Search

The use of magnesium (Mg) and its alloys as potential materials for bone implants is gaining attention of researchers. This is due to their biocompatibility, mechanical properties, and ability to degrade in the body. Plasma Electrolytic Oxidation (PEO) is a promising surface modification technique for enhancing the performance of magnesium and its alloys in orthopedic and dental implants. It helps develop an oxide ceramic layer on the surface. This article provides an in-depth analysis of the recent advancements in PEO of magnesium and related alloys for use in bone implants. It begins by explaining the fundamental principles of PEO, including the electrochemical and plasma processes involved in forming ceramic coatings on magnesium substrates. It then describes how various factors affect the oxide layers. These include the electrolyte mixture, voltage, current density, and treatment length. It focuses on the microstructure, biocompatibility, and corrosion resistance of PEO-treated magnesium alloys. Additionally, it explains the biocompatibility and bioactivity performance of the PEO-coated magnesium alloys. This involves their interactions with biological systems, cell adhesion, proliferation, and osseointegration. The review also covers challenges and limitations of PEO. Its comprehensive analysis of PEO technique, surface characteristics, mechanical properties, corrosion behavior, and biocompatibility aspects is valuable. It's a resource for researchers, clinicians, and materials scientists creating novel, biocompatible magnesium-based materials. These materials are suitable for dental and orthopedic implants. As the field continues to evolve, further research directions and potential breakthroughs are outlined to propel the application of PEO-treated magnesium alloys in the realm of bone implants, offering patients improved medical outcomes and enhanced quality of life. [ABSTRACT FROM AUTHOR]

Manufacturing technology has been refined and described for the fabrication of honeycomb-based bioresorbable networks for temporal bone replacement applications. Two novel techniques, digital light processing and investment casting, were utilized to produce customized, shape-optimized cellular constructs with additional orifices promoting tissue ingrowth during osteo-regeneration. For this purpose, a conventional magnesium casting alloy (AZ91) was chosen. Numerical simulations were conducted to predict the compressive behavior of the proposed biodegradable lightweight scaffolds. Spatial castings were adjusted to possess mechanical properties comparable to the ones of cortical or trabecular bones. Two kinds of protective coatings (plasma electrolytic oxidation and organic ones based on natural polyphenols from tea extract) were deposited and characterized. They can be utilized to control the degradation rate during exploitation to achieve a predictable implant lifespan. The elaborated layers aim to mitigate the rapid corrosion of magnesium substrates by prolonging their bioresorption time and thus expanding their applicability in osseointegration. To evaluate this assumption, immersion tests in phosphate-buffered saline were performed, showing better chemical resistance of PEO coating and as-cast sample (for both mass gain by below 1%), and visible increase in mass of sample coated with organic coating (increase by almost 5%). Compressive strength results from numerical approach were further validated by experimental compression tests, showing that PEO coating deteriorated compressive strength by almost 3%, and organic coating improved it by over 9%. Results achieved in numerical approach were better than expected for stiffer sample, and slightly lower for the one with bigger pores. [ABSTRACT FROM AUTHOR]

Magnesium alloys have received a lot of attention as prospective bioimplant material due to their biocompatibility, mechanical properties, and biodegradability. Magnesium alloys and composites hold enormous promise as a replacement for permanent metallic implants, as there is no need for secondary surgeries after recovery. To address the corrosion and biodegradation rate of magnesium, different approaches can be adopted, such as composite preparation and surface modification. This comprehensive review emphasizes the processing route, matrix, and reinforcement for Mg alloy and composite, with the aim of enhancing their mechanical, biological, and chemical properties. It also discusses the corrosion and biocompatibility aspects of Mg alloys and composites. The article also sheds light on the potential of magnesium composites to become a dominant player in the field of bioimplant materials. [ABSTRACT FROM AUTHOR]

A novel acrylic monomer containing a nitrofuran motif, referred to as longchain nitrofuran methacrylate (LNFMA), is reported. In comparison to the previously reported nitrofuran methacrylate (NFMA), LNFMA has a longer side chain, and when incorporated into bone cement, the resulting LNFMA bone cement exhibits improved mechanical strength. At the same concentration, NFMA-5% cement has only 21.6 ± 1.3 MPa, while LNFMA-5% cement has a compressive strength of 42.64 ± 0.94 MPa. LNFMA bone cements exhibit antimicrobial activity against Staphylococcus aureus, with LNFMA-30% cement reaching 57.38% ± 5.53%. Moreover, LNFMA cement demonstrates excellent biocompatibility both in vitro and in vivo. The results showed that LNFMA monomer had optimized mechanical strength compared with previously reported NFMA monomers, and LNFMA bone cement had good antibacterial activity and biocompatibility. [ABSTRACT FROM AUTHOR]

Porous implants composed of periodically-repeating porous units have been applied in orthopedic surgeries to replace damaged bones. An important requirement for bone implants is to find a balance between biological and mechanical properties, that is, to ensure high pore connectivity and a certain strength. In this work, center-supported and perimeter-supported porous optimization models were established by a swarm intelligence optimization algorithm, and the corresponding titanium porous samples were fabricated by laser powder bed fusion (L-PBF). The effects of cell topology and porosity on the compressive behavior of L-PBF titanium porous structures were systematically investigated by a combination of compression simulation and experiments. Compression simulation shows that the deformation failure behavior of center-supported and perimeter-supported porous structures consists of three stages: elastic deformation, plastic deformation and compression collapse, showing the characteristics of elastic-plastic porous materials. According to the compression test results, the compressive strength of center-supported and perimeter-supported structure samples are 151–188 MPa and 178–196 MPa, respectively, and the compressive stability of the perimeter-supported structure is better than that of the center-supported structure. The porosity error of center-supported structure is 1.6%–2.9%, and the porosity error of perimeter-supported structure is 3.1%–4.5%. The compressive strength of the same type of structure decreases with the increase of the porosity of the porous structure. The simulation/experimental compressive strength errors of center-supported and perimeter-supported structures are less than 6% and 5.9%, respectively. The constructed quasi-static compression model has certain guiding significance for the study of the fracture of the titanium implants under external force.

Total hip replacement is one of the most successful orthopedic operations in modern times. Osteolysis of the femur bone results in implant loosening and failure due to improper loading. To reduce induced stress, enhance load transfer, and minimize stress, the use of Ti-6Al-4V alloy in bone implants was investigated. The objective of this study was to perform a three-dimensional finite element analysis (FEA) of the femoral stem to optimize its shape and analyze the developed deformations and stresses under operational loads. In addition, the challenges associated with the manufacturing optimization of the femoral stem using large strain-based finite element modeling were addressed. The numerical findings showed that the optimized femoral stem using Ti-6Al-4V alloy under the normal daily activities of a person presented a strains distribution that promote uniform load transfer from the proximal to the distal area, and provided a mass reduction of 26%. The stress distribution was found to range from 700 to 0.2 MPa in the critical neck area of the implant. The developed computational tool allows for improved customized designs that lower the risk of prosthesis loss due to stress shielding. [ABSTRACT FROM AUTHOR]

This literature review deals with the electrophoretic deposition of bioactive glass coatings on metallic substrates to produce bone implants. Biocompatible metallic materials, such as titanium alloys or stainless steels, are commonly used to replace hard tissue functions because their mechanical properties are appropriate for load-bearing applications. However, metallic materials barely react in the body. They need a bioactive surface coating to trigger beneficial biological and chemical reactions in the physiological environment. Bioactive coatings aim to improve bone bonding, shorten the healing process after implantation, and extend the lifespan of the implant. Bioactive glasses, such as 45S5, 58S, S53P4, 13-93, or 70S30C, are amorphous materials made of a mixture of oxides that are accepted by the human body. They are used as coatings to improve the surface reactivity of metallic bone implants. Their high bioactivity in the physiological environment induces the formation of strong chemical bonding at the interface between the metallic implant and the surrounding bone tissue. Electrophoretic deposition is one of the most effective solutions to deposit uniform bioactive glass coatings at low temperatures. This article begins with a review of the different compositions of bioactive glasses described in the scientific literature for their ability to support hard tissue repair. The second part details the different stages of the bioactivity process occurring at the surface of bioactive glasses immersed in a physiological environment. Then, the mechanisms involved in the electrophoretic deposition of bioactive glass coatings on metallic bone implants are described. The last part of the article details the current developments in the process of improving the properties of bioactive glass coatings by adding biocompatible elements to the glassy structure. [ABSTRACT FROM AUTHOR]

Biopolymers are materials specifically engineered to interact with biological systems. They can be derived from either natural or synthetic sources, depending on the biological resources used or the manufacturing process employed. Over recent decades, these materials have gained significant popularity within the medical field due to their remarkable attributes such as biodegradability, bioactivity, and compatibility with human tissue. One notable application is their use as scaffolds for bone regeneration. Biopolymers, being renewable biomaterials, provide opportunities for continuous manufacturing and technological progress across various industries. These biomaterials have demonstrated great promise in medical sectors, including nerve regeneration and the production of surgical devices. Additionally, their versatility extends to non-biomedical applications, like food packaging. This paper aims to provide a comprehensive overview of different biopolymers, elucidating their properties, showcasing their latest applications, and delving into the state-of-the-art manufacturing technologies used in their production. Special emphasis is placed on their suitability as bone tissue repair and regeneration scaffolds, owing to their unique properties, which render them an ideal choice for this specific application. [ABSTRACT FROM AUTHOR]

This study investigates the viability of utilizing poultry manure, an abundant and low-cost waste material, for the synthesis of hydroxyapatite (HAp), a critical biomaterial for bone regeneration. Calcination of poultry manure was conducted at 750°C, 800°C, and 850°C for 5 h to produce HAp. The processed poultry manure was then characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS), X-ray fluorescence (XRF), and X-ray diffraction (XRD) analyses. The FTIR analysis confirmed the formation of HAp through characteristic phosphate absorption bands, with the highest purity observed at 850°C. SEM analysis revealed that increasing calcination temperature enhanced the crystallinity and particle uniformity of the samples. XRF analysis showed a significant increase in CaO (40.229–43.328 %) and P2O5 (17.905–19.239 %) content with rising temperatures, crucial for HAp synthesis. The Ca/P ratios were determined to be 1.28, 1.54, and 1.71, respectively, indicating variations in purity and phase composition. The 800°C provides a near-ideal Ca/P ratio while the 850°C achieves a ratio slightly above the ideal, indicating a high-purity HAp phase. XRD analysis corroborated these findings, identifying hydroxyapatite (Ca10P6O26H2), as the predominant phase with minimal secondary phases. These results suggest that calcination at 850°C is optimal for producing high-purity HAp from poultry manure, offering a sustainable and cost-effective alternative to synthetic HAp production for biomedical applications.

Additively manufactured (AM) biodegradable porous iron-manganese (FeMn) alloys have recently been developed as promising bone-substituting biomaterials. However, their corrosion fatigue behavior has not yet been studied. Here, we present the first study on the corrosion fatigue behavior of an extrusion-based AM porous Fe35Mn alloy under cyclic loading in air and in the revised simulated body fluid (r-SBF), including the fatigue crack morphology and distribution in the porous structure. We hypothesized that the fatigue behavior of the architected AM Fe35Mn alloy would be strongly affected by the simultaneous biodegradation process. We defined the endurance limit as the maximum stress at which the scaffolds could undergo 3 million loading cycles without failure. The endurance limit of the scaffolds was determined to be 90 % of their yield strength in air, but only 60 % in r-SBF. No notable crack formation in the specimens tested in air was observed even after loading up to 90 % of their yield strength. As for the specimens tested in r-SBF, however, cracks formed in the specimens subjected to loads exceeding 60 % of their yield strength appeared to initiate on the periphery and propagate toward the internal struts. Altogether, the results show that the extrusion-based AM porous Fe35Mn alloy is capable of tolerating up to 60 % of its yield strength for up to 3 million cycles, which corresponds to 1.5 years of use of load-bearing implants subjected to repetitive gait cycles. The fatigue performance of the alloy thus further enhances its potential for trabecular bone substitution subjected to cyclic compressive loading. Fatigue behavior of extrusion-based AM porous Fe35Mn alloy scaffolds in air and revised simulated body fluid was studied. The Fe35Mn alloy scaffolds endured 90 % of their yield strength for up to 3 × 106 loading cycles in air. Moreover, the scaffolds tolerated 3 × 106 loading cycles at 60 % of their yield strength in revised simulated body fluid. The Fe35Mn alloy scaffolds exhibited a capacity of withstanding 1.5-year physiological loading when used as bone implants. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of coating Ni–Ti alloy with sea buckthorn extract via a hydrothermal method for targeted delivery of beneficial phenolic compounds to bone tissue. The qualitative analysis confirmed the presence of flavonoids and tannins in sea buckthorn extract, supporting its osteogenic potential. The microhardness of the NiTi alloy substrate was suitable for biomedical applications, and successful coating was achieved without compromising its properties. NiTi alloy samples were coated with 18.1, 20.1, and 12.4 mg of extract, respectively. Comprehensive evaluations confirmed the successful integration of the extract onto the alloy's surface. The coated system exhibited sustained release properties over five days, with the highest release occurring on the first day (on average 32.1 % for the first peak and 72.1 % for the second peak), as determined by HPLC analysis. The findings demonstrate the potential of this novel approach in developing dual-functionality implants for bone health promotion. Overall, this study underscores the promising potential of Ni–Ti alloy coated with sea buckthorn extract as a targeted drug delivery system for bone tissue.

As a biomedical material, porous titanium alloy has gained widespread recognition and application within the field of orthopedics. Its remarkable biocompatibility, bioactivity, and mechanical properties establish it as a promising material for facilitating bone regeneration. A well-designed porous structure can lower the material's modulus while retaining ample strength, rendering it more akin to natural bone tissue. The progression of additive manufacturing (AM) technology has significantly propelled the advancement of porous implants, simplifying the production of such structures. AM allows for the customization of porous implants with various shapes and sizes tailored to individual patients. Additionally, it enables the design of microscopic-scale porous structures to closely mimic natural bone, thus opening up avenues for the development of porous titanium alloy bone implants that can better stimulate bone regeneration. This article reviews the research progress on the structural design and preparation methods of porous titanium alloy bone implants, analyzes the porous structure design parameters that affect the performance of the implant, and discusses the application of porous medical titanium alloys. By comparing the effects of the parameters of different porosity, pore shape, and pore size on implant performance, it was concluded that pore diameters in the range of 500~800 μm and porosity in the range of 70%–90% have better bone-regeneration effects. At the same time, when the pore structure is a diamond, rhombohedral, or cube structure, it has better mechanical properties and bone-regeneration effects, providing a reference range for the application of clinical porous implants. [ABSTRACT FROM AUTHOR]

β-Tricalcium phosphate (β-TCP) is widely used as bone implant material. It has been observed that doping the β-TCP structure with certain cations can help in combating bacteria and pathogenic microorganisms. Previous literature investigations have focused on tricalcium phosphate structures with silver, copper, zinc, and iron cations. However, there are limited studies available on the biological properties of β-TCP containing nickel and cobalt ions. In this work, Ca10.5−xNix(PO4)7 and Ca10.5−xCox(PO4)7 solid solutions with the β-Ca3(PO4)2 structure were synthesized by a high-temperature solid-state reaction. Structural studies revealed the β-TCP structure becomes saturated at 9.5 mol/% for Co2+ or Ni2+ ions. Beyond this saturation point, Ni2+ and Co2+ ions form impurity phases after complete occupying of the octahedral M5 site. The incorporation of these ions into the β-TCP crystal structure delays the phase transition to the α-TCP phase and stabilizes the structure as the temperature increases. Biocompatibility tests conducted on adipose tissue-derived mesenchymal stem cells (aMSC) using the (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) (MTT) assay showed that all prepared samples did not exhibit cytotoxic effects. Furthermore, there was no inhibition of cell differentiation into the osteogenic lineage. Antibacterial properties were studied on the C. albicans fungus and on E. coli, E. faecalis, S. aureus, and P. aeruginosa bacteria strains. The Ni- and Co-doped β-TCP series exhibited varying degrees of bacterial growth inhibition depending on the doping ion concentration and the specific bacteria strain or fungus. The combination of antibacterial activity and cell-friendly properties makes these phosphates promising candidates for anti-infection bone substitute materials. [ABSTRACT FROM AUTHOR]

Osteoblastic and chemical responses to Poly (ether ether ketone) (PEEK) material have been improved using a variety of low-temperature plasmas (LTPs). Surface chemical properties are modified, and can be used, using low-temperature plasma (LTP) treatments which change surface functional groups. These functional groups increase biomineralization, in simulated body fluid conditions, and cellular viability. PEEK scaffolds were treated, with a variety of LTPs, incubated in simulated body fluids, and then analyzed using multiple techniques. First, scanning electron microscopy (SEM) showed morphological changes in the biomineralization for all samples. Calcein staining, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) confirmed that all low-temperature plasma-treated groups showed higher levels of biomineralization than the control group. MTT cell viability assays showed LTP-treated groups had increased cell viability in comparison to non-LTP-treated controls. PEEK treated with triethyl phosphate plasma (TEP) showed higher levels of cellular viability at 82.91% ± 5.00 (n = 6) and mineralization. These were significantly different to both the methyl methacrylate (MMA) 77.38% ± 1.27, ethylene diamine (EDA) 64.75% ± 6.43 plasma-treated PEEK groups, and the control, non-plasma-treated group 58.80 ± 2.84. FTIR showed higher levels of carbonate and phosphate formation on the TEP-treated PEEK than the other samples; however, calcein staining fluorescence of MMA and TEP-treated PEEK had the highest levels of biomineralization measured by pixel intensity quantification of 101.17 ± 4.63 and 96.35 ± 3.58, respectively, while EDA and control PEEK samples were 89.53 ± 1.74 and 90.49 ± 2.33, respectively. Comparing different LTPs, we showed that modified surface chemistry has quantitatively measurable effects that are favorable to the cellular, biomineralization, and chemical properties of PEEK. [ABSTRACT FROM AUTHOR]

Unmet medical needs in treating critical-size bone defects have led to the development of numerous innovative bone tissue engineering implants. Although additive manufacturing allows flexible patient-specific treatments by modifying topological properties with various materials, the development of ideal bone implants that aid new tissue regeneration and reduce post-implantation bone disorders has been limited. Natural biomolecules are gaining the attention of the health industry due to their excellent safety profiles, providing equivalent or superior performances when compared to more expensive growth factors and synthetic drugs. Supplementing additive manufacturing with natural biomolecules enables the design of novel multifunctional bone implants that provide controlled biochemical delivery for bone tissue engineering applications. Controlled release of naturally derived biomolecules from a three-dimensional (3D) printed implant may improve implant-host tissue integration, new bone formation, bone healing, and blood vessel growth. The present review introduces us to the current progress and limitations of 3D printed bone implants with drug delivery capabilities, followed by an in-depth discussion on cutting-edge technologies for incorporating natural medicinal compounds embedded within the 3D printed scaffolds or on implant surfaces, highlighting their applications in several pre- and post-implantation bone-related disorders. Multifunctional 3D printed scaffolds incorporated with natural medicinal compounds (NMCs) and drug delivery vehicles as a bone-targeted local drug delivery system. [Display omitted] • Drug delivery from 3D printed devices provides targeted and site-specific therapy. • Natural medicines (NMCs) have demonstrated potential to treat various bone disorders. • NMCs can be strategically incorporated within 3D printed bone substitutes. • Release of NMCs from 3D printed devices can be controlled by various methods. • With dosage optimization NMCs have great possibilities in tissue engineering. [ABSTRACT FROM AUTHOR]

Total hip replacement is one of the most successful orthopedic operations in modern times. Osteolysis of the femur bone results in implant loosening and failure due to improper loading. To reduce induced stress, enhance load transfer, and minimize stress, the use of Ti-6Al-4V alloy in bone implants was investigated. The objective of this study was to perform a three-dimensional finite element analysis (FEA) of the femoral stem to optimize its shape and analyze the developed deformations and stresses under operational loads. In addition, the challenges associated with the manufacturing optimization of the femoral stem using large strain-based finite element modeling were addressed. The numerical findings showed that the optimized femoral stem using Ti-6Al-4V alloy under the normal daily activities of a person presented a strains distribution that promote uniform load transfer from the proximal to the distal area, and provided a mass reduction of 26%. The stress distribution was found to range from 700 to 0.2 MPa in the critical neck area of the implant. The developed computational tool allows for improved customized designs that lower the risk of prosthesis loss due to stress shielding.

Background/Purpose: Due to the general application of in vitro test, cell culture is generally selected to evaluate the cytocompatibility of devices and materials. The choice of test condition should depend on the probable site and clinical application. The oxygen content of human body could be estimated around 5%∼12%, and the oxygen level of healing bone fracture range from 0.8%∼3.8%%. However, materials for bone implant are traditionally evaluated under laboratory normoxia condition (21% O2) in vitro. The aim was to study the effect of oxygen level on osteoblast upon high stiffness titanium with different roughness. Methods: After sandblasted and acid-etched (SLA) process, we create titanium surfaces with four different roughness. The differentiation and proliferation of MC3T3-E1 osteoblast cultured on SLA-treated specimens were evaluated in designed chamber with oxygen level of 1%, 5%, 10%, 21%. Results: By scanning electron microscopy, all samples had sub-micro pit inside the micro-holes upon SLA-treated Ti disk surface. The decrease of oxygen level from 21% to 5% promoted osteoblast growth of SLA-treated specimens, but 1% O2 delayed cell proliferation. The surface roughness of specimens influenced osteoblast cell differentiation. The differentiation and proliferation ability of the cells upon SLA-treated specimens is proportional to oxygen level. Conclusion: Our results demonstrated that 5% O2 will easily discriminate osteoblasts responses on different SLA-treated specimens. These results suggest that hypoxia (5% O2) environment is better model for biological evaluation of bone-related materials.

Traumatic, osteoarthritic, tumoral, and congenital bone issues impact human lives and health. The next generation of bone implants is made from biodegradable materials, including Fe-based materials with superior mechanical properties and high biocompatibility. However, efforts to inhibit the risk of inflammation and bacterial infection due to the biological response and corrosion properties of metals are a significant challenge. This study aims to develop biomaterials based on Fe-Cr-Mn alloys to obtain superior physical and mechanical properties through plasma nitriding. Each sample was plasma-nitridated in a vacuum chamber at various temperatures of 250–450 °C for 3 hours at a pressure of 1.8 kPa. Several main tests were performed to investigate the effects of plasma nitriding, such as the chemical compositions of raw material, surface nitrogen contents, phase changes, thickness, hardness, and corrosion. Those parameters were then used to evaluate plasma nitriding’s effectiveness, including observing the change in phenomena at each temperature treatment. The results indicated that forming the S phase on the surface of Fe-13.8Cr-8.9Mn alloy is a saturated solution of nitrogen in ɣ-Fe, where the nitrogen content on the surface increases with increasing nitriding temperature. The layer’s surface hardness is uniform across its whole thickness, which reduces as the grade of raw material passes through the nitride layer. The highest hardness at a nitriding temperature of 450 °C reached 625.3 VHN. The findings showed that the corrosion rate decreased significantly, reaching the lowest value, 0.0018 mm/year, at a plasma nitriding temperature of 450 °C. Plasma nitriding could enhance the physical and mechanical properties of Fe-Cr-Mn alloy. [ABSTRACT FROM AUTHOR]

Bone substitutes are biomaterials applied in surgical therapy to repair many cases of a damaged bone. More than two million bone surgeries using biomaterials are realised each year worldwide. In this line of research, the researchers of this project study developed a bioresorbable synthetic bone substitute designated by (β-TCP/DCPD)-PHBV which is a mixture of the two materials: β-TCP/DCPD and PHBV in a 60/40 weight fraction. This research study attempts to categorize the (β-TCP/DCPD)-PHBV and evaluate its ability on triggering bone regeneration by making bone implants on 12 New Zealand white male rabbits. The RESEARCHERS performed multi-scale studies namely; a uniaxial compression test, an examination by scanning electron microscopy, and analysis with infrared spectroscopy in order to get the characteristics. The neoformed bone is examined by SEM coupled with energy dispersive spectroscopy (EDS). In addition to the salient mechanical benefits; attenuation of the modulus of elasticity and limitation of brittleness, the biomaterial has also proven to be effective in giving rise to new bone tissues having a suitable mineral composition. [ABSTRACT FROM AUTHOR]

BACKGROUND Digital radiography has been used to evaluate the progress of bone growth with a collagen-hydroxyapatite implant in rabbit tibias. This study aimed to introduce digital radiography methods that provide comprehensive data availability for continuous information retrieval from the implant preparation to the cultivation period. METHODS 38 digital radiographs were divided into 3 treatment groups, namely a single defect without implant (control), single-implant, and three-implant. Radiographic acquisitions were performed at preparation time and post-implantation from 0 to 56 days. Observations were concentrated on the implantation site, followed by creating a lateral profile. The prediction of implantation growth was determined using relative bone density (RBD) percentage. RESULTS Based on the profile, the recovery process consisted of implant absorption and new bone tissue deposition. The absorption process was highly influenced by the defect size. In the control and single-implant groups, regardless of the different recovery processes, similar recovery results were observed 56 days post-implantation, with an RBD value of approximately 90%. Meanwhile, the three-implant group only had an RBD value of 62%. CONCLUSIONS Radiography can evaluate absorption and new bone growth during implantation in New Zealand white rabbits. Radiographs, which can be obtained at any time during cultivation, offered more information on the recovery implantation process than the other method that relies on data obtained after sacrificing the animals. [ABSTRACT FROM AUTHOR]

The advent of three-dimensional (3D) printing technology has revolutionized the production of customized titanium (Ti) alloy implants. The success rate of implantation and the long-term functionality of these implants depend not only on design and material selection but also on their surface properties. Surface modification techniques play a pivotal role in improving the biocompatibility, osseointegration, and overall performance of 3D-printed Ti alloy implants. Hence, the primary objective of this review is to comprehensively elucidate various strategies employed for surface modification to enhance the performance of 3D-printed Ti alloy implants. This review encompasses both conventional and advanced surface modification techniques, which include physical–mechanical methods, chemical modification methods, bioconvergence modification technology, and the functional composite method. Furthermore, it explores the distinct advantages and limitations associated with each of these methods. In the future, efforts in surface modification will be geared towards achieving precise control over implant surface morphology, enhancing osteogenic capabilities, and augmenting antimicrobial functionality. This will enable the development of surfaces with multifunctional properties and personalized designs. By continuously exploring and developing innovative surface modification techniques, we anticipate that implant performance can be further elevated, paving the way for groundbreaking advancements in the field of biomedical engineering. [ABSTRACT FROM AUTHOR]

In this work, we have developed and characterized a ceramic composite based on a core of directionally solidified calcium zirconate-calcium stabilized zirconia (CZO-CSZ) eutectic composite coated with a bioactive glass-ceramic. The aim is to research new orthopedic implants as an alternative to conventional 3Y-TZP bioinert ceramics. The CZO-CSZ eutectic rods were grown from the melt of rods of CaO-ZrO2 in the eutectic composition using the laser floating zone technique (LFZ). The mechanical results indicated that directional eutectics prepared with this technique exhibited good mechanical strength and significant hardness and toughness. The LFZ technique was also used to melt the bioactive coating previously placed by dip coating on the CZO-CSZ rod surface. Depending on the thickness of the coating and the applied laser power, an alloying or coating process was achieved. In the first case, the coating was diluted with the surface of the eutectic cylinder, leading to the segregation of the calcium zirconate and zirconia phases and the formation of a bioactive phase embedding zirconia particles. In the second case, a layer of ceramic glass was formed, well attached to the eutectic cylinder. These layers were both studied from the microstructural and bioactivity points of view. [ABSTRACT FROM AUTHOR]

Orthopedic implants are an important tool in the treatment of musculoskeletal conditions and helped many patients to improve their quality of life. Various inorganic-organic biocomposites have been broadly investigated particularly in the area of load-bearing orthopedic/dental applications. Polyimide (PI) is a promising organic material and shows excellent mechanical properties, biocompatibility, bio-stability, and its elastic modulus is similar to human bone but it lacks bioactivity, which is very important for cell adhesion and ultimately for bone regeneration. In this research, tantalum pentoxide (Ta2O5) coating was prepared on the surface of PI by polydopamine (PDA) bonding. The results showed that Ta2O5 was evenly coated on the surface of PI, and with the concentration of Ta2O5 in the PDA suspension increased, the content of Ta2O5 particles on the surface of PI increased significantly. In addition, the Ta2O5 coating significantly increased the roughness and hydrophilicity of the PI matrix. Cell experiments showed that PI surface coating Ta2O5 could promote the proliferation, adhesion, and osteogenic differentiation of bone marrow-derived stromal cells (BMSCs). The results demonstrated that fabricating Ta2O5 coating on the surface of PI through PDA bonding could improve the biocompatibility as well as bioactivity of PI, and increase the application potential of PI in the field of bone repair materials.

Based on the triply periodic minimal surface (TPMS), 3D auxetic structures are successfully implemented using a dual-period function. A series of shape-controllable, dual-period deformation functions are obtained by summarising the characteristics of periodic deformation functions and applying Bezier curve fitting methods. Then, with the geometry originating from the Schwarz primitive (P) of TPMS, the periodic shape transformation of TPMS is achieved using the dual-period deformation functions. The property (negative Poisson’s ratio) of the auxetic structure is investigated based on the control parameters (the TPMS c value, periodic function η, and deformation index γ). The auxetic structures can exhibit excellent 3D negative Poisson’s ratio properties, and the Poisson’s ratio can be effectively adjusted. Moreover, a heterostructure with positive and negative Poisson’s ratio structures is obtained and applied to a stem in the hip joint. The simulation proves that the heterostructure can effectively prevent the failure of the bone implant.

Due to the general application of in vitro test, cell culture is generally selected to evaluate the cytocompatibility of devices and materials. The choice of test condition should depend on the probable site and clinical application. The oxygen content of human body could be estimated around 5%∼12%, and the oxygen level of healing bone fracture range from 0.8%∼3.8%%. However, materials for bone implant are traditionally evaluated under laboratory normoxia condition (21% O 2) in vitro. The aim was to study the effect of oxygen level on osteoblast upon high stiffness titanium with different roughness. After sandblasted and acid-etched (SLA) process, we create titanium surfaces with four different roughness. The differentiation and proliferation of MC3T3-E1 osteoblast cultured on SLA-treated specimens were evaluated in designed chamber with oxygen level of 1%, 5%, 10%, 21%. By scanning electron microscopy, all samples had sub-micro pit inside the micro-holes upon SLA-treated Ti disk surface. The decrease of oxygen level from 21% to 5% promoted osteoblast growth of SLA-treated specimens, but 1% O 2 delayed cell proliferation. The surface roughness of specimens influenced osteoblast cell differentiation. The differentiation and proliferation ability of the cells upon SLA-treated specimens is proportional to oxygen level. Our results demonstrated that 5% O 2 will easily discriminate osteoblasts responses on different SLA-treated specimens. These results suggest that hypoxia (5% O 2) environment is better model for biological evaluation of bone-related materials. [ABSTRACT FROM AUTHOR]

Magnesium alloy has become one of the third-generation biomedical materials to promote bone tissue regeneration. Compared to other metal implants, magnesium metal is biodegradable and continues to degrade as the bone tissue heals, eliminating the need for secondary surgical removal. The Young's modulus of magnesium alloys is closer to human bone, and the magnesium ions produced by degradation are osteoinductive and antimicrobial, which can stimulate new bone formation, diminish stress shielding effects and reduce the risk of implant failure due to infection. However, the rapid corrosion rate of pure magnesium in a physiological environment can result in the mechanical integrity of the implant being compromised before the bone tissue has fully healed and the requirements associated with bone implantation cannot be met. In order to reduce the degradation rate of magnesium implants, the mechanical properties and corrosion properties of magnesium-based implants can be improved through machining, alloying and topology optimization to match the degradation rate of magnesium-based implants with the healing rate of bone tissue. As a bone implant fixation material, the mechanical properties, corrosion performance and biocompatibility of magnesium alloys are crucial. This work reviews studies related to the organization, mechanics, biocompatibility and corrosion properties of different magnesium-based alloys and analyzes the effect of different manufacturing processes on the mechanical properties of magnesium alloy implants. In addition, this paper also investigated the corrosion and wear behavior of magnesium alloy implants after implantation and analyzed the effect of different factors such as pH, temperature and stress on the corrosion behavior of magnesium alloy. Finally, in order to improve the implantation success rate of magnesium implants, the effects of different coatings on the biocompatibility and corrosion properties of magnesium implants are discussed.

Abstract Nanotopographical cues of bone implant surface has direct influences on various cell types during the establishment of osseointegration, a prerequisite of implant bear-loading. Given the important roles of monocyte/macrophage lineage cells in bone regeneration and remodeling, the regulation of nanotopographies on macrophages and osteoclasts has arisen considerable attentions recently. However, compared to osteoblastic cells, how nanotopographies regulate macrophages and osteoclasts has not been properly summarized. In this review, the roles and interactions of macrophages, osteoclasts and osteoblasts at different stages of bone healing is firstly presented. Then, the diversity and preparation methods of nanotopographies are summarized. Special attentions are paid to the regulation characterizations of nanotopographies on macrophages polarization and osteoclast differentiation, as well as the focal adhesion-cytoskeleton mediated mechanism. Finally, an outlook is indicated of coordinating nanotopographies, macrophages and osteoclasts to achieve better osseointegration. These comprehensive discussions may not only help to guide the optimization of bone implant surface nanostructures, but also provide an enlightenment to the osteoimmune response to external implant.

Porous tantalum metal has good biocompatibility and osteoconductivity, with a lower modulus of elasticity and a higher coefficient of friction to avoid stress-shielding compared with traditional implant metal materials. In addition, its porous structure, similar to that of human cancellous bone. Porous tantalum has received increasing attention in recent years due to its advantages in mechanical properties and excellent biological properties, and has been developed and applied in the treatment of various bone defects. With the progress of the preparation methods of porous tantalum materials and the proposal of various modification methods, the prosperity of porous tantalum in clinical applications has been further demonstrated. In this paper, the application of porous tantalum implant in bone defects treatment was reviewed, considering its preparation technology, cytotoxicity, osseointegration properties, and current clinical applications. Furthermore, the developments of porous tantalum including surface modification for establishing composite systems, optimization of preparation processes and personalized preparation techniques are expected to facilitate the clinical application of porous tantalum implants in the treatment of bone defects.

Obtaining accurate models and well-fitting prostheses during the fabrication of complete implant-supported prostheses has been a significant challenge. Conventional impression methods involve multiple clinical and laboratory steps that can lead to distortions, potentially resulting in inaccurate prostheses. In contrast, digital impressions may eliminate some of these steps, leading to better-fitting prostheses. Therefore, it is important to compare conventional and digital impressions for producing implant-supported prostheses. This study aimed to compare the quality of digital intraoral and conventional impressions by measuring the vertical misfit of implant-supported complete bars obtained using both types of techniques. Five digital impressions using an intraoral scanner and five impressions using elastomer were made in a four-implant master model. The plaster models produced with conventional impressions were scanned in a laboratory scanner to obtain virtual models. Screw-retained bars (n = five) were designed on the models and milled in zirconia. The bars fabricated using digital (DI) and conventional (CI) impressions were screwed to the master model, initially with one screw (DI1 and CI1) and later with four screws (DI4 and CI4), and were analyzed under a SEM to measure the misfit. ANOVA was used to compare the results (p < 0.05). There were no statistically significant differences in the misfit between the bars fabricated using digital and conventional impressions when screwed with one (DI1 = 94.45 µm vs. CI1 = 101.90 µm: F = 0.096; p = 0.761) or four screws (DI4 = 59.43 µm vs. CI4 = 75.62 µm: F = 2.655; p = 0.139). Further, there were no differences when the bars were compared within the same group screwed with one or four screws (DI1 = 94.45 µm vs. DI4 = 59.43 µm: F = 2.926; p = 0.123; CI1 = 101.90 µm vs. CI4 = 75.62 µm: F = 0.013; p = 0.907). It was concluded that both impression techniques produced bars with a satisfactory fit, regardless of whether they were screwed with one or four screws. [ABSTRACT FROM AUTHOR]

In the present study, the TiO2 nanotubes were grown on the surface of porous titanium foam by the anodization method. The surface of titanium foam before and after the coating of TiO2 nanotubes was structurally and morphologically characterized by X-ray diffraction (XRD), field emission electron microscope (FESEM) equipped with energy-dispersive X-ray (EDX). Additionally, the cytocompatibility of TiO2-coated porous titanium foam was evaluated by methyl thiazol tetrazolium (MTT) assay. The results have shown that the anatase crystalline phase was formed on the surface with a uniform thickness of 2.5 µm. Finally, TiO2-coated porous titanium foam was biocompatible and significantly enhanced the proliferation and attachment of MG-63 osteoblast cells compared to the uncoated substrate. All the results postulated that the coating of titanium substrate with TiO2 nanotube shows excellent promise for orthopedic implant application. [ABSTRACT FROM AUTHOR]

This review deals with the design of bioactive calcium phosphate coatings deposited on metallic substrates to produce bone implants. The bioceramic coating properties are used to create a strong bonding between the bone implants and the surrounding bone tissue. They provide a fast response after implantation and increase the lifespan of the implant in the body environment. The first part of the article describes the different compounds belonging to the calcium phosphate family and their main properties for applications in biomaterials science. The calcium-to-phosphorus atomic ratio (Ca/P)at. and the solubility (Ks) of these compounds define their behavior in a physiological environment. Hydroxyapatite is the gold standard among calcium phosphate materials, but other chemical compositions/stoichiometries have also been studied for their interesting properties. The second part reviews the most common deposition processes to produce bioactive calcium phosphate coatings for bone implant applications. The last part describes key physicochemical properties of calcium phosphate coatings and their impact on the bioactivity and performance of bone implants in a physiological environment. [ABSTRACT FROM AUTHOR]

Millions of people suffer from bone loss and diseases each year, which give rise to bone-related medical treatments. Multi-material coatings composed of Silicon Substituted Hydroxyapatite (Si-HA) and Silver Substituted Hydroxyapatite (Ag-HA) potentiated its usage as an ideal bone implant material with favourable biological response and antibacterial properties, respectively. Each patient has different conditions (e.g. bone ages, bone density, position, and infection status) and specific bone implant requirement, thus requiring specific designs of Si-HA and Ag-HA bone implant material ratios. In this paper, a recommender system which took advantage of Wide&Deep recommendation architecture and DenseNet architecture was provided and a semi-supervised training process was utilized to recommend appropriate bone implant material ratio (Si-HA:Ag-HA) for each patient to improve the bone disease treatment and recovery. The proposed recommendation system could achieve high accuracy ( 92.2 % ) and efficiency (using only 10 % of labeled data) on test dataset, which could be potentially utilized in future clinical usages and provide doctors with decision support to make better clinical decisions. [ABSTRACT FROM AUTHOR]

Ion-substituted calcium phosphate (CP) coatings have been extensively studied as promising materials for biomedical implants due to their ability to enhance biocompatibility, osteoconductivity, and bone formation. This systematic review aims to provide a comprehensive analysis of the current state of the art in ion-doped CP-based coatings for orthopaedic and dental implant applications. Specifically, this review evaluates the effects of ion addition on the physicochemical, mechanical, and biological properties of CP coatings. The review also identifies the contribution and additional effects (in a separate or a synergistic way) of different components used together with ion-doped CP for advanced composite coatings. In the final part, the effects of antibacterial coatings on specific bacteria strains are reported. The present review could be of interest to researchers, clinicians, and industry professionals involved in the development and application of CP coatings for orthopaedic and dental implants. [ABSTRACT FROM AUTHOR]

Critical-sized bone defects resulting from trauma, inflammation, and tumor resections are individual in their size and shape. Implants for the treatment of such defects have to consider biomechanical and biomedical factors, as well as the individual conditions within the implantation site. In this context, 3D printing technologies offer new possibilities to design and produce patient-specific implants reflecting the outer shape and internal structure of the replaced bone tissue. The selection or modification of materials used in 3D printing enables the adaption of the implant, by enhancing the osteoinductive or biomechanical properties. In this study, scaffolds with bone spongiosa-inspired structure for extrusion-based 3D printing were generated. The computer aided design process resulted in an up scaled and simplified version of the bone spongiosa. To enhance the osteoinductive properties of the 3D printed construct, polycaprolactone (PCL) was combined with 20% (wt) calcium phosphate nano powder (CaP). The implants were designed in form of a ring structure and revealed an irregular and interconnected porous structure with a calculated porosity of 35.2% and a compression strength within the range of the natural cancellous bone. The implants were assessed in terms of biocompatibility and osteoinductivity using the osteosarcoma cell line MG63 and patient-derived mesenchymal stem cells in selected experiments. Cell growth and differentiation over 14 days were monitored using confocal laser scanning microscopy, scanning electron microscopy, deoxyribonucleic acid (DNA) quantification, gene expression analysis, and quantitative assessment of calcification. MG63 cells and human mesenchymal stem cells (hMSC) adhered to the printed implants and revealed a typical elongated morphology as indicated by microscopy. Using DNA quantification, no differences for PCL or PCL-CaP in the initial adhesion of MG63 cells were observed, while the PCL-based scaffolds favored cell proliferation in the early phases of culture up to 7 days. In contrast, on PCL-CaP, cell proliferation for MG63 cells was not evident, while data from PCR and the levels of calcification, or alkaline phosphatase activity, indicated osteogenic differentiation within the PCL-CaP constructs over time. For hMSC, the highest levels in the total calcium content were observed for the PCL-CaP constructs, thus underlining the osteoinductive properties.

Polyetheretherketone (PEEK) is a thermoplastic polymer that has been recently employed for bone tissue engineering as a result of its biocompatibility and mechanical properties being comparable to human bone. PEEK, however, is a bio-inert material and, when implanted, does not interact with the host tissues, resulting in poor integration. In this work, the surfaces of 3D-printed PEEK disks were functionalized with: (i) an adhesive peptide reproducing [351–359] h-Vitronectin sequence (HVP) and (ii) HVP retro-inverted dimer (D2HVP), that combines the bioactivity of the native sequence (HVP) with the stability toward proteolytic degradation. Both sequences were designed to be anchored to the polymer surface through specific covalent bonds via oxime chemistry. All functionalized PEEK samples were characterized by Water Contact Angle (WCA) measurements, Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectroscopy (XPS) to confirm the peptide enrichment. The biological results showed that both peptides were able to increase cell proliferation at 3 and 21 days. D2HVP functionalized PEEK resulted in an enhanced proliferation across all time points investigated with higher calcium deposition and more elongated cell morphology. [ABSTRACT FROM AUTHOR]

Purpose: To quantify union rate, complication rate, reintervention rate, as well as functional outcome after vascularized fibular bone grafts (VFGs) for the treatment of long-bone defects. Methods: A comprehensive search was performed in the PubMed, Web of Science, and Cochrane databases up to August 18, 2020. Randomized controlled trials, comparative studies, and case series describing the various techniques available involving VFGs for the reconstruction of segmental long-bone defects were included. A meta-analysis was performed on union results, complications, and reinterventions. Assessment of risk of bias and quality of evidence was performed with the Downs and Black's "Checklist for Measuring Quality". Results: After full-text assessment, 110 articles on 2226 patients were included. Among the retrieved studies, 4 were classified as poor, 83 as fair, and 23 as good. Overall, good functional results were documented and a union rate of 80.1% (CI 74.1–86.2%) was found, with a 39.4% (CI 34.4–44.4%) complication rate, the most common being fractures, non-unions and delayed unions, infections, and thrombosis. Donor site morbidity represented 10.7% of the total complications. A 24.6% reintervention rate was documented (CI 21.0–28.1%), and 2.8% of the patients underwent amputation. Conclusions: This systematic review and meta-analysis documented good long-term outcomes both in the upper and lower limb. However, VFG is a complex and demanding technique; this complexity means an average high number of complications, especially fractures, non-unions, and vascular problems. Both potential and limitations of VFG should be considered when choosing the most suitable approach for the treatment of long-bone defects. [ABSTRACT FROM AUTHOR]

Purpose: The research was focused on determining basic mechanical properties, surface, and phase structure taking into consideration basic cytotoxicity analysis towards human cells. Methods: Biological tests were performed on human C-12302 fibroblasts cells using 3D-printed Ti6Al4V alloy (Ti64), produced by laser-based powder bed fusion (LB-PBF) and Alumina Toughened Zirconia 20 (ATZ20), produced by lithography-based ceramic manufacturing (LCM). Surface modifications included electropolishing and hydroxyapatite or hydroxyapatite/zinc coating. Structure analysis was carried out using a variety of techniques such as X-Ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM), followed by mechanical properties evaluation using nanoindentation testing. Results: Samples subjected to surface modifications showed diversity among surface and phase structure and mechanical properties. However, the cytotoxicity towards tested cells was not significantly higher than the control. Though, a trend was noted among the materials analysed, indicating that HAp/Zn coating on Ti64 and ATZ20 resulted in the best biological performance increasing cell survivability by more than 10%. Conclusions: Hydroxyapatite coating on Ti64 and ATZ20 resulted in the best biological properties. Tested materials are suitable for in vivo toxicity testing. [ABSTRACT FROM AUTHOR]

Currently, numerous bone tumor patients undergo tumor recurrence after surgical resection, which seriously affects their quality of life. In this study, the ceria (CeO 2) nanoparticle was added to Poly-L-Lactic Acid (PLLA) bone implants endowing the bone implant with antitumor function. The results showed that the reactive oxygen species increased in U2OS cells while it dropped in HEK293 cells as the CeO 2 content increased. Meanwhile, the PLLA-8CeO 2 showed a high cell inhibition rate of 53.66 % for U2OS cells and possessed a high cell viability of 76.96 ± 2.20 % for HEK293 cells, meaning that the implant could kill bone tumor cells meanwhile show good cytocompatibility for normal cells. These were mainly due to the fact that the CeO 2 nanoparticles acted as a superoxide dismutase in tumor cells reducing superoxide to hydrogen peroxide, inducing an increase in reactive oxygen species levels. The excess reactive oxygen species could result in tumor cell apoptosis by disrupting mitochondrial structure, oxidizing proteins, and promoting DNA denaturation. Moreover, the compressive strength of PLLA was improved by the CeO 2 addition due to its particle dispersion strengthening. Besides, the PLLA-CeO 2 had a faster degradation rate compared to PLLA. Overall, the PLLA-CeO 2 is a promising implant material for bone tumor treatment. [ABSTRACT FROM AUTHOR]

To investigate the feasibility of high-entropy alloys as the coating materials for the application of bone implants, TiZrNbTa refractory medium-entropy alloy (RMEA) and TiZrHfNbTa refractory high-entropy alloy (RHEA) nanofilms were prepared on AISI 316L stainless steel by DC magnetron sputtering and post-annealing treatment. Then, the microstructure, mechanical properties, wear resistance, corrosion resistance, biocompatibility and osteogenic activity of the nanofilms were systematically studied. The results showed that both the films exhibited uniform and dense nanostructures. Post-annealing treatment not only improved the adhesion strength, but also formed an oxidized layer. Notably, owing to the enhanced high-entropy and lattice distortion effects, the RHEA nanofilm showed finer grain sizes, higher hardness (14 GPa), H / E , H 3/ E 2 and better wear resistance. The in vitro experiments proved that RHEA nanofilm had the highest E corr (−0.127 V), with the I corr value was two orders of magnitude lower than substrate. Its osteoblast proliferative capacity was 1.5 times higher than substrate (after culturing for 5 days), and the collagen secretion and extracellular matrix mineralization reached an optimal level, showing excellent osteogenic activity. Therefore, RHEA nanofilm coated biomaterials can be a more attractive candidate for bone replacement. • Oxide layer obtained on the TiZrNbTa RMEA and TiZrHfNbTa RHEA nanofilms after annealing. • Attached nanofilms improved mechanical properties, wear and corrosion resistance, and osteogenic activity of substrate. • RHEA nanofilm has the highest H , the lowest wear rate, the best corrosion resistance, biocompatibility and osteogenesis. [ABSTRACT FROM AUTHOR]

In this work, we have developed and characterized a ceramic composite based on a core of directionally solidified calcium zirconate-calcium stabilized zirconia (CZO-CSZ) eutectic composite coated with a bioactive glass-ceramic. The aim is to research new orthopedic implants as an alternative to conventional 3Y-TZP bioinert ceramics. The CZO-CSZ eutectic rods were grown from the melt of rods of CaO-ZrO2 in the eutectic composition using the laser floating zone technique (LFZ). The mechanical results indicated that directional eutectics prepared with this technique exhibited good mechanical strength and significant hardness and toughness. The LFZ technique was also used to melt the bioactive coating previously placed by dip coating on the CZO-CSZ rod surface. Depending on the thickness of the coating and the applied laser power, an alloying or coating process was achieved. In the first case, the coating was diluted with the surface of the eutectic cylinder, leading to the segregation of the calcium zirconate and zirconia phases and the formation of a bioactive phase embedding zirconia particles. In the second case, a layer of ceramic glass was formed, well attached to the eutectic cylinder. These layers were both studied from the microstructural and bioactivity points of view.

The aim of this work is to analyze the usefulness of Sr3(PO4)2 as a potential antibacterial agent in fast-degradable polymer coatings. The Ti implant was anodized and then covered by a poly(adipic anhydride) layer blended with Sr3(PO4)2 particles by dip coating. The average size of the particles was 450 nm ± 53 nm (Zetasizer analysis), and phase analysis (X-ray diffractometer) showed mainly crystalline phases. Surface morphology and surface roughness were analyzed by scanning electron microscopy with energy dispersive X-ray (EDX). The oxide layer thickness on the implant surface was between 4.57 μm and 8.09 μm. The polymer layer with Sr3(PO4)2 particles was determined by confocal microscopy, and the average thickness was 25 μm. The contact angle of the anodized Ti implant alone was 37.3° ± 9.9° and decreased with time up to 20° after 1900s. After 1 h of implant immersion in Ringer solution, 42.15% of the Sr compound loaded in the polymer layer was released (determined by inductively coupled plasma atomic emission spectrometry (ICP-AES)). Fast degradation of the polymer caused 65.21% of the loaded Sr compound to be released from the implant surface after 24 h. The concentration of Sr3(PO4)2 was enough to significantly inhibit the adhesion of Staphylococcus aureus ATCC 25923 bacteria on the implant surface. The implant surface is cytocompatible with osteoblast-like MG-63 cells. The preliminary results of hybrid coating analysis showed that Sr3(PO4)2 may be used as an alternative ceramic material for the formation of a functional layer for orthopedic applications.

Nanotopographical cues of bone implant surface has direct influences on various cell types during the establishment of osseointegration, a prerequisite of implant bear-loading. Given the important roles of monocyte/macrophage lineage cells in bone regeneration and remodeling, the regulation of nanotopographies on macrophages and osteoclasts has arisen considerable attentions recently. However, compared to osteoblastic cells, how nanotopographies regulate macrophages and osteoclasts has not been properly summarized. In this review, the roles and interactions of macrophages, osteoclasts and osteoblasts at different stages of bone healing is firstly presented. Then, the diversity and preparation methods of nanotopographies are summarized. Special attentions are paid to the regulation characterizations of nanotopographies on macrophages polarization and osteoclast differentiation, as well as the focal adhesion-cytoskeleton mediated mechanism. Finally, an outlook is indicated of coordinating nanotopographies, macrophages and osteoclasts to achieve better osseointegration. These comprehensive discussions may not only help to guide the optimization of bone implant surface nanostructures, but also provide an enlightenment to the osteoimmune response to external implant. [ABSTRACT FROM AUTHOR]

The coating of hydroxyapatite (HAP) on the surface of bio-inert metallic implants to augment their bioactivity is in use for the last two decades. Substitution of various materials in HAP further improves the functionality of these coatings. We demonstrate coating of Ti6Al4V alloy sheets with strontium and niobium reinforced HAP using microwave (MW) irradiation technique. Physical characterization revealed, uniform semicrystalline hydroxyapatite coating with enhanced surface roughness and microhardness. The increased surface roughness was accompanied by higher wettability and more protein adsorption. Electrochemical corrosion assessment showed a dramatic increase in corrosion potential and a noticeable decline in corrosion current density suggesting an enhanced anticorrosive behaviour. These implants also exhibited improved hemocompatibility and bacteriostatic properties. Cell viability and confocal microscopy studies of the coated samples showed enhanced cell attachment on the surface. We propose microwave irradiation as a fast and hassle-free alternative for one-pot synthesis and deposition of ionic substituted HAP on metallic implants. [ABSTRACT FROM AUTHOR]

Meta-biomaterials are applied to orthopedic implants to avoid stress shielding effects; however, there is no reason for the yield strength to be comparable to that of human bone. In this study, a composite unit cell was designed by combining the positive Poisson's ratio (PPR) and negative Poisson's ratio (NPR) unit cells, inspired by the second-phase strengthening theory. The purpose was to increase the strength while maintaining the elastic modulus. All structures were successfully fabricated from Ti-6Al-4V via selective laser melting. The relative density is between 0.08 and 0.24, which falls within the optimal range for bone growth. Mechanical tests indicated that the center of the inclined rod fractured in a stepwise fracture mode, which was consistent with the predictions of the Johnson–Cook model. The elastic modulus ranged from 0.652 ± 0.016 to 5.172 ± 0.021 GPa, and the yield strength varied from 10.62 ± 0.112 to 87.158 ± 2.215 MPa. An improved Gibson–Ashby law was proposed to facilitate the design of gradient structures. When the re-entrant angle was 40°, a hybrid body-centered cubic NPR structure was formed, resulting in a significant improvement in the mechanical properties. Importantly, the yield strength of the proposed composite structures increased by 43.23%, and the compression strength increased by 44.70% under the same elastic modulus. The strengthening mechanism has been proven to apply to other bending-dominated structures. Overall, this imparts unprecedented mechanical performance to auxetic meta-biomaterials and provides insights into improving the reported porous structures. Auxetic meta-biomaterials exhibit auxetic properties that can improve the contact between the bone-implant interface and reduce the risk of aseptic failure. To avoid the stress shielding effect, the elastic modulus has traditionally been decreased by increasing the porosity. However, the strength is simultaneously reduced. Therefore, a composite unit cell was proposed to increase strength rather than modulus by combining the positive and negative Poisson's ratio unit cells, inspired by the second-phase strengthening theory. We observed a 43.23% increase in the yield strength of the composite structure without increasing the elastic modulus. This strengthening mechanism has been proven to apply to other bending-dominated structures. Our approach provides insights into improving other bending-dominated structures and broadening their applications for bone implantation. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)