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    28 June 2019, Volume 23 Issue 18 Previous Issue    Next Issue
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    Three-dimensional printing porous titanium alloy scaffold repairs radial bone defect in rabbits
    Rui Min, Zheng Xin, Zhang Yunqing, Jiang Xuefeng, Gu Jiaye, Zhao Fengchao, Guo Kaijin
    2019, 23 (18):  2789-2793.  doi: 10.3969/j.issn.2095-4344.1705
    Abstract ( 401 )   PDF (820KB) ( 176 )   Save
    BACKGROUND: Various methods have been applied in the treatment of long bone defects, but each of them had some defects, making great challenge to clinicians. Three-dimensional-printed bone grafting material is expected to become an alternative method for long bone defects.
    OBJECTIVE: To investigate the bone regeneration of three-dimensional-printed titanium alloy scaffold in repairing large radical defects of rabbits in vivo and to explore its feasibility in clinical practice．
    METHODS: Twenty healthy male New Zealand White rabbits aged 9 months were included (provided by Laboratory Animal Center of Xuzhou Medical University). The rabbit bilateral forelimbs were scanned by CT preoperatively. The porous titanium alloy scaffolds were produced by three-dimensional printing technology based on the right side of middle radical shaft, which cut during the operation. The internal porosity and connectivity of the scaffold were observed by scanning electron microscope. A 20 mm radial segmental bone defect was made in the bilateral radius. Titanium alloy scaffolds were implanted in one side (experimental group), and the other side was filled with nothing (control group). On the first day and at 12 weeks postoperatively, X-ray was taken. The rabbits were sacrificed at 12 weeks postoperatively, and the forearms were harvested for gross observation and histological observation. Besides, the bone healing was evaluated by micro-CT.
    RESULTS AND CONCLUSION: (1) The inner structure of scaffold was alveolate, and the pores were connected to each other with an average pore size of about 300 μm and a porosity of 60% to 65%. (2) Continuous bridged callus with a smooth surface were observed on the surface of titanium alloy scaffolds at postoperative 12 weeks. However, both ends were closed in control group, and the defect area was filled with fibrous tissue. (3) In the experimental group, osseous connection between titanium alloy scaffolds and both ends was observed on X-ray images at 12 weeks postoperatively, and small amount of callus was noticed at both ends and the ulnar side of the radius in the control group, with closed marrow cavity. (4) Both micro-CT and histological analysis showed that the titanium alloy scaffolds had good ability to facilitate the osteointegration. The bone volume fraction in the experimental group (26.35%±3.89%) was significantly higher than that in the control group (2.19%±1.36%) (P < 0.05). (5) In summary, porous titanium alloy scaffold produced by three-dimensional printing technology possesses admirable biocompatibility and osteoconductivity. It can be designed as required shape and be used as the appropriate biological material for bone defect repairing.
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    Effect of geometric design of tibial liner of knee prosthesis on its contact mechanics and kinematics
    Wang Meng, Li Xing, Cheng Bo, Wang Junyuan, Du Wenhua, Liu Feng
    2019, 23 (18):  2794-2799.  doi: 10.3969/j.issn.2095-4344.1697
    Abstract ( 331 )   PDF (751KB) ( 160 )   Save
    BACKGROUND: Geometric parameter of knee prosthesis makes important effect on sport performance and contact force, and decides the service life of knee prosthesis.
    OBJECTIVE: To analyze the effects of anterior sagittal radius, the posterior sagittal radius and the coronal radius of curvature of the tibial liner of knee prosthesis on the contact mechanics and kinematics of the knee joint.
    METHODS: The standard model based on the product of total knee arthroplasty DePuy PFC CR posterior cruciate ligament retained prosthesis from Johnson & Johnson’s Orthopaedic Company was applied. The three-dimensional solid model of tibia coronal radius enlargement prosthesis, tibia sagittal radius enlargement prosthesis and tibia coronal posterior radius enlargement prosthesis were established by changing the sagittal anterior radius, sagittal posterior radius and coronal curvature radius of tibial liner of the knee prosthesis. The force-controlled display dynamic gait cycle finite element was built to simulate the gait periodic motion after knee arthroplasty. The results of the maximum contact pressure, contact area, anterior and posterior displacement of tibial and internal and external rotation angle of the tibial pad during one gait cycle were obtained.
    RESULTS AND CONCLUSION: (1) Compared with the standard model, the contact pressure of the tibial liner was increased significantly and the contact area was decreased obviously. But decreased sagittal conformity would not lead to significant increase in maximum contact pressure and contact area. (2) Compared with the standard model, a distinct tibial backward movement was observed when the anterior curvature radius of the tibial liner increased. A slight tibial backward movement was observed when the sagittal posterior curvature radius increased. The increased anterior and posterior curvature radii of tibial liner led to a significant internal rotation, especially for the standing stage when the maximum rotation angle reached to 10° from 8°. The increase in coronal curvature of the tibial liner showed an unnoticeable impact on the kinematic performance of the prosthesis. (3) These results showed that the conformity of femoral condyle of the knee joint prosthesis and tibial liner in coronal plane is the main geometric parameter affecting the contact area and contact pressure of the tibial liner. Decreasing the coronal conformity properly will not cause a significant impact on the stability of knee joint motion. The consistency of the sagittal curvature radius of the prosthesis is the main geometric parameter affecting knee joint motion.
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    Application of beta-tricalcium phosphate/alpha-calcium sulfate hemihydrate combined bone grafts in  multi-segment arthrodesis of spine: micro-CT evaluation
    Liang Maohua, Mao Keya, Xia Bo, Liu Qiang, Tang Peifu, Wang Jifang
    2019, 23 (18):  2800-2805.  doi: 10.3969/j.issn.2095-4344.1731
    Abstract ( 323 )   PDF (744KB) ( 118 )   Save
    BACKGROUND: Because of the limitation of physico-chemical properties, one kind of graft material alone in spinal arthrodesis cannot match the clinical demands, therefor combined bone grafts consisted of more than two kinds of materials are the issue of concern.
    OBJECTIVE: To evaluate the new bone formation and the graft materials resorption of β-tricalcium phosphate/α-calcium sulphate hemihydrate combined bone grafts in rabbit model of multi-segments posterolateral arthrodesis of thoracic vertebrae by micro-CT.
    METHODS: Thirty-six rabbits (provide by Experimental Animal Center of General Hospital of PLA) were selected, and their superior/inferior articular processes, bilateral vertebral plate and transverse processes of T4-8 were removed. β-Tricalcium phosphate/α-calcium sulphate hemihydrate combined bone grafts were transplanted into the lateral posterior part of left vertebral plate of T4-8 (control group), and autologous bone was transplanted into the another side (control group). The thoracic vertebrae were removed at postoperative 4, 8 and 12 weeks for micro-CT scanning. The morphologic changes of fusion masses were observed. The total bone mineral content, material mineral content, and material volume fraction in the experimental group were analyzed. The experimental protocol was approved by the Animal Ethics Committee of General Hospital of PLA, approval number: 201511007.
    RESULTS and CONCLUSION: (1) At the end of 4th week postoperatively, there were a few osteophytes attached to the laminae, transverse processes and zygapophysial joints at both sides of graft areas. In the experimental group, the morphology of bone graft was clear, and there were few newly born bones surrounding the graft. At the end of 8th week postoperatively, there were large amount of osteophytes in the graft areas, fusion masses had involved in the complete motion segments, and the newly born bones being surrounded the graft in the experimental group. At the end of 12th week postoperatively, the fusion masses were enlarged, appeared to be columnar, and the fusion masses were fused into the zygapophysial joints. There were abundant newly born bones surrounding the graft materials in the experimental group, and the scaffold degraded. The fusion mass in the experimental group was obviously larger than that in the control group. (2) The bone mineral content, material mineral content, and material volume fraction in the experimental group were decreased with time. (3) In summary, stable fusion effect of combined bone grafts can be achieved in rabbit models of multi-segments posterolateral thoracic arthrodesis, the combined bone grafts degrade with time, and the degrade speed matches with new bone formation.   
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    Supercritical bone defect repaired by composite bioscaffolds loaded with recombinant human bone morphogenetic protein 2/poly(lactic acid)
    Zhou Sirui, Xiao Hongli, Huang Wenliang, Deng Jiang, Ye Peng
    2019, 23 (18):  2806-2811.  doi: 10.3969/j.issn.2095-4344.1732
    Abstract ( 250 )   PDF (807KB) ( 98 )   Save
    BACKGROUND: Preliminary study has prepared the silk fibroin/chitosan/nano-hydroxyapatite composite bioscaffold and the recombinant human bone morphogenetic protein 2/polylactic acid sustained release system.
    OBJECTIVE: To observe the effect of radial bone defect repairing in dogs with composite bioscaffold loaded with recombinant human bone morphogenetic protein 2/poly(lactic acid) sustained-release microspheres.
    METHODS: Silk fibroin/chitosan/nano-hydroxyphosphorous bioscaffolds were prepared by vacuum freeze-drying and chemical crosslinking. Recombinant human bone morphogenetic protein 2/poly(lactic acid) sustained-release microspheres were prepared by compound emulsion volatilization, and then prepared the three-dimensional bioscaffold. Eight adult dogs (provided by the Experimental Animal Center of Zunyi Medical University) were used to make a critical bone defect model of the radius (3 cm in the middle radius). Four bone defects were implanted with the three-dimensional bioscaffold with sustained release microspheres and autologous cancellous bones (experimental group 1). The other four only implanted with autologous cancellous bone (control group 1). Another eight adult dogs were used to make a superficial bone defect model of the radius (5 cm in the middle radius). Four bone defects were implanted with the three-dimensional biological scaffold with sustained release microspheres and autologous cancellous bone (experimental group 2). The other four were implanted only with autologous cancellous bone (control group 2). X-ray examination was performed at postoperative 4, 8, and 12 weeks. At postoperative 12 weeks, the radius of the defect area was removed for histopathological observation. The study was approved by the Ethics Committee of Zunyi Medical University, approval number: (2016)2-071.
    RESULTS AND CONCLUSION: (1)X-ray: at postoperative 12 weeks, the medullary cavity in the experimental group 1 was recanalized and the cortical bone was formed. The defect in the control group 1 was basically completely connected, but the medullary cavity recanalization and cortical bone shaping were incomplete. In the experimental group 2, the medullary cavity was basically recanalized, the cortical bone shaping and bone ingrowth were basically completed. The control group 2 appeared no bone connection, no cortical bone shaping. (2) Histological observation: in the experimental group 1, the bone defect was connected completely, and the cortical bone formation and complete medullary cavity recanalization were observed. In the control group 1, bone tissue was formed, and a large amount of fibrous tissues were observed, no cortical bone was formed, and the medullary cavity was not recanalized. In experimental group 2, the cortical bone formation and the completion of the medullary cavity were recanalized in the bone defect. The control group 2 showed a small amount of bones, no cortical bone formation and recanalization of the medullary cavity. The experimental group 1 has better bone repair effect than the experimental group 2. (3) These results imply that the three-dimensional bioscaffolds loaded with recombinant human bone morphogenetic protein 2/poly (lactic acid) sustained-release microspheres can effectively repair the critical and supercritical bone defects of canine tibia to some extent.
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    Effects of mixed use of different materials of implants on fracture healing
    Lü Guodong
    2019, 23 (18):  2812-2816.  doi: 10.3969/j.issn.2095-4344.1726
    Abstract ( 346 )   PDF (768KB) ( 82 )   Save
    BACKGROUND: As the two most commonly used implant materials in orthopedic surgery, stainless steel and titanium alloy, are inevitably to contact with each other in clinical application. But the effect of the combined application of internal fixation on peripheral tissue disturbance and fracture healing is rarely reported.
    OBJECTIVE: To observe and evaluate the effects of simple and mixed use of different materials of implants (stainless steel and titanium alloy) on inflammatory response and bone healing in the surrounding tissues of fractures.
    METHODS: Twenty-four New Zealand white rabbits (provided by the Animal Lab of the First Affiliated Hospital of aotou Medical College of Inner Mongolia University of Science & Technology) were selected to establish the model of tibial fracture. The rabbit models were randomly divided into four groups, and underwent internal fixation with stainless steel plate and screw (group A), stainless steel plate and titanium screw (group B), titanium plate and screw (group C), or titanium plate and stainless screw (group D). The tibia specimens were removed at 6 and 12 weeks after surgery for X-ray and histological examinations.
    RESULTS AND CONCLUSION: (1) Hematoxylin-eosin staining: at 6 weeks after surgery, all the specimens around the plants in each group had medium amount of inflammatory cell infiltration, with abundant lymphocytes, few neutrophils, and visible capillaries and fibrous cells. At 12 weeks after surgery, the number of lymphocytes in each group was decreased, with occasional macrophages and neutrophils. The thickness of the fibrous membrane on the surface of the bone plate was decreased significantly compared with that at 6 weeks after surgery. There was no significant difference between groups at different time points after surgery. (2) X-ray results: at 6 weeks after surgery, the fracture reduction was good in each group, the position of internal fixators was good, and the fracture line was blurred. No obvious callus formation was observed on the fracture line and around the implant, and no significant difference was found among groups. At 12 weeks after surgery, the fracture lines in each group disappeared. The internal fixators were in good position, and the callus could not be revealed well due to internal fixator covering. After removal of internal fixators, callus formation was observed along the edge of fixed part, and obvious callus formation was observed at the fracture end of the original fracture. There was no significant difference among groups. (3) These results indicate that in animal experiments, the internal fixation of fracture with different materials (stainless steel and titanium) implants cannot cause severe inflammatory reaction and makes no effect on the speed of fracture healing.
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    Measuring osteotomy versus gap balance in total knee arthroplasty
    Wu Jianming, Hu Wei, Liu Xiangyang, Zhao Hui
    2019, 23 (18):  2817-2821.  doi: 10.3969/j.issn.2095-4344.1155
    Abstract ( 470 )   PDF (672KB) ( 115 )   Save
    BACKGROUND: Total knee arthroplasty is often used to treat knee joint diseases. The intraoperative osteotomy mainly measures osteotomy and gap balance technology, which can ensure the stability of prosthesis implantation and improve the prognosis by reasonable osteotomy.
    OBJECTIVE: To statistically analyze the clinical efficacy of the osteotomy and gap balance technique in patients undergoing total knee arthroplasty.
    METHODS: Data of 76 cases of primary osteoarthritis from May 2015 to October 2016 were collected. The patients were divided into control and trial groups (n=38/group). The control group used the measurement osteotomy technique, and the trial group used the gap balance technique to compare the surgical indexes and prognostic effects at 1 year postoperatively.
    RESULTS AND CONCLUSION: The femoral distal osteotomy and thickness of polyethylene liner in the trial group were significantly higher than those in the control group at postoperative 3 days (P < 0.05). Compared with the control group, the knee joint stability and knee flexion 90° femoral angle were improved better in the trial group (P < 0.05). The excellent and good rate of the lower limb strength and the anatomical axis of the lower leg in the control and trial groups was 47% and 61%, respectively (P > 0.05). There was no case of loosening of the prosthesis in the two groups during the follow-up, and there were no significant differences in other complications (P > 0.05). After 1 year of follow-up, the Visual Analogue Scale and Western Ontario and McMaster Universities Osteoarthritis Index pain scores in the trial group were significantly decreased, and the Knee Society Score function was significantly improved (P < 0.05). These results imply that the gap balance technique used in total knee arthroplasty, can significantly improve the clinical symptoms and prognosis.
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    Changes of stress and displacement of three-dimensional finite element model of ankle joint using different material assignment methods
    Luo Jian, Wang Lihua, Wang Tao, Wen Hui
    2019, 23 (18):  2822-2826.  doi: 10.3969/j.issn.2095-4344.1194
    Abstract ( 292 )   PDF (671KB) ( 96 )   Save
    BACKGROUND: Three-dimensional finite element simulation analysis of human body is widely used in human biomechanical research because of its own superiority, but the assignment of bone material properties has not been definitive.
    OBJECTIVE: To explore a more practical method of material attribute assignment by conducting finite element analysis of ankle joint biomechanics.
    METHODS: Three-dimensional reconstruction of the ankle joint CT data from a normal male volunteer was performed and underwent surface fitting. Then the finite element model was meshed, and the two methods of uniform assignment and gray value assignment were used to give the material properties of bones. The biomechanical response of the ankle joint in five working conditions: double leg standing, single foot standing, normal gait, upstairs and downstairs were simulated.
    RESULTS AND CONCLUSION: (1) In the five working conditions, the peak stress of body of talus in the uniformity group was obviously higher than that in the gray value assignment group. The stress value of the fibular joint surface was similar in the two methods. (2) In the uniform assignment group, the stress distribution was concentrated and the distribution area was narrow in the talar neck. The gray value assignment group had a uniform stress distribution at the talar neck and the distribution area covered the entire talar neck. (3) The tibial deformation was greater than fibula in the uniform assignment group, and the fibula deformation was greater than tibia in the gray value assignment group. (4) The uniform assignment group was larger than the gray value assignment group in the difference between the deformation of the tibia and the fibula. (5) In summary, in the finite element analysis of the ankle joint biomechanics, the gray value assignment method is more in line with the clinical actual situation, which has high accuracy and can solve the modeling error caused by the individual difference to some extent.
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    Evaluation of the effect of early total weight-bearing training after cementless total hip arthroplasty
    Wu Weiyong, Xu Weiguo
    2019, 23 (18):  2827-2832.  doi: 10.3969/j.issn.2095-4344.1196
    Abstract ( 414 )   PDF (717KB) ( 103 )   Save
    BACKGROUND: There is no consensus on the way of weight-bearing after total hip arthroplasty, and early weight-bearing exercise in clinical practice still remains controversial.
    OBJECTIVE: To investigate the clinical efficacy of applying enhanced recovery after surgery in guiding early weight-bearing exercises after cementless total hip arthroplasty.
    METHODS: One hundred patients undergoing cementless total hip arthroplasty for femoral neck fractures at Department of Orthopedics, Tianjin Hospital from March 2016 to April 2017 were enrolled, and were then randomized into two groups (n=50/group). The trial group received early weight-bearing exercise with the concept of enhanced recovery after surgery, and control group was given weight-bearing exercise at 3 weeks with the traditional rehabilitation concept. Informed consents were obtained from all patients, and the trial was approved by the Ethics Committee of Tianjin Hospital.
    RESULTS AND CONCLUSION: (1) All patients were followed up for 18 months. (2) The Visual Analog Scale score in the trial group was significantly lower than that in the control group at 3 days, 2 weeks and 3 months after operation (P < 0.05). (3) Hip range of motion in the trail group was significantly superior to the control group at postoperative 3 months (P < 0.05). (4) The Harris hip score in the trial group was significantly superior to the control group at 6 months, 1 and 1.5 years postoperatively (P < 0.05). (5) At postoperative 1.5 years, the SF-36 score showed that the physiological function and bodily pain in the trial group were significantly superior to the control group (P < 0.05). (6) X-ray measurements was performed at 1.5 years postoperatively, and there was no significant difference in the incidence of femoral prosthesis subsidence (P=0.117). (7) The incidence of postoperative complications in the trial group (18%) was significantly lower than that in the control group (38%) (P=0.022). The incidences of nausea and vomiting and venous thrombosis perioperatively, and postoperative anxiety in the trial group were significantly lower than those in the control group (P < 0.05). (8) In summary, the application of enhanced recovery after surgery combined with early weight-bearing exercises in cementless total hip arthroplasty can achieve a good clinical effect, and will not cause prosthesis loosening.
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    Preparation and properties of degradable polymethyl methacrylate bone cement incorporated with　N-acetyl cysteine
    Zhao Kangquan, Pi Bin, Sha Weiping, Ge Jianfei, Yang Huilin, Wang Liming
    2019, 23 (18):  2833-2841.  doi: 10.3969/j.issn.2095-4344.1671
    Abstract ( 311 )   PDF (1033KB) ( 107 )   Save

    BACKGROUND: Polymethyl methacrylate bone cement is popular in kyphoplasty and vertebrolplasty, while some of its key properties still need improvement.

    OBJECTIVE: To prepare degradable polymethyl methacrylate bone cement incorporated with N-acetyl cysteine and search for its compressive strength, operability, surface appearance, N-acetyl cysteine release, degradation property, biocompatibility and osteogenic capacity.
    METHODS: Traditional polymethyl methacrylate bone cement and degradable polymethyl methacrylate bone cement incorporated with 25 mmo/L N-acetyl cysteine and 5% 2-methylene-1,3-dioxepane (NAC/5%MDO) were prepared. Setting time of bone cement, microstructure, degradation property and N-acetyl cysteine release in vitro were detected. MC3T3-E1 cells were allotted into three groups, and cultured with traditional polymethyl methacrylate bone cement, NAC/5%MDO extract and conventional culture solution (control group), respectively for 1, 3, and 5 days. The cell proliferation was detected by cell counting-kit 8 assay. Cell morphology was observed by hematoxylin-eosin staining. The cell adhesion was observed by scanning electron microscope after 3 days of culture. The osteogenic capacity of bone cement was detected by Alizarin red staining at 21 days.
    RESULTS AND CONCLUSION: (1) There was no significant difference in the setting time of bone cement between polymethyl methacrylate and NAC/5%MDO groups (P > 0.05). (2) Scanning electron microscope observed that no pore structure was observed on the bracken face in the polymethyl methacrylate and NAC/5%MDO groups. (3) NAC/5%MDO bone cement could release N-acetyl cysteine in PBS slowly and continuously. (4) Number-average molecular of NAC/5%MDO bone cement at 1 and 5 days after immersed in acetic acid was significantly decreased compared with baseline (P < 0.05), and traditional polymethyl methacrylate bone cement did not change significantly. (5) The cell proliferation was insignificant difference among groups (P > 0.05). Hematoxylin-eosin staining results revealed good cell morphology and density in each group. Scanning electron microscope observed that the cell adhered to the NAC/5%MDO bone cement with good shape. The Alizarin red staining in the NAC/5%MDO group was deeper than that in the traditional polymethyl methacrylate. (6) These results indicate that degradable polymethyl methacrylate bone cement incorporated with N-acetyl cysteine possesses good cytocompatibility, degradation property, sustained-release and osteogenic capacity.
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    Effects of different types of fluoride-free toothpaste on the remineralization of enamel after acid erosion: an in vivo study
    Wu Tingyun, Wang Detang, Zhu Youjia, Ruan Qiong, Wu Aimin, He Shangqun, Zeng Xiaofang
    2019, 23 (18):  2842-2846.  doi: 10.3969/j.issn.2095-4344.1727
    Abstract ( 441 )   PDF (685KB) ( 92 )   Save
    BACKGROUND: The development of the swallowing reflex in young children is incomplete, and there is a risk of fluorosis when using fluoride toothpaste. By contrast, fluoride-free toothpaste is much safer for children.
    OBJECTIVE: To compare the effects of OHOLV toothpaste, GC MI paste and fluoride-free toothpaste on the remineralization of demineralized enamel in family oral care.
    METHODS: Fifteen patients, aged 12-18 years, who were prepared to receive extractions of healthy first premolars (60 teeth in total) due to orthodontic needs in the Department of Stomatology of Jingmen Rehabilitation Hospital, were included. Left maxillary and mandibular first premolars as controls were extracted immediately after acid eroding on the buccal surface. Five patients were randomly selected and included into fluoride-free toothpaste group. After their right maxillary and mandibular first premolars were eroded, fluoride-free toothpaste was applied every morning and evening, and after 10 days, these teeth were extracted. Five patients were randomly selected and included into OHOLV toothpaste group. After their right maxillary and mandibular first premolars were eroded, OHOLV toothpaste was applied every morning and evening, and after 10 days, these teeth were extracted. Similarly, for the five patients in the GC MI paste group, the same erosion was performed before the application of GC MI paste for 3 minutes every morning and evening, and after 10 days, these teeth were also extracted. Buccal enamel specimens were isolated, observed and analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy.
    RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that the enamel surface in the control group was irregular, porous and honeycomb-shaped, the center of the enamel rod dissolved, and many porous defects appeared. A few scattered mineral deposits could be seen on the enamel surface in the fluoride-free toothpaste group. There were still a lot of honeycomb-shaped pores on the enamel surface in the OHOLV toothpaste and GC MI paste groups. Meanwhile, there were also a large number of mineral deposits and the pores became smaller. The mineralized particles were small and the deposits were uneven. The GC MI paste group had a larger amount of deposits. (2) Energy-dispersive X-ray spectroscope showed no difference in calcium and phosphorus levels between control and fluoride-free toothpaste groups (P > 0.05). No difference was observed in the calcium and phosphorus levels between OHOLV toothpaste and GC MI paste groups (P > 0.05). The OHOLV toothpaste and the GC MI paste groups had higher calcium and phosphorus levels than the control and fluoride-free toothpaste groups (P < 0.05). (3) These results suggest that OHOLV toothpaste and GC MI paste can significantly promote the remineralization of demineralized enamel, especially GC.
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    Preparation and characterization of liver extracellular matrix hydrogel
    Cao Yulun, Cheng Yuan, He Guolin, Li Yang, Peng Qing, Gao Yi, Pan Mingxin
    2019, 23 (18):  2847-2851.  doi: 10.3969/j.issn.2095-4344.1682
    Abstract ( 459 )   PDF (578KB) ( 129 )   Save
    BACKGROUND: Liver extracellular matrix hydrogel has been shown to promote the behavior of liver-specific cells closer to the body, enhance the activity and function of hepatocytes, and promote the vascularization of endothelial cells and the bile duct formation of bile duct epithelial cells, but the characteristics of liver matrigelis little known.
    OBJECTIVE: To prepare the liver extracellular matrix hydrogel by mild decellularization technique and to investigate its characterization preliminarily.
    METHODS: Fresh frozen pig liver tissue sections were taken and placed in deionized water at room temperature for 4 times, transferred to 0.02% trypsin/0.05% EDTA solution preheated at 37 °C, stirred at 37 °C for 1 hour, and washed with deionized water, put into 3% Triton X-100 solution and stirred for 1.5 hours. The liver piece was rinsed with deionized water, stirred in 4% sodium deoxycholate solution for 1.5 hours, and rinsed with excess deionized water to obtain the decellularized liver scaffold. The liver scaffold was transferred into 0.1% peracetic acid solution and stirred for 2.0-3.0 hours, placed in 1×PBS solution for 15 minutes, stirred in deionized water for twice, rinsed in 1×PBS for 15 minutes, and then lyophilized and liquid nitrogen-milled. Digested into a liver matrix solution, and after subsequent trimming, the polypeptide molecules self-assemble into a liver matrix hydrogel. The degree of decellularization, DNA content, composition, turbidity dynamics and microstructure of the liver matrix hydrogel were examined.
    RESULTS AND CONCLUSION: (1) The decellularized liver scaffold was obtained by mild decellularization technique, and the decellularization was complete. (2) The DNA content of the decellularized liver scaffold was significantly lower than that of normal liver tissue (P < 0.001). (3) The liver matrix hydrogel precursor solution retained many components of the pig liver extracellular matrix, such as collagen, elastin, glycan and its precursors. (4) The turbidity kinetics experiment showed that the absorbance value of the plateau increased with the increase of the mass concentration of the liver matrix gel. (5) Scanning electron microscope showed that the liver matrix hydrogel possessed a fibrous network porous structure, and the nano-scale extracellular matrix fibers were interlaced with each other. As the mass concentration of the liver matrix hydrogel increased, the fiber density increased relatively and the diameter revealed no change. (6) These results indicate that the liver matrix hydrogel is prepared by gentle decellularization technique and exhibits a three-dimensional network structure, which provides a structural basis for cell adhesion and growth.
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    Effect of surface treatment reagents and treatment time on bond strength of glass fiber posts to resin cement
    Zhou Han, Hui Min, Miao Detian, Wang Le, Dong Xiling, Zhang Xiaoming
    2019, 23 (18):  2852-2857.  doi: 10.3969/j.issn.2095-4344.1734
    Abstract ( 332 )   PDF (776KB) ( 118 )   Save
    BACKGROUND: At present, there is no uniform standard for the treatment time of chemical reagents for surface treatment of glass fiber posts. Therefore, studying the effect of treatment time of glass fiber post surface treatment reagents on the bond strength between fiber posts and resin cements is of great significance.
    OBJECTIVE: To evaluate the effect of two chemical agents on the bonding strength of glass fiber post and resin cement after surface pretreatment of glass-fiber posts at different times.
    METHODS: Forty-eight glass fiber posts were randomly divided into eight groups according to different surface treatment methods, six in each group. Group A received no special treatment; group B was treated with silanization for 1 minute; group C1 underwent a 30% hydrogen peroxide surface treatment for 5 minutes prior to 1-minute silanization; group C2 underwent a 30% hydrogen peroxide surface treatment for 10 minutes prior to 1-minute silanization; group C3 underwent a 30% hydrogen peroxide surface treatment for 15 minutes prior to 1-minute silanization; group D1 underwent a 35% phosphoric acid surface treatment for 30 seconds prior to 1-minute silanization; group D2 underwent a 35% phosphoric acid surface treatment for 60 seconds prior to 1-minute silanization; group D3 underwent a 35% phosphoric acid surface treatment for 90 seconds prior to 1-minute silanization. The surface morphology of the treated glass fiber posts was observed under scanning electron microscope. The glass fiber post was bonded to the resin cement to form a cylindrical resin block and cut into a thin sample. The sheet was placed on a universal testing machine for micro-extrusion experiments. The failure mode of the specimens was observed under a stereo microscope.
    RESULTS AND CONCLUSION: (1) Scanning electron microscope: the surface of the fiber post had different degrees of matrix dissolution and fiber bundle exposure after hydrogen peroxide and phosphoric acid treatment, but did not destroy the integrity of the fiber bundle. (2) Micro-extrusion experiments: the order of the bonding strength was as follows: group C3 > group C2 > group C1 > group D2 > group D3 > group D1 > group B > group A, and there was significant difference between groups (P < 0.05) except for groups A and B, groups C2 and C3, and groups D2 and D3. (3) Stereo microscope: the failure mode in the groups A and B was almost destruction in adhesion. The other six groups showed destruction in adhesion, but the cohesive failure and mixed failure were increased, and the failure mode changed from destruction in adhesion into cohesive failure and mixed failure. (4) These results indicate that the optimal treatment time of 30% hydrogen peroxide is 10 minutes, and the optimal treatment time of 35% phosphoric acid is 60 seconds. 30% hydrogen peroxide solution treatment of fiber post surface for 10 minutes has great clinical application value.
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    Preparation and property analysis of drug-loaded sustained-release scaffold with antibacterial and anti-inflammatory roles
    Wu Jianxin, Luo Dan, Li Kun, Xu Ning, Ye Xiaojian
    2019, 23 (18):  2858-2864.  doi: 10.3969/j.issn.2095-4344.1670
    Abstract ( 339 )   PDF (1252KB) ( 155 )   Save
    BACKGROUND: When handling the local infection of the soft tissue of the wound, systemic oral antibiotics due to local concentration is low, cannot satisfy the bacteriostatic needs of local trauma. Although local antibiotics spraying powder can get a temporary high concentration, it is difficult to obtain satisfactory antibacterial effect, and high concentrations of drugs play destructive effect on local tissues.
    OBJECTIVE: To develop a drug-loaded sustained-release scaffold that can carry multiple drugs, so as to be used for the local antibacterial and anti-inflammatory treatment of trauma.
    METHODS: Mesoporous silica nanoparticles loaded with drug microspheres were prepared by mixing levofloxacin, tinidazole and methylprednisone solution with mesoporous silica nanoparticles in a negative pressure suction device. According to the designed CAD model in advance, the layer upon layer porous network structure of mesoporous silica nanoparticles loaded with drug microspheres and poly lactide-glycolide acid was alternately printed by three-dimensional printer. Finally, the membrane drug-loaded composite scaffold was obtained (experimental group). Meanwhile, calcium phosphate porous ceramic scaffolds loaded with three drugs were served as control group. The drug loading rate of scaffolds was detected. The two kinds of scaffolds were respectively co-cultured with fibroblasts. The cell proliferation was detected by cell counting-kit 8 assay to evaluate the cytotoxicity of scaffolds. The two scaffolds were immersed in PBS, respectively, to detect the drug release rule in vitro. These scaffolds were applied to the soft tissue injury sites of New Zealand white rabbits (provided by the Laboratory Animal Center of the Navy Medical University). The liver and kidney function, blood samples and drug concentrations in the surrounding tissues were detected at postoperative different time points.
    RESULTS AND CONCLUSION: (1) The drug loading rates of levofloxacin, tinidazole and methylprednisolone in the scaffold of the experimental group were 31.21%, 22.14% and 23.58%, respectively. The drug loading rates of the three drugs in the scaffold of the control group were 19.44%, 11.14% and 9.32%, respectively. (2) The cell proliferation rates of in the two kinds of scaffolds at different time points were more than 80%, with grade 1 cytotoxicity. (3) In vitro, the release of the three drugs in the scaffold of the control group was basically complete at 2 weeks, the release of levofloxacin in the scaffold of the experimental group was up to 10 weeks, and the release of tinidazole and methylprednisolone in the scaffold of the experimental group was up to 8 weeks. (4) In vivo, the release time of the three drugs in blood samples and local tissues in the experimental group was longer than that in the control group, and the effective release time of the drugs was more than 10 weeks. The scaffold of the experimental group had transient effect on the liver function of rabbits (5) In summary, the multi-drug sustained-release scaffolds are successfully prepared by three-dimensional printing technology, which is expected to achieve combined, high and continuous local antibacterial and anti-inflammatory effects in the local wound, and be effectively applied in the adjuvant treatment of various local wounds.
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    Coaxial printed double crosslinked alginate/silk fibroin vascular network scaffold
    Li Ningning, Xu Mingen, Suo Hairui, Wang Ling
    2019, 23 (18):  2865-2871.  doi: 10.3969/j.issn.2095-4344.1733
    Abstract ( 460 )   PDF (852KB) ( 197 )   Save
    BACKGROUND: Construction of tissue engineering vascular structures is a key to the regeneration of complex tissues and organs. The use of three-dimensional printing technology to construct vascular structures has become a hotspot.
    OBJECTIVE: A highly connected and perfusable vascular network was rapidly deposited by a three-dimensional bioprinter with a coaxial nozzle using alginate/silk fibroin bioink.
    METHODS: A mixed solution containing 5% sodium alginate and 5% silk fibroin as the bio-ink, and a mixed solution containing 5% calcium chloride and 13% F127 as the crosslinker, alginate/silk fibroin gel was printed using a bio-printer and subjected to optical coherence tomography and scanning electron microscopy. The solution containing 5% sodium alginate and 5% silk fibroin mixed with the suspension of human liver cancer cells (C3A) as the bio-ink, and a mixed solution containing 5% calcium chloride and 13% F127 as the crosslinker, the cell-containing sodium alginate/silk fibroin gel was printed on a bio-printer. Then, the printed scaffold was placed in the medium for 24 hours, and then stained by Calcein-AM and observed under a fluorescence microscope.
    RESULTS AND CONCLUSION: (1) Optical coherence tomography: a multi-layer composite hollow tube network formed the structure of the scaffold. The gel filament had a complete hollow structure, and the channels were interconnected. The structure was similar to the hollow passage of the blood vessel, which was beneficial to the transportation of nutrients and metabolic waste. (2) Scanning electron microscope: the hollow pipe structure with the diameter of about 400 μm arranged in parallel, and the pipe boundaries were clear. The microporous structure caused by the removal of F127 was formed between the boundaries. (3) Fluorescence microscope: the cells were evenly dispersed in the material on both sides of the channel, and the cells grew well in the scaffold with the survival rate of above 95%. (4) These results suggest that three-dimensional bioprinting technology based on coaxial nozzles and sodium alginate/silk fibroin bio-ink can be used to construct vascularized functional tissues in the future.
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    Physicochemical properties and cellularization of hydroxyapatite/zirconium dioxide foam ceramics
    Chai Le, Quan Renfu, Lü Jianlan, Huang Xiaolong, Zhang Can, Ren Weifan, Qian Jiansheng
    2019, 23 (18):  2871-2879.  doi: 10.3969/j.issn.2095-4344.1653
    Abstract ( 387 )   PDF (962KB) ( 118 )   Save
    BACKGROUND: Studies have confirmed that hydroxyapatite/zirconium dioxide foam ceramic materials have the ability to promote bone regeneration, but their genotoxicity has not been reported.
    OBJECTIVE: To detect the porosity, compressive strength, genotoxicity and cytotoxicity of hydroxyapatite/zirconium dioxide foam ceramics and to explore the osteogenic differentiation of artificially induced pluripotent stem cells cultured on the hydroxyapatite/zirconium dioxide foam ceramics.
    METHODS: The hydroxyapatite/zirconium dioxide foam ceramics was prepared by high temperature sintering method with addition of pore-forming agent. The porosity and compressive strength of hydroxyapatite/zirconium dioxide foam ceramics were detected, and the genotoxicity of the material were tested using Salmonella typhimurium reverse mutation test. L929 cells were cultured with hydroxyapatite/zirconium dioxide foam ceramics extract (experimental group), phenol solution (positive control group), and normal saline (negative control group). After 24 hours of culture, the cytotoxicity was detected using cell counting kit-8 toxicity test. Artificially induced pluripotent stem cells-derived mesenchymal stem cells were inoculated onto the hydroxyapatite/zirconium dioxide foam ceramics. On the 3rd, 7th, 10th and 14th days of culture, the amount of alkaline phosphatase secreted by the cells was detected. On the 14th day of culture, the expression of type I collagen in the cells was detected by immunohistochemistry, and cell adhesion was observed by scanning electron microscope.
    RESULTS AND CONCLUSION: (1) The porosity and compressive strength of hydroxyapatite/zirconium dioxide foam ceramics were (76.72±0.75)% and (11.60±1.35) MPa, respectively. (2) In the Salmonella typhimurium reverse mutation test, the metabolites of hydroxyapatite/zirconium dioxide foam ceramics were not mutagenic or carcinogenic. (3) In the cell counting kit8 test, the survival rate of the cells in the experimental group was close to that in the negative control group (P > 0.05), but still significantly higher than that in the positive control group (P < 0.05). (4) With the extension of culture time, the secretion amount of alkaline phosphatase was increased gradually, and there was significant difference at different observational time points (P < 0.05). (5) On the 14th day of culture, a great amount of artificially induced pluripotent stem cells-derived mesenchymal stem cells evenly distributed and grew well on the surface of hydroxyapatite/zirconium dioxide foam ceramics, and these cells had good morphology and highly expressed type I collagen. To conclude, the hydroxyapatite/zirconium dioxide foam ceramics has a certain compressive capacity and does not exhibit mutagenic effects and cytotoxicity, and promote the osteogenic differentiation of artificially induced pluripotent stem cells-derived mesenchymal stem cells cultured on its surface.
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    Effects of adding strontium ions into photocrosslinked alginate hydrogels on its mechanical and biological properties
    Zhao Delu, Tie Chaorong, Wang Xin, Zhu Huaian, Yang Sisi, Li Xiaobao, Yin Miao
    2019, 23 (18):  2880-2887.  doi: 10.3969/j.issn.2095-4344.1711
    Abstract ( 360 )   PDF (1114KB) ( 128 )   Save
    BACKGROUND: Photocrosslinked alginate gels have been attracting great interest due to its good stability, controllability and biocompatibility. However, as bone tissue engineering scaffolds, it still has some deficiencies, such as insufficient strength, poor cell adhesion performance and lack of bone induction.
    OBJCTIVE: To explore the changes of mechanical and biological properties of photocrosslinked alginate gels doped strontium ions.
    METHODS: After methacrylated alginate to form photocrosslinked methacrylated alginate hydrogels, photocrosslinked alginate hydrogels chelated strontium ions strontium ion-co-photocrosslinked methacrylated alginate were prepared by soaking photocrosslinked methacrylated alginate in strontium ion solution of different concentrations (0, 10, 30, 50, 80 and 100 mmol/L). The swelling ratio and elastic modulus of the gels were measured, and the surface morphology and elements of the materials were analyzed by scanning electric microscope and energy dispersive spectroscopy, respectively. MC3T3-E1 cells were seeded on the surface of photocrosslinked alginate gels that were incorporated with different concentrations of strontium ion for 4 hours, and then live/dead staining was used to observe the cell adhesion. The cell spreading on day 3 was determined by live/dead staining.
    RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that the density of photocrosslinked alginate gels increased and the pore size decreased with the increase of strontium ion concentration. (2) Energy dispersive spectroscopy showed that the strontium content on the surface of the gels increased along with the augment of the strontium ion concentration. (3) With the increase of strontium ion concentration, the swelling ratio of the hydrogels gradually decreased while the elastic modulus of photocrosslinked alginate gels gradually increased. (4) As strontium ion concentration increased, the early adhesion rate of MC3T3-E1 cells on the surface of photocrosslinked alginate gels was on a rise, and the cell extension gradually became better. (5) In summary, the addition of strontium ions into the photocrosslinked alginate gels can improve its mechanical properties and promote cell adhesion and extension.
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    Osteogenic differentiation of MC3T3-E1 cells induced by osteopractic total flavone and nano-hydroxyapatite/collagen composite and the underlying mechanism
    Li Jinyu, Yu Xing, Jiang Junjie, Xu Lin, Zhao Xueqian, Sun Qi, Zheng Chenying, Bai Chunxiao, Liu Chuyin, Zhang Zhe, Jia Yusong
    2019, 23 (18):  2888-2893.  doi: 10.3969/j.issn.2095-4344.1713
    Abstract ( 313 )   PDF (1559KB) ( 110 )   Save
    BACKGROUND: Preliminary study has found that osteopractic total flavone can promote osteogenic differentiation of MC3T3-E1 cells on the surface of nano-hydroxyapatite/collagen composite, but the underlying mechanism needs to be studied in depth.
    OBJECTIVE: To investigate the effect of osteopractic total flavone combined with nano-hydroxyapatite/collagen composite on the osteogenic differentiation of MC3T3-E1 cells and its mechanism.
    METHODS: MC3T3-E1 cells were seeded on the surface of nano-hydroxyapatite/collagen composite and cultured in culture media containing 0, 100 and 250 mg/L osteopractic total flavone, respectively. After 1, 3, 5, 7, 9, 11 and 14 days of culture, the activity of alkaline phosphatase was detected. After 1, 2, 3 and 4 weeks of culture, the level of osteocalcin in the culture supernatant was detected by ELISA. Alizarin red staining was used to observe the formation of calcified nodules at 7, 14 and 21 days of culture. At 14 days of culture, the expression of osteogenic related genes was detected by PCR.
    RESULTS AND CONCLUSION: (1) There was no significant difference in the alkaline phosphatase activity at 1, 3 and 14 days among groups (P > 0.05). At 5, 7 and 9 days of culture, the alkaline phosphatase activity in the 100 and 250 mg/L groups was higher than that in the 0 mg/L group (P < 0.05), and there was no significant difference between 100 and 250 mg/L groups (P > 0.05). (2) The mass concentration of osteocalcin in the 100 and 250 mg/L groups was higher than that in the 0 mg/L group at 1, 2, 3 and 4 weeks of culture (P < 0.05), and there was no significant difference between 100 and 250 mg/L groups (P > 0.05). (3) At 7, 14 and 21 days of culture, obvious calcified nodules were visible in the 100 and 250 mg/L groups. (4) At 14 days of culture, the mRNA expression levels of osteocalcin, type I collagen and osteopontin in the 100 and 250 mg/L groups were higher than that in the 0 mg/L group (P < 0.05), and there was no significant difference between 100 and 250 mg/L groups (P > 0.05). (5) These results imply that osteopractic total flavone combined with nano-hydroxyapatite/collagen composite can induce MC3T3-E1 cells to differentiate into osteoblasts, which may be by increasing alkaline phosphatase activity, osteocalcin level and mRNA expression of type I collagen, osteocalcin and osteopontin.
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    Patent analysis of tissue-engineered scaffold, technology and prosthesis in recent decade based on Derwent Innovations Index
    Fang Mengya, Wang Qinghua, Xu Lai, Gu Xiaosong, Jiang Kui
    2019, 23 (18):  2894-2899.  doi: 10.3969/j.issn.2095-4344.1698
    Abstract ( 324 )   PDF (758KB) ( 92 )   Save
    BACKGROUND: Tissue engineering technology provides an effective medical means to solve the problems of organ donor insufficiency and tissue trauma reconstruction.
    OBJECTIVE: To provide information reference for researchers of tissue engineering through the analysis of the patents data to grasp the hotspot and core technologies of tissue engineering.
    METHODS: The information including the annual distribution of patents, priority countries, patentees, hotspot of technology and core patents by Excel after extracting the data by programming based on Derwent Innovations Index.
    RESULTS AND CONCLUSION: In the past decade, the number of patents in the field of tissue engineering is on a rise. The most prolific countries are the United States, China and Japan. Zhejiang University, Donghua University, and the University of California are the leading institutions. Two United States companies, TYCO HEALTHCARE GROUP LP and ETHICON INC, each have two of the 20 core patents. The market of the relevant tissue-engineered products is led by the United States. Scaffolds, tissue engineering technology and prosthesis are the hot areas of tissue engineering. Scaffold materials, extracellular matrix, drug delivery, construction technology, and devices are the core technologies in the field of tissue engineering.
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    Preparation of agarose/gelatin/hyaluronic acid/extracellular matrix hydrogel and its property characterization
    Li Jingjing, Guo Xuan, Xie Jun, Huang Lei, Suo Jinrong, Fu Songtao
    2019, 23 (18):  2900-2908.  doi: 10.3969/j.issn.2095-4344.1728
    Abstract ( 448 )   PDF (905KB) ( 111 )   Save
    BACKGROUND: Due to no vascular structure or nerve tissue, cartilage tissue lacks the intrinsic ability of self-repair and regeneration. Therefore, the repair of cartilage defect in clinic remains a challenge.
    OBJECTIVE: To prepare a thermo-sensitive injectable bioactive hydrogel used for cartilage tissue engineering.
    METHODS: Agarose/gelatin/hyaluronic acid hydrogel was prepared by mixing 0.4% agarose, 10% gelatin and 10 g/L hyaluronic acid solution. Then 0, 10, 20, and 30 g/L cartilage extracellular matrix particles were added into the hydrogel respectively to prepare four kinds of thermo-sensitive injectable bioactive hydrogels, for further scanning electron microscope, transmission electron microscope, equilibrium swelling ratio, biomechanical strength and degradation rate. The thermo-sensitive injectable bioactive hydrogel containing 20 g/L cartilage extracellular matrix was co-cultured with chondrocyte-bone marrow mesenchymal stem cells for 1, 3, and 7 days, and the cytocompatibility was assessed by live/dead fluorescence double staining.
    RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that all four hydrogels had good three-dimensional grid structure and large pore size. Transmission electron microscope showed that extracellular matrix particles were evenly distributed in the hydrogels, and the particle size was mainly in the range of 50-200 nm. (2) With the extracellular matrix particle concentration increasing, the equilibrium swelling rate of the hydrogel was decreased. (3) The degradation rate in vitro in the four groups of hydrogels containing 0, 10, 20, and 30 g/L extracellular matrix particles immersed in PBS for 4 weeks was 42.32%, 67.36%, 89.05% and 99.47%, respectively. (4) When the concentration of extracellular matrix particles was added at 0-20 g/L, the biomechanical strength of the hydrogel was gradually increased. (5) Within 7 days after culture, chondrocytes-bone marrow mesenchymal stem cells were uniformly distributed and grew in the hydrogel and proliferated continuously, with the cell survival rate of above 90%. (6) These results showed that the agarose/gelatin/hyaluronic acid hydrogel modified with extracellular matrix particles is a good medical biomaterial that can be used for cartilage tissue engineering.
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    Influence of reference electrode on face recognition event-related potential components
    Wang Yi, Huang Hua, Lai Hongyu, Zhang Junpeng
    2019, 23 (18):  2909-2914.  doi: 10.3969/j.issn.2095-4344.1694
    Abstract ( 355 )   PDF (709KB) ( 142 )   Save
    BACKGROUND: Selecting the electroencephalograph reference electrode is a key step in the analysis of event-related potential, but there are few studies on the influence of reference electrode event-related potential components.
    OBJECTIVE: To compare and analyze the effects of mean reference, left ear papillary reference and zero reference on face recognition event-related potential components were analyzed from the perspectives of statistics and scalp potential topology.
    METHODS: The electroencephalograph data were from the multimodal human neuroimaging dataset in the Open fMRI database. Nineteen normal or normal corrected vision volunteers underwent visual stimulation test, and the visual stimulation factors were strange and disrupt faces. The latency and amplitude of N170 under three references (mean reference, left ear papillary reference and zero reference) was analyzed. The brainstorm potential topology and source localization calculation were performed using brainstorm software. Finally, the experimental results under the three references were compared and analyzed.
    RESULTS AND CONCLUSION: (1) Compared with disturbing the face, the strange face-induced event-related potential N170 had a shorter latency and larger N170 amplitude. There was no significant difference in the N170 latency, and the N170 amplitude has a significant difference. (2) Topological results indicated that the right temporal lobe of the brain was more intense than the left occipital lobe under the same stimuli, and only the REST reference could best reveal the right temporal and prefrontal regions of the brain in strange faces and disturbing people. There is a significant difference in face stimulation. (3) These results show that the electroencephalograph data obtained by REST reference is more realistic and accurate, which helps us to further study the neural mechanism of face recognition, and provides a basis for the selection of experimental reference electrodes for face recognition.
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    Application of additive manufacturing technology in bone defects
    Fang Xu, Dong Junfeng
    2019, 23 (18):  2915-2920.  doi: 10.3969/j.issn.2095-4344.1706
    Abstract ( 290 )   PDF (665KB) ( 90 )   Save
    BACKGROUND: Additive material manufacturing technology is widely used in the treatment of bone defects because of its advantages of rapid and accurate preparation of prostheses.
    OBJECTIVE: To review the current situation of material addition technology applied in bone defects.
    METHODS: The first author searched the articles related to additive manufacturing and bone defect repair in PubMed, CNKI, and WanFang databases published from 2000 to 2018. The keywords were “bone defect, additive manufacturing (AM), 3D printing, bone tumour” in Chinese and English, respectively.
    RESULTS AND CONCLUSION: (1) The additive manufacturing technology can rapidly reconstruct the three-dimensional prosthesis in vitro with modern imaging technology. (2) In the treatment of bone defects, we cannot only establish the model of bone defects before operation to simulate the operation, familiarize and compare the operation methods, and effectively reduce the operation time, but also can quickly and accurately prepare different varieties of implants, significantly improving the success rate of surgery. (3) Additive manufacturing technology shows good prospects in the clinical application of bone defects.
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    Material composite and properties of magnetic bone cement
    Wang Runsheng, Liu Jianheng, Mao Keya, Tang Peifu
    2019, 23 (18):  2921-2926.  doi: 10.3969/j.issn.2095-4344.1735
    Abstract ( 325 )   PDF (771KB) ( 104 )   Save
    BACKGROUND: Magnetic materials are the crucial part of magnetic bone cement, with the explicit investigation of the heating emission mechanism of nanoparticles in magnetic radio-frequency fields, magnetic nanoparticles with good biocompatibility and high heating efficiency may become the hotspot for clinical transformation. Magnetic bone cement consist with magnetic nanoparticles with different ingredient, ratio and bone cement matrix, there are many research progresses in physicochemical property, in vitro and in vivo biocompatibility, heating efficiency and the hyperthermia effect.
    OBJECTIVE: To review the research progress of magnetic bone cement.
    METHODS: The articles about magnetic bone cement and magnetic hyperthermia were retrieved from PubMed, Web of science, Embase and WanFang databases. The keywords were “magnetic bone cement, magnetic hyperthermia”. The logical operator between them was “AND”.
    RESULTS AND CONCLUSION: Magnetic bone cement consists of magnetic materials and bone cement matrix, the magnetic materials were chosen from micron ferrite particles to nanoscale ferrite particles, because of the increasing of heating efficiency. Consequently, the mass percent of magnetic materials in magnetic bone cement will decrease with the increasing of heating efficiency. Then, the physicochemical property, such as, mechanical strength, and setting time, in vitro and in vivo biocompatibility, and hyperthermia effect change. The bone cements with low toxicity and high heating efficiency are the main research direction. In the future, magnetic bone cement will not only preserve the function of hyperthermia, but also have the function of chemotherapy, radiotherapy and immunotherapy. Multi-functional magnetic bone cement may become a new filling material to treat bone metastasis.
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    Intertrochanteric fracture of the femur: improvement of internal fixation device, surgical changes and related disputes 
    Hao Liang, Zhang Zhonglin, Wang Baodong, Bi Zhenggang
    2019, 23 (18):  2927-2935.  doi: 10.3969/j.issn.2095-4344.1135
    Abstract ( 254 )   PDF (866KB) ( 78 )   Save
    BACKGROUND: Treatment methods of intertrochanteric fracture are various, which can be divided into extramedullary fixation system, intramedullary fixation system and arthroplasty. Different treatment methods have their own advantages and disadvantages. With the deepening of research, relevant controversial issues have become the hotspot of clinical research.
    OBJECTIVE: To review the improvement of internal fixation device for intertrochanteric fracture, the changes of operative methods and the related controversial issues, thus providing reference for further clinical research.
    METHODS: The first author retrieved CNKI, WanFang, PubMed, Web of Science and SpringerLink databases with the keywords of “intertrochanteric fracture, osteoporosis, hip fracture, fracture fixation, internal, arthroplasty, displacement, hip, bone plates, internal fixators, prosthesis implantation, aged” in Chinese and English, respectively. Relevant studies published from January 2008 to August 2018 were collected, and finally 56 eligible studies were included for analysis by reading the title and abstract.
    RESULTS AND CONCLUSION: (1) With the in-depth study on the characteristics of anatomy and biomechanics of proximal femur, the intertrochanteric fracture classification system is gradually developing and improving to correctly evaluate the severity of fracture and determine the prognosis. (2) There is no unified “gold standard” for the surgical treatment of intertrochanteric fracture. Therefore, individualized treatment plan should be selected for the patient dialectically. (3) As a “turn-of-the-century surgery” in the history of orthopedic surgery, arthroplasty is increasingly applied in elderly patients with intertrochanteric fractures, but the surgical indications should be strictly controlled. (4) There are many controversial issues in the treatment of intertrochanteric fracture, and a large number of multi-center and big data clinical studies are still needed to solve the problem. (5) The rapid development of digital medicine will change the treatment pattern of intertrochanteric fracture.
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    Application and progress of strontium in bone tissue engineering
    Zhang Jun, You Qi, Zou Gang, Ge Zhen, Liu Yi
    2019, 23 (18):  2936-2940.  doi: 10.3969/j.issn.2095-4344.1712
    Abstract ( 365 )   PDF (618KB) ( 124 )   Save
    BACKGROUND: Strontium has been widely used in bone tissue engineering to promote osteoblast differentiation and inhibit osteoclast absorption.
    OBJECTIVE: To review the application and progress of strontium in bone tissue engineering.
    METHODS: A computer-based search of CNKI, PubMed, and Elsevier databases was performed for retrieving articles concerning the application of strontium in bone tissue engineering published from January 1960 to December 2018. The keywords were “strontium, Sr, bone, bone defects, bone repair, tissue engineering” in Chinese and English, respectively. The types of literature included review, basic and clinical research. The literature was screened preliminarily by reading title and abstract, and the irrelevant articles were excluded. Finally 48 articles eligible for inclusion and exclusion criteria were enrolled for result analysis.  
    RESULTS AND CONCLUSION: As an important component of bones, strontium plays an important role in the development and formation of bone. Strontium-doped bone substitute materials have become the hotspot of bone tissue engineering research. A large number of studies have confirmed that the incorporation of strontium can effectively improve the mechanical properties of bone substitute materials, improve the recruitment ability and differentiation ability of osteoblasts, and promote the osteogenesis and angiogenesis in vivo. However, there are still some shortcomings in the current research: the strontium-doping methods used in different studies are different, so the results are not comparable. The results of different studies on the amount of strontium doping are different. There is no relatively well-recognized strontium-incorporating concentration that can be used to induce osteogenic differentiation.
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    Silver dressings for treating chronic infected wound: a meta-analysis
    Gu Yingxuan, Hu Qu, Huang Linfeng, Hu Xiaohui, Quan Xiaoming, Wang Xiaojun, Wang Haijiao
    2019, 23 (18):  2941-2946.  doi: 10.3969/j.issn.2095-4344.1710
    Abstract ( 368 )   PDF (907KB) ( 141 )   Save

    BACKGROUND: Silver dressings have good anti-infective effect, but there is still a lack of evidence from randomized controlled studies on the efficacy of silver dressings in the treatment of chronic infected wounds.

    OBJECTIVE: To systematically evaluate the efficacy of silver dressings in the treatment of chronic infected wounds.

    METHODS: Databases of PubMed, Cochrane Library, EMbase, Web of science, CNKI, CBM, WanFang and Baidu Scholar were searched for the randomized controlled trials reporting the efficacy of silver dressings on chronic infected wounds published before August 2018. Literature screening, data extraction and quality assessment were conducted by two researchers, and a meta-analysis was performed on RevMan 5.3 software.
    RESULTS AND CONCLUSION: Nine randomized controlled trials including 1 268 patients were enrolled. The trial group was treated with silver dressings, and the control group was treated with dialginate dressings, conventional dressings, foam dressings, general dressings, sterile gauze, vaseline gauze, sterilized gauze or povidone iodine gauze. The meta-analysis results showed that compared with the control group, the wound healing rate in the trial group was increased [OR=4.53, 95%CI (2.87, 7.15), P < 0.000 01], the rate of wound area reduction was increased [MD=8.90, 95%CI (2.05, 15.76), P=0.01], the times of dressing change was decreased [MD=-8.91, 95%CI (-14.33, -3.48), P=0.001], and the debridement time was shortened [MD=-8.92, 95%CI (-10.03, -7.81), P < 0.000 01]. To conclude, silver dressings can promote healing of chronic infected wounds.
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    Analysis on the hotspot of the platelet-rich plasma based on VOSviewer
    Wang Haijiao, Huang Ruina, Wang Xiaojun, Zheng Bili, Chen Peina, Zeng Xiujuan
    2019, 23 (18):  2947-2952.  doi: 10.3969/j.issn.2095-4344.1737
    Abstract ( 433 )   PDF (689KB) ( 188 )   Save
    BACKGROUND: Platelet-rich plasma is a platelet concentrate obtained from autologous whole blood after centrifugation, which contains a lot of growth factors and proteins. Activated platelets can release a variety of growth factors so as to accelerate cell proliferation and differentiation, and can effectively promote tissue repair. Platelet-rich plasma has been widely used in various clinical fields because of its convenient sampling and simple preparation. Overseas research on platelet-rich plasma has been carried out for a long time, and has achieved certain results.
    OBJECTIVE: To review the research advance of platelet-rich plasma at abroad in recent 5 years.
    METHODS: PubMed database was retrieved with the keywords of “plasma, platelet-rich, platelet rich plasma, platelet-rich plasma’’ and the retrieval time was from 2014-2018. The visual tool VOSviewer was used to deeply search the title information of the papers retrieved. The annual and national published number, and research topics were discussed. The knowledge map generated by software is used to visually display the hotspot of platelet-rich plasma research at abroad.
    RESULTS AND CONCLUSION: Thirty-eight relevant articles were retrieved. The results show that in the past five years the number of papers published on platelet-rich plasma in foreign countries has increased year by year, and the United States has the largest number of publications. Through co-word clustering analysis, the hotspots of platelet-rich plasma are mainly concentrated on the following five aspects: animal experiments, orthopedics, cytology experiments, stomatology and chronic wounds. Research results provide reference for the direction and hotspot of research on platelet-rich plasma in China.
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