronal microleakage and bonding strength of fiber posts. OBJECTIVE: To evaluate the coronal microleakage and the bonding strength of fiber posts treated with three kinds of resin cements. METHODS: Totally 32 upper incisors were randomly divided into five groups, including three experimental groups and two control groups. After the root canal preparation, three kinds of resin cements (EMBRACE WetBond, LuxaCore, Medental Multi-cure) were used to fiber posts with the bond diameter of 1.4 mm. Stereomicroscope was used to observe the microleakage. Then, the specimens were cut into 2 mm wafer along the axis of tooth, and universal testing machine for push-out test was used to observe the failure mode. In the positive control group, no root canal preparation was done, the root was coated with nail polish, and the crown was directly exposed to the dye. In the negative control group, no root canal preparation was done, the root canal orifice was covered with the resin, the tooth was overall coated with nail polish and then embedded 1 mm below the section. RESULTS AND CONCLUSION: The microleakage was observed in all the three resin cements, Medental Multi-cure showed the least microleakage and LuxaCore showed the largest microleakage, and there was significantly different among the three kinds of resin cements (P < 0.05). The bonding strength of three cements had significant differences  (P < 0.05), and ranked from high to low: Mdental Multi-cure, LuxaCore, and EMBRACE WetBond. The main fracture modes were binder/fiber post fracture and mixed failure. The results suggest that the total-etch resin cement binds tightly with the dentin, and owns a superiority in the microleakage and bonding property as compared with the self-etch resin cements and self-bonding resin cements. Figures and Tables | References | Related Articles | Metrics

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Occlusion of dentinal tubules using tricalcium silicate Yang Qing-ling, Chen Si-jie, Wan Yin, Geng Cong, Rong Guang-ying 2013, 17 (38):  6741-6746.  doi: 10.3969/j.issn.2095-4344.2013.38.006 Abstract ( 493 )   PDF (768KB) ( 556 )   Save BACKGROUND: A number of in vitro experiments have confirmed that the tricalcium silicate not only can be closely integrated with the dentin through self-curing process, but also can induce dentin remineralization in the physiological environment, thereby effectively blocking the dentinal tubules. OBJECTIVE: To further verify the effects of tricalcium silicate solution on the occlusion of dentinal tubules. METHODS: Thirty-six dentinal discs were made of free first premolars from orthodontic patients, and divided into three pretreatment groups randomly. The teeth were soaked in pretreatment solution for 2 minutes, namely    0.29 mol/L ethylene diamine tetraacetie acid, 6% citric acid, and rinsed ultrasonically with deionized water      20 minutes, respectively. Every above-mentioned group was randomly assigned into experimental group (tricalcium silicate), control group (sodium fluoride) and blank group, and corresponding materials in each group were used to coat the outer dentinal tubules (2 minutes/time). Then, the dentinal discs were saved in artificial saliva in a 37 ℃ thermostat. After 14 days, the morphology of the dentinal tubules before and after treatment was observed using scanning electron microscope. Diameter and area of open dentinal tubules were calculated. RESULTS AND CONCLUSION: After pretreatment, the dentinal tubules were at open state; except for the blank control group to maintain the original state, acid etching and ethylene diamine tetraacetie acid pretreatment solutions had a stronger capacity of demineralization, which led to the dentinal tubules open. After the dentinal tubules were treated with sodium fluoride and tricalcium silicate, there were varying degrees of sediments, and open dentinal tubule area and average diameter in the sodium fluoride and tricalcium silicate groups were lower than those in the control group (P < 0.05). The dentinal tubule treated with tricalcium silicate was almost entirely closed homogeneously, and occasionally, a single open dentinal tubule was seen. Open dentinal tubule area and average diameter in the tricalcium silicate group were significantly lower than those in the sodium fluoride group (P < 0.05). The findings verify that dentin occlusion using tricalcium silicate is superior to that using sodium fluoride; and dentin tubule pretreatment with acid etching or ethylene diamine tetraacetie acid is beneficial to desensitization effects. Figures and Tables | References | Related Articles | Metrics

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Fatigue rupture study of HL-3 Buccal Multiloops for simulation of oral movements Pan Yu1, Hou Lu1, Xu Shi-qian2 2013, 17 (38):  6747-6752.  doi: 10.3969/j.issn.2095-4344.2013.38.007 Abstract ( 415 )   PDF (811KB) ( 375 )   Save BACKGROUND: Concerning the problem of the ruptured phenomenon in clinic work of HL-1 and HL-2 Buccal Multiloops removable appliance, we invented HL-3 Buccal Multiloops. OBJECTIVE: Through the Buccal Multiloops Fatigue Testing Machine which can imitate oral movements, to compare the fatigue strength of the HL-2 and HL-3 Buccal Multiloops in the same condition. METHODS: A pair of the HL-2 or HL-3 Buccal Multiloops with the completely symmetrical size, symmetrical height and symmetrical direction was fixed on the Buccal Multiloops Fatigue Testing Machine which could simulate oral movements, then keep the Buccal Multiloops Fatigue Testing Machine working untill any Buccal Multiloops broke. The cyclic loading times of this pair Buccal Multiloops was recorded. Scanning electron microscope was used to observe the appearance of broken end of the Buccal Multiloops. RESULTS AND CONCLUSION: The cyclic loading times of HL-3 Buccal Multiloops were more than HL-2 Buccal Multiloops (P < 0.01), suggesting that HL-3 Buccal Multiloops has stronger fatigue strength than HL-2 Buccal Multiloops. Scanning electron microscope observation showed that the fractures of HL-2 and HL-3 Buccal Multiloops all had the typical fatigue fracture morphology, indicating that the rupture of HL-2 and HL-3 Buccal Multiloops belongs to fatigue fracture. However, HL-3 Buccal Multiloops exhibited bigger crack compared with HL-2 Buccal Multiloops, the presence of running-in region, suggesting that HL-3 Buccal Multiloops reduced the  probability of fatigue fracture and prolonged the time of fatigue fracture. Figures and Tables | References | Related Articles | Metrics

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Shape-memory polymer based on D,L-poly(lactic acid): Biosecurity and cytocompatibility Xu Jian, Peng Kun, Gan Xiao-ling, Wang Yi-zhen, Duan Qiao-ling, Li Yong-gang 2013, 17 (38):  6753-6758.  doi: 10.3969/j.issn.2095-4344.2013.38.008 Abstract ( 313 )   PDF (2189KB) ( 391 )   Save BACKGROUND: Previous experiments have prepared shape memory polymer based on D,L-poly(lactic acid). According to domestic technical requirements for biologically evaluating biomaterials and medical equipments, tissue-engineered grafts must be subjected to preclinical experiment for biosecurity and cytocompatibility evaluation. OBJECTIVE: To observe the biosecurity of the shape memory polymer based on D,L-poly(lactic acid). METHODS: (1) Bacterial endotoxin test: polymer extract, endotoxin working standard solution and checking standard water were added into limulus reagent, respectively. (2) Sensitization test: Polymer extract + Freund’s complete adjuvant + physiological saline and Freund’s complete adjuvant + physiological saline were injected into the scapula of Kunming mice. After induction by intradermal injection, local induction and excitation, stimulate skin erythema and edema degree were observed in animals. (3) Acute toxicity test: Kunming mice received intraperitoneal injection of 100%, 50%, 25% polymer leaching solution and physiological saline, respectively. (4) 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay for cell proliferation: The direct method was that human umbilical cord vascular endothelial cells were inoculated onto the polymer film, lactic acid and glass, respectively; the indirect method was that human umbilical cord vascular endothelial cells were inoculated into the polymer leaching solution, acrylamide solution and 1640 culture solution. RESULTS AND CONCLUSION: This shape memory polymer based on D,L-poly(lactic acid) is free of bacterial contamination in compliance with the biosecurity standards, and it has no allergenic and toxicity but has good cytocompatibility. Figures and Tables | References | Related Articles | Metrics

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Dipsacus asperoides combined with composite calcium phosphate bone implant for bone defect repair Li Shan-chang, Ren Yuan-yuan 2013, 17 (38):  6759-6765.  doi: 10.3969/j.issn.2095-4344.2013.38.009 Abstract ( 386 )   PDF (2749KB) ( 446 )   Save BACKGROUND: Physical structure and inorganic composition of composite calcium phosphate bone implants are similar to human bone, and the implants have good bioabsorbable ability and biocompatibility. Studies have confirmed that Dipsacus powder can significantly improve the speed of bone defect repair. OBJECTIVE: To study the effects of Dipsacus asperoides/composite calsium phosphate bone implant material in the repair of bone defects. METHODS: Bone defects of 1.0 cm×0.5 cm×0.3 cm were made on the bilateral mandibular bodies. The right side was implanted with Dipsacus asperoides/ composite calsium phosphate bone implant as experimental group and the left side implanted with calcium phosphate bone material served as control group. Samples were collected at 4, 8, 12 weeks after implantation for gross observation, cone beam CT, scanning electron microscope observation and histological observation. RESULTS AND CONCLUSION: (1) Gross observation: the osteogenic speed, degradation rate and hardness in the experimental group were higher than those in the control group. (2) Cone beam CT detection: the implant in the experimental group was more tightly integrated with the surrounding tissues than that in the control group, and the degradation speed in the experimental group was higher than that in the control group. (3) Scanning electron microscope observation: there were many fibrous connective tissues between the implants and the surrounding tissues in the two groups, which was more obvious in the experimental group than the control group. With time gone, the implants were combined with the surrounding tissues more tightly. (4) Histological observation: the osteogenic speed and activity in the experimental group were superior to those in the control group. These findings indicate that Dipsacus asperoides combined with composite calcium phosphate bone implant can accelerate bone repair. Figures and Tables | References | Related Articles | Metrics

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Biocompatibility of a novel chitosan-collagen scaffold and periodontal ligament cells Tang Qian, Sun Wen-juan, Huang Nan-nan, Chen Xi, Ren Li, Hou Si-run 2013, 17 (38):  6766-6772.  doi: 10.3969/j.issn.2095-4344.2013.38.010 Abstract ( 324 )   PDF (2354KB) ( 476 )   Save BACKGROUND: At present, collagen as a material in periodontal tissue engineering has some disadvantages such as poor mechanical strength and rapid degradation speed. Collagen combined with chitosan can improve above-mentioned problems. OBJECTIVE: To evaluate the biocompatibility of a novel chitosan-collagen scaffold in vitro. METHODS: Cytotoxicity of the extract of chitosan-collagen scaffold in different concentrations (100%, 75%, 50%, 25%) was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Human periodontal ligament cells at 4-6 passages were cocultured with the chitosan-collagen scaffold. Cell growth on the scaffold was observed. Changes in alkaline phosphatase activity were detected in periodontal ligament cells before and after coculture. RESULTS AND CONCLUSION: The novel chitosan-collagen scaffold was made up of double layers with one dense layer and another loose layer. The grade of the cytotoxicity of the scaffold was from 0 to 1. Scanning electron microscope and histological observation demonstrated that cells grew well on the chitosan-collagen scaffold; the dense layer could prevent cells to migrate into the scaffold. There were no significant differences in alkaline phosphatase activity in human periodontal ligament cells before and 24 hours after combined culture (P > 0.05). Alkaline phosphatase activity in human periodontal ligament cells was greatly higher at 48 and 72 hours after combined culture compared with that before culture (P < 0.05). Above results indicated that the novel chitosan-collagen scaffold has a good biocompatibility and barrier function, and potential as a scaffold for periodontal tissue engineering. Figures and Tables | References | Related Articles | Metrics

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Safety of a novel biodegradable stent implanted in the coronary artery in a porcine model Li Hu, Li Xiao-yan, Jiang Xue-jun, Zheng Xiao-xin, Feng Gao-ke, He Su-yuan, Ren Shan, Yi Xin 2013, 17 (38):  6773-6778.  doi: 10.3969/j.issn.2095-4344.2013.38.011 Abstract ( 314 )   PDF (2195KB) ( 411 )   Save BACKGROUND: At present, the main research fields about coronary stents are the whole degradation biological materials with high biocompatibility and drug controlled release systems. OBJECTIVE: To evaluate the safety after the two novel biodegradable stents implanted in coronary arteries in porcine models. METHODS: The normal fully biodegradable stents were made up of the poly-L-lactide and the antiproliferative drugs paclitaxel, and the novel biodegradable stents were added in amorphic calcium phosphate at the basis of normal biodegradable stents. (1) Five normal fully biodegradable stents were randomly implanted into the coronary arteries of five porcines, and five novel biodegradable stents were randomly implanted into the coronary arteries of the remaining five porcines by coronary angiography. The blood biochemistry and C-reactive protein levels were measured pre-operation and at 28 days after operation. Coronary angiography was utilized to observe the lumen unobstructed at 28 days after surgery. (2) Under a microscope, seven normal fully biodegradable stents and seven novel biodegradable stents were implanted into right external iliac arteries of 14 rabbits. Blood urea nitrogen and creatinine levels were measured before surgery and at 28 days after operation. RESULTS AND CONCLUSION: At 28 days after operation, there were no significant changes in porcine glutamic-pyruvic transaminase, aspartate aminotransferase, triacylglycerol, total cholesterol, low density lipoprotein and C-reactive protein levels compared with that before operation, but urea nitrogen and creatinine levels were significantly higher than that before operation (P < 0.05). The result of coronary angiography showed that no in-stent thrombosis or stenosis was detected in either group. There was no significant difference in urea nitrogen and creatinine levels in both groups. These results suggested that it is safe and compatible after the two novel biodegradable stents implanted in coronary arteries of porcine models, and the stents had good histocompatibility. Figures and Tables | Related Articles | Metrics

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Cell co-culture technology accelerates premicrovascular-like structure formation Wang Ji-wen, Li Xiang-dong, Wei Guo-feng 2013, 17 (38):  6779-6784.  doi: 10.3969/j.issn.2095-4344.2013.38.012 Abstract ( 281 )   PDF (1933KB) ( 329 )   Save BACKGROUND: Constructing a three-dimensional tissue-like structure in vitro plays a critical role in modern tissue engineering and regenerative medicine. Several advances have been made in the past decade. However, it is still a challenge to promote microvascular-like structure formation and improve limited nutritional transportation, thereby promoting cell viability. OBJECTIVE: To explore the feasibility of constructing a three-dimensional microvascular-like structure through the co-culture technique. METHODS: Human bone marrow mesenchymal stem cells and human endothelial cells were co-cultured on a three-dimensional porous silk scaffold. Cell proliferation was analyzed by Pico-green DNA assay. Their growth profiles were evaluated by scanning electron microscope and laser scanning confocal microscopy, respectively. The mRNA levels of von Willebrand factor and CD31, two key functional markers of endothelial cells, in the co-cultured endothelial cells was assayed by real-time quantitative reverse transcription-PCR. RESULTS AND CONCLUSION: The three-dimensional culture system constructed by the silk scaffold and bone marrow mesenchymal stem cells provided an ideal microenvironment for cell growth and proliferation in vitro. Moreover, this microenvironment was capable of promoting endothelial cell differentiation evidenced by their significantly improved mRNA levels of von Willebrand factor and CD31. Premicrovascular-like structure was also observed in the co-cultures under the confocal microscope. Thus, all the data supported that the unique co-culture system could promote endothelial cell differentiation and self-assembling in vitro. This culture system provides a robust tool for the studies addressing microvessel-based tissue engineering. Figures and Tables | References | Related Articles | Metrics

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Cytotoxicity tests for the mussel adhesive protein dressing for wound healing Liu Qian, Lan Hua-lin, Gu Ming, Gao Min, Wang Zhao-xu 2013, 17 (38):  6785-6790.  doi: 10.3969/j.issn.2095-4344.2013.38.013 Abstract ( 1129 )   PDF (1962KB) ( 906 )   Save BACKGROUND: In the cytotoxicity test of the mussel adhesive protein dressing for wound healing, because of positive charge properties of the protein, when extracting ratio is 1:9, the cells exhibit poly-group phenomenon that results in errors in the cytotoxicity test of mussel adhesive protein samples. OBJECTIVE: According to the existing standards, to improve the leaching proportion and pretreatment of mussel adhesive protein dressing for wound healing based on the special properties and working condition of mussel adhesive protein. METHODS: (1) Extract method: Extract solution of mussel adhesive protein dressing was prepared with mussel adhesive protein dressing and cell medium at extracting ratios of 1:9 and 1:131. Then, L929 cells were cultured in extract solutions of mussel adhesive protein dressing, natural latex and high-density polyethylene, respectively. (2) Method of direct contact: Distilled water, solutions of mussel adhesive protein dressing, dimethyl sulfoxide and cell medium were used to culture L929 cells. RESULTS AND CONCLUSION: When the extracting ratio was 1:9, the cells agglomerated which is not suitable for cytotoxicity test. When the extracting ratio was 1:131, flocculated sediment and cell aggregation disappeared, the cytotoxicity test results showed no cytotoxicity with higher reliability. Direct contact method showed the samples had no cytotoxicity. The extract method with adjusted extracting radio or direct contact method can be applied to test the in vitro cytotoxicity of mussel adhesive protein dressing for wound healing. Figures and Tables | Related Articles | Metrics

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Bone marrow mononuclear cells combined with nano-hydroxyapatite/collagen for repair of mandibular defects Wu Guang-xin, Wang Jian-guo, Du Xiao-yan 2013, 17 (38):  6791-6796.  doi: 10.3969/j.issn.2095-4344.2013.38.014 Abstract ( 270 )   PDF (2096KB) ( 394 )   Save BACKGROUND: Nano-hydroxyapatite/collagen combined with mononuclear cells can promote the growth of a variety of stem cells to induce the formation of new bone and vascularization, finally inducing osteogenesis. OBJECTIVE: To investigate the feasibility of bone marrow mononuclear cells combined with the nano-hydroxyapatite/collagen for repair of mandibular defects in a rabbit. METHODS: Twenty-seven New Zealand white rabbits were selected to prepare bilateral mandibular bone defect models, and then divided into three groups. In experiment group, bone marrow mononuclear cells combined with the nano-hydroxyapatite/collagen were implanted into mandibular defects; in control group, nano-hydroxyapatite/collagen scaffold was implanted; and in blank control group, nothing was implanted. Tissue specimens were prepared at weeks 4, 8, 12 for gross observation, imaging analysis, hematoxylin-eosin staining and scanning electron microscope. RESULTS AND CONCLUSION: The imaging examination and histological staining showed that the bone quality and healing degree in the experimental group was better than those in the other groups. Scanning electron microscope showed that better histocompatibility and no inflammation reaction in the experimental group. Dental CT data showed that the experimental group had better repair effect than the other groups (P < 0.05). These findings indicate that bone marrow mononuclear cells combined with the nano-hydroxyapatite/collagen have capacity of bone induction and bone formation, which can be used to repair mandibular defects. Figures and Tables | References | Related Articles | Metrics

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Cytocompatibility of calcium metaphosphate nanoparticles Wu Yue-heng1, Mai Li-ping1, Chen Peng2, Zhang Ling-min, Huang Huan-lei, Zeng Xiang-jun,Tang Shun-qing, Xiao Xue-jun, Yu Xi-yong 2013, 17 (38):  6797-6803.  doi: 10.3969/j.issn.2095-4344.2013.38.015 Abstract ( 349 )   PDF (2614KB) ( 558 )   Save BACKGROUND: Calcium metaphosphate has excellent biocompatibility, degradability, and cell affinity. Human bone marrow mesenchymal stem cells can grow and proliferate in the pores of the porous calcium metaphosphate, but less is known about calcium metaphosphate nanoparticles. OBJECTIVE: To prepare calcium metaphosphate nanoparticles, and to analyze the effect of calcium metaphosphate nanoparticles at different concentrations on apoptosis of human bone marrow mesenchymal stem cells by flow cytometry. METHODS: The calcium metaphosphate nanoparticles were prepared by wet ball milling. Scanning electron microscopy and transmission electron microscopy were used to observe the morphology of the calcium metaphosphate nanoparticles, and the crystal structure of nanoparticles was analyzed by X-ray diffraction. Calcium metaphosphate nanoparticles were mixed in the CYAGON OricellTM basal medium, and the ncentrations of calcium metaphosphate nanoparticles in the medium were 10, 1, 0.1 mg/L. Human bone marrow mesenchymal stem cells were cultured for 7 days in the above-mentioned media, and apoptosis of human bone marrow mesenchymal stem cells was analyzed by flow cytometry. RESULTS AND CONCLUSION: Calcium metaphosphate nanoparticles were successfully prepared by wet ball milling, irregular in shape, and the mean diameter was 10-30 nm. X-ray diffraction results showed the crystal structure of nonaparticles was mainly β-Ca(PO3)2. The cell ratio of G0/G1 phase and G2/M phase in 10 mg/L group was obviously higher than that in 1, 0.1 mg/L groups (P < 0.01). The cell apoptosis rates during the early, middle, late stages in 10 mg/L group were obviously higher than those in 1, 0.1 mg/L groups (P < 0.01), and the total cell apoptosis was also significantly increased in 10 mg/L group (P < 0.01). These findings indicate that human bone marrow mesenchymal stem cells proliferation can be inhibited by calcium metaphosphate nanoparticles, and apoptosis rate is increased significantly when the concentration of calcium metaphosphate nanoparticles increases from 1 mg/L to 10 mg/L. Figures and Tables | References | Related Articles | Metrics

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Magnetic nanoparticles versus a commercial kit for apolipoprotein E gene polymorphism analysis Wu Ting, Yi Li, Huang Ying, Wu Jun 2013, 17 (38):  6804-6810.  doi: 10.3969/j.issn.2095-4344.2013.38.016 Abstract ( 439 )   PDF (2494KB) ( 550 )   Save BACKGROUND: Relative to blood samples, mouth swab samples are more beneficial for apolipoprotein E gene polymorphism analysis among large cohorts. However, agreement has not yet been reached about how to extract genomic DNA form mouth swab samples. OBJECTIVE: To develop an appropriate method to extract genomic DNA form mouth swab samples, which are suitable for apolipoprotein E gene polymorphism analysis. METHODS: Fifty mouth swab samples from patients with sporadic Alzheimer’s disease were collected. Magnetic nanoparticles and PicoDNA trace nucleic acid extraction kit were used to extract genomic DNA form mouth swab samples. And the purity and concentration of the genomic DNA extracted by the two methods were analyzed. Then PCR amplifications and DNA electrophoresis were performed to confirm whether the genomic DNA was able to amplify desired DNA fragments. DNA sequencing was applied to analyze apolipoprotein E gene polymorphisms. RESULTS AND CONCLUSION: Genomic DNA extracted by the two methods was of high purity. The concentration of genomic DNA extracted by magnetic nanoparticles was higher than by PicoDNA trace nucleic acid extraction kit, and the difference had statistical significance (P < 0.05). All the genomic DNA were able to performed PCR amplifications to obtain desired PCR products, but results of DNA electrophoresis showed that DNA fragments were more clear by nanoparticles method. The results of DNA sequencing were the same by the two methods. The distribution of ε2, ε3, ε4 genotypes of apolipoprotein E gene was 6%, 71%, 23%, respectively. Magnetic nanoparticles were better than PicoDNA trace nucleic acid extraction kit for extracting genomic DNA form mouth swab samples for apolipoprotein E gene polymorphism analysis. Figures and Tables | References | Related Articles | Metrics

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Simulated body fluid immersion method for assessing biological characteristics of calcium citrate Ding Xiu-ming, Peng Lei, Wen Feng, Tan Zhao-wei, Mu Zhong-lin 2013, 17 (38):  6811-6816.  doi: 10.3969/j.issn.2095-4344.2013.38.017 Abstract ( 498 )   PDF (816KB) ( 540 )   Save BACKGROUND: Calcium citrate has a better solubility than calcium phosphate, calcium sulfate, and other calcium biomaterials. The synthetic calcium citrate has a good denseness, and stably releases calcium ions at a high efficiency during the degradation. Consequently, it may be more suitable for the filling of fracture defects, providing needed calcium ions for early fracture healing. OBJECTIVE: To prepare calcium citrate biomaterials with a novel formulation based on the natural bio-mineralized oyster shells and citric acid so as to expect to get a good application in fracture healing repair. METHODS: Crushing, grinding, and chemical reaction methods were used for refinement. Particle size analyzer, X-ray diffraction, scanning electron microscope, and Fourier transform infrared spectroscopy were adopted for analysis of the size distribution, composition, mineral phases, and micro-morphology. Biological characteristics were evaluated through a simulated body fluid experiment.  RESULTS AND CONCLUSION: Oyster shell powder was reacted with saturated citric acid to produce the calcium citrate material that had uniform crystal structure and compact bonding among crystal bodies, and exhibited a certain mechanical ability. The calcium citrate material had a good crystal structure that was conductive to prolong the degradation time. The calcium citrate released calcium ions slowly, and did not produce dramatic changes in the pH value (7.20-7.46) of the surrounding in the dissolution process. With the gradual degradation of calcium citrate materials, Ca2+ concentration in solution increased gradually and stably, and ultimately achieved an appropriate concentration of   7 mmol/L, suitable for osteoblast proliferation and differentiation. Calcium citrate prepared using natural oyster shell has good biological properties, and exhibits a natural superiority to artificial bone materials. Figures and Tables | References | Related Articles | Metrics

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Preparation and evaluation of biodegradable molecularly imprinted polymers Li Man, Zhu Quan-hong, Li Min-ting, Wang Wen-na, Dai Jiao-jiao, Yin Yong-guan 2013, 17 (38):  6817-6824.  doi: 10.3969/j.issn.2095-4344.2013.38.018 Abstract ( 471 )   PDF (900KB) ( 527 )   Save BACKGROUND: The cross-linking reagent is the main unit to support the skeleton of molecularly imprinted polymers, which is closely related to the bio-friendly adaption of polymers. The biocompatible and biodegradable capacities of common crosslinking agents are unclear. OBJECTIVE: To prepare a novel biodegradable molecularly imprinted polymer and to evaluate the adsorption and biodegradability properties of the polymer. METHODS: The biodegradable molecularly imprinted polymer was synthesized with the acrylated poly ε-caprolactone as the cross-linking reagent under the UV polymerization. The adsorption of the polymer was evaluated by adsorption isotherm, Scatchard analysis and kinetic curves. The biodegradation of the polymer was observed in the simulated physiological environment system in vitro. RESULTS AND CONCLUSION: Both the molecularly imprinted polymer and non-molecularly imprinted polymer showed an adsorption effect on theophylline, the template. But the adsorption amount of the molecularly imprinted polymer was significantly more than that of the non-molecularly imprinted polymer. The drug loading and encapsulation efficiency of the molecularly imprinted polymer were 1.54% and 12.48%, respectively. The degradation rates of molecularly imprinted polymer and poly(ε-caprolactone) diol were 6.60% and 1.33%, respectively, within the observation time in vitro. The obtained molecularly imprinted polymer not only exhibited specific adsorption to certain molecules but also showed good biodegradable properties in the simulated physiological environment system, which is necessary to be a potent drug carrier. Figures and Tables | References | Related Articles | Metrics

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Constructing a tissue engineered intervertebral disc scaffold Zhang Zi-yan, Yan Hua-dong, Tong Kun, Jiang Rui, Wu Han 2013, 17 (38):  6825-6831.  doi: 10.3969/j.issn.2095-4344.2013.38.019 Abstract ( 315 )   PDF (648KB) ( 420 )   Save BACKGROUND: Advancement in bioengineering based upon tissue engineering techniques may offer the possibility of repairing degenerative intervertebral disc. OBJECTIVE: To summarize the research progress in the scaffolds of tissue engineered intervertebral disc. METHODS: A computer-based retrieval was performed to search manuscripts describing tissue engineered intervertebral disc scaffolds published between January 1st, 1900 and December 31st, 2012 in PubMed database with the key words of “tissue engineering, intervertebral disc, scaffold” in English.   RESULTS AND CONCLUSION: Scaffold is an important part of tissue-engineered research. There are three kinds of materials for intervertebral disc scaffolds: natural biomaterials, synthetic materials, and composite materials. A variety of scaffold materials have their own advantages and disadvantages. Up to now, none of these scaffold materials is accepted as the most suitable one. The selection of scaffold materials is still to be further studied. The study and development of nanoscale biomaterials is an inevitable trend. Otherwise, with the help of bionics, improving scaffolds is also an inexorable trend in progress of simulating human intervertebral disc. Furthermore, injectable scaffold is also an research hot spot, and the selection range of injectable scaffold materials mainly focuses on chitosan, type Ⅱ collagen, hyaluronic acid, fibrin, elastin, and alginate. Currently, studies on chitosan as a scaffold material are relatively more. Figures and Tables | References | Related Articles | Metrics

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Insight into bone tissue engineering scaffold materials and their vascularization Zhao Tian-yuan, Sun Hong 2013, 17 (38):  6832-6838.  doi: 10.3969/j.issn.2095-4344.2013.38.020 Abstract ( 344 )   PDF (710KB) ( 532 )   Save BACKGROUND: With the development of tissue engineering technology, repairing large-area bone defects using tissue-engineered bone has become a hot spot. OBJECTIVE: To introduce the bone tissue engineering seed cells, cytokines, as well as the characteristics of scaffold materials and their vascularization.  METHODS: With the key words of “bone tissue engineering, scaffold, vascularization ” in Chinese and in English, respectively, a computer-based search of articles published from January 2000 to January 2012 was performed in CNKI and PubMed databases. Articles with the summary of bone tissue engineering, bone tissue engineering scaffolds and scaffold vascularization were included. RESULTS AND CONCLUSION: The selection of seed cells, application of cytokines, scaffold material performance and degree of vascularization in bone tissue engineering has an important influence on the repair of bone injuries. Appropriate seed cells is the study foundation in bone tissue engineering, cytokines serve as catalysts, and scaffold materials with good three-dimensional structure can promote cell growth and proliferation,tissue ingrowth, osteogenesis and vascularization. Each scaffold has its own inadequacies, so the combination of a variety of materials can reach a combined effect to meet the clinical demand. In addition, it is important to actively seek new material preparation technology and improve the existing methods, in order to create a more excellent scaffold. But the vascularization is still a major test for bone tissue engineering. Current methods to promote vascularization of tissue-engineered bone have some defects. For examples, the use of growth factors to promote vascularization can lead to disease progression in patients with metabolic abnormalities during; microsurgical techniques for tissue engineering bone vascularization are easy to cause trauma and deformity at other parts, which is not conducive to the patient’s physical rehabilitation. Figures and Tables | References | Related Articles | Metrics

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Biodegradable polymeric biomaterials as oral insulin carriers Li Yu-ping, Sun Li-zhen, Xiong Xiang-yuan, Li Zi-ling, Gong Yan-chun, Han Xiao 2013, 17 (38):  6839-6845.  doi: 10.3969/j.issn.2095-4344.2013.38.021 Abstract ( 411 )   PDF (759KB) ( 979 )   Save BACKGROUND: The carriers made from biodegradable and biocompatible polymeric materials represent an exciting approach to increase the bioavailability and stability of orally administered insulin by the chemical reaction or physical encapsulation of insulin. OBJECTIVE: To mainly review the research progress of the material types, preparation methods, physicochemical characteristics, in vitro release kinetics, and bioavailability of polymeric materials adopted as oral insulin carriers. METHODS: The first author searched PubMed, Elsevier and CNKI databases for articles (2002-01/2013-02) concerning the polymeric materials and oral insulin carriers with the key words of “polymeric biomaterials, oral insulin, carrier” in English and in Chinese. RESULTS AND CONCLUSION: Currently, there are mainly two kinds of polymeric biomaterials used for oral insulin delivery systems, that is, natural polymeric biomaterials (such as chitosan and alginates) and synthetic polymeric biomaterials. The most commonly used synthetic polymeric materials for the preparation of these vehicles are polyesters, polyacrylates and their copolymers, which are well known for their good biodegradability, biocompatibility, and physiological properties. Although researchers have tried to develop promptly oral insulin formulation using various technologies, the reports about clinical application or commercial success have not been seen because of several questions such as polymer material as a carrier, the lower bioavailability of insulin, the quality standards and stability of the formulation. Hence, future studies will focus on the development of a new type of polymer-based material as carriers by choosing the new materials or modifying physical and chemical characteristics of existing polymers, to avoid gastrointestinal destruction of the insulin and increase bioavailability of insulin in the body, so as to obtain the good controlled release rate and effect. Figures and Tables | References | Related Articles | Metrics

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Toothpaste containing NovaMin is applied to treat dentine hypersensitivity Li Chan-xiu, Huang Jiang-yong, Liang Huan-you 2013, 17 (38):  6846-6852.  doi: 10.3969/j.issn.2095-4344.2013.38.022 Abstract ( 524 )   PDF (616KB) ( 1096 )   Save BACKGROUND: NovaMin is a kind of bioactive glass, and its active ingredients react with saliva to form hydroxyapatite crystals, which deposit on the surface of the teeth and can close the exposed dentinal tubules. It can be used for the treatment of dentin hypersensitivity. OBJECTIVE: To study the effect of toothpaste containing NovaMin on tooth hypersensitivity patients after subgingival scaling and root planing surgery. METHODS: According to inclusion and exclusion criteria, 96 patients were picked out from 543 patients to participate in the experiment. In compliance with the principle of randomized, double-blind, comparison, 98 subjects were randomly divided into two groups: experiment group in which the toothpaste containing NovaMin was used, and control group in which the toothpaste without NovaMin was used. Visual analog scale scoring was used to evaluate the degree of sensitivity to air stimulus respectively before and 4 weeks after allergy experiment. RESULTS AND CONCLUSION: Totally 88 patients completed the experiment. After treatment with toothpaste for 4 weeks, visual analog scale scores in the experiment group decreased from 4.25±1.87 at baseline to 2.53±1.22 by air stimulus, and visual analog scale scores in the control group decreased from 4.03±1.92 at baseline to 3.63±1.45. The visual analog scale scores in the experiment group and control group both reduced, and the difference was with statistics significance (P < 0.05). Compared with the control group, visual analog scale scores in the experiment group decreased more significantly. It showed that the toothpaste containing NovaMin has significant effect on dentin hypersensitivity after subgingival scaling and root planing surgery. Figures and Tables | References | Related Articles | Metrics

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Influence on the bacteria and fungi taken from the impressions after the use of two kinds of mouthwashes Shi Xu-xu, Zhou Wen, Yang Wen-xiang 2013, 17 (38):  6853-6860.  doi: 10.3969/j.issn.2095-4344.2013.38.023 Abstract ( 488 )   PDF (742KB) ( 429 )   Save BACKGROUND: There are many methods for dental impression disinfection, including ultraviolet disinfection method, spraying, immerses disinfection method, argon plasma jet and radio frequency glow discharge on the argon gas ionization disinfection method. At present, there is still lack of studies addressing the disinfection effect after gargling with mouthwash. OBJECTIVE: To detect the killing effect on bacteria and fungi from the dental impressions, which are taken after gargling with cetylpyridinium chloride gargle and stable chlorine dioxide gargle, respectively. METHODS: One hundred patients were randomly divided into cetylpyridinium chloride gargle group and stable chlorine dioxide gargle group. They were told to gargle with clean water for 1 minute, and then impressions were taken to remove the models with sterile cotton swab sampling in neutralizing agent which were sent to laboratory for bacteria and fungi culture. After 1 hour, the patients were asked to gargle with the different mouthwashes for   1 minute again, and then sterile cotton swab sampling was done at the same position for bacteria and fungi culture. The number of colonies was recorded, and the killing effects on killing bacteria and fungi on the surface of the impressions before and after gargling with different mouthwashes were observed. RESULTS AND CONCLUSION: The number of bacteria and fungi before gargal had no significance difference before gargling. After gargling, the number of bacteria and fungi on the model was significantly lower than before (P < 0.001). Two groups did not appear with any adverse reactions, and patients felt refreshed and comfortable after gargling with mouthwash. To gargle with mouthwash before taking impressions can control the number of bacteria and fungi on the samples effectively, thereby achieving the aim of controlling the mutual infections between the doctor and the patients effectively. Figures and Tables | References | Related Articles | Metrics