The bone tissue compatibility of a new Ti35Nb2Ta3Zr alloy with a low Young's modulus

Heat Treatment's Vital Role: Elevating Orthodontic Mini-Implants for Superior Performance and Longevity-Pilot Study

Orthodontic mini-implants are devices used for anchorage in various orthodontic treatments. We conducted a pilot study which aimed to observe preliminary trends regarding the impact of heat treatment on the elastic modulus of Ti6Al4V alloy and stainless steel 316L mini-implants. The initial phase involved testing the impact of heat treatment on the mechanical properties of Ti6Al4V alloy and stainless steel 316L mini-implants.

MATERIAL AND METHODS

Ten self-drilling mini-implants sourced from two distinct manufacturers (Jeil Medical Corporation® and Leone®) with dimensions of 2.0 mm diameter and 10 mm length were tested. They were separated into two material groups: Ti6Al4V and 316L. Using the CETRUMT-2 microtribometer equipment, indentation testing was conducted employing a diamond-tipped Rockwell penetrator at a constant force of 4.5 N.

RESULTS

Slight differences were observed in the elastic modulus of the Ti6Al4V alloy (103.99 GPa) and stainless steel 316L (203.20 GPa) compared to natural bone. The higher elastic moduli of these materials indicate that they are stiffer, which could potentially lead to stress-shielding phenomena and bone resorption. Heat treatment resulted in significant changes in mechanical properties, including elastic modulus reductions of approximately 26.14% for Ti6Al4V and 24.82% for 316L, impacting their performance in orthodontic applications.

CONCLUSION

Understanding the effects of heat treatment on these alloys is crucial for optimizing their biomechanical compatibility and longevity in orthodontic treatment. To fully evaluate the effects of heat treatment on mini-implants and to refine their design and efficacy in clinical practice, further research is needed.

Bioactive apatite-wollastonite glass ceramics coating on metallic titanium for biomedical applications: effect of boron

Metallic titanium (Ti) implant surfaces need improvement for bioproperties and antibacterial behavior. For this purpose, a new boron-doped bioactive apatite-wollastonite (AW) coating was successfully developed on the Ti plate surface. The effects of boron addition on the microstructure, mechanical properties, and bioproperties of the AW coating were investigated. With the addition of boron (B), the AW coating morphology became less porous and compact. In terms of bio properties, the rate of apatite formation increased with the addition of B, and the cell viability rate increased from approximately 66-81%. B addition increased the elastic modulus of the AW coating from about 24-46 GPa and increased its hardness about 2.5 times. In addition, while no antibacterial activity was observed in the AW coating, the addition of boron slightly introduced antibacterial properties. The novel AW/B composite coating obtained is promising for Ti implant surfaces.

Research Progress of Titanium-Based Alloys for Medical Devices

Biomaterials are currently a unique class of materials that are essential to improving the standard of human life and extending it. In the assent of the appearance of biomaterials that contain non-toxic elements, in this study, we examine a system of Ti25Mo7Zr15TaxSi (x = 0, 0.5, 0.75, 1 wt.%) for future medical applications. The alloys were developed in a vacuum electric arc furnace and then studied from a structural, mechanical and in vivo assessment (on rabbits) perspective. The effect of the silicon addition was clearly seen in both the structural and the mechanical characteristics, standing out as beta alloys with a dendritic structure and lowering the mechanical properties as a result of the silicon addition. In experimental rabbits, the proliferation of mesenchymal stem cells was observed in the periosteum and peri-implant area, differentiating into osteoblasts and then into osteocytes. Osteoclasts were discovered within the cartilaginous islands that provide structural support to newly formed bone, playing a primary role in bone remodeling. The newly formed spongy tissue adhered to the fibrous capsule that surrounds the alloy, ensuring good osseointegration of metallic implants. The overexpression of Osteopontin, Metalloproteinase-2 (also known as gelatinase A), and Metallopeptidase-9 (also known as gelatinase B) underscores the processes of osteogenesis, bone mineralization, and normal bone remodeling.

Biomaterials and Clinical Application of Dental Implants in Relation to Bone Density-A Narrative Review

Titanium has been the material of choice for dental implant fixtures due to its exceptional qualities, such as its excellent balance of rigidity and stiffness. Since zirconia is a soft-tissue-friendly material and caters to esthetic demands, it is an alternative to titanium for use in implants. Nevertheless, bone density plays a vital role in determining the material and design of implants. Compromised bone density leads to both early and late implant failures due to a lack of implant stability. Therefore, this narrative review aims to investigate the influence of implant material/design and surgical technique on bone density from both biomechanical and biological standpoints. Relevant articles were included for analysis. Dental implant materials can be fabricated from titanium, zirconia, and PEEK. In terms of mechanical and biological aspects, titanium is still the gold standard for dental implant materials. Additionally, the macro- and microgeometry of dental implants play a role in determining and planning the appropriate treatment because it can enhance the mechanical stress transmitted to the bone tissue. Under low-density conditions, a conical titanium implant design, longer length, large diameter, reverse buttress with self-tapping, small thread pitch, and deep thread depth are recommended. Implant material, implant design, surgical techniques, and bone density are pivotal factors affecting the success rates of dental implant placement in low-density bone. Further study is required to find the optimal implant material for a clinical setting's bone state.

Success Factors of Additive Manufactured Root Analogue Implants

Dental implantation is an effective method for the treatment of loose teeth, but the threaded dental implants used in the clinic cannot match with the tooth extraction socket. A root analogue implant (RAI) has the congruence shape, which reduces the damage to bone and soft tissue. Additive manufacturing (AM) technologies have the advantages of high precision, flexibility, and easy operation, becoming the main manufacturing method of RAI in basic research. The purpose of this systematic review is to summarize AM technologies used for RAI manufacturing as well as the factors affecting successful implantation. First, it introduces the AM technologies according to different operating principles and summarizes the advantages and disadvantages of each method. Then the influences of materials, structure design, surface characteristics, implant site, and positioning are discussed, providing reference for designers and dentists. Finally, it addresses the gap between basic research and clinical application for additive manufactured RAIs and discusses the current challenges and future research directions for this field.

2D materials for bone therapy

Due to their prominent physicochemical properties, 2D materials are broadly applied in biomedicine. Currently, 2D materials have achieved great success in treating many diseases such as cancer and tissue engineering as well as bone therapy. Based on their different characteristics, 2D materials could function in various ways in different bone diseases. Herein, the application of 2D materials in bone tissue engineering, joint lubrication, infection of orthopedic implants, bone tumors, and osteoarthritis are firstly reviewed comprehensively together. Meanwhile, different mechanisms by which 2D materials function in each disease reviewed below are also reviewed in detail, which in turn reveals the versatile functions and application of 2D materials. At last, the outlook on how to further broaden applications of 2D materials in bone therapies based on their excellent properties is also discussed.

In-silico design and experimental validation of TiNbTaZrMoSn to assess accuracy of mechanical and biocompatibility predictive models

Numerical design of TiNbTaZrMoSn alloy preceded its manufacture and mechanical, physico-chemical and in vitro characterisation. The specifications of the alloy required a multi-objective optimisation including lower modulus of elasticity than c.p.Ti, high strength, stabilised β crystal structure with a low martensitic start temperature, a narrow solidification range and high biocompatibility. The results reveal that there was a good match between the bulk mechanical properties exhibited by the alloy experimentally and those predicted. Regarding surface properties, independent of roughness effects, the oxide thickness and surface zeta-potential, measured in biologically relevant electrolytes and at physiological pH, arose as important factors in osteoblastic activity (i.e., cell proliferation, measured via DNA, protein and metabolite content, and differentiation, via ALP levels), but not in cell adhesion and viability. The thinner oxide layer and lower absolute value of surface zeta-potential on the TiNbTaZrMoSn alloy explain its lesser osteogenic properties (i.e., inhibition of ALP activity) compared to the c.p. Ti. This study demonstrates that the numerical models to predict microstructure and bulk mechanical properties of β-Ti alloys are robust, but that the prediction of cellular bioactivity lags behind and still requires parameterisation to account for features such as oxide layer composition and thickness, electro-chemical properties and surface charge, and topography to optimise cell response in silico before committing to the costly manufacture and deployment of these alloys in regenerative medicine.

Multi-scale hybrid modified coatings on titanium implants for non-cytotoxicity and antibacterial properties

Titanium and its alloys are among the widely used materials in the biomedical field, but they have poor wear resistance and antibacterial properties. In the present study, anodization, photo-reduction, and spin-coating technologies were integrated to prepare a hybrid modified coating for bio-inert titanium implants, having excellent comprehensive performance. The surface roughness of Ti-35Nb-2Ta-3Zr was specifically optimized by surface modification leading to improved wear resistance. Ag ions are still detectable after 28 days of submersion in saline. The antibacterial rate of the composite coating group reaches 100% by plate counting due to the antibacterial mechanism of direct and indirect contact. Both bacteria morphology and fluorescence staining experiments confirm these results. Besides, no cytotoxicity was detected in our fabricated implants during the CCK-8 assay. Accordingly, fabrication of hybrid modified coatings on Ti-35Nb-2Ta-3Zr is an effective strategy for infection and cytotoxicity prevention. These hybrid modified coatings can be regarded as promising multifunctional biomaterials.

Metal Material, Properties and Design Methods of Porous Biomedical Scaffolds for Additive Manufacturing: A Review

Design an implant similar to the human bone is one of the critical problems in bone tissue engineering. Metal porous scaffolds have good prospects in bone tissue replacement due to their matching elastic modulus, better strength, and biocompatibility. However, traditional processing methods are challenging to fabricate scaffolds with a porous structure, limiting the development of porous scaffolds. With the advancement of additive manufacturing (AM) and computer-aided technologies, the development of porous metal scaffolds also ushers in unprecedented opportunities. In recent years, many new metal materials and innovative design methods are used to fabricate porous scaffolds with excellent mechanical properties and biocompatibility. This article reviews the research progress of porous metal scaffolds, and introduces the AM technologies used in porous metal scaffolds. Then the applications of different metal materials in bone scaffolds are summarized, and the advantages and limitations of various scaffold design methods are discussed. Finally, we look forward to the development prospects of AM in porous metal scaffolds.

Comparison of Biocompatible Coatings Produced by Plasma Electrolytic Oxidation on cp-Ti and Ti-Zr-Nb Superelastic Alloy

The paper compares the coatings produced by plasma electrolytic oxidation (PEO) on commercially pure titanium and a novel superelastic alloy Ti-18Zr-15Nb (at. %) for implant applications. The PEO coatings were produced on both alloys in the identical pulsed bipolar regime. The properties of the coatings were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The PEO process kinetics was modeled based on the Avrami theorem and Cottrell equation using a relaxation method. The resultant coatings contain TiO2, for both alloys, and NbO2, Nb2O5, ZrO2 for Ti-18Zr-15Nb alloy. The coating on the Ti-18Zr-15Nb alloy has a higher thickness, porosity, and roughness compared to that on cp-Ti. The values of the kinetic coefficients of the PEO process—higher diffusion coefficient and lower time constant for the processing of Ti-18Zr-15Nb—explain this effect. According to the electrochemical studies, PEO coatings on Ti-18Zr-15Nb alloy provide better corrosion protection. Higher corrosion resistance, porosity, and roughness contribute to better biocompatibility of the PEO coating on Ti-18Zr-15Nb alloy compared to cp-Ti.

Influence of Isothermal ω Transitional Phase-Assisted Phase Transition From β to α on Room-Temperature Mechanical Performance of a Meta-Stable β Titanium Alloy Ti-10Mo-6Zr-4Sn-3Nb (Ti-B12) for Medical Application

The microstructural evolution and tensile performance of a meta-stable β-type biomedical Ti−10Mo−6Zr−4Sn−3Nb (Ti-B12) alloy subjected to one-stage aging (OSA) and two-stage aging (TSA) are investigated in this work. The OSA treatment is performed at 510°C for 8 h. The TSA treatments are composed of low-temperature aging and high-temperature aging. In the first step, low-temperature aging is conducted at 325°C for 2 h. In the second step, the aging temperature is the same as that in the OSA. The result of the microstructure evolution shows that the precipitated secondary phase after aging is mainly influenced by the process of phase transition. There is a marked difference in the microstructure of the Ti-B12 alloy subjected to the OSA and TSA treatments. The needle-shaped α phases are precipitated in the parent β phase after the OSA treatment. Conversely, the short shuttle-like α phases precipitated after the TSA treatment are formed in the β matrix with the aid of the role of the isothermal ω transitional phase-assisted phase transition. The electron backscattered diffraction results indicate that the crystallographic orientation relationship of the α phases precipitated during the TSA treatment is basically analogous to those in the OSA treatment. The relatively higher tensile strength of 1,275 MPa is achieved by strengthening the effect of the short shuttle-like α precipitation with a size of 0.123 μm in length during the TSA treatment, associating with a suitable elongation of 12% at room temperature simultaneously. The fracture surfaces of the samples after the OSA and TSA treatments indicate that preventing the coarsening of the α layers in the grain boundaries is favorable for the enhancement of strength of Ti-B12 at room temperature. MTT test was carried out to evaluate the acute cytotoxicity and biocompatibility of the implanted material using L929 cells. The relative proliferation rates of cytotoxicity levels 0, 1, 2, 3, and 4 are ≥100, 80–99, 50–79, 30–49, and 0–29%, respectively. The cytotoxicity of the Ti-B12 alloy is slightly better than that of the Ti−6Al−4V alloy, which can meet the requirements of medical materials for biomedical materials.

A Novel Design of Temporomandibular Joint Prosthesis for Lateral Pterygoid Muscle Attachment: A Preliminary Study

Introduction: In temporomandibular joint (TMJ) replacement operation, due to the condylectomy, the lateral pterygoid muscle (LPM) lost attachment and had impact on the mandible kinematic function. This study aimed to design a novel TMJ replacement prosthesis for LPM attachment and to verify its feasibility by preliminary in vitro and in vivo experiments.

Materials and Methods: An artificial TMJ prosthesis designed with a porous structure on the condylar neck region for LPM attachment was fabricated by a 3D printed titanium (Ti) alloy. A rat myoblast cell line (L6) was tested for adhesion and biocompatibility with porous titanium scaffolds in vitro by cell counting Kit-8 (CCK-8), scanning electron microscope (SEM), flow cytometry (FCM), real-time quantitative polymerase chain reaction (RT-qPCR), immunocytofluorescense, western blotting, etc. The porous titanium scaffolds were further embedded in the rat intervertebral muscle to analyze muscle growth and biomechanical strength in vivo. The novel artificial TMJ prosthesis was implanted to reconstruct the goat's condyle and LPM reattachment was analyzed by hard tissue section and avulsion force test.

Results: L6 muscle cells showed good proliferation potential on the porous Ti scaffold under SEM scanning and FCM test. In RT-qPCR, immunocytofluorescense and western blotting tests, the L6 cell lines had good myogenic capacity when cultured on the scaffold with high expression of factors such as Myod1 and myoglobin, etc. In the in vivo experiment, muscles penetrated into the porous scaffold in both rats and goats. In rat's intervertebral muscle implantation, the avulsion force was 0.716 N/mm² in 4 weeks after operation and was significantly increased to 0.801 N/mm² at 8 weeks (p < 0.05). In goat condylar reconstruction with the porous scaffold prosthesis, muscles attached to the prosthesis with the avulsion force of 0.436 N/mm² at 8 weeks, but was smaller than the biological muscle-bone attachment force.

Conclusion: The novel designed TMJ prosthesis can help LPM attach to its porous titanium scaffold structure area for future function.

Nano-Modified Titanium Implant Materials: A Way Toward Improved Antibacterial Properties

Titanium and its alloys have superb biocompatibility, low elastic modulus, and favorable corrosion resistance. These exceptional properties lead to its wide use as a medical implant material. Titanium itself does not have antibacterial properties, so bacteria can gather and adhere to its surface resulting in infection issues. The infection is among the main reasons for implant failure in orthopedic surgeries. Nano-modification, as one of the good options, has the potential to induce different degrees of antibacterial effect on the surface of implant materials. At the same time, the nano-modification procedure and the produced nanostructures should not adversely affect the osteogenic activity, and it should simultaneously lead to favorable antibacterial properties on the surface of the implant. This article scrutinizes and deals with the surface nano-modification of titanium implant materials from three aspects: nanostructures formation procedures, nanomaterials loading, and nano-morphology. In this regard, the research progress on the antibacterial properties of various surface nano-modification of titanium implant materials and the related procedures are introduced, and the new trends will be discussed in order to improve the related materials and methods.

Surface Modification Techniques of Titanium and its Alloys to Functionally Optimize Their Biomedical Properties: Thematic Review

Depending on the requirements of specific applications, implanted materials including metals, ceramics, and polymers have been used in various disciplines of medicine. Titanium and its alloys as implant materials play a critical role in the orthopedic and dental procedures. However, they still require the utilization of surface modification technologies to not only achieve the robust osteointegration but also to increase the antibacterial properties, which can avoid the implant-related infections. This article aims to provide a summary of the latest advances in surface modification techniques, of titanium and its alloys, specifically in biomedical applications. These surface techniques include plasma spray, physical vapor deposition, sol-gel, micro-arc oxidation, etc. Moreover, the microstructure evolution is comprehensively discussed, which is followed by enhanced mechanical properties, osseointegration, antibacterial properties, and clinical outcomes. Future researches should focus on the combination of multiple methods or improving the structure and composition of the composite coating to further enhance the coating performance.

Research Progress of Titanium-Based High Entropy Alloy: Methods, Properties, and Applications

With the continuous progress and development in the biomedicine field, metallic biomedical materials have attracted the considerable attention of researchers, but the related procedures need to be further developed. Since the traditional metal implant materials are not highly compatible with the human body, the modern materials with excellent mechanical properties and proper biocompatibility should be developed urgently in order to solve any adverse reactions caused by the long-term implantations. The advent of the high-entropy alloy (HEA) as an innovative and advanced idea emerged to develop the medical implant materials through the specific HEA designs. The properties of these HEA materials can be predicted and regulated. In this paper, the progression and application of titanium-based HEAs, as well as their preparation and biological evaluation methods, are comprehensively reviewed. Additionally, the prospects for the development and use of these alloys in implant applications are put forward.

The Influence of Severe Plastic Deformation on Microstructure and In Vitro Biocompatibility of the New Ti-Nb-Zr-Ta-Fe-O Alloy Composition

In this work, severe plastic deformation (SPD) of the newly designed Ti-Nb-Zr-Ta-Fe-O GUM metal was successfully conducted at room temperature using high speed high pressure torsion (HSHPT) followed by cold rolling (CR) to exploit the suitability of the processed alloy for bone staples. The Ti-31.5Nb-3.1Zr-3.1Ta-0.9Fe-0.16O GUM alloy was fabricated in a levitation melting furnace using a cold crucible and argon protective atmosphere. The as-cast specimens were subjected to SPD, specifically HSHPT, and then processed by the CR method to take the advantages of both grain refinement and larger dimensions. This approach creates the opportunity to obtain temporary orthopedic implants nanostructured by SPD. The changes induced by HSHPT technology from the coarse dendrite directly into the ultrafine grained structure were examined by optical microscopy, scanning electron microscopy and X-ray diffraction. The structural investigations showed that by increasing the deformation, a high density of grain boundaries is accumulated, leading gradually to fine grain size. In addition, the in vitro biocompatibility studies were conducted in parallel on the GUM alloy specimens in the as-cast state, and after HSHPT- and HSHPT+CR- processing. For comparative purposes, in vitro behavior of the bone-derived MC3T3-E1 cells on the commercially pure titanium has also been investigated regarding the viability and proliferation, morphology and osteogenic differentiation. The results obtained support the appropriateness of the HSHPT technology for developing compression staples able to ensure a better fixation of bone fragments.

Influence of Titanium Alloy Scaffolds on Enzymatic Defense against Oxidative Stress and Bone Marrow Cell Differentiation

Studies have been directed towards the production of new titanium alloys, aiming for the replacement of Ti-6 Aluminium-4 Vanadium (TiAlV) alloy in the future. Many mechanisms related to biocompatibility and chemical characteristics have been studied in the field of implantology, but enzymatic defenses against oxidative stress remain underexplored. Bone marrow stromal cells have been explored as source of cells, which have the potential to differentiate into osteoblasts and therefore could be used as cells-based therapy. The objective of this study was to evaluate the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in porous scaffolds of Ti-6 Aluminium-4 Vanadium (TiAlV), Ti-35 Niobium (TiNb), and Ti-35 Niobium-7 Zirconium-5 Tantalum (TiNbZrTa) on mouse bone marrow stromal cells. Porous titanium alloy scaffolds were prepared by powder metallurgy. After 24 hours, cells plated on the scaffolds were analyzed by scanning electron microscopy (SEM). The antioxidant enzyme activity was measured 72 hours after cell plating. Quantitative real time PCR (qRT-PCR) was performed after 3, 7, and 14 days, and Runx2 (Runt-related transcription factor2) expression was evaluated. The SEM images showed the presence of interconnected pores and growth, adhesion, and cell spreading in the 3 scaffolds. Although differences were noted for SOD and CAT activity for all scaffolds analyzed, no statistical differences were observed (p > 0.05). The osteogenic gene Runx2 presented high expression levels for TiNbZrTa at day 7, compared to the control group (TiAlV day 3). At day 14, all scaffolds had more than 2-fold induction for Runx2 mRNA levels, with statistically significant differences compared to the control group. Even though we were not able to confirm statistically significant differences to justify the replacement of TiAlV regarding antioxidant enzymes, TiNbZrTa was able to induce faster bone formation at early time points, making it a good choice for biomedical and tissue bioengineering applications.

Multi-Scale Surface Treatments of Titanium Implants for Rapid Osseointegration: A Review

The propose of this review was to summarize the advances in multi-scale surface technology of titanium implants to accelerate the osseointegration process. The several multi-scaled methods used for improving wettability, roughness, and bioactivity of implant surfaces are reviewed. In addition, macro-scale methods (e.g., 3D printing (3DP) and laser surface texturing (LST)), micro-scale (e.g., grit-blasting, acid-etching, and Sand-blasted, Large-grit, and Acid-etching (SLA)) and nano-scale methods (e.g., plasma-spraying and anodization) are also discussed, and these surfaces are known to have favorable properties in clinical applications. Functionalized coatings with organic and non-organic loadings suggest good prospects for the future of modern biotechnology. Nevertheless, because of high cost and low clinical validation, these partial coatings have not been commercially available so far. A large number of in vitro and in vivo investigations are necessary in order to obtain in-depth exploration about the efficiency of functional implant surfaces. The prospective titanium implants should possess the optimum chemistry, bionic characteristics, and standardized modern topographies to achieve rapid osseointegration.

Materials for Orthopedic Bioimplants: Modulating Degradation and Surface Modification Using Integrated Nanomaterials

Significant research and development in the field of biomedical implants has evoked the scope to treat a broad range of orthopedic ailments that include fracture fixation, total bone replacement, joint arthrodesis, dental screws, and others. Importantly, the success of a bioimplant depends not only upon its bulk properties, but also on its surface properties that influence its interaction with the host tissue. Various approaches of surface modification such as coating of nanomaterial have been employed to enhance antibacterial activities of a bioimplant. The modified surface facilitates directed modulation of the host cellular behavior and grafting of cell-binding peptides, extracellular matrix (ECM) proteins, and growth factors to further improve host acceptance of a bioimplant. These strategies showed promising results in orthopedics, e.g., improved bone repair and regeneration. However, the choice of materials, especially considering their degradation behavior and surface properties, plays a key role in long-term reliability and performance of bioimplants. Metallic biomaterials have evolved largely in terms of their bulk and surface properties including nano-structuring with nanomaterials to meet the requirements of new generation orthopedic bioimplants. In this review, we have discussed metals and metal alloys commonly used for manufacturing different orthopedic bioimplants and the biotic as well as abiotic factors affecting the failure and degradation of those bioimplants. The review also highlights the currently available nanomaterial-based surface modification technologies to augment the function and performance of these metallic bioimplants in a clinical setting.

Mechanical aspects of dental implants and osseointegration: A narrative review

With the need of rapid healing and long-term stability of dental implants, the existing Ti-based implant materials do not meet completely the current expectation of patients. Low elastic modulus Ti-alloys have shown superior biocompatibility and can achieve comparable or even faster bone formation in vivo at the interface of bone and the implant. Porous structured Ti alloys have shown to allow rapid bone ingrowth through their open structure and to achieve anchorage with bone tissue by increasing the bone-implant interface area. In addition to the mechanical properties of implant materials, the design of the implant body can be used to optimize load transfer and affect the ultimate results of osseointegration. The aim of this narrative review is to define the mechanical properties of dental implants, summarize the relationship between implant stability and osseointegration, discuss the effect of metallic implant mechanical properties (e.g. stiffness and porosity) on the bone response based on existing in vitro and in vivo information, and analyze load transfer through mechanical properties of the implant body. This narrative review concluded that although several studies have presented the advantages of low elastic modulus or high porosity alloys and their effect on osseointegration, further in vivo studies, especially long-term observational studies are needed to justify these novel materials as a replacement for current Ti-based implant materials.

RETRACTED: In vitro corrosion resistance and in vivo osseointegration testing of new multifunctional beta-type quaternary TiMoZrTa alloys

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of authors. Due to communication issues between Professor dr. Lucia Carmen Trincă and Professor dr. Vizureanu Petrica and Assist. dr. Bălţatu Simona, the first author was not aware that the specimens processed by corrosion by Assoc. Professor dr. Daniel Mareci and evaluated in the aforementioned article would be included by Assistant dr. Bălţatu Simona in her PhD thesis that was defended in June 2017 and then in an international patent application (Indonesia) No: PI 2019006569, in November 2019. The authors understand and respect the intellectual property rights of the international (Indonesia) patent application holders no: PI 2019006569/2019 and thus request the retraction of the article.

Effect of DLC Films with and without Silver Nanoparticles Deposited On Titanium Alloy

Abstract Diamond-like carbon (DLC) film is a biocompatible hard coating material that can prevent the leaching of metal ions. This study evaluates the structural characteristics of DLC, with and without silver nanoparticles, deposited by plasma (PECVD) on titanium alloy (Ti-6Al-4V) and bone formation in contact with DLC films. Sixty Ti-6Al-4V samples were used divided in: uncoated, coated with DLC and coated with DLC-Ag. After structural characterization, samples were fixed bilaterally at the rabbit's mandible. After 15 and 90 days, samples were characterized again and bone formation in the area was analyzed by histomorphometry. Statistical analysis was performed by two-way ANOVA. Both the DLC and DLC-Ag films were firmly adhered and showed a high electrical resistance without significant changes in the Raman spectrum after in vivo integration. After 15 days, there were immature bone trabeculae in the interface and partially covering the surface. After 90 days, mature bone filled the interface and coved the surface. There was no statistically significant difference among the three groups in both periods. In conclusion, osseointegration with DLC, DLC-Ag and uncoated Ti-6Al-4V is similar. However, DLC and DLC-Ag coverings have the advantage of electrical insulation and can presumably control bacterial activity and ion leaching.

In vitro and in vivo biological performance of porous Ti alloys prepared by powder metallurgy

Titanium (Ti) and Ti-6 Aluminium-4 Vanadium alloys are the most common materials in implants composition but β type alloys are promising biomaterials because they present better mechanical properties. Besides the composition of biomaterial, many factors influence the performance of the biomaterial. For example, porous surface may modify the functional cellular response and accelerate osseointegration. This paper presents in vitro and in vivo evaluations of powder metallurgy-processed porous samples composed by different titanium alloys and pure Ti, aiming to show their potential for biomedical applications. The porous surfaces samples were produced with different designs to in vitro and in vivo tests. Samples were characterized with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and elastic modulus analyses. Osteogenic cells from newborn rat calvaria were plated on discs of different materials: G1—commercially pure Ti group (CpTi); G2—Ti-6Al-4V alloy; G3—Ti-13 Niobium-13 Zirconium alloy; G4—Ti-35 Niobium alloy; G5—Ti-35 Niobium-7 Zirconium-5 Tantalum alloy. Cell adhesion and viability, total protein content, alkaline phosphatase activity, mineralization nodules and gene expression (alkaline phosphatase, Runx-2, osteocalcin and osteopontin) were assessed. After 2 and 4 weeks of implantation in rabbit tibia, bone ingrowth was analyzed using micro-computed tomography (μCT). EDS analysis confirmed the material production of each group. Metallographic and SEM analysis revealed interconnected pores, with mean pore size of 99,5μm and mean porosity of 42%, without significant difference among the groups (p>0.05). The elastic modulus values did not exhibit difference among the groups (p>0.05). Experimental alloys demonstrated better results than CpTi and Ti-6Al-4V, in gene expression and cytokines analysis, especially in early experimental periods. In conclusion, our data suggests that the experimental alloys can be used for biomedical application since they contributed to excellent cellular behavior and osseointegration besides presenting lower elastic modulus.

Plasma-Activated Tropoelastin Functionalization of Zirconium for Improved Bone Cell Response

The mechanical strength, durability, corrosion resistance, and biocompatibility of metal alloys based on zirconium (Zr) and titanium (Ti) make them desirable materials for orthopedic implants. However, as bioinert metals, they do not actively promote bone formation and integration. Here we report a plasma coating process for improving integration of such metal implants with local bone tissue. The coating is a stable carbon-based plasma polymer layer that increased surface wettability by 28%, improved surface elasticity to the range exhibited by natural bone, and additionally covalently bound the extracellular matrix protein, tropoelastin, in an active conformation. The thus biofunctionalized material was significantly more resistant to medical-grade sterilization by steam, autoclaving or gamma-ray irradiation, retaining >60% of the adhered tropoelastin molecules and preserving full bioactivity. The interface of the coating and metal was robust so as to resist delamination during surgical insertion and in vivo deployment, and the plasma process employed was utilized to also coat the complex 3D geometries typical of orthopedic implants. Osteoblast-like osteosarcoma cells cultured on the biofunctionalized Zr surface exhibited a significant 30% increase in adhesion and up to 70% improvement in proliferation. Cells on these materials also showed significant early stage up-regulation of bone marker expression (alkaline phosphatase, 1.8 fold; osteocalcin, 1.4 fold), and sustained up-regulation of these genes (alkaline phosphatase, 1.3 fold; osteocalcin, 1.2 fold) in osteogenic conditions. In addition, alkaline phosphatase production significantly increased (2-fold) on the functionalized surfaces, whereas bone mineral deposition increased by 30% above background levels compared to bare Zr. These findings have the potential to be readily translated to the development of improved Zr and Ti-based implants for accelerated bone repair.

Newly developed Ti-Nb-Zr-Ta-Si-Fe biomedical beta titanium alloys with increased strength and enhanced biocompatibility

Beta titanium alloys are promising materials for load-bearing orthopaedic implants due to their excellent corrosion resistance and biocompatibility, low elastic modulus and moderate strength. Metastable beta-Ti alloys can be hardened via precipitation of the alpha phase; however, this has an adverse effect on the elastic modulus. Small amounts of Fe (0-2 wt.%) and Si (0-1 wt.%) were added to Ti-35Nb-7Zr-6Ta (TNZT) biocompatible alloy to increase its strength in beta solution treated condition. Fe and Si additions were shown to cause a significant increase in tensile strength and also in the elastic modulus (from 65 GPa to 85 GPa). However, the elastic modulus of TNZT alloy with Fe and Si additions is still much lower than that of widely used Ti-6Al-4V alloy (115 GPa), and thus closer to that of the bone (10-30 GPa). Si decreases the elongation to failure, whereas Fe increases the uniform elongation thanks to increased work hardening. Primary human osteoblasts cultivated for 21 days on TNZT with 0.5Si+2Fe (wt.%) reached a significantly higher cell population density and significantly higher collagen I production than cells cultured on the standard Ti-6Al-4V alloy. In conclusion, the Ti-35Nb-7Zr-6Ta-2Fe-0.5Si alloy proves to be the best combination of elastic modulus, strength and also biological properties, which makes it a viable candidate for use in load-bearing implants.

Increased osteoblast function in vitro and in vivo through surface nanostructuring by ultrasonic shot peening

Surface topography has significant influence on good and fast osseointegration of biomedical implants. In this work, ultrasonic shot peening was conducted to modify titanium to produce nanograined (NG) surface. Its ability to induce new bone formation was evaluated using an in vivo animal model. We demonstrated that the NG surface enhanced osteoblast adhesion, proliferation, differentiation, and mineralization in in vitro experiments compared to coarse-grained titanium surface. Push-out test, histological observations, fluorescent labeling, and histomorphometrical analysis consistently indicated that the NG surfaces developed have the higher osseointegration than coarse-grained surfaces. Those results suggest that ultrasonic shot peening has the potential for future use as a surface modification method in biomedical application.

The in vitro and in vivo performance of a strontium-containing coating on the low-modulus Ti35Nb2Ta3Zr alloy formed by micro-arc oxidation

The β-titanium alloy is thought to be a promising alloy using as orthopedic or dental implants owing to its characteristics, which contains low elastic modulus, high corrosion resistance and well biocompatibility. Our previous study has reported that a new β-titanium alloy Ti35Nb2Ta3Zr showed low modulus close to human bone, equal tissue compatibility to a traditional implant alloy Ti6Al4V. In this study, micro-arc oxidation (MAO) was applied on the Ti35Nb2Ta3Zr alloy to enhance its surface characteristics and biocompatibility and osseointegration ability. Two different coatings were formed, TiO2 doped with calcium-phosphate coating (Ca-P) and calcium-phosphate-strontium coating (Ca-P-Sr). Then we evaluated the effects of the MAO coatings on the Ti35Nb2Ta3Zr alloy through in vitro and in vivo tests. As to the characteristics of the coatings, the morphology, chemical composition, surface roughness and contact angle of MAO coatings were tested by scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, and video contact-angle measurement system respectively. Besides, we performed MTT assay, ALP test and cell morphology-adhesion test on materials to evaluate the MAOed coating materials' biocompatibility in vitro. The in vivo experiment was performed through rabbit model. Alloys were implanted into rabbits' femur shafts, then we performed micro-CT, histological and sequential fluorescent labeling analysis to evaluate implants' osseointegration ability in vivo. Finally, the Ca-P specimens and Ca-P-Sr specimens exhibited a significant enhancement in surface roughness, hydrophilicity, cell proliferation, cell adhesion. More new bone was found around the Ca-P-Sr coated alloy than Ca-P coated alloy and Ti35Nb2Ta3Zr alloy. In conclusion, the MAO treatment improved in vitro and in vivo performance of Ti35Nb2Ta3Zr alloy. The Ca-P-Sr coating may be a promising modified surface formed by MAO for the novel β-titanium alloy Ti35Nb2Ta3Zr.