Electrophoretic bilayer deposition of zirconia and reinforced bioglass system on Ti6Al4V for implant applications: An in vitro investigation

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.

Biocomposite-based strategies for dental bone regeneration

OBJECTIVE

Because of the anatomical complexity of the oral and maxillofacial sites, repairing bone defects in these regions is very difficult. This review article aims to consider the application of biocomposites-based strategies for dental bone regeneration.

STUDY DESIGN

Research papers related to the topic, published over the last 20 years, were selected using the Web of Science, Pubmed, Scopus, and Google Scholar databases.

RESULTS

The strategies of monophasic, biphasic/multiphasic scaffolds, and biopolymer-based nanocomposite scaffolds containing nanomaterials compared with traditional methods used for bone regeneration, such as autografts, allografts, xenografts, and alloplasts are found to be superior because of their ability to overcome the issues (e.g., limited bone sources, pain, immune responses, high cost) related to the applications of the traditional methods.

CONCLUSIONS

In addition, additive manufacturing technologies were found to be highly advantageous for improving the efficacy of biocomposite scaffolds for treating dental bone defects.

Biological MWCNT/chitosan composite coating with outstanding anti-corrosion property for implants

Biocompatible coatings that can protect metal implants have great potential in tissue engineering. In this work, MWCNT/chitosan composite coatings with hydrophobic-hydrophilic asymmetric wettability were facilely prepared by one-step in situ electrodeposition. The resultant composite coating exhibits excellent thermal stability and mechanical strength (0.76 MPa), benefiting from the compact internal structure. The thickness of the coating can be controlled precisely by the amounts of transferred charges. The MWCNT/chitosan composite coating demonstrates a lower corrosion rate due to its hydrophobicity and compact internal structure. Compared with exposed 316 L stainless steel, its corrosion rate is reduced by two orders of magnitude from 3.004 × 10^-1 mm/yr to 5.361 × 10^-3 mm/yr. The content of iron released from 316 L stainless steel into the simulated body fluid drops to 0.1 mg/L under the protection of the composite coating. In addition, the composite coating enables efficient calcium enrichment from simulated body fluids and promotes the formation of bioapatite layers on the coating surface. This study contributes to furthering the practical application of chitosan-based coatings in implant anticorrosion.

Cell Viability Assay and Surface Morphology Analysis of Carbonated Hydroxyapatite/Honeycomb/Titanium Alloy Coatings for Bone Implant Applications

In this work, carbonated hydroxyapatite/titanium alloy (CHA/Ti) and carbonated hydroxyapatite/honeycomb/titanium alloy (CHA/HCB/Ti) plates were coated using the electrophoretic deposition dip coating (EP2D) method. Analysis of cell viability and surface morphology of CHA/Ti and CHA/HCB/Ti coatings were carried out using the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and scanning electron microscopy (SEM), respectively. In a previous study, the thickness and average compressive strength values for the CHA/Ti and CHA/HCB/Ti plates were about 63−89 μm and 54−75 MPa, respectively. The result for thickness and compressive strength in this research followed the thickness and compressive strength parameters for coating in bone implants. In this work, the cell viability for incubation times during 24 h and 48 h of CHA/Ti plates is demonstrably superior to that of CHA/HCB/Ti plates, respectively, where the cell viability for CHA/Ti plates increased to ((67 ± 2)%) after incubation for 48 h. According to the one-way analysis of variance (ANOVA), the p-value was <0.05, indicating a significant difference in the average cell viability value across the three groups. Furthermore, the surface of CHA/Ti is not changed after the coating process. These results will yield many positive biomedical applications, especially in bone implants. Overall, CHA/Ti and CHA/HCB/Ti plates can be considered candidates for biomedical applications based on an analysis of surface morphology and cell viability.

Bioactive Glass—An Extensive Study of the Preparation and Coating Methods

Diseases or complications that are caused by bone tissue damage affect millions of patients every year. Orthopedic and dental implants have become important treatment options for replacing and repairing missing or damaged parts of bones and teeth. In order to use a material in the manufacture of implants, the material must meet several requirements, such as mechanical stability, elasticity, biocompatibility, hydrophilicity, corrosion resistance, and non-toxicity. In the 1970s, a biocompatible glassy material called bioactive glass was discovered. At a later time, several glass materials with similar properties were developed. This material has a big potential to be used in formulating medical devices, but its fragility is an important disadvantage. The use of bioactive glasses in the form of coatings on metal substrates allows the combination of the mechanical hardness of the metal and the biocompatibility of the bioactive glass. In this review, an extensive study of the literature was conducted regarding the preparation methods of bioactive glass and the different techniques of coating on various substrates, such as stainless steel, titanium, and their alloys. Furthermore, the main doping agents that can be used to impart special properties to the bioactive glass coatings are described.

Carbonated Hydroxyapatite-Based Honeycomb Scaffold Coatings on a Titanium Alloy for Bone Implant Application—Physicochemical and Mechanical Properties Analysis

In this work, carbonated hydroxyapatite (CHA) based on abalone mussel shells (Haliotis asinina) is synthesized using the co-precipitation method. The synthesized CHA was mixed with honeycomb (HCB) 40 wt.% for the scaffold fabrication process. CHA and scaffold CHA/HCB 40 wt.% were used for coating a Titanium (Ti) alloy using the electrophoretic deposition dip coating (EP2D) method with immersion times of 10, 20, and 30 min. The synthesized B-type CHA with a stirring time of 45 min could have lower transmittance values and smaller crystallite size. Energy dispersive X-ray spectroscopy (EDS) showed that the Ca/P molar ratio was 1.79. The scaffold CHA/HCB 40 wt.% had macropore size, micropore size, and porosity of 102.02 ± 9.88 μm, 1.08 ± 0.086 μm, and 66.36%, respectively, and therefore it can also be applied in the coating process for bone implant applications due to the potential scaffold for bone growth. Thus, it has the potential for coating on Ti alloy applications. In this study, the compressive strength for all immersion time variations was about 54–83 MPa. The average compression strengths of human cancellous bone were about 0.2–80 MPa. The thickness obtained was in accordance with the thickness parameters required for a coating of 50–200 μm.

Comparative evaluation of surface-modified zirconia for the growth of bone cells and early osseointegration

STATEMENT OF PROBLEM

Rapid osseointegration between implant and bone tissue for early loading of a prosthesis with sufficient primary stability depends on the surface characteristics of the implant. The development and characterization of suitable surface coatings on dental implants is a major challenge.

PURPOSE

The purpose of this in vitro study was to evaluate and compare the osteogenic potential and cytotoxicity of unmodified zirconia, acid-etched zirconia, bioactive glass-coated zirconia, and tamarind kernel polysaccharide with hydrophilic acrylic acid (TKP-AA) hydrogel-coated zirconia.

MATERIAL AND METHODS

Thirty-six disks each of unmodified zirconia, acid-etched, 45S5 bioactive glass-coated, and TKP-AA hydrogel-coated zirconia were evaluated for osteogenic potential and cytotoxic effect by using human osteoblast Saos-2 cells. The surface topography of the disks and the morphology of the cells grown on these surfaces were examined by scanning electron microscopy (n=3). The cell attachment was evaluated by confocal imaging (n=3). The cytotoxic effect was evaluated by cell viability assay (n=9). Osteoblast maturation was assessed by alkaline phosphatase assay (n=9) and cell mineralization by alizarin red staining (n=9). ANOVA and Bonferroni multiple comparison post hoc tests were used to evaluate the statistical significance of the intergroup differences in these characteristics (α=.05).

RESULTS

The surface modifications resulted in distinct changes in the surface morphology of zirconia disks and the growth of Saos-2 cells. Zirconia disks coated with TKP-AA promoted higher proliferation of osteoblasts compared with unmodified disks (P<.001). Similarly, the surface modifications significantly increased the differentiation of mesenchymal stem cells to osteoblasts as compared with uncoated zirconia (P<.001). However, the rate of differentiation to osteoblasts was similar among the surface modifications. Acid-etched and TKP-AA-coated disks promoted mineralization of osteoblasts to the same extent, except bioactive glass coating, which significantly increased the rate of mineralization (P<.001).

CONCLUSIONS

Surface modification of zirconia by acid etching and coating with Bioglass or TKP-AA hydrogel resulted in the improved growth and differentiation of osteoblasts. TKP-AA hydrogel coating promoted the proliferation of osteoblasts, whereas Bioglass coating showed better mineralization. TKP-AA hydrogel coating is a promising candidate for improving the osseointegration of dental implants that warrants further investigation.

The Preparation and Properties of Multilayer Cu-MTa2O5 Composite Coatings on Ti6Al4V for Biomedical Applications

For the enhancement of the anticorrosion and antibacterial performance of the biomedical alloy Ti6Al4V, a novel Cu incorporated multilayer Ta2O5ceramic composite coating Cu-Ta2O5/Ta2O5/Ta2O5-TiO2/TiO2/Ti (coating codeCu-MTa2O5) was developed by radio frequency (RF) and direct current (DC) reactive magnetron sputtering. Meanwhile, to better display the multilayer Ta2O5 coating mentioned above, a monolayer Ta2O5 ceramic coating was deposited onto the surface of Ti6Al4V alloy as a reference. The surface morphology, microstructure, phase constituents, and elemental states of the coating were evaluated by atomic force microscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, respectively. The adhesion strength, wettability, anticorrosion and antibacterial properties of the coating were examined by a scratch tester, contact angle measurement, electrochemical workstations, and plate counting method, respectively. The results showed that the deposited coatings were amorphous and hydrophobic. Cu doped into the Ta2O5 coating existed as CuO and Cu2O. A Ta2O5-TiO2/TiO2/Ti multi-interlayer massively enhanced the adhesion strength of the coating, which was 2.9 times stronger than that of the monolayer Ta2O5coating. The multilayer Cu-MTa2O5 coating revealed a higher corrosion potential and smaller corrosion current density as compared to the uncoated Ti6Al4V, indicating the better anticorrosion performance of Ti6Al4V. Moreover, a 99.8% antibacterial effect of Cu-MTa2O5 coated against Staphylococcus aureuswas obtained.

Bioglass implant-coating interactions in synthetic physiological fluids with varying degrees of biomimicry

Synthetic physiological fluids are currently used as a first in vitro bioactivity assessment for bone grafts. Our understanding about the interactions taking place at the fluid-implant interface has evolved remarkably during the last decade, and does not comply with the traditional International Organization for Standardization/final draft International Standard 23317 protocol in purely inorganic simulated body fluid. The advances in our knowledge point to the need of a true paradigm shift toward testing physiological fluids with enhanced biomimicry and a better understanding of the materials' structure-dissolution behavior. This will contribute to "upgrade" our vision of entire cascades of events taking place at the implant surfaces upon immersion in the testing media or after implantation. Starting from an osteoinductive bioglass composition with the ability to alleviate the oxidative stress, thin bioglass films with different degrees of polymerization were deposited onto titanium substrates. Their biomineralization activity in simulated body fluid and in a series of new inorganic-organic media with increasing biomimicry that more closely simulated the human intercellular environment was compared. A comprehensive range of advanced characterization tools (scanning electron microscopy; grazing-incidence X-ray diffraction; Fourier-transform infrared, micro-Raman, energy-dispersive, X-ray photoelectron, and surface-enhanced laser desorption/ionization time-of-flight mass spectroscopies; and cytocompatibility assays using mesenchymal stem cells) were used. The information gathered is very useful to biologists, biophysicists, clinicians, and material scientists with special interest in teaching and research. By combining all the analyses, we propose herein a step forward toward establishing an improved unified protocol for testing the bioactivity of implant materials.

Engineering three-dimensional structures using bio-inspired dopamine and strontium on titanium for biomedical application

Poly(dopamine) films facilitate the initial attachment and proliferation of cells. Cell differentiation is enhanced by the release of strontium from the coatings.