Influence of titanium and titanium-zirconium alloy as implant materials on implant stability of maxillary implant retained overdenture: a randomized clinical trial.

BACKGROUND: Long-term success of implant restoration depends on many factors one of them is the sufficient implant stability which is lowered in compromised bone density sites such as the maxilla as it is categorized as type III & IV bone, so searching for a new innovation and updates in implant material and features is very mandatory. So, the aim of this study was to compare between two implant materials (roxolid and traditional titanium) on the primary and secondary stability of implant retained maxillary overdenture. METHODS: Eighteen completely edentulous patients were selected. All patients received maxillary implant-retained overdentures and lower complete dentures; patients were divided equally into two groups according to the type of implant materials. Group A received a total number of 36 implants made of roxolid material and Group B received a total number of 36 implants made of traditional titanium alloys. Implant stability was assessed using ostell device, the primary implant stability was measured at the day of implant installation however, secondary implant stability was measured after six weeks of implant placement. Paired t-test was used to compare between primary and secondary stability in the same group and an independent t-test was used to compare between the two groups with a significant level < 0.05. RESULTS: Independent t-test revealed a significant difference between the two groups with p -value = 0.0141 regarding primary stability and p-value < 0.001 regarding secondary stability, as roxolid implant group was statistically higher stability than titanium group in both. Paired t- test showed a statistically significant difference in roxolid implant group with p-value = 0.0122 however, there was non-statistically significant difference in titanium group with p-value = 0.636. Mann Whitney test showed a significant difference between the two groups regarding amount of change in stability with p value = 0.191. roxolid implant group showed a higher amount of change in stability than the titanium implant group. CONCLUSION: Within the limitation of this study, it could be concluded that: Roxolid implants showed promising results regarding primary and secondary stability compared to conventional Titanium implants and can be a better alternative in implant retained maxillary overdentures. TRIAL REGISTRATION: Retrospectively NCT06334770 at 26-3-2024.

Tailored Bioactive Glass Coating: Navigating Devitrification Toward a Superior Implant Performance.

The development of well-adherent, amorphous, and bioactive glass coatings for metallic implants remains a critical challenge in biomedical engineering. Traditional bioactive glasses are susceptible to crystallization and exhibit a thermal expansion mismatch with implant materials. This study introduces a novel approach to overcome these limitations by employing systematic Na2O substitution with CaO in borosilicate glasses. In-depth structural analysis (MD simulations, Raman spectroscopy, and NMR) reveals a denser network with smaller silicate rings, enhancing thermal stability, reducing thermal expansion, and influencing dissolution kinetics. This tailored composition exhibited optimal bioactivity (in vitro formation of bone-like apatite within 3 days) and a coefficient of thermal expansion closely matching Ti-6Al-4V, a widely used implant material. Furthermore, a consolidation process, meticulously designed with insights from crystallization kinetics and the viscosity-temperature relationship, yielded a crack-free, amorphous coating on Ti-6Al-4V substrates. This novel coating demonstrates excellent cytocompatibility and strong antibacterial action, suggesting superior clinical potential compared with existing technologies.

Finite element modeling of stress distribution and safety factors in a Ti-27Nb alloy hip implant under real-world physiological loading scenarios.

Total hip arthroplasty (THA) is one of the most successful orthopaedic interventions globally, with over 450,000 procedures annually in the U.S. alone. However, issues like aseptic loosening, dislocation, infection and stress shielding persist, necessitating complex, costly revision surgeries. This highlights the need for continued biomaterials innovation to enhance primary implant integrity and longevity. Implant materials play a pivotal role in determining long-term outcomes, with titanium alloys being the prominent choice. However, emerging evidence indicates scope for optimized materials. The nickel-free ß titanium alloy Ti-27Nb shows promise with excellent biocompatibility and mechanical properties. Using finite element analysis (FEA), this study investigated the biomechanical performance and safety factors of a hip bone implant made of nickel-free titanium alloy (Ti-27Nb) under actual loading during routine day life activities for different body weights. The FEA modelled physiological loads during walking, jogging, stair ascent/descent, knee bend, standing up, sitting down and cycling for 75 kg and 100 kg body weights. Comparative analyses were conducted between untreated versus 816-hour simulated body fluid (SBF) treated implant conditions to determine in vivo degradation effects. The FEA predicted elevated von Mises stresses in the implant neck for all activities, especially stair climbing, due to its smaller cross-section. Stresses increased substantially with a higher 100 kg body weight compared to 75 kg, implying risks for heavier patients. Safety factors were reduced by up to 58% between body weights, although remaining above the desired minimum value of 1. Negligible variations were observed between untreated and SBF-treated responses, attributed to Ti-27Nb's excellent biocorrosion resistance. This comprehensive FEA provided clinically relevant insights into the biomechanical behaviour and integrity of the Ti-27Nb hip implant under complex loading scenarios. The results can guide shape and material optimization to improve robustness against repetitive stresses over long-term use. Identifying damage accumulation and failure risks is crucial for hip implants encountering real-world variable conditions. The negligible SBF effects validate Ti-27Nb's resistance to physiological degradation. Overall, the study significantly advances understanding of Ti-27Nb's suitability for reliable, durable hip arthroplasties with low revision rates.

Investigation of the Relationship between Surface Features, Protein Adsorption, and Osteoimmunomodulation: The Case of a Chemically Treated Titanium Alloy.

This paper deals with the combined effects of immune response and osseointegration because of the lack of comprehensive studies on this topic. An antibacterial Ti surface was considered because of the high risk of infection for titanium bone implants. A chemically treated Ti6Al4 V alloy [Ti64(Sr-Ag)] with a microporous and Sr-Ag doped surface was compared to a polished version (Ti64) regarding protein adsorption (albumin and fibronectin) and osteoimmunomodulation. Characterization via fluorescence microscopy and zeta potential showed a continuous fibronectin layer on Ti64(Sr-Ag), even with preadsorbed albumin, while it remained filamentous on Ti64. Macrophages (differentiated from THP-1 monocytes) were cultured on both surfaces, with viability and cytokine release analyzed. Differently from Ti64, Ti64(Sr-Ag) promoted early anti-inflammatory responses and significant downregulation of VEGF. Ti64(Sr-Ag) also enhanced human bone marrow mesenchymal cell differentiation toward osteoblasts, when a macrophage-conditioned medium was used, influencing ALP production. Surface properties in relation to protein adsorption and osteoimmunomodulation were discussed.

Influence of casein on the degradation process of polylactide-casein coatings for resorbable alloys.

This study used the dip-coating method to develop a new biocompatible coating composed of polylactide (PLA) and casein for ZnMg1.2 wt% alloy implants. It evaluated its impact on the alloy's degradation in a simulated body fluid. After 168 h of immersion in Ringer's solution, surface morphology analysis showed that the PLA-casein coatings demonstrated uniform degradation, with the corrosion current density measured at 48 µA/cm2. Contact angle measurements indicated that the average contact angles for the PLA-casein-coated samples were below 80°, signifying a hydrophilic nature that promotes cell adhesion. Fourier-transform infrared spectroscopy (FTIR) revealed no presence of lactic acid on PLA-casein coatings after immersion, in contrast to pure PLA coatings. Pull-off adhesion tests showed tensile strength values of 7.6 MPa for pure PLA coatings and 5 MPa for PLA-casein coatings. Electrochemical tests further supported the favorable corrosion resistance of the PLA-casein coatings, highlighting their potential to reduce tissue inflammation and improve the biocompatibility of ZnMg1.2 wt% alloy implants.

Clinical performance of implanted devices used in surgical treatment of patients with spinal tumors: a systematic review.

PURPOSE: Implanted devices used in metastatic spine tumor surgery (MSTS) include pedicle screws, fixation plates, fixation rods, and interbody devices. A material to be used to fabricate any of these devices should possess an array of properties, which include biocompatibility, no toxicity, bioactivity, low wear rate, low to moderate incidence of artifacts during imaging, tensile strength and modulus that are comparable to those of cortical bone, high fatigue strength/long fatigue life, minimal or no negative impact on radiotherapy (RT) planning and delivery, and high capability for fusion to the contiguous bone. The shortcomings of Ti6Al4V alloy for these applications with respect to these desirable properties are well recognized, opening the field for an investigation about novel biomaterials that could replace the current gold standard. Previously published reviews on this topic have exhibited significant shortcomings in the studies they included, such as a small, heterogenous sample size and the lack of a cost-benefit analysis, extremely useful to understand the practical possibility of applying a novel material on a large scale. Therefore, this review aims to collect information about the clinical performance of these biomaterials from the most recent literature, with the objective of deliberating which could potentially be better than titanium in the future, with particular attention to safety, artifact production and radiotherapy planning interference. The significant promise showed by analyzing the clinical performance of these devices warrants further research through prospective studies with a larger sample size also taking into account each aspect of the production and use of such materials. METHODS: The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were used to improve the reporting of the review. The search was performed from March 2022 to September 2023. RESULTS: At the end of the screening process, 20 articles were considered eligible for this study. Polyetheretherketone (PEEK), Carbon-fibre reinforced polyetheretherketone (CFR-PEEK), long carbon fiber reinforced polymer (LCFRP), Polymethylmethacrylate (PMMA), and carbon screw and rods were used in the included studies. CONCLUSION: CFR-PEEK displays a noninferior safety and efficacy profile to titanium implanted devices. However, it also has other advantages. By decreasing artifact production, it is able to increase detection of local tumor recurrence and decrease radiotherapy dose perturbation, ultimately bettering prognosis for patients necessitating adjuvant treatment. Nonetheless, its drawbacks have not been explored fully and still require further investigation in future studies. This does not exclude the fact that CFR-PEEK could be a valid alternative to titanium in the near future.

Enhancing Bactericidal Properties of Ti6Al4V Surfaces through Micro and Nano Hierarchical Laser Texturing.

Orthopedic and dental implants made from Ti6Al4V are widely used due to their excellent mechanical properties and biocompatibility. However, the long-term performance of these implants can be compromised by bacterial infections. This study explores the development of hierarchically textured surfaces with enhanced bactericidal properties to address such challenges. Hierarchical surface structures were developed by combining microscale features produced by a microsecond laser and superimposed submicron features produced using a femtosecond laser. Microscale patterns were produced by the pulsed laser surface melting process, whereas submicrometer laser-induced periodic surface structures were created on top of them by femtosecond laser processing. Escherichia coli bacterial cells were cultured on the textured surface. After 24 h, a staining analysis was performed using SYTO9 and PI dyes to investigate the samples with a confocal microscope for live dead assays. Results showed bacterial colony formation onto the microscale surface textures with live bacterial cells, whereas the hierarchical surface textures display segregated and physically damaged bacterial cell attachments on surfaces. The hierarchical surface textures showed ∼98% dead bacterial cells due to the combined effect of its multiscale surface features and oxide formation during the laser processing steps. The efficacy of hierarchical surface textures in enhancing the antibacterial behavior of Ti6Al4V implants is evident from the conducted research. Such laser-based surface treatments can find potential applications in different industrial sectors.

Advancing Dental Implant Design: A Comprehensive Study of Machining Parameters, Corrosion Behavior, and Microstructural Evaluation.

In this research, we investigate the impact of varying machining parameters [depth of cutting (mm) and spindle rotation speed (rpm)] on the microstructure and electrochemical behavior of Ti6Al4V-ELI dental implants. This comprehensive study employs an approach, leveraging potentiodynamic methods and electrochemical impedance spectroscopy, to analyze corrosion behavior in a phosphate-buffered saline solution. To further deepen our understanding of corrosion kinetics, we used an alternating current circuit model, based on a simple Randles equivalent circuit. This model elucidates the corrosion interface interactions of the Ti6Al4-V-ELI alloy implant within the PBS solution. In addition, our research delves into the microstructural implications of different machining parameters, utilizing scanning electron microscopy and X-ray diffraction (XRD) techniques to reveal significant phase changes. The changes in texture were examined qualitatively by comparing the intensities of the peaks of the XRD pattern. A detailed correlation analysis further links the machining parameters with the corrosion properties of dental implants, offering a comprehensive perspective rarely explored in the existing literature. The results obtained for the three samples showed that the corrosion resistance would be higher by increasing the machining depth and the spindle rotation and that the corrosion current would be lower. As a result, a lower corrosion rate was obtained. Finally, experimental results from electrochemical analyses are compared and discussed.

Modulating cell stiffness for improved vascularization: leveraging the MIL-53(fe) for improved interaction of titanium implant and endothelial cell.

Vascularization plays a significant role in promoting the expedited process of bone regeneration while also enhancing the stability and viability of artificial bone implants. Although titanium alloy scaffolds were designed to mimic the porous structure of human bone tissues to facilitate vascularization in bone repair, their biological inertness restricted their broader utilization. The unique attribute of Metal-organic framework (MOF) MIL-53(Fe), known as "breathing", can facilitate the efficient adsorption of extracellular matrix proteins and thus provide the possibility for efficient interaction between scaffolds and cell adhesion molecules, which helps improve the bioactivity of the titanium alloy scaffolds. In this study, MIL-53(Fe) was synthesized in situ on the scaffold after hydrothermal treatment. The MIL-53(Fe) endowed the scaffold with superior protein absorption ability and preferable biocompatibility. The scaffolds have been shown to possess favorable osteogenesis and angiogenesis inducibility. It was indicated that MIL-53(Fe) modulated the mechanotransduction process of endothelial cells and induced increased cell stiffness by promoting the adsorption of adhesion-mediating extracellular matrix proteins to the scaffold, such as laminin, fibronectin, and perlecan et al., which contributed to the activation of the endothelial tip cell phenotype at sprouting angiogenesis. Therefore, this study effectively leveraged the intrinsic "breathing" properties of MIL-53 (Fe) to enhance the interaction between titanium alloy scaffolds and vascular endothelial cells, thereby facilitating the vascularization inducibility of the scaffold, particularly during the sprouting angiogenesis phase. This study indicates that MIL-53(Fe) coating represents a promising strategy to facilitate accelerated and sufficient vascularization and uncovers the scaffold-vessel interaction from a biomechanical perspective.

One-step synthesized multisize AuAg alloy nanoparticles with high SERS sensitivity in directly detecting SARS-CoV-2 spike protein.

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in widespread disease transmission, challenging the stability of global healthcare systems. Surface-enhanced Raman scattering (SERS) as an easy operation, fast, and low-cost technology illustrates a good potential in detecting SARS-CoV-2. In the study, one-step fabrication of gold-silver alloy nanoparticles (AuAgNPs) with adjustable metal proportions and diameters is employed as SERS substrates. The angiotensin-converting enzyme 2 (ACE2) functionalized AuAgNPs are applied as sensor surfaces to detect SARS-CoV-2 S protein. By optimizing the SERS substrates, ACE2/Au35Ag65NPs illustrate higher performance in detecting the SARS-CoV-2 S protein with a limit of detection (LOD) of 10 fg/mL in both phosphate-buffered saline (PBS) and pharyngeal swabs solution (PSS). It also provides excellent reproducibility with a relative standard deviation (RSD) of 7.7 % and 7.9 %, respectively. This easily preparable and highly reproducible SERS substrate has good potential in the practical application of detecting SARS-CoV-2.

Cutibacterium acnes biofilm formation is influenced by bone microenvironment, implant surfaces and bacterial internalization.

BACKGROUND: The bacterial persistence, responsible for therapeutic failures, can arise from the biofilm formation, which possesses a high tolerance to antibiotics. This threat often occurs when a bone and joint infection is diagnosed after a prosthesis implantation. Understanding the biofilm mechanism is pivotal to enhance prosthesis joint infection (PJI) treatment and prevention. However, little is known on the characteristics of Cutibacterium acnes biofilm formation, whereas this species is frequently involved in prosthesis infections. METHODS: In this study, we compared the biofilm formation of C. acnes PJI-related strains and non-PJI-related strains on plastic support and textured titanium alloy by (i) counting adherent and viable bacteria, (ii) confocal scanning electronic microscopy observations after biofilm matrix labeling and (iii) RT-qPCR experiments. RESULTS: We highlighted material- and strain-dependent modifications of C. acnes biofilm. Non-PJI-related strains formed aggregates on both types of support but with different matrix compositions. While the proportion of polysaccharides signal was higher on plastic, the proportions of polysaccharides and proteins signals were more similar on titanium. The changes in biofilm composition for PJI-related strains was less noticeable. For all tested strains, biofilm formation-related genes were more expressed in biofilm formed on plastic that one formed on titanium. Moreover, the impact of C. acnes internalization in osteoblasts prior to biofilm development was also investigated. After internalization, one of the non-PJI-related strains biofilm characteristics were affected: (i) a lower quantity of adhered bacteria (80.3-fold decrease), (ii) an increase of polysaccharides signal in biofilm and (iii) an activation of biofilm gene expressions on textured titanium disk. CONCLUSION: Taken together, these results evidenced the versatility of C. acnes biofilm, depending on the support used, the bone environment and the strain.

Development of implantable electrode based on bioresorbable Mg alloy for tissue welding application.

An implantable electrode based on bioresorbable Mg-Nd-Zn-Zr alloy was developed for next-generation radiofrequency (RF) tissue welding application, aiming to reduce thermal damage and enhance anastomotic strength. The Mg alloy electrode was designed with different structural features of cylindrical surface (CS) and continuous long ring (LR) in the welding area, and the electrothermal simulations were studied by finite element analysis (FEA). Meanwhile, the temperature variation during tissue welding was monitored and the anastomotic strength of welded tissue was assessed by measuring the avulsion force and burst pressure. FEA results showed that the mean temperature in the welding area and the proportion of necrotic tissue were significantly reduced when applying an alternating current of 110 V for 10 s to the LR electrode. In the experiment of tissue welding ex vivo, the maximum and mean temperatures of tissues welded by the LR electrode were also significantly reduced and the anastomotic strength of welded tissue could be obviously improved. Overall, an ideal welding temperature and anastomotic strength which meet the clinical requirement can be obtained after applying the LR electrode, suggesting that Mg-Nd-Zn-Zr alloy with optimal structure design shows great potential to develop implantable electrode for next-generation RF tissue welding application.

Degradation Behavior of Medical MgZZC-1 in Various Simulated Body Fluids.

Magnesium-based biodegradable metal bone implants exhibit superior mechanical properties compared to biodegradable polymers for orthopedic and cardiovascular stents. In this study, MgZZC-x (x = 1, 1.2) alloys were screened by in vitro biocompatibility tests in three simulated body fluids under nontoxic conditions. The MgZZC-1 alloys with better biocompatibility were selected to predict the days required for complete degradation. The evolution of degradation products was analyzed, and the mechanism of formation of the product film was inferred. A degradation kinetic model was established to investigate the effect of MEM components on the degradation of the alloys. The results demonstrate that the proteins in MEM can greatly retard the degradation progress by attaching to the surface of MgZZC-1 alloys, which are predicted to degrade completely within 341 days. The carbonate and phosphate buffers were adjusted to pH in MEM solution, delaying the degradation of magnesium alloys. This process in MEM more accurately reflects the actual degradation in the body and is superior to that in Hanks and SBF solutions. This study will promote the application of biodegradable materials in clinical medicine.

Mesoscale characterization of osseointegration around an additively manufactured genistein-coated implant.

Given the hierarchical nature of bone and bone interfaces, osseointegration, namely the formation of a direct bone-implant contact, is best evaluated using a multiscale approach. However, a trade-off exists between field of view and spatial resolution, making it challenging to image large volumes with high resolution. In this study, we combine established electron microscopy techniques to probe bone-implant interfaces at the microscale and nanoscale with plasma focused ion beam-scanning electron microscopy (PFIB-SEM) tomography to evaluate osseointegration at the mesoscale. This characterization workflow is demonstrated for bone response to an additively manufactured Ti-6Al-4V implant which combines engineered porosity to facilitate bone ingrowth and surface functionalization via genistein, a phytoestrogen, to counteract bone loss in osteoporosis. SEM demonstrated new bone formation at the implant site, including in the internal implant pores. At the nanoscale, scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy confirmed the gradual nature of the bone-implant interface. By leveraging mesoscale analysis with PFIB-SEM tomography that captures large volumes of bone-implant interface with nearly nanoscale resolution, the presence of mineral ellipsoids varying in size and orientation was revealed. In addition, a well-developed lacuno-canalicular network and mineralization fronts directed both towards the implant and away from it were highlighted.

Investigating mechanical deformation's role in cochlear implant durability.

Platinum and platinum-based alloys are used as the electrode material in cochlear implants because of the biocompatibility and the favorable electrochemical properties. Still, these implants can fail over time. The present study was conducted to shed light on the effects of microstructure on the electrochemical degradation of platinum. After three days of stimulation with a square wave signal, corrosive attack appeared on the platinum surface. The influence of mechanical deformation, in particular rolling, on the corrosion resistance of platinum was also prominent. The cyclic voltammetry showed a clear dependence on the electrolyte used, which was interpreted as an influence of the buffer in the artificial perilymph used. In addition, the polarization curves showed a shift with grain size that was not expected. This could be attributed to the defects present on the surface. These findings are crucial for the manufacture of cochlear implants to ensure their long-term functionality.

Enhanced Antimicrobial Activity of AgCu Nanoparticles: The Role of Particle Size and Alloy Composition.

AgCu bimetallic· nanoparticles (NPs) represent a novel class of inorganic, broad-spectrum antimicrobial agents that offer enhanced antimicrobial effectiveness and reduced cytotoxicity compared to conventional Ag NP antibacterial materials. This study examines the antimicrobial performance and structural characteristics of AgCu nanoparticles (NPs) synthesized via two distinct chemical reduction processes using PVP-PVA as stabilizers. Despite identical chemical elements and sphere-like shapes in both synthesis methods, the resulting AgCu nanoparticles exhibited significant differences in size and antimicrobial properties. Notably, AgCu NPs with smaller average particle sizes demonstrated weaker antimicrobial activity, as assessed by the minimum inhibitory concentration (MIC) measurement, contrary to conventional expectations. However, larger average particle-sized AgCu NPs showed superior antimicrobial effectiveness. High-resolution transmission electron microscopy analysis revealed that nearly all larger particle-sized nanoparticles were AgCu nanoalloys. In contrast, the smaller particle-sized samples consisted of both AgCu alloys and monometallic Ag and Cu NPs. The fraction of Ag ions (relative to the total silver amount) in the larger AgCu NPs was found to be around 9%, compared to only 5% in that of the smaller AgCu NPs. This indicates that the AgCu alloy content significantly contributes to enhanced antibacterial efficacy, as a higher AgCu content results in the increased release of Ag ions. These findings suggest that the enhanced antimicrobial efficacy of AgCu NPs is primarily attributed to their chemical composition and phase structures, rather than the size of the nanoparticles.

A fucoidan-loaded hydrogel coating for enhancing corrosion resistance, hemocompatibility and endothelial cell growth of magnesium alloy for cardiovascular stents.

Although magnesium alloy has received tremendous attention in biodegradable cardiovascular stents, the poor in vivo corrosion resistance and limited endothelialization are still the bottlenecks for its application in cardiovascular stents. Fabrication of the multifunctional bioactive coating with excellent anti-corrosion on the surface is beneficial for rapid re-endothelialization and the normal physiological function recovery of blood vessels. In the present study, a bioactive hydrogel coating was established on the surface of magnesium alloy by copolymerization of sulfobetaine methacrylate (SBMA) and acrylamide (AM) via ultraviolet (UV) polymerization, followed by the immobilization of fucoidan (Fu). The results showed that the as-prepared multifunctional hydrogel coating could enhance the corrosion resistance and the surface wettability of the magnesium alloy surface, endowing it with the ability of selective albumin adsorption; meanwhile, it could augment biocompatibility. The following introduction of fucoidan on the surface could further improve the hemocompatibility characterized by reducing protein adsorption, minimizing hemolysis, and preventing platelet aggregation and activation. Additionally, the immobilized fucoidan promoted endothelial cell (EC) growth, as well as up-regulated the expression of vascular endothelial growth factor (VEGF) and nitric oxide (NO) in endothelial cells (ECs). Consequently, this research paves a novel approach to developing a versatile bioactive coating for magnesium alloy surfaces and lays a foundation in cardiovascular biomaterials.

Wear and corrosion of titanium alloy spinal implants in vivo.

To investigate the wear and corrosion of titanium alloy spinal implants in vivo, we evaluated removed implants and their surrounding scar tissues from 27 patients between May 2019 and April 2021. We performed scanning electron microscopy, energy-dispersive X-ray spectroscopy, and histological analysis. The results revealed metal-like particles in the soft tissues of seven patients, without any considerable increase in inflammatory cell infiltration. Patients with fractures showed lower percentages of wear and corrosion compared with other patients (42% and 17% vs. 59% and 26%). Polyaxial screws exhibited higher wear and corrosion percentages (53% and 23%) compared with uniaxial screws (39% and 3%), although in patients with fracture, the reverse was observed (20% and 0% vs. 39% and 3%). We found that titanium alloy spinal implants experience some degree of wear and corrosion in vivo. The titanium alloy particles formed by wear exhibited good histocompatibility, not causing inflammation, foreign body reactions, or osteolysis. Therefore, spinal implants should be removed cautiously when treating titanium alloy spinal metallosis. The wear and corrosion of the implants increase with the increase in implantation time, although the screw structure does not significantly affect these changes.

Silver/gold nanoalloy implant coatings with antibiofilm activity via pH-triggered silver ion release.

Implant infections are a major challenge for the healthcare system. Biofilm formation and increasing antibiotic resistance of common bacteria cause implant infections, leading to an urgent need for alternative antibacterial agents. In this study, the antibiofilm behaviour of a coating consisting of a silver (Ag)/gold (Au) nanoalloy is investigated. This alloy is crucial to reduce uncontrolled potentially toxic Ag+ ion release. In neutral pH environments this release is minimal, but the Ag+ ion release increases in acidic microenvironments caused by bacterial biofilms. We perform a detailed physicochemical characterization of the nanoalloys and compare their Ag+ ion release with that of pure Ag nanoparticles. Despite a lower released Ag+ ion concentration at pH 7.4, the antibiofilm activity against Escherichia coli (a bacterium known to produce acidic pH environments) is comparable to a pure nanosilver sample with a similar Ag-content. Finally, biocompatibility studies with mouse pre-osteoblasts reveal a decreased cytotoxicity for the alloy coatings and nanoparticles.