超声引导下胎儿心肌壁注射KCl在KCl减胎术中的应用效果

目的 探讨超声引导下胎儿心肌壁注射氯化钾（KCl）在中孕期双绒毛膜双羊膜囊双胎妊娠KCl减胎术中的手术效果。方法 回顾性分析2017年9月至2020年1月安徽医科大学第一附属医院收治的因中孕期双绒毛膜双羊膜囊双胎妊娠伴有双胎之一异常行KCl减胎术的27例孕妇临床资料。根据术中KCl注射部位不同将研究对象分为心腔内注射组（超声引导下胎儿心腔内注射KCl）13例及心肌壁注射组（超声引导下胎儿心肌壁注射KCl）14例。比较两组手术时间、KCl用量和围产儿结局的差异。结果 心腔内注射组手术时间为（33.69±2.46）min,长于心肌壁注射组的（19.86±1.51）min,差异有统计学意义（P<0.05）;心腔内注射组KCl用量为（6.00±0.71）mL,多于心肌壁注射组的（2.79±0.54）mL,差异有统计学意义（P<0.05）;分娩28天后电话随访,两组孕妇的分娩孕周及新生儿体质量比较,差异均无统计学意义（P>0.05）。结论 在中孕期KCl减胎术中,心肌壁注射KCl较传统的心腔内注射KCl手术耗时更少,KCl用量更少,且不影响保留胎儿的分娩孕周及新生儿出生体质量。     

Mechanical Properties of Different Nanopatterned TiO2 Substrates and Their Effect on Hydrothermally Synthesized Bioactive Hydroxyapatite Coatings

Nanotechnology is a very attractive tool for tailoring the surface of an orthopedic implant to optimize its interaction with the biological environment. Nanostructured interfaces are promising, especially for orthopedic applications. They can not only improve osseointegration between the implant and the living bone but also may be used as drug delivery platforms. The nanoporous structure can be used as a drug carrier to the surrounding tissue, with the intention to accelerate tissue–implant integration as well as to reduce and treat bacterial infections occurring after implantation. Titanium oxide nanotubes are promising for such applications; however, their brittle nature could be a significantly limiting factor. In this work, we modified the topography of commercially used titanium foil by the anodization process and hydrothermal treatment. As a result, we obtained a crystalline nanoporous u-shaped structure (US) of anodized titanium oxide with improved resistance to scratch compared to TiO₂ nanotubes. The US titanium substrate was successfully modified with hydroxyapatite coating and investigated for bioactivity. Results showed high bioactivity in simulated body fluid (SBF) after two weeks of incubation.     

Effect of SiO2–Al2O3 Glass Composite Coating on the Oxidation Behavior of Ti60 Alloy

A SiO₂–Al₂O₃ glass composite coating was prepared on Ti60 alloy via air spraying slurry and then a suitable baking process. It was composed of potassium silicate glass, alumina and quartz powders. The high temperature oxidation performance of the alloy with and without coating was evaluated in static air at both 800 °C and 900 °C. The results show that catastrophic oxidation occurs for Ti60 bare alloy. It had a mass gain of about 2 mg/cm² after oxidation at 800 °C and 17 mg/cm² at 900 °C for 100 h. On the contrary, the oxidation resistance of alloy coated with composite coating was much improved with the mass gain about 0.36 mg/cm² and 0.95 mg/cm² at 800 °C and at 900 °C, respectively. The microstructure evolution of the composite coating and the alloy was analyzed by scanning electron microscope and electron probe microanalyzer. The effect of the composite coating on the oxidation performance of the alloy is discussed especially in terms of oxygen diffusion and interfacial reaction.     

Strength Properties of a Porous Titanium Alloy Ti6Al4V with Diamond Structure Obtained by Laser Power Bed Fusion (LPBF)

This paper presents the results of experimental research on the strength properties of porous structures with different degrees of density manufactured of Ti6Al4V titanium alloy by Laser Power Bed Fusion. In the experiment, samples with diamond structure of porosity: 34%, 50%, 73% and 81% were used, as well as samples with near-zero porosity. Monotonic tensile tests were carried out to determine the effective values of axial modulus of elasticity, ultimate tensile strength, offset yield strength, ultimate elongation and Poisson ratio for titanium alloys with different porosities. The paper also proposes relationships that can be easily used to estimate the strength and rigidity of a porous material manufactured by 3D printing. They were obtained by the approximation of two quotients. The first one refers to the relationship between the tensile strength of a material with a defined porosity to the strength of full-filled material. The second similarly determines the change in the value of the axial modulus of elasticity. The analysis of microscopic observations of fracture surfaces and also microtomography visualization of the material structure are also presented.     

Fabrication of Metallic Biomedical Scaffolds with the Space Holder Method: A Review

Bone tissue engineering has been increasingly studied as an alternative approach to bone defect reconstruction. In this approach, new bone cells are stimulated to grow and heal the defect with the aid of a scaffold that serves as a medium for bone cell formation and growth. Scaffolds made of metallic materials have preferably been chosen for bone tissue engineering applications where load-bearing capacities are required, considering the superior mechanical properties possessed by this type of materials to those of polymeric and ceramic materials. The space holder method has been recognized as one of the viable methods for the fabrication of metallic biomedical scaffolds. In this method, temporary powder particles, namely space holder, are devised as a pore former for scaffolds. In general, the whole scaffold fabrication process with the space holder method can be divided into four main steps: (i) mixing of metal matrix powder and space-holding particles; (ii) compaction of granular materials; (iii) removal of space-holding particles; (iv) sintering of porous scaffold preform. In this review, detailed procedures in each of these steps are presented. Technical challenges encountered during scaffold fabrication with this specific method are addressed. In conclusion, strategies are yet to be developed to address problematic issues raised, such as powder segregation, pore inhomogeneity, distortion of pore sizes and shape, uncontrolled shrinkage and contamination.     

Assessment of cytotoxicity and antibacterial effects of silver nanoparticle-doped titanium alloy surfaces

ObjectivesThis study aimed to develop silver nanoparticle (AgNP)-doped Ti₆Al₄V alloy surfaces and investigate their antibacterial properties against representative periopathogens and potential cytotoxicity on osteoblastic cells.MethodsAgNPs of different size distributions (5 and 30 nm) were incorporated onto the Ti₆Al₄V surfaces by electrochemical deposition, using colloid silver dispersions with increasing AgNP concentrations (100, 200 and 300 ppm). The time-course silver release from the specimen surfaces to cell culture media was assessed by Atomic Absorption Spectroscopy (AAS). Cell attachment, viability and proliferation were investigated by SEM, live/dead staining MTT and BrdU assays. The antibacterial effects were assessed against P. gingivalis and P. intermedia by serial dilution spotting assays.ResultsA time- and concentration-dependent silver release from the experimental surfaces was observed. Overall, cell viability and attachment on the AgNP-doped surfaces, suggested adequate cytocompatibility at all concentrations. A transient cytotoxic effect was detected at 24 h for the 5 nm-sized groups that fully recovered at later time-points, while no cytotoxicity was observed for the 30 nm-sized groups. A statistically significant, concentration-dependent decrease in cell proliferation rates was induced at 48 h in all AgNP groups, followed by recovery at 72 h in the groups coated with 5 nm-sized AgNPs. A statistically significant, concentration-dependent antibacterial effect up to 30% was confirmed against both periopathogens.SignificanceThis study sheds light to the optimal size-related concentrations of AgNP-doped Ti₆Al₄V surfaces to achieve antibacterial effects, without subsequent cytotoxicity. These results significantly contribute to the development of antibacterial surfaces for application in oral implantology.     

The effect of calcium ion concentration on the bone response to oxidized titanium implants

Aim: To investigate the effect of calcium concentration on the bone tissue response to Ca‐incorporated titanium implants Materials and methods: Two titanium surfaces containing 4.2% and 6.6% calcium were prepared using the micro‐arc oxidation process. The implants were inserted in the tibia of nine New Zealand White rabbits. After 6 weeks of healing, the bone response to the implants was quantitatively compared by biomechanical and histomorphometrical measurements. Results: Ca 4.2% and Ca 6.6% containing implants revealed no distinctive differences in their qualitative surface chemistry; chemical bonding state of Ca in titanium oxide was mainly calcium titanates. No significant differences were observed between two implants in peak removal torque and shear strength comparisons (P>0.05). Histomorphometrical analyses presented no significant differences in bone–metal contact, bone area and newly formed bone measurements between two implants (P>0.05). Conclusions: From biomechanical and histomorphometrical measurements, the two calcium concentrations in this study did not differ significantly with respect to their influence on the bone tissue response. This similar bone response in rabbit tibiae may be explained by the similarity of the qualitative Ca chemistry in titanium surfaces.