Bacterial and osteoblast behavior on titanium, cobalt-chromium alloy and stainless steel treated with alkali and heat: a comparative study for potential orthopedic applications

Surface characteristics of additively manufactured CoCr and Ti6Al4V dental alloys: The effects of carbon and gold thin film coatings, and alkali-heat treatment

This study investigates the impact of surface modifications on additively manufactured CoCr and Ti6Al4V dental alloys, focusing on surface properties. Thin film carbon (C) and gold (Au) coatings, as well as alkali-heat treatment, were applied to the high- and low-polished specimens. Scanning electron microscopy (SEM) showed that thin film coatings retained the underlying surface topography, while the alkali-heat treatment induced distinct morphological changes. Energy-dispersive x-ray spectroscopy (EDS) analysis revealed that C-coating enriched surfaces with C, and Au-coating introduced detectable amounts of Au. Nevertheless, signs of coating delamination were observed in the high-polished specimens. Alkali-heat treatment led to the formation of a sodium titanate layer on Ti6Al4V surfaces, confirmed by sodium presence and Fourier transform infrared spectroscopy (FTIR) results showing carbonate bands. Surface roughness measurements with atomic force microscopy (AFM) showed that C-coating increased surface roughness in both high- and low-polished alloys. Au-coating slightly increased roughness, except for low-polished Au-coated Ti6Al4V, where a decrease in roughness was observed compared to low-polished bare Ti6Al4V, likely due to surface defects present in the latter resulting from the additive manufacturing process. Alkali-heat treatment led to a pronounced increase in roughness for both alloys, particularly for Ti6Al4V. Both thin film coatings decreased the water contact angles in all specimens in varying magnitudes, indicating an increase in wettability. However, the alkali-heat treatment caused a substantial decrease in contact angles, resulting in a highly hydrophilic state for Ti6Al4V. These findings underscore the substantial impact of surface modifications on additively manufactured dental alloys, potentially influencing their clinical performance. RESEARCH HIGHLIGHTS: Thin film coatings and chemical/heat treatment modify the surface properties of additively manufactured dental alloys. The surfaces of the alloys get rougher and more hydrophilic after alkali-heat treatment. Thin gold coatings exhibit potential adhesion challenges.

The progress in titanium alloys used as biomedical implants: From the view of reactive oxygen species

Titanium and Titanium alloys are widely used as biomedical implants in oral and maxillofacial surgery, due to superior mechanical properties and biocompatibility. In specific clinical populations such as the elderly, diabetics and patients with metabolic diseases, the failure rate of medical metal implants is increased significantly, putting them at increased risk of revision surgery. Many studies show that the content of reactive oxygen species (ROS) in the microenvironment of bone tissue surrounding implant materials is increased in patients undergoing revision surgery. In addition, the size and shape of materials, the morphology, wettability, mechanical properties, and other properties play significant roles in the production of ROS. The accumulated ROS break the original balance of oxidation and anti-oxidation, resulting in host oxidative stress. It may accelerate implant degradation mainly by activating inflammatory cells. Peri-implantitis usually leads to a loss of bone mass around the implant, which tends to affect the long-term stability and longevity of implant. Therefore, a great deal of research is urgently needed to focus on developing antibacterial technologies. The addition of active elements to biomedical titanium and titanium alloys greatly reduce the risk of postoperative infection in patients. Besides, innovative technologies are developing new biomaterials surfaces conferring anti-infective properties that rely on the production of ROS. It can be considered that ROS may act as a messenger substance for the communication between the host and the implanted material, which run through the entire wound repair process and play a role that cannot be ignored. It is necessary to understand the interaction between oxidative stress and materials, the effects of oxidative stress products on osseointegration and implant life as well as ROS-induced bactericidal activity. This helps to facilitate the development of a new generation of well-biocompatible implant materials with ROS responsiveness, and ultimately prolong the lifespan of implants.

Selenomethionine-Modified Polyethylenimine-Based Nanoparticles Loaded with miR-132-3p Inhibitor-Biofunctionalized Titanium Implants for Improved Osteointegration

Titanium and its alloys have been widely used as bone implants, but for reduced treatment span, improvements are urgently needed to achieve faster and better osteointegration. In this study, we found that miR-132-3p inhibited bone-marrow-derived stem cell (BMSC) osteogenic differentiation via targeting BMP2, and that inhibiting miR-132-3p could significantly improve the osteogenic capability of BMSCs. Moreover, we fabricated a biocompatible selenomethionine (SEMET)-modified polyethylene glycol (PEG)/polyethylenimine (PEI) nanoparticle (SeNP) cross-linked with 0.2% gelatin solutions and delivered miR-132-3p inhibitor to biofunctionalize alkali heat-treated titanium implants, resulting in the development of a novel coating for reverse transfection. The biological performances of PEG/PEI/miR-132-3p inhibitor and SeNP/miR-132-3p inhibitor-biofunctionalized titanium were compared. The biological effects, including cell viability, cytotoxicity, adhesion, cellular uptake, and osteogenic capacity of SeNP/miR-132-3p inhibitor-biofunctionalized titanium implants, were then assessed. Results showed that SeNPs presented appropriate morphology, diameter, and positive zeta potential for efficient gene delivery. The transfection efficiency of the SeNP/miR-132-3p inhibitor was comparable to that of the PEG/PEI/miR-132-3p inhibitor, but the former induced less reactive oxygen species (ROS) production and lower apoptosis rates. Confocal laser scanning microscopy (CLSM) demonstrated that SeNP/miR-132-3p inhibitor nanoparticles released from the titanium surfaces and were taken up by adherent BMSCs. In addition, the release profile showed that transfection could obtain a long-lasting silencing effect for more than 2 weeks. The cell viability, cytotoxicity, and cell spreading of SeNP/miRNA-132-3p inhibitor-biofunctionalized titanium were comparable with those of untreated titanium and the SeNP/miRNA-132-3p inhibitor negative control (NC)-biofunctionalized titanium but resulted in higher ALP activity and osteogenic gene expression levels. In vivo animal studies further certified that SeNP/miRNA-132-3p inhibitor nanoparticles from titanium surfaces promoted osteointegration, which was revealed by microcomputed tomography (micro-CT) and histological observations. Taken together, these findings suggested that selenomethionine-modified PEI-based nanoparticles could achieve better biocompatibility. Moreover, titanium implants biofunctionalized by SeNP/miRNA-132-3p inhibitor nanoparticles might have significant clinical potential for more effective osteointegration.

Bactericidal efficiency of micro- and nanostructured surfaces: a critical perspective

Micro/nanostructured surfaces (MNSS) have shown the ability to inactivate bacterial cells by physical means. An enormous amount of research has been conducted in this area over the past decade. Here, we review the various surface factors that affect the bactericidal efficiency. For example, surface hydrophobicity of the substrate has been accepted to be influential on the bactericidal effect of the surface, but a review of the literature suggests that the influence of hydrophobicity differs with the bacterial species. Also, various bacterial viability quantification methods on MNSS are critically reviewed for their suitability for the purpose, and limitations of currently used protocols are discussed. Presently used static bacterial viability assays do not represent the conditions of which those surfaces could be applied. Such application conditions do have overlaying fluid flow, and bacterial behaviours are drastically different under flow conditions compared to under static conditions. Hence, it is proposed that the bactericidal effect should be assessed under relevant fluid flow conditions with factors such as shear stress and flowrate given due significance. This review will provide a range of opportunities for future research in design and engineering of micro/nanostructured surfaces with varying experimental conditions.

Co-Cr-Mo-Cu alloys for clinical implants with osteogenic effect by increasing bone induction, formation and development in a rabbit model

Background

Co-Cr-Mo alloy has been widely used in clinical implants because of its excellent mechanical and anti-corrosion properties, but there is an urgent need to address its disadvantages, such as implant-related infections and implant loosening. We synthesized Co-Cr-Mo-Cu (Co-Cu) alloys with different Cu contents to modify implant performance to be suitable as a bone-compatible implant material.

Methods

Microstructure, phase content and mechanical properties of the Co-Cr-Mo alloy were characterized. Histological and immunohistochemical analyses were performed after implantation in rabbits. The experimental alloy was implanted on the lateral side of the lower tibial condyle and the tibial nodule.

Results

Phase content and mechanical properties revealed that the crystallographic structure and wear resistance were changed. Experimental implantation results demonstrated that osteogenic capability was markedly enhanced, ascribed to the excellent antibacterial and osseointegration capacities of Cu phases, and with the release of Cu ions. In particular, Co-Cu alloy containing 2 wt% Cu exhibited the best osteogenic performance among all samples.

Conclusions

The results indicated that osteogenic performance of the Co-Cr-Mo alloy could be enhanced by adding Cu. In particular, the Co-2Cu alloy exhibited the best properties according to both immunohistochemical and histological analyses. Our study not only provides deep insight into the osteogenic effect of Cu but presents a new Co-Cu alloy for clinical implants.

Anatase Forming Treatment without Surface Morphological Alteration of Dental Implant

The osseointegration of titanium implants is allowed by the TiO₂ layer that covers the implants. Titania can exist in amorphous form or in three different crystalline conformations: anatase, rutile and brookite. Few studies have characterized TiO₂ covering the surface of dental implants from the crystalline point of view. The aim of the present study was to characterize the evolution of the TiO₂ layer following different surface treatments from a crystallographic point of view. Commercially pure titanium and Ti-6Al-4V implants subjected to different surface treatments were analyzed by Raman spectroscopy to evaluate the crystalline conformation of titania. The surface treatments evaluated were: machining, sandblasting, sandblasting and etching and sandblasting, etching and anodization. The anodizing treatment evaluated in this study allowed to obtain anatase on commercially pure titanium implants without altering the morphological characteristics of the surface.

Enhanced durability, bio-activity and corrosion resistance of stainless steel through severe surface deformation

Owing to its good biocompatibility and low cost, stainless steel is one of the most widely utilized biomaterial. However, longtime assessment of stainless steel has shown problems related to material degradation, especially localized corrosion and bio-film formation. In addition, the leaching of toxic nickel and chromium ions from stainless steel leads to additional health complications. Here, we utilized submerged friction stir processing, a severe surface deformation technique for significantly enhancing its durability, bio-activity as well as antibacterial resistance. The processing was done with a wide variation in strain rates to produce tunable surface microstructure. High strain-rate processing resulted in nearly single-phase fine-grained microstructure, while slow strain-rate processing developed a dual-phase fine-grained microstructure. The bio-corrosion rate of processed steel was reduced by more than 60 % along with significant enhancement in the pitting resistance. The processed steel showed nearly no bacterial adhesion/biofilm formation, evaluated using S. aureus and E. coli bacterial strains. Further, the processed stainless steel surface demonstrated minimum leaching of the toxic elements, significantly enhancing its appeal for bio-implant applications. The observed behavior was explained based on the formation of a stable passive layer, rich in Cr₂O₃, as determined using x-ray photoelectron microscopy (XPS) and increased hydrophilicity.

Enhanced Osseointegration and Bio-Decontamination of Nanostructured Titanium Based on Non-Thermal Atmospheric Pressure Plasma

Alkali-treated titanate layer with nanonetwork structures (TNS) is a promising surface for improving osseointegration capacity in implants. Nevertheless, there is a risk of device failure as a result of insufficient resistance to biofilm contamination. This study tested whether treatment using a handheld non-thermal plasma device could efficiently eliminate biofilm contamination without destroying the surface nanostructure while re-establishing a surface that promoted new bone generation. TNS specimens were treated by a piezoelectric direct discharge (PDD) plasma generator. The effect of decontamination was performed utilizing Staphylococcus aureus. The evaluation of initial cell attachment with adhesion images, alkaline phosphatase activity, extracellular matrix mineralization, and expression of genes related to osteogenesis was performed using rat bone marrow mesenchymal stem cells, and the bone response were evaluated in vivo using a rat femur model. Nanotopography and surface roughness did not significantly differ before and after plasma treatments. Cell and bone formation activity were improved by TNS plasma treatment. Furthermore, plasma treatment effectively eliminated biofilm contamination from the surface. These results suggested that this plasma treatment may be a promising approach for the treatment of nanomaterials immediately before implantation and a therapeutic strategy for peri-implantitis.

Microstructure, Wettability, Corrosion Resistance and Antibacterial Property of Cu-MTa2O5 Multilayer Composite Coatings with Different Cu Incorporation Contents

Bacterial infection and toxic metal ions releasing are the challenges in the clinical application of Ti6Al4V alloy implant materials. Copper is a kind of long-acting, broad-spectrum and safe antibacterial element, and Ta2O5 has good corrosion resistance, wear-resistance and biocompatibility, they are considered and chosen as a potential coating candidate for implant surface modification. In this paper, magnetron sputtering technology was used to prepare copper doped Ta2O5 multilayer composite coating Cu-Ta2O5/Ta2O5/Ta2O5-TiO2/TiO2/Ti (Cu-MTa2O5 for short) on Ti6Al4V alloy surface, for studying the effect of copper incorporation on the microstructure, wettability, anticorrosion and antibacterial activities of the composite coating. The results showed that Cu-MTa2O5 coating obviously improves the hydrophobicity, corrosion resistance and antibacterial property of Ti6Al4V alloy. In the coating, both copper and Ta2O5 exhibit an amorphous structure and copper mainly presents as an oxidation state (Cu2O and CuO). With the increase of the doping amount of copper, the grain size, roughness, and hydrophobicity of the modified surface of Ti6Al4V alloy are increased. Electrochemical experiment results demonstrated that the corrosion resistance of Cu-MTa2O5 coated Ti6Al4V alloy slightly decreased with the increase of copper concentration, but this coating still acts strong anticorrosion protection for Ti6Al4V alloy. Moreover, the Cu-MTa2O5 coating can kill more than 97% of Staphylococcus aureus in 24 h, and the antibacterial rate increases with the increase of copper content. Therefore, Cu-MTa2O5 composite coating is a good candidate for improving anticorrosion and antibacterial properties of Ti6Al4V alloy implant medical devices.

Optimization of clinically applied orthodontic archwire electrothermal treatment conditions by heat tint and mechanical properties: An experimental study

OBJECTIVE

Electric resistance heat treatment procedures are performed by most orthodontists; however, the effects of electrothermal treatment on the mechanical properties, surface morphology, phase transition, colour and arch width of stainless steel archwires remain controversial and are worthy of investigation.

MATERIALS AND METHODS

Stainless steel archwires (0.017×0.025 and 0.019×0.025 inches) were heat-treated using a spot-welder machine at a power setting of 3 for 5, 10, 15 or 20s and were then cooled in air. After the heat treatment, we analysed the surface morphology of the samples by scanning electron microscopy (SEM) and the flexural modulus with a universal testing machine. The changes in phase and the austenite content after heat treatment were determined by X-ray diffraction (XRD). The changes in the colour of the sample were analysed by a digital single-lens reflex (DSLR) camera, and the arch width changes were measured with Vernier calippers.

RESULTS

The flexural modulus and austenite content of the orthodontic stainless steel archwires increased after heat treatment (P<0.05). The colour changed from silver to yellow-brown-blue. Heat treatment of the stainless steel wires increased the inter-canine and inter-molar widths only when the amount of heat received was low.

CONCLUSION

Heat treatment of stainless steel orthodontic archwires using an electric resistance device is an effective and convenient method to improve their flexural modulus. The colour of the wire surface after heat treatment can help determine the heating conditions, and the maximum flexural modulus of the stainless steel wires was obtained when the colour changed to brownish yellow.

Titanium Surfaces Functionalized with siMIR31HG Promote Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells

Titanium (Ti) implants are widely used in the clinic as bone substitutes and dental implants, but further improvements are needed to obtain high osteogenic ability and consequent osseointegration. Knockdown of long noncoding RNA MIR31HG promotes osteogenic differentiation and bone formation. In this study, we fabricated a Ti surface functionalized with siRNA targeting MIR31HG (siMIR31HG) and accelerated osteogenesis of bone marrow mesenchymal stem cells (BMSCs). Chitosan/siRNA complex was loaded onto the thermal alkali-treated Ti surface to fabricate the siMIR31HG-functionalized Ti surface. The surface morphology, siRNA loading and release efficiency, and transfection efficacy were investigated, and the biological effects, such as cell proliferation, cell morphology, and osteogenic activity, were determined. The results showed that the siMIR31HG-functionalized Ti implant generated an ∼50% knockdown of MIR31HG, with no apparent cytotoxicity, which consequently enhanced osteogenic differentiation of BMSCs, as indicated by the increase of ALP production, extracellular matrix mineralization, osteogenic gene expression, and ectopic bone formation in vivo. The siMIR31HG biofunctionalization can be used to obtain better osseointegration of Ti implant in the clinic.

ZnO Nanopillar Coated Surfaces with Substrate-Dependent Superbactericidal Property

ZnO nanopillars coated on various surfaces are able to kill adhered bacteria and fungi due to their physical structure through a rupturing mechanism. Remarkably, zinc foil and galvanized steel surfaces with ZnO nanopillar coatings demonstrate an excellent remote bacteria-killing property. Their bacterial killing efficacy is several orders higher than ZnO nanopillars coated on other surfaces as well as ZnO nanoparticles themselves. Mechanistic study shows that the nanostructure surface kills adhered microbial cells by rupturing the cell wall, while superoxide (^• O₂^- ) released from the ZnO coating with electrons donated from zinc via the Zn/ZnO interface rather than photoirritation is responsible for the superior remote killing. The results of this study represent a novel mechanism of surface disinfection and its application in water disinfection is also demonstrated.

Review: the potential impact of surface crystalline states of titanium for biomedical applications

In many biomedical applications, titanium forms an interface with tissues, which is crucial to ensure its long-term stability and safety. In order to exert control over this process, titanium implants have been treated with various methods that induce physicochemical changes at nano and microscales. In the past 20 years, most of the studies have been conducted to see the effect of topographical and physicochemical changes of titanium surface after surface treatments on cells behavior and bacteria adhesion. In this review, we will first briefly present some of these surface treatments either chemical or physical and we explain the biological responses to titanium with a specific focus on adverse immune reactions. More recently, a new trend has emerged in titanium surface science with a focus on the crystalline phase of titanium dioxide and the associated biological responses. In these recent studies, rutile and anatase are the major two polymorphs used for biomedical applications. In the second part of this review, we consider this emerging topic of the control of the crystalline phase of titanium and discuss its potential biological impacts. More in-depth analysis of treatment-related surface crystalline changes can significantly improve the control over titanium/host tissue interface and can result in considerable decreases in implant-related complications, which is currently a big burden on the healthcare system.

Effect of ultraviolet treatment on bacterial attachment and osteogenic activity to alkali-treated titanium with nanonetwork structures

Purpose

Alkali-treated titanium with nanonetwork structures (TNS) possesses good osteogenic activity; however, the resistance of this material to bacterial contamination remains inadequate. As such, TNS implants are prone to postoperative infection. In this work, we attempted to alter the biological properties of TNS by treatment with short-duration high-intensity ultraviolet (UV) irradiation.

Methods

TNS discs were treated with UV light (wavelength =254 nm, strength =100 mW/cm²) for 15 minutes using a UV-irradiation machine. We carried out a surface characterization and evaluated the discs for bacterial film formation, protein adsorption, and osteogenic features.

Results

The superhydrophilicity and surface hydrocarbon elimination exhibited by the treated material (UV-treated titanium with a nanonetwork structure [UV-TNS]) revealed that this treatment effectively changed the surface characteristics of TNS. Notably, UV-TNS also showed reduced colonization by Actinomyces oris during an initial attachment period and inhibition of biofilm formation for up to 6 hours. Moreover, compared to conventional TNS, UV-TNS showed superior osteogenic activity as indicated by increased levels of adhesion, proliferation, alkaline phosphatase activity, osteogenic factor production, and osteogenesis-related gene expression by rat bone marrow mesenchymal stem cells (rBMMSCs). This inverse relationship between bacterial attachment and cell adhesion could be due to the presence of electron–hole pairs induced by high-intensity UV treatment.

Conclusion

We suggest that simple UV treatment has great clinical potential for TNS implants, as it promotes the osseointegration of the TNS while reducing bacterial contamination, and can be conducted chair-side immediately prior to implantation.

Electrophoretic deposition of colloidal particles on Mg with cytocompatibility, antibacterial performance, and corrosion resistance

Magnesium (Mg) has recently received increasing attention due to its unique biological performance, including cytocompatibility, antibacterial and biodegradable properties. However, rapid corrosion in physiological environment and potential toxicity limits its clinical applications. To improve the corrosion resistance meanwhile not compromise other excellent performance, self-assembled colloidal particles were deposited onto magnesium surfaces in ethanol by a simple and effective electrophoretic deposition (EPD) method. The fabricated functional nanostructured coatings were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses, and scanning electron microscopy (SEM). The electrochemical test, pH value, and Mg ion concentration data show that the corrosion resistance of Mg samples is enhanced appreciably after surface treatment. In vitro cellular response and antibacterial capability of the modified Mg substrates are performed. Significantly increased cell adhesion and viability are observed from the coated Mg samples, and the amounts of adherent bacteria on the treated Mg surfaces diminish remarkably compared to the bare Mg. Furthermore, the bare and coated Mg samples were implanted in New Zealand white rabbits for 12 weeks to examine the in vivo long-term corrosion performance and in situ inflammation behavior. The experiment results confirmed that compared with bare Mg substrate the corrosion and foreign-body reactions of the coated Mg samples were suppressed. The above results suggested that our coatings, which effectively enhance the biocompatibility, antimicrobial properties, and corrosion resistance of Mg substrate, provide a simple and practical strategy to expedite clinical acceptance of biodegradableMg and its alloys.

STATEMENT OF SIGNIFICANCE

Biomedical Mg metals have been considered as promising biodegradable implants because of their intended functions, such as cytocompatibility, antibacterial, and biodegradable properties. However, rapid corrosion in physiological environment limits their clinical applications. Alloying and surface coatings have been used to reduce the degradation rate. But this would compromise other excellent performance of Mg samples, including antibacterial and anti-inflammatory activity. Thus, while the rapid degradation of Mg samples must be solved, good antibacterial property and acceptable cytocompatibility are also necessary. In this study, polymer-based coatings were fabricated on Mg surfaces by electrophoretic deposition of poly(isobornyl acrylate-co-dimethylaminoethyl methacrylate)/tannic acid (P(ISA-co-DMA)/TA) colloidal particles. It suggested that the coating materials effectively improved the biocompatibility, antimicrobial behavior, and corrosion resistance of biomedical Mg.

Novel chitosan/diclofenac coatings on medical grade stainless steel for hip replacement applications

Corrosion resistance, biocompatibility, improved osteointegration, as well the prevention of inflammation and pain are the most desired characteristics of hip replacement implants. In this study we introduce a novel multi-layered coating on AISI 316LVM stainless steel that shows promise with regard to all mentioned characteristics. The coating is prepared from alternating layers of the biocompatible polysaccharide chitosan and the non-steroid anti-inflammatory drug (NSAID), diclofenac. Electrochemical methods were employed to characterize the corrosion behavior of coated and uncoated samples in physiological solution. It is shown that these coatings improve corrosion resistance. It was also found that these coatings release the incorporated drug in controlled, multi-mechanism manner. Adding additional layers on top of the as-prepared samples, has potential for further tailoring of the release profile and increasing the drug dose. Biocompatibility was proven on human-derived osteoblasts in several experiments. Only viable cells were found on the sample surface after incubation of the samples with the same cell line. This novel coating could prove important for prolongation of the application potential of steel-based hip replacements, which are these days often replaced by more expensive ceramic or other metal alloys.

Chitosan/siCkip-1 biofunctionalized titanium implant for improved osseointegration in the osteoporotic condition

Biofunctionalization with siRNA targeting the key negative modulators of bone turnover involved in the molecular mechanism of osteoporosis, such as casein kinase-2 interacting protein-1 (Ckip-1), may lead to enhanced Ti osseointegration in the osteoporotic condition. In this study, even siRNA loading was accomplished by the thermal alkali (TA) treatment to make the Ti ultrahydrophilic and negatively charged to facilitate the physical adsorption of the positively charged CS/siR complex, designated as TA-CS/siR. The intracellular uptake of the CS/siR complex and the gene knockdown efficiency were assessed with bone marrow mesenchymal stem cells (MSCs) as well as the green fluorescent protein (GFP) expressing H1299 cells. In vitro osteogenic activity of TA-CS/siCkip-1 targeting Ckip-1 was assessed with MSCs. In vivo osseointegration of TA-CS/siCkip-1 was assessed in the osteoporotic rat model. TA-CS/siR showed excellent siRNA delivery efficiency and gene silencing effect. TA-CS/siCkip-1 significantly improved the in vitro osteogenic differentiation of MSCs in terms of the enhanced alkaline phosphatase and collagen product and extracellular matrix mineralization, and led to dramatically enhanced in vivo osseointegration in the osteoporostic rat model, showing promising clinical potential for the osteoporotic condition application. TA-CS/siR may constitute a general approach for developing the advanced Ti implants targeting specific molecular mechanism.

Bidirectional regulation of zinc embedded titania nanorods: antibiosis and osteoblastic cell growth

A bifunctional regulation in antibiosis and osteoblastic cell growth is achieved by well-organized TiO₂–Zn nanoarrays.

Crystalline anatase-rich titanium can reduce adherence of oral streptococci

Dental implant abutments that emerge through the mucosa are rapidly covered with a salivary protein pellicle to which bacteria bind, initiating biofilm formation. In this study, adherence of early colonizing streptococci, Streptococcus gordonii, Streptococcus oralis, Streptococcus mitis and Streptococcus sanguinis to two saliva-coated anodically oxidized surfaces was compared with that on commercially pure titanium (CpTi). Near edge X-ray absorption (NEXAFS) showed crystalline anatase was more pronounced on the anodically oxidized surfaces than on the CpTi. As revealed by fluorescence microscopy, a four-species mixture, as well as individual bacterial species, exhibited lower adherence after 2 h to the saliva-coated, anatase-rich surfaces than to CpTi. Since wettability did not differ between the saliva-coated surfaces, differences in the concentration and/or configuration of salivary proteins on the anatase-rich surfaces may explain the reduced bacterial binding effect. Anatase-rich surfaces could thus contribute to reduced overall biofilm formation on dental implant abutments through diminished adherence of early colonizers.