Enhanced effects of nano-scale topography on the bioactivity and osteoblast behaviors of micron rough ZrO2 coatings

Modification of titanium orthopedic implants with bioactive glass: a systematic review of in vivo and in vitro studies

Bioactive glasses (BGs) are ideal biomaterials in the field of bio-restoration due to their excellent biocompatibility. Titanium alloys are widely used as a bone graft substitute material because of their excellent corrosion resistance and mechanical properties; however, their biological inertness makes them prone to clinical failure. Surface modification of titanium alloys with bioactive glass can effectively combine the superior mechanical properties of the substrate with the biological properties of the coating material. In this review, the relevant articles published from 2013 to the present were searched in four databases, namely, Web of Science, PubMed, Embase, and Scopus, and after screening, 49 studies were included. We systematically reviewed the basic information and the study types of the included studies, which comprise in vitro experiments, animal tests, and clinical trials. In addition, we summarized the applied coating technologies, which include pulsed laser deposition (PLD), electrophoretic deposition, dip coating, and magnetron sputtering deposition. The superior biocompatibility of the materials in terms of cytotoxicity, cell activity, hemocompatibility, anti-inflammatory properties, bioactivity, and their good bioactivity in terms of osseointegration, osteogenesis, angiogenesis, and soft tissue adhesion are discussed. We also analyzed the advantages of the existing materials and the prospects for further research. Even though the current research status is not extensive enough, it is still believed that BG-coated Ti implants have great clinical application prospects.

Strategies to improve bioactive and antibacterial properties of polyetheretherketone (PEEK) for use as orthopedic implants

Polyetheretherketone (PEEK) has gradually become the mainstream material for preparing orthopedic implants due to its similar elastic modulus to human bone, high strength, excellent wear resistance, radiolucency, and biocompatibility. Since the 1990s, PEEK has increasingly been used in orthopedics. Yet, the widespread application of PEEK is limited by its bio-inertness, hydrophobicity, and susceptibility to microbial infections. Further enhancing the osteogenic properties of PEEK-based implants remains a difficult task. This article reviews some modification methods of PEEK in the last five years, including surface modification of PEEK or incorporating materials into the PEEK matrix. For surface modification, PEEK can be modified by chemical treatment, physical treatment, or surface coating with bioactive substances. For PEEK composite material, adding bioactive filler into PEEK through the melting blending method or 3D printing technology can increase the biological activity of PEEK. In addition, some modification methods such as sulfonation treatment of PEEK or grafting antibacterial substances on PEEK can enhance the antibacterial performance of PEEK. These strategies aim to improve the bioactive and antibacterial properties of the modified PEEK. The researchers believe that these modifications could provide valuable guidance on the future design of PEEK orthopedic implants.

Drug infused Al2O3-bioactive glass coatings toward the cure of orthopedic infection

A unique implant coated substrate with dual-drug-eluting system exhibiting antibacterial, anti-inflammatory, and bone regenerative capacity has been fabricated using spray pyrolysis deposition (SPD) method. Bioglass (BG) and BG-alumina (BG-Al) composites coatings with different concentrations of Al incorporated on BG network over the Cp-Ti substrate were fabricated using SPD technique. Phase purity of BG and BG-Al composites were analyzed by XRD in which Na₂Ca₂Si₃O₉ and β-Na₂Ca₄(PO₄)₂SiO₄) and Na_7.15(Al_7.2Si_8.8O₃₂) phases were formed. Surface morphology of the coated substrates was analyzed by SEM. Uniformity of the coatings were evaluated by surface profilometer and the uniform distribution the nanoparticles were confirmed with Elemental mapping. Systematically, each apatite layer formation on coated substrate was confirmed by immersing the samples for 1, 3, and 7 days in simulated body fluid and the needle-like structure was characterized using SEM. Cumulative release of Tetracycline hydrochloride (Tet) antibiotic and Dexamethasone (Dex) anti-inflammatory drug-loaded BG-Al and BG-Al composite-coated substrate were studied for 24 h. Antibacterial activity of the coated substrates were evaluated by time-dependent growth inhibition and minimal inhibitory concentration (MIC) assays in which BG-Al and BG-Al composite loaded with Tet showed considerable growth inhibition against S. aureus. Osteoblast-like cells (MG-63) exhibited profound proliferation with no cytotoxic effects which was due to release of Dex drug-coated substrates. Thus, surface modification of Cp-Ti substrate with BG, BG-Al composites coatings loaded with Tet and Dex drug can be considered for post-operative orthopedic implant infection application.

Acceleration of Bone Formation and Adhesion Ability on Dental Implant Surface via Plasma Electrolytic Oxidation in a Solution Containing Bone Ions

The present study examined the in vitro and in vivo bone formation and adhesion ability on the surface of a titanium dental implant made by plasma electrolytic oxidation (PEO) in electrolytes containing bioactive ions. To achieve this goal, screw-shaped fabricated Ti-6Al-4V alloy implants were processed via PEO using an electrolyte solution containing calcium (Ca), phosphorous (P), magnesium (Mg), zinc (Zn), strontium (Sr), silicon (Si), and manganese (Mn) species. The screw implants doped with bioactive elements via PEO were placed in rabbit tibia, and the results were compared to the sand-blasted Ti-6Al-4V alloy implants. At eight-week post-surgery, there was no significant difference in the values of removal torque between sand-blasted and PEO-treated implants. However, it was observed that the PEO treatment of dental implants led to the formation of more periphery bone as compared to the case of sand-blasted implants. Accordingly, the PEO-treated implants have the potential to be used as promising materials for dental applications.

Metal-based nanoparticles for bone tissue engineering

Tissue is vital to the organization of multicellular organisms, because it creates the different organs and provides the main scaffold for body shape. The quest for effective methods to allow tissue regeneration and create scaffolds for new tissue growth has intensified in recent years. Tissue engineering has recently used some promising alternatives to existing conventional scaffold materials, many of which have been derived from nanotechnology. One important example of these is metal nanoparticles. The purpose of this review is to cover novel tissue engineering methods, paying special attention to those based on the use of metal-based nanoparticles. The unique physiochemical properties of metal nanoparticles, such as antibacterial effects, shape memory phenomenon, low cytotoxicity, stimulation of the proliferation process, good mechanical and tensile strength, acceptable biocompatibility, significant osteogenic potential, and ability to regulate cell growth pathways, suggest that they can perform as novel types of scaffolds for bone tissue engineering. The basic principles of various nanoparticle-based composites and scaffolds are discussed in this review. The merits and demerits of these particles are critically discussed, and their importance in bone tissue engineering is highlighted.

Functionalized Polycaprolactone/Hydroxyapatite Composite Microspheres for Promoting Bone Consolidation in a Rat Distraction Osteogenesis Model

Distraction osteogenesis (DO) is an ideal model to study bone regeneration. The major limitation is the relatively long period required for new bone consolidation. Here, we investigated whether the application of polycaprolactone (PCL) and hydroxyapatite (HA) composite microspheres could enhance bone formation in DO. Pure PCL microspheres and composite PCL and 10% HA microspheres were synthesized. Bone mesenchymal stem cells isolated from green fluorescent protein rats (GFP-rBMSCs) were cultured with microspheres in a rotary bioreactor system. Scanning electron microscopy was used to examine the microstructures. Osteogenic differentiation of rBMSCs was confirmed. Moreover, PCL/HA (20 mg) and PCL (20 mg) were locally administered into the distraction gap in the rat DO model toward the end of the distraction period. Imaging detection, mechanical and histological examinations were performed to assess the quality of the 4-week regenerates. Results showed that the microspheres were of uniform size and monodisperse. After incubation with rBMSCs in culture, PCL/HA microspheres showed a better ability for cell adhesion and osteogenic differentiation compared with PCL microspheres. In vivo, bone volume/total tissue volume, bone mineral density, and mechanical properties of the new callus were significantly higher in the PCL/HA group compared with the PCL group. Histological analyses confirmed improved bone formation and vascularization in PCL/HA group. We presented an effective protocol for the generation of functionalized microspheres and demonstrated implantation of PCL/HA microspheres into the distraction regenerate could significantly enhance bone consolidation. Thus, the application of PCL/HA composite microspheres may be a novel approach for promoting bone regeneration. This article is protected by copyright. All rights reserved © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:961-971, 2020.

Biomechanical and histological evaluation of the osseointegration capacity of two types of zirconia implant

The purpose of this study was to evaluate the biomechanical and histological behavior of a ceria-stabilized zirconia-alumina nanocomposite (NanoZr) in comparison with that of 3 mol% yttria-stabilized tetragonal zirconia polycrystalline (3Y-TZP) in Sprague Dawley rats. Cylindrical NanoZr and 3Y-TZP implants (diameter 1 mm, length 2 mm) were used. Implant-surface morphology and surface roughness were determined by scanning white-light interferometry and scanning electron microscopy, respectively. The cylindrical zirconia implants were placed at the distal edge of the femur of Sprague Dawley rats. At weeks 2, 4, and 8, the interfacial shear strength between implant and bone was measured by push-in test. Histological analysis was performed using hard-tissue sections. Bone-implant contact (BIC), the thickness of new bone around the implant within the bone marrow area, and osteoclast numbers were evaluated. The average surface roughness of 3Y-TZP (Sa 0.788 μm) was significantly higher than that of NanoZr (Sa 0.559 μm). The shear strengths of 3Y-TZP and NanoZr were similar at 2 weeks, but at 4 and 8 weeks the shear strength of NanoZr was higher than that of 3Y-TZP. The average BIC values within the bone marrow area for 3Y-TZP and NanoZr were 25.26% and 31.51% at 2 weeks, 46.78% and 38% at 4 weeks, and 47.88% and 56.81% at 8 weeks, respectively. The average BIC values within the cortical area were 38.86% and 58.42% at 2 weeks, 66.82% and 57.74% at 4 weeks, and 79.91% and 78.97% at 8 weeks, respectively. The mean BIC value did not differ significantly between the two zirconia materials at any time point. The NanoZr implants were biocompatible, capable of establishing close BIC, and may be preferred for metal-free dental implants.

Enhanced in Vitro Mineralization and in Vivo Osteogenesis of Composite Scaffolds through Controlled Surface Grafting of L-Lactic Acid Oligomer on Nanohydroxyapatite

Nanocomposite of hydroxyapatite (HA) surface grafted with L-lactic acid oligomer (LAc oligomer) (op-HA) showed improved interface compatibility, mechanical property, and biocompatibility in our previous study. In this paper, composite scaffolds of op-HA with controlled grafting different amounts of LAc oligomer (1.1, 5.2, and 9.1 wt %) were fabricated and implanted to repair rabbit radius defects. The dispersion of op-HA nanoparticles was more uniform than n-HA in chloroform and nanocomposites scaffold. Calcium and phosphorus exposure, in vitro biomineralization ability, and cell proliferation were much higher in the op-HA1.1 wt %/PLGA scaffolds than the other groups. The osteodifferentiation and bone fusion in animal tests were significantly enhanced for op-HA5.2 wt %/PLGA scaffolds. The results indicated that the grafted LAc oligomer of 5.2 or 9.1 wt %, which formed a barrier layer on the HA surface, prevented the exposure of nucleation sites. The shielded nucleation sites of op-HA particles (5.2 wt %) might be easily exposed as the grafted LAc oligomer was decomposed easily by enzyme systems in vivo. Findings from this study have revealed that grafting 1.1 wt % amount of LAc oligomer on hydroxyapatite could improve in vitro mineralization, and 5.2 wt % could promote in vivo osteogenesis capacity of composite scaffolds.

rBMSC and bacterial responses to isoelastic carbon fiber-reinforced poly(ether-ether-ketone) modified by zirconium implantation

PEEK-based biomaterials have great potential applications as hard tissue substitutes in bone tissue engineering. However, inherent bio-inert properties limited their clinical use. In order to improve the bioactivity, in this work, zirconium ions were implanted into the carbon fiber-reinforced PEEK (CFR-PEEK) using plasma immersion ion implantation (PIII) technology. Surface morphologies and chemical compositions of Zr-PIII treated samples were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), respectively. The results indicated that nanostructures and ZrO₂ nanoparticles were formed on the surface of CFR-PEEK after Zr-PIII. Mechanical tests revealed that nanohardness, elastic modulus, and elastic resistance increased after implantation, especially for the elastic modulus with a maximum value of about 14 GPa, which is much close to that of human natural bone. In vitro cellular experiments showed that Zr-PIII treated samples enhanced the initial adhesion of rBMSCs, spreading and proliferation significantly. Moreover, the heightened ALP activity, collagen secretion, and extracellular matrix mineralization suggested that Zr-PIII treatment could greatly lead to an up-regulated osteogenic differentiation of rBMSCs on CFR-PEEK. In addition, antibacterial properties were also investigated and the results showed that Zr-PIII treated CFR-PEEK with nanostructures exhibited obvious antibacterial activity against S. aureus but no effect on E. coli.

Enhancing orthopedic implant bioactivity: refining the nanotopography

Advances in nanotechnology open up new possibilities to produce biomimetic surfaces that resemble the cell in vivo growth environment at a nanoscale level. Nanotopographical changes of biomaterials surfaces can positively impact the bioactivity and ossointegration properties of orthopedic and dental implants. This review introduces nanofabrication techniques currently used or those with high potential for use as surface modification of biomedical implants. The interactions of nanotopography with water, proteins and cells are also discussed, as they largely determine the final success of the implants. Due to the well-documented effects of surface chemistry and microtopography on the bioactivity of the implant, we here elaborate on the ability of the nanofabrication techniques to combine the dual (multi) modification of surface chemistry and/or microtopography.

The bifunctional regulation of interconnected Zn-incorporated ZrO2 nanoarrays in antibiosis and osteogenesis

Bifunctional regulation in antibiosis and osteogenesis is obtained using well-organized Zn-incorporated ZrO₂ nanoarrays with interconnected internal space.

Enhancement of osteogenesis on micro/nano-topographical carbon fiber-reinforced polyetheretherketone-nanohydroxyapatite biocomposite

As an FDA-approved implantable material, carbon fiber-reinforced polyetheretherketone (CFRPEEK) possesses excellent mechanical properties similar to those of human cortical bone and is a prime candidate to replace conventional metallic implants. The bioinertness and inferior osteogenic properties of CFRPEEK, however, limit its clinical application as orthopedic/dental implants. The present work aimed at developing a novel carbon fiber-reinforced polyetheretherketone-nanohydroxyapatite (PEEK/CF/n-HA) ternary biocomposite with micro/nano-topographical surface for the enhancement of the osteogenesis as a potential bioactive material for bone grafting and bone tissue-engineering applications. The combined modification of oxygen plasma and sand-blasting could improve the hydrophily and generate micro/nano-topographical structures on the surface of the CFRPEEK-based ternary biocomposite. The results clearly showcased that the micro-/nano-topographical PEEK/n-HA/CF ternary biocomposite demonstrated the outstanding ability to promote the proliferation and differentiation of MG-63 cells in vitro as well as to boost the osseointegration between implant and bone in vivo, thereby boding well application to bone tissue engineering.

Osseointegrative properties of electrospun hydroxyapatite-containing nanofibrous chitosan scaffolds

Our long-term goal is to develop smart biomaterials that can facilitate regeneration of critical-size craniofacial lesions. In this study, we tested the hypothesis that biomimetic scaffolds electrospun from chitosan (CTS) will promote tissue repair and regeneration in a critical size calvarial defect. To test this hypothesis, we first compared in vitro ability of electrospun CTS scaffolds crosslinked with genipin (CTS-GP) to those of mineralized CTS-GP scaffolds containing hydroxyapatite (CTS-HA-GP), by assessing proliferation/metabolic activity and alkaline phosphatase (ALP) levels of murine mesenchymal stem cells (mMSCs). The cells' metabolic activity exhibited a biphasic behavior, indicative of initial proliferation followed by subsequent differentiation for all scaffolds. ALP activity of mMSCs, a surrogate measure of osteogenic differentiation, increased over time in culture. After 3 weeks in maintenance medium, ALP activity of mMSCs seeded onto CTS-HA-GP scaffolds was approximately two times higher than that of cells cultured on CTS-GP scaffolds. The mineralized CTS-HA-GP scaffolds were also osseointegrative in vivo, as inferred from the enhanced bone regeneration in a murine model of critical size calvarial defects. Tissue regeneration was evaluated over a 3 month period by microCT and histology (Hematoxylin and Eosin and Masson's Trichrome). Treatment of the lesions with CTS-HA-GP scaffolds induced a 38% increase in the area of de novo generated mineralized tissue area after 3 months, whereas CTS-GP scaffolds only led to a 10% increase. Preseeding with mMSCs significantly enhanced the regenerative capacity of CTS-GP scaffolds (by ∼3-fold), to 35% increase in mineralized tissue area after 3 months. CTS-HA-GP scaffolds preseeded with mMSCs yielded 45% new mineralized tissue formation in the defects. We conclude that the presence of HA in the CTS-GP scaffolds significantly enhances their osseointegrative capacity and that mineralized chitosan-based scaffolds crosslinked with genipin may represent a unique biomaterial with possible clinical relevance for the repair of critical calvarial bone defects.

Osteoblastic cell response to spark plasma-sintered zirconia/titanium cermets

Ceramic/metal composites, cermets, arise from the idea to combine the dissimilar properties in the pure materials. This work aims to study the biocompatibility of new micro-nanostructured 3 Y-TZP/Ti materials with 25, 50 and 75 vol.% Ti, which have been successfully obtained by spark slasma sintering technology, as well as to correlate their surface properties (roughness, wettability and chemical composition) with the osteoblastic cell response. All samples had isotropic and slightly waved microstructure, with sub-micrometric average roughness. Composites with 75 vol.% Ti had the highest surface hydrophilicity. Surface chemical composition of the cermets correlated well with the relative amounts used for their fabrication. A cell viability rate over 80% dismissed any cytotoxicity risk due to manufacturing. Cell adhesion and early differentiation were significantly enhanced on materials containing the nanostructured 3 Y-TZP phase. Proliferation and differentiation of SaOS-2 were significantly improved in their late-stage on the composite with 75 vol.% Ti that, from the osseointegration standpoint, is presented as an excellent biomaterial for bone replacement. Thus, spark plasma sintering is consolidated as a suitable technology for manufacturing nanostructured biomaterials with enhanced bioactivity.

Effect of zirconium nitride physical vapor deposition coating on preosteoblast cell adhesion and proliferation onto titanium screws

STATEMENT OF PROBLEM

Titanium has long been used to produce dental implants. Problems related to its manufacturing, casting, welding, and ceramic application for dental prostheses still limit its use, which highlights the need for technologic improvements. The aim of this in vitro study was to evaluate the biologic performance of titanium dental implants coated with zirconium nitride in a murine preosteoblast cellular model.

PURPOSE

The purpose of this study was to evaluate the chemical and morphologic characteristics of titanium implants coated with zirconium nitride by means of physical vapor deposition.

MATERIAL AND METHODS

Chemical and morphologic characterizations were performed by scanning electron microscopy and energy dispersive x-ray spectroscopy, and the bioactivity of the implants was evaluated by cell-counting experiments.

RESULTS

Scanning electron microscopy and energy dispersive x-ray spectroscopy analysis found that physical vapor deposition was effective in covering titanium surfaces with zirconium nitride. Murine MC-3T3 preosteoblasts were seeded onto titanium-coated and zirconium nitride-coated screws to evaluate their adhesion and proliferation. These experiments found a significantly higher number of cells adhering and spreading onto zirconium nitride-coated surfaces (P<.05) after 24 hours; after 7 days, both titanium and zirconium nitride surfaces were completely covered with MC-3T3 cells.

CONCLUSIONS

Analysis of these data indicates that the proposed zirconium nitride coating of titanium implants could make the surface of the titanium more bioactive than uncoated titanium surfaces.

Influence of extracellular matrix proteins and substratum topography on corneal epithelial cell alignment and migration

The basement membrane (BM) of the corneal epithelium presents biophysical cues in the form of topography and compliance that can impact the phenotype and behaviors of cells and their nuclei through modulation of cytoskeletal dynamics. In addition, it is also well known that the intrinsic biochemical attributes of BMs can modulate cell behaviors. In this study, the influence of the combination of exogenous coating of extracellular matrix proteins (ECM) (fibronectin-collagen [FNC]) with substratum topography was investigated on cytoskeletal architecture as well as alignment and migration of immortalized corneal epithelial cells. In the absence of FNC coating, a significantly greater percentage of cells aligned parallel with the long axis of the underlying anisotropically ordered topographic features; however, their ability to migrate was impaired. Additionally, changes in the surface area, elongation, and orientation of cytoskeletal elements were differentially influenced by the presence or absence of FNC. These results suggest that the effects of topographic cues on cells are modulated by the presence of surface-associated ECM proteins. These findings have relevance to experiments using cell cultureware with biomimetic biophysical attributes as well as the integration of biophysical cues in tissue-engineering strategies and the development of improved prosthetics.

Characterization and bioactive properties of zirconia based polymeric hybrid for orthopedic applications

Zirconia is a transition metal oxide with current applications to orthopedic implants. It has been shown to up-regulate specific genes involved in bio-integration and injury repair. This study examines the effects of zirconia and polydimethylsiloxane (PDMS) hybrids on the proliferation and viability of human primary osteoblast and fibroblast cells. In this study, zirconia-PDMS hybrid coatings were synthesized using a modified sol gel process. The hybrid material was characterized using optical microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle analysis. This study demonstrates that Zr-PMDS surface materials display hydrophobic surface properties coupled with a preferential deposition of polymer near the surface. Primary osteoblast and fibroblast proliferation and viability on hybrid coated surfaces were evaluated via a rapid screening methodology using WST-1 and calcein AM assays. The cells were seed at 5,000 cells per well in 96-well plates coated with various composition of Zr-PDMS hybrids. The results showed increasing cell proliferation with increasing zirconia concentration, which peaked at 90 % v/v zirconia. Proliferation of osteoblasts and fibroblasts displayed similar trends on the hybrid material, although osteoblasts displayed a bi-phasic dose response by the calcein AM assay. The results of this current study show that Zr-PDMS may be used to influence tissue-implant integration, supporting the use of the hybrid as a promising coating for orthopedic trauma implants.

Direct synthesis and morphological characterization of gold-dendrimer nanocomposites prepared using PAMAM succinamic acid dendrimers: preliminary study of the calcification potential

Gold-dendrimer nanocomposites were obtained for the first time by a simple colloidal approach based on the use of polyamidoamine dendrimers with succinamic acid terminal groups and dodecanediamine core. Spherical and highly crystalline nanoparticles with dimensions between 3 nm and 60 nm, and size-polydispersity depending on the synthesis conditions, have been generated. The influence of the stoichiometric ratio and the structural and architectural features of the dendrimers on the properties of the nanocomposites has been described. The self-assembling behaviour of these materials produces gold-dendrimer nanostructured porous networks with variable density, porosity, and composition. The investigations of the reaction systems, by TEM, at two postsynthesis moments, allowed to preliminary establish the control over the properties of the nanocomposite products. Furthermore, this study allowed better understanding of the mechanism of nanocomposite generation. Impressively, in the early stages of the synthesis, the organization of gold inside the dendrimer molecules has been evidenced by micrographs. Growth and ripening mechanisms further lead to nanoparticles with typical characteristics. The potential of such nanocomposite particles to induce calcification when coating a polymer substrate was also investigated.

Refining nanotopographical features on bone implant surfaces by altering surface chemical compositions

Nb₂O₅/TiO₂ composite coatings with controllable nanostructures were achieved by adjusting the amount of Nb₂O₅ in one simple and single plasma spraying process and Nb₂O₅ doping showed its potential use in enhancing the biological properties of biomedical TiO₂ coatings.

Nanosilica coating for bonding improvements to zirconia

Resin bonding to zirconia cannot be established from standard methods that are currently utilized in conventional silica-based dental ceramics. The solution–gelatin (sol–gel) process is a well developed silica-coating technique used to modify the surface of nonsilica-based ceramics. Here, we use this technique to improve resin bonding to zirconia, which we compared to zirconia surfaces treated with alumina sandblasting and tribochemical silica coating. We used the shear bond strength test to examine the effect of the various coatings on the short-term resin bonding of zirconia. Furthermore, we employed field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and Fourier transform infrared spectroscopy to characterize the zirconia surfaces. Water–mist spraying was used to evaluate the durability of the coatings. To evaluate the biological safety of the experimental sol–gel silica coating, we conducted an in vitro Salmonella typhimurium reverse mutation assay (Ames mutagenicity test), cytotoxicity tests, and in vivo oral mucous membrane irritation tests. When compared to the conventional tribochemical silica coating, the experimental sol–gel silica coating provided the same shear bond strength, higher silicon contents, and better durability. Moreover, we observed no apparent mutagenicity, cytotoxicity, or irritation in this study. Therefore, the sol–gel technique represents a promising method for producing silica coatings on zirconia.

Antimicrobial activity and cytocompatibility of Ag plasma-modified hierarchical TiO2 film on titanium surface

To improve the antimicrobial ability and cytocompatibility of biomedical titanium implants, many efforts have been made to modify their surface topography and chemical composition. In this work, Ag plasma-modified hierarchical TiO2 film was fabricated on titanium surface via acid etching to produce micropit, hydrothermal treatment to generate TiO2 nanorod and subsequent plasma immersion ion implantation process to impregnate Ag into TiO2 surface. In view of the potential clinical applications, their antimicrobial activity, bioactivity and cytocompatibility were systematically evaluated. The hierarchical TiO2 film showed enhanced bioactivity and bacteriostatic effect on both microbes due to more negative zeta potential, constructing the first defense line against microbial adhesion by electrostatic repulsion. Addition of embedded Ag remarkably enhanced the antimicrobial efficiency toward both microbes based on Schottky contact without Ag(+) release, establishing the second defense line targeting microbial membrane. Furthermore, the addition of Ag degraded the bioactivity very little and exerted nearly no adverse or even promoted effect on MG63 cell functions, including adhesion, spreading and proliferation. This work illustrates a two-defense-line antimicrobial activity in darkness with both prior electrostatic repulsion to inhibit most microbes adhesion and posterior biocidal action to kill residual ones that luckily infiltrated through the first defense line, and provide proof of concept using both clinically relevant human pathogens. In conclusion, the Ag-embedded hierarchical TiO2 film with excellent antimicrobial activity, bioactivity and cytocompatibility provides a promising candidate for orthopedic and dental implants.

Delicate refinement of surface nanotopography by adjusting TiO2 coating chemical composition for enhanced interfacial biocompatibility

Surface topography and chemistry have significant influences on the biological performance of biomedical implants. Our aim is to produce an implant surface with favorable biological properties by dual modification of surface chemistry and topography in one single simple process. In this study, because of its chemical stability, excellent corrosion resistance, and biocompatibility, titanium oxide (TiO2) was chosen to coat the biomedical Ti alloy implants. Biocompatible elements (niobium (Nb) and silicon (Si)) were introduced into TiO2 matrix to change the surface chemical composition and tailor the thermophysical properties, which in turn leads to the generation of topographical features under specific thermal history of plasma spraying. Results demonstrated that introduction of Nb2O5 resulted in the formation of Ti0.95Nb0.95O4 solid solution and led to the generation of nanoplate network structures on the composite coating surface. By contrast, the addition of SiO2 resulted in a hairy nanostructure and coexistence of rutile and quartz phases in the coating. Additionally, the introduction of Nb2O5 enhanced the corrosion resistance of TiO2 coating, whereas SiO2 did not exert much effect on the corrosion behaviors. Compared to the TiO2 coating, TiO2 coating doped with Nb2O5 enhanced primary human osteoblast adhesion and promoted cell proliferation, whereas TiO2 coatings with SiO2 were inferior in their bioactivity, compared to TiO2 coatings. Our results suggest that the incorporation of Nb2O5 can enhance the biological performance of TiO2 coatings by changing the surface chemical composition and nanotopgraphy, suggesting its potential use in modification of biomedical TiO2 coatings in orthopedic applications.

Distinct cell functions of osteoblasts on UV-functionalized titanium- and zirconia-based implant materials are modulated by surface topography

Though recent studies report decisive positive effects on cells, elicited by ultraviolet (UV)-induced bioactivation of biomaterial implant surfaces, they frequently employ cells other than of human origin or cells not representing oral implant targets. Therefore, the present study aims at exploring distinct cell functions of primary human alveolar bone osteoblasts (PHABO) in response to bioactivated microstructured titanium and zirconia implant surfaces with matched controls. UV-treatment significantly reduced surface carbon, while concomitantly increasing wettability. In case of titanium or zirconia biomaterial source of equal roughness, bioactivation did not significantly improve cell functions, including initial cell attachment, morphogenesis, proliferation, and gene expression of osteogenic biomarkers osteocalcin, alkaline phosphatase and collagen type I. However, cell functions discriminated surface roughness by either comparing titanium and zirconia or interindividual zirconia surfaces. While rough surfaces primarily favored primary adhesion, proliferation appeared improved on smooth surfaces, and gene expression seemed to be stronger modulated on the smoothest biomaterial. Our results show for the first time that bioactivation appears to be not the main causative for the observed modulation of the distinct cell functions analyzed in PHABO, but add to the body of evidence that they were more governed by surface architecture rather than by bioactivation.

Peri-implant bone formations around (Ti,Zr)O(2) -coated zirconia implants with different surface roughness

AIM

The aim of this study was to evaluate and compare the osseointegration in rabbit tibiae of smooth and roughened powder injection moulded (PIM) zirconia implants with or without (Ti,Zr)O2 surface coatings.

MATERIAL AND METHODS

Twenty-five rabbits received four types of external hex implants with identical geometry on the tibiae: PIM zirconia implants, roughened PIM zirconia implants, (Ti,Zr)O2 -coated PIM zirconia implants and (Ti,Zr)O2 -coated roughened PIM zirconia implants. The surface characteristics of the four types of implants were evaluated. Removal torque tests and histomorphometric analyses were performed.

RESULTS

The (Ti,Zr)O2 coatings substantially changed the surface topography and chemical composition of the both type of PIM zirconia implants. There were statistically significant differences in the bone to implant contact ratios and removal torque values (RT) among the tested implant types (p < 0.001). The histological response favoured the coated surface at smooth PIM zirconia implants. The removal torque values favoured the rough surface whether coated or uncoated.

CONCLUSIONS

Within the limit of this study, the (Ti,Zr)O2 coated PIM zirconia implants, both smooth and rough, showed enhanced histological response (bone to implant contact) compared with uncoated ones. On the other hand, the mechanical anchorage (RT) was higher for rough surface implants, coated or uncoated.

Peri-implant bone formation and surface characteristics of rough surface zirconia implants manufactured by powder injection molding technique in rabbit tibiae

OBJECTIVE

To evaluate osseointegration in rabbit tibiae and to investigate surface characteristics of novel zirconia implants made by powder injection molding (PIM) technique, using molds with and without roughened inner surfaces.

MATERIAL AND METHODS

A total of 20 rabbits received three types of external hex implants with identical geometry on the tibiae: machined titanium implants, PIM zirconia implants without mold etching, and PIM zirconia implants with mold etching. Surface characteristics of the three types of implant were evaluated. Removal torque tests and histomorphometric analyses were performed.

RESULTS

The roughness of PIM zirconia implants was higher than that of machined titanium implants. The PIM zirconia implants exhibited significantly higher bone-implant contact and removal torque values than the machined titanium implants (P < 0.001). The PIM zirconia implants using roughened mold showed significantly higher removal torque values than PIM zirconia implants without using roughened mold (P < 0.001).

CONCLUSIONS

It is concluded that the osseointegration of PIM zirconia implant is promising and PIM using roughened mold etching technique can produce substantially rough surfaces on zirconia implants.