The effect of the solute on the structure, selected mechanical properties, and biocompatibility of Ti-Zr system alloys for dental applications

A review in titanium-zirconium binary alloy for use in dental implants: Is there an ideal Ti-Zr composing ratio?

Binary titanium-zirconium alloys have been studied as promising alternatives for Ti implants. The commercial Ti-15Zr alloy (Roxolid, Straumann) has been the major subject of numerous binary Ti-Zr alloys-related studies and has gained wide recognition in laboratory studies and clinical practices. However, binary Ti-Zr alloys of other composition ratios are still being investigated by researchers. This review aims to provide information on the potential of binary Ti-Zr alloys other than Ti-15Zr as implant materials in terms of mechanical strengths, chemical or electrochemical corrosion resistance capabilities, and biological performances. In addition, in this review, the Ti-15Zr alloy is discussed only when compared with other binary Ti-Zr alloys. From the included 26 studies, it is confirmed that the mechanical, chemical, electrochemical, and biological properties of Ti-Zr alloys are related to the Ti and Zr composition ratio in the alloy, phase, manufacturing process, and surface treatment. Among the studied alloys, α-or α' phase-Ti-5 wt, 45 wt/30at, and 50 wt. %Zr exhibited relatively more promising results for further investigation. More research is necessary to evaluate the potential for future use of these materials for implants.

Combined First-Principles and Experimental Study on the Microstructure and Mechanical Characteristics of the Multicomponent Additive-Manufactured Ti-35Nb-7Zr-5Ta Alloy

New β-stabilized Ti-based alloys are highly promising for bone implants, thanks in part to their low elasticity. The nature of this elasticity, however, is as yet unknown. We here present combined first-principles DFT calculations and experiments on the microstructure, structural stability, mechanical characteristics, and electronic structure to elucidate this origin. Our results suggest that the studied β Ti-35Nb-7Zr-5Ta wt % (TNZT) alloy manufactured by the electron-beam powder bed fusion (E-PBF) method has homogeneous mechanical properties (H = 2.01 ± 0.22 GPa and E = 69.48 ± 0.03 GPa) along the building direction, which is dictated by the crystallographic texture and microstructure morphologies. The analysis of the structural and electronic properties, as the main factors dominating the chemical bonding mechanism, indicates that TNZT has a mixture of strong metallic and weak covalent bonding. Our calculations demonstrate that the softening in the Cauchy pressure (C' = 98.00 GPa) and elastic constant C̅44 = 23.84 GPa is the origin of the low elasticity of TNZT. Moreover, the nature of this softening phenomenon can be related to the weakness of the second and third neighbor bonds in comparison with the first neighbor bonds in the TNZT. Thus, the obtained results indicate that a carefully designed TNZT alloy can be an excellent candidate for the manufacturing of orthopedic internal fixation devices. In addition, the current findings can be used as guidance not only for predicting the mechanical properties but also the nature of elastic characteristics of the newly developed alloys with yet unknown properties.

Microscopic and Mechanical Characterization of Co-Cr Dental Alloys Joined by the TIG Welding Process

Due to their good mechanical and other properties, cobalt-chromium alloys (Co-Cr) are often used in prosthetic therapy. The metal structures of prosthetic works can be damaged and break, and depending on the extent of the damage, they can be re-joined. Tungsten inert gas welding (TIG) produces a high-quality weld with a composition very close to that of the base material. Therefore, in this work, six commercially available Co-Cr dental alloys were joined by TIG welding, and their mechanical properties were evaluated to determine the quality of the TIG process as a technology for joining metallic dental materials and the suitability of the Co-Cr alloys used for TIG welding. Microscopic observations were made for this purpose. Microhardness was measured using the Vickers method. The flexural strength was determined on a mechanical testing machine. The dynamic tests were carried out on a universal testing machine. The mechanical properties were determined for welded and non-welded specimens, and the results were statistically evaluated. The results show the correlation between the investigated mechanical properties and the process TIG. Indeed, characteristics of the welds have an effect on the measured properties. Considering all the results obtained, the TIG-welded I-BOND NF and Wisil M alloys showed the cleanest and most uniform weld and, accordingly, satisfactory mechanical properties, highlighting that they withstood the maximum number of cycles under dynamic load.

Mechanical Properties, Corrosion Behavior, and In Vitro Cell Studies of the New Ti-25Ta-25Nb-5Sn Alloy

This study aims to characterize a new Ti-25Ta-25Nb-5Sn alloy for biomedical application. Microstructure, phase formation, mechanical and corrosion properties, along with the cell culture study of the Ti-25Ta-25Nb alloy with Sn content 5 mass% are presented in this article. The experimental alloy was processed in an arc melting furnace, cold worked, and heat treated. For characterization, optical microscopy, X-ray diffraction, microhardness, and Young's modulus measurements were employed. Corrosion behavior was also evaluated using open-circuit potential (OCP) and potentiodynamic polarization. In vitro studies with human ADSCs were performed to investigate cell viability, adhesion, proliferation, and differentiation. Comparison among the mechanical properties observed in other metal alloy systems, including CP Ti, Ti-25Ta-25Nb, and Ti-25Ta-25-Nb-3Sn showed an increase in microhardness and a decrease in the Young's modulus when compared to CP Ti. The potentiodynamic polarization tests indicated that the corrosion resistance of the Ti-25Ta-25Nb-5Sn alloy was similar to CP Ti and the experiments in vitro demonstrated great interactions between the alloy surface and cells in terms of adhesion, proliferation, and differentiation. Therefore, this alloy presents potential for biomedical applications with properties required for good performance.

Processing and Characterization of a New Quaternary Alloy Ti10Mo8Nb6Zr for Potential Biomedical Applications

The study of new metallic biomaterials for application in bone tissue repair has improved due to the increase in life expectancy and the aging of the world population. Titanium alloys are one of the main groups of biomaterials for these applications, and beta-type titanium alloys are more suitable for long-term bone implants. The objective of this work was to process and characterize a new Ti₁₀Mo₈Nb₆Zr beta alloy. Alloy processing involves arc melting, heat treatment, and cold forging. The characterization techniques used in this study were X-ray fluorescence spectroscopy, X-ray diffraction, differential scanning calorimetry, optical microscopy, microhardness measurements, and pulse excitation technique. In vitro studies using adipose-derived stem cells (ADSC) were performed to evaluate the cytotoxicity and cell viability after 1, 4, and 7 days. The results showed that the main phase during the processing route was the beta phase. At the end of processing, the alloy showed beta phase, equiaxed grains with an average size of 228.7 µm, and low Young's modulus (83 GPa). In vitro studies revealed non-cytotoxicity and superior cell viability compared to CP Ti. The addition of zirconium led to a decrease in the beta-transus temperature and Young's modulus and improved the biocompatibility of the alloy. Therefore, the Ti₁₀Mo₈Nb₆Zr alloy is a promising candidate for application in the biomedical field.

Microstructure, mechanical strength, chemical resistance, and antibacterial behavior of Ti-5Cu-x%Nb biomedical alloy

Titanium-based biomedical alloys are susceptible as they are used as a substitute for human bone. In this study, titanium alloy, Ti-5Cu-x%Nb (x= 0, 5, 10, 15) (%wt) was developed by powder metallurgy route. The effect of alloying niobium with Ti-5Cu alloy and its effect on the microstructure, mechanical strength, corrosion resistance, and antibacterial properties have been evaluated. The results show that the sintered alloy has bothα-Ti and Ti₂Cu phases. With increasing niobium content in the alloy,β-Ti was also detected. Additionally, it was found that the micro-hardness and compressive strength of the studied alloy was better than commercially pure titanium (cpTi), while the Young's modulus was lower than cpTi. These properties are highly favorable for using this alloy to replicate the human cortical bone. The alloy was also tested for anticorrosive property in Ringer's solution. The antibacterial activity was also examined forStaphylococcus aureusandEscherichia colibacteria. The alloy showed promising anticorrosive and antibacterial ability.

Bone response in vivo of Ti-45Zr alloy as dental implant material

Ti-Zr alloys have gained increasing attention as a new metallic biomaterial, being used as implants for both orthopedics and dentistry. More recently, our group found promising results for the Ti-45Zr alloy, which presented a low elastic modulus, a pronounced and excellent mechanic character, and excellent cell compatibility in vitro. However, its biocompatibility and potential to promote osteogenesis in vivo remained unclear. In the present study, the biocompatibility, osteointegration ability, and immune response effects of the Ti-45Zr alloy were evaluated in animal experiments. The results showed that the alloy had good blood compatibility and no body side effects. After implantation in vivo, the inflammation turned out well and was beneficial to the polarization of macrophages. Additionally, the Ti-45Zr alloy presented a good osteointegration ability. Overall, these results confirmed that the Ti-45Zr alloy can be used as a dental implant material.

The Influence of Thermomechanical Treatments on the Structure, Microstructure, and Mechanical Properties of Ti-5Mn-Mo Alloys

With the increase in the world’s population, the rising number of traffic accidents, and the increase in life expectancy, the need for implants, dental work, and orthopedics is growing ever larger. Researchers are working to improve the biomaterials used for these purposes, improve their functionality, and increase the human body’s life span. Thus, new titanium alloys are being developed, usually with β-stabilizer elements (which decrease the elastic modulus), with the Ti-Mn-Mo alloys being one example of these. This study of the Ti-5Mn-10Mo and Ti-5Mn-15Mo alloys only showed signs of the β phase in the structure and microstructure, presenting a combination of low modulus of elasticity and high corrosion resistance compared to the values of commercial alloys. In this sense, this work presents an analysis of the influence of some thermomechanical treatments, such as homogenization, hot-rolling, solution, and annealing, on the structure, microstructure, and selected mechanical properties of the Ti-5Mn-10Mo and Ti-5Mn-15Mo alloys.

Mechanical Characterization and In Vitro Assay of Biocompatible Titanium Alloys

Metals that come into contact with the body can cause reactions in the body, so biomaterials must be tested to avoid side effects. Mo, Zr, and Ta are non-toxic elements; alloyed with titanium, they have very good biocompatibility properties and mechanical properties. The paper aims to study an original Ti20Mo7ZrxTa system (5, 10, 15 wt %) from a mechanical and in vitro biocompatibility point of view. Alloys were examined by optical microstructure, tensile strength, fractographic analysis, and in vitro assay. The obtained results indicate very good mechanical and biological properties, recommending them for future orthopedic medical applications.

Fabrication and Characterization of New Functional Graded Material Based on Ti, Ta, and Zr by Powder Metallurgy Method

In view of the aging population and various diseases worldwide, the demand for implants has been rapidly increasing. Despite the efforts of doctors, engineers, and medical companies, the fabrication of and procedures associated with implants have not yet been perfected. Therefore, a high percentage of premature implantations has been observed. The main problem with metal implants is the mechanical mismatch between human bone and the implant material. Zirconium/titanium-based materials with graded porosity and composition were prepared by powder metallurgy. The whole samples are comprised of three zones, with a radial gradient in the phase composition, microstructure, and pore structure. The samples were prepared by a three-step powder metallurgy method. The microstructure and properties were observed to change gradually with the distance from the center of the sample. The x-ray diffraction analysis and microstructure observation confirmed the formation of diffusive connections between the particular areas. Additionally, the mechanical properties of the obtained materials were checked, with respect to the distance from the center of the sample. An analysis of the corrosion properties of the obtained materials was also carried out.

Synthesis, Surface Nitriding and Characterization of Ti-Nb Modified 316L Stainless Steel Alloy Using Powder Metallurgy

The powder metallurgy (PM) technique has been widely used for producing different alloy compositions by the addition of suitable reinforcements. PM is also capable of producing desireable mechanical and physical properties of the material by varying process parameters. This research investigates the addition of titanium and niobium in a 316L stainless steel matrix for potential use in the biomedical field. The increase of sintering dwell time resulted in simultaneous sintering and surface nitriding of compositions, using nitrogen as the sintering atmosphere. The developed alloy compositions were characterized using OM, FESEM, XRD and XPS techniques for quantification of the surface nitride layer and the nitrogen absorbed during sintering. The corrosion resistance and cytotoxicity assessments of the developed compositions were carried out in artificial saliva solution and human oral fibroblast cell culture, respectively. The results indicated that the nitride layer produced during sintering increased the corrosion resistance of the alloy and the developed compositions are non-cytotoxic. This newly developed alloy composition and processing technique is expected to provide a low-cost solution to implant manufacturing.

Cytocompatibility of Ti-xZr alloys as dental implant materials

Ti-xZr (x = 5, 15, 25, 35, 45% wt%) alloys with low elastic modulus and high mechanical strength were fabricated as a novel implant material. The biocompatibility of the Ti-xZr alloys was evaluated by osteoblast-like cell line (MG63) in terms of cytotoxicity, proliferation, adhesion, and osteogenic induction using CCK-8 and live/dead cell assays, electron microscopy, and real-time PCR. The Ti-xZr alloys were non-toxic and showed superior biomechanics compared to commercially pure titanium (cpTi). Ti-45Zr had the optimum strength/elastic modulus ratio and osteogenic activity, thus is a promising to used as dental implants.

Prediction of tribocorrosion processes in titanium-based dental implants using acoustic emission technique: Initial outcome

The use of dental implants is growing rapidly for the last few decades and Ti-based dental implants are a commonly used prosthetic structure in dentistry. Recently, the combined effect of corrosion and wear, called tribocorrosion, is considered as a major driving process in the early failure of dental implants. However, no previous study has reported the prediction of tribocorrosion processes in advance. Therefore, this study is a novel investigation on how the acoustic emission (AE) technique can predict tribocorrosion processes in commercially-pure titanium (cpTi) and titanium-zirconium (TiZr) alloys. In this study, tribocorrosion tests were performed under potentiostatic conditions and AE detection system associated with it captures AE data. Current evolution and friction coefficient data obtained from the potentiostatic evaluations were compared with AE absolute energy showcased the same data interpretation of tribocorrosion characteristics. Other AE data such as duration, count, and amplitude, matched more closely with other potentiostatic corrosion evaluations and delivered more promising results in the detection of tribocorrosion. Hence, AE can be consider as a tool for predicting tribocorrosion in dental implants. Experimental results also reveal Ti5Zr as one of the most appropriate dental implant materials while exposing Ti10Zr's lower effectiveness to withstand in the simulated oral environment.

Improving the Mechanical Properties of a β-type Ti-Nb-Zr-Fe-O Alloy

The influence of complex thermo-mechanical processing (TMP) on the mechanical properties of a Ti-Nb-Zr-Fe-O bio-alloy was investigated in this study. The proposed TMP program involves a schema featuring a series of severe plastic deformation (SPD) and solution treatment (STs). The purpose of this study was to find the proper parameter combination for the applied TMP and thus enhance the mechanical strength and diminish the Young’s modulus. The proposed chemical composition of the studied β-type Ti-alloy was conceived from already-appreciated Ti-Nb-Ta-Zr alloys with high β-stability by replacing the expensive Ta with more accessible Fe and O. These chemical additions are expected to better enhance β-stability and thus avoid the generation of ω, α’, and α” during complex TMP, as well as allow for the processing of a single bcc β-phase with significant grain diminution, increased mechanical strength, and a low elasticity value/Young’s modulus. The proposed TMP program considers two research directions of TMP experiments. For comparisons using structural and mechanical perspectives, the two categories of the experimental samples were analyzed using SEM microscopy and a series of tensile tests. The comparison also included some already published results for similar alloys. The analysis revealed the advantages and disadvantages for all compared categories, with the conclusions highlighting that the studied alloys are suitable for expanding the database of possible β-Ti bio-alloys that could be used depending on the specific requirements of different biomedical implant applications.

Microstructure and Porosity Evolution of the Ti-35Zr Biomedical Alloy Produced by Elemental Powder Metallurgy

In the present study, the structure and porosity of binary Ti-35Zr (wt.%) alloy were investigated, allowing to consider powder metallurgy as a production method for new metallic materials for potential medical applications. The porous Ti-Zr alloys were obtained by milling, cold isostatic pressing and sintering. The pressure during cold isostatic pressing was a changing parameter and was respectively 250, 500, 750 and 1000 MPa. The X-ray diffraction study revealed only the α phase, which corresponds to the Ti-Zr phase diagram. The microstructure of the Ti-35Zr was observed by optical microscopy and scanning electron microscopy. These observations revealed that the volume fraction of the pores decreased from over 20% to about 7% with increasing pressure during the cold isostatic pressing. The microhardness measurements showed changes from 137 HV0.5 to 225 HV0.5.

Development and properties of dental Ti-Zr binary alloys

In this study, two medium Zr-containing Ti-based alloys with commercially pure titanium as control were systematically investigated to assess their potential biomedical application. After samples subjected to TMP and CR, it was found that the Zr addition significantly affected the microstructure, phase constitutions, mechanical properties and cytocompatibility. The microstructural results showed that increasing Zr concentrations resulted in more refined grains. Furthermore, Zr changed the phase constitution: CR Ti-20Zr was formed by the single α-phase while CR Ti-30Zr alloy was formed by the coexistence of α and deformation-induced FCC phases. The P-type FCC phase was dominant and more prone to occur than the B-type one. The mechanical tests demonstrated that the increasing Zr content led to a simultaneous increase in micro-hardness, strength and plasticity of CR samples due to the combined effects of solution strengthening, work hardening and the FCC phase. The SEM fractography indicated that the brittle fracture of CR Ti-20Zr due to deformation twins and ductile fracture of CR Ti-30Zr because of FCC phase. Furthermore, Ti-Zr alloys presented comparable cytocompatibility to the CP-Ti control based on cell viability, proliferation and intracellular O^2- content of MSCs. Specifically, alkaline phosphatase activity in BMSCs were significantly higher for grain refined CR Ti-30Zr. Considering all these results, CR Ti-30Zr alloy exhibited the optimal comprehensive performance to be potential dental materials.

Titanium Alloys for Dental Implants: A Review

The topic of titanium alloys for dental implants has been reviewed. The basis of the review was a search using PubMed, with the large number of references identified being reduced to a manageable number by concentrating on more recent articles and reports of biocompatibility and of implant durability. Implants made mainly from titanium have been used for the fabrication of dental implants since around 1981. The main alloys are so-called commercially pure titanium (cpTi) and Ti-6Al-4V, both of which give clinical success rates of up to 99% at 10 years. Both alloys are biocompatible in contact with bone and the gingival tissues, and are capable of undergoing osseointegration. Investigations of novel titanium alloys developed for orthopaedics show that they offer few advantages as dental implants. The main findings of this review are that the alloys cpTi and Ti-6Al-4V are highly satisfactory materials, and that there is little scope for improvement as far as dentistry is concerned. The conclusion is that these materials will continue to be used for dental implants well into the foreseeable future.

Preparation, structural, microstructural, mechanical and cytotoxic characterization of as-cast Ti-25Ta-Zr alloys

Titanium alloys have been widely used as biomaterials, especially for orthopedic prostheses and dental implants, but these materials have Young's modulus almost three times greater than human cortical bones. Because of this, new alloys are being produced for the propose of decreasing Young's modulus to achieve a more balanced mechanical compatibility with the bone. In this paper, it is reported the development of Ti-25Ta alloys as a base material, in which was introduced zirconium, with concentration varying between 0 and 40 wt%, with the aim of biomedical applications. The alloys were prepared in an arc-melting furnace. The microstructural analysis was performed by x-ray diffraction as well as optical and scanning electron microscopy. Selected mechanical properties were analyzed by microhardness and Young's modulus measurements, and cytotoxicity analysis by indirect test. X-ray measurements revealed the presence of α″ phase in the alloy without zirconium; α″ + β phases for alloys with 10, 20, and 30 wt% of zirconium, and β phase only for the alloy with 40 wt% of zirconium. These results were corroborated by the microscopy results. The hardness of the alloy was higher than that of cp-Ti due to the actions of zirconium and tantalum as hardening agents. The Young's modulus decreases with high levels of zirconium due to the stabilization of the β phase. The cytotoxicity test showed that the extracts of studied alloys are not cytotoxic for osteoblast cells in short periods of culture.

Preparation, structural, microstructural, mechanical, and cytotoxic characterization of Ti-15Nb alloy for biomedical applications

Titanium alloys are widely used in the biomedical field due to their excellent resistance to corrosion, high mechanical strength/density ratio, low elastic modulus, and good biocompatibility. Niobium is a β-stabilizer element that has the potential to decrease elastic modulus and possesses excellent corrosion resistance. In this article, Ti-15Nb alloy was prepared via arc-melting, with the aim of using it in biomedical applications to replace implants that fail due to mechanical incompatibility with human bone. This Ti-15Nb alloy was structurally, chemically, and microstructurally characterized. Its mechanical properties were analyzed via Vickers microhardness and elastic modulus measurements. The cytotoxicity of the alloy was evaluated via direct and indirect MTT tests. In the direct MTT test, the cells were grown on alloy and in the indirect test, Ti-15Nb alloy extracts were prepared (1 g/1 mL at 310 K for 48 hours). The results of chemical composition showed that the alloy produced has good quality and low content of gaseous impurities, such as oxygen and nitrogen. The obtained results for structure and microstructure indicated the presence of the martensite α' phase. The microhardness of the Ti-15Nb alloy is superior to that of cp-Ti due to solid solution hardening, and the alloy has a better elastic modulus as compared to pure titanium. Cytotoxic effects were not observed. The Ti-15Nb alloy shows good results of mechanical properties and does not show cytotoxic effects. In addition, morphological variations were not found in the cells and good cell adhesion in all the studied conditions was observed. In general, the alloy proposed in this article has satisfactory characteristics as a biomedical material.

On the Future Design of Bio-Inspired Polyetheretherketone Dental Implants

Polyetheretherketone (PEEK) is a promising implant material because of its excellent mechanical characteristics. Although this polymer is a standard material in spinal applications, PEEK is not in use in the manufacturing of dental implants, where titanium is still the most-used material. This may be caused by its relative bio-inertness. By the use of various surface modification techniques, efforts have been made to enhance its osseointegrative characteristics to enable the polymer to be used in dentistry. In this feature paper, the state-of-the-art for dental implants is given and different surface modification techniques of PEEK are discussed. The focus will lie on a covalently attached surface layer mimicking natural bone. The usage of such covalently anchored biomimetic composite materials combines many advantageous properties: A biocompatible organic matrix and a mineral component provide the cells with a surrounding close to natural bone. Bone-related cells may not recognize the implant as a foreign body and therefore, may heal and integrate faster and more firmly. Because neither metal-based nor ceramics are ideal material candidates for a dental implant, the combination of PEEK and a covalently anchored mineralized biopolymer layer may be the start of the desired evolution in dental surgery.

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.

Mechanical and biological properties of Ti-(0-25 wt%)Nb alloys for biomedical implants application

Binary titanium–niobium (Ti–Nb) alloys have recently been attracted due to low Young’s moduli and non-toxic properties. This study explores the influence of low Nb content (0–25 wt%) on the comprehensive parameters of tensile stress–strain relationships (ultimate strength (σ_UTS), yield strength (σ_0.2) and elastic modulus (E)), surfaces properties (Vickers microhardness, surface roughness (R_a), water contact angle (WCA), X-ray diffraction (XRD) and scanning electron microscopy (SEM)), corrosion resistance (in artificial saliva and lactic acid) and biological properties (cytotoxicity and alkaline phosphatase activity of MC3T3-E1 pre-osteoblasts) of Ti–xNb alloys (x = 5, 10, 15, 20 and 25 wt%), with using commercially pure grade 2 titanium (cp-Ti) as control. XRD results shown that all the Ti–xNb alloys comprised α + β Ti alloy phases, such that the β phase increased correspondingly with the increased amount of Nb in the alloy, as well as the reduction of E (69–87 GPa). Except Ti–5Nb, all other Ti–xNb alloys showed a significantly higher hardness, increased σ_UTS and σ_0.2, and decreased WCA compared with cp-Ti. No corrosion was detected on Ti–xNb alloys and cp-Ti in artificial saliva and lactic acid solutions. The cytotoxicity of Ti–xNb alloys was comparable to that of cp-Ti in MC3T3-E1 pre-osteoblasts without interference from differentiation behaviour, but the proliferation rate of the Ti–5Nb alloy was lower than other groups. In overall, binary Ti–(10–25 wt%)Nb alloys are promising candidate for orthopaedic and dental implants due to their improved mechanical properties and comparable biological performance, while Ti–5Nb should be used with caution.

Characterization and Mechanical Proprieties of New TiMo Alloys Used for Medical Applications

Ti-based alloys are accessible for use in the human body due to their good mechanical properties, corrosion resistance, and biocompatibilities. These main properties of alloys are important criteria for choosing biomedical implants for human bones or for other kinds of applications in general medicine. This paper presents a comparison of four new Ti-based alloys desired to satisfy various requirements for biomedical implants. The materials were prepared with recipes for two new system alloys, TiMoZrTa (TMZT) and TiMoSi (TMS), alloys with nontoxic elements. The presented research contains microstructure images, indentation tests, Vickers hardness, XRD, and corrosion resistance, showing better characteristics than most commercial products used as implants (Young’s modulus closer to the human bone).

An Efficient Approach for Nitrogen Diffusion and Surface Nitriding of Boron-Titanium Modified Stainless Steel Alloy for Biomedical Applications

Austenitic 316L stainless steel has been the most widely acceptable biomaterial for producing implants. The downside of this material includes the leaching of nickel ions from the matrix that limits its’ usage in implant manufacturing. In this research, production of stainless steel alloy modified with boron and titanium is investigated. The sintering of the alloy systems is carried out in nitrogen atmosphere for a dwell time of 8 h. The X-Ray diffraction (XRD) analysis reveals that dwell time and alloy composition leads to the formation of strong nitrides and borides. The X-Ray Photoelectron Spectroscopy (XPS) results show the presence of nitrogen on to the surface of sintered specimens. The nitride layer on the surface of the specimens is helpful in the retention of nickel ions in the stainless steel matrix, as indicated in the weight loss measurements. The cytotoxicity assessment indicates that the developed alloys are biocompatible and can be used as implant materials.

Microstructure, mechanical properties, and preliminary biocompatibility evaluation of binary Ti-Zr alloys for dental application

The microstructure, mechanical properties, and in vitro biocompatibility of vacuum-sintered Ti-xZr binary alloys (x = 5, 15, 25, 35, 45 wt%) were investigated. The results indicated that α and α' phase existed in Ti-xZr alloys. The hardness of the Ti-Zr alloys increased as the contents increased and ranged from 473 HV (Ti-5Zr) to 525 HV (Ti-45Zr). Increasing Zr content could lead to an increase in compressive and bending strength. Additionally, the Ti-45Zr alloy exhibited the maximum bending strength of 867.1 MPa and the maximum compressive strength of 1599.8 MPa which were much larger than that of CP-Ti. Moreover, all Ti-Zr alloys showed a lower elastic modulus (ranging from 53.5 to 59.3 GPa) compared with CP-Ti (103 GPa). The in vitro cytotoxicity tests were carried out for biocompatibility evaluation. The alloys presented no cytotoxic effects and the surface of the alloys exhibited great growth conditions for MG-63 cells. The Ti-45Zr alloy exhibited better mechanical properties and biocompatibility. In conclusion, Ti-45Zr alloy is of great potential for dental applications.

Dose-response effect of chlorhexidine on a multispecies oral biofilm formed on pure titanium and on a titanium-zirconium alloy

This study aimed to test the dose-response effect of chlorhexidine on multispecies biofilms formed on commercially pure titanium (cpTi) and titanium-zirconium (TiZr) alloy. Biofilms were formed on cpTi and TiZr discs and treated two times per day with five different chlorhexidine concentrations (0.12, 0.20, 0.50, 1, 2%). The biofilms were collected for microbiological, biochemical and microscopic analyses. The significance of differences among groups was evaluated by linear regression, ANOVA, Bonferroni and Tukey tests. The mean number of colony-forming units decreased as the chlorhexidine concentration increased for both cpTi and TiZr (p < 0.05). The maximum effect was observed with the 0.5% concentration. Confocal microscopy images suggested an increase in the number of dead bacterial cells with increased chlorhexidine concentration. The biofilm pH increased after chlorhexidine exposure (p < 0.05). Chlorhexidine showed an antimicrobial dose-response effect in controlling biofilm on cpTi and TiZr. 0.5% chlorhexidine can be used to achieve the maximum antimicrobial effect on both materials.

Comparison of the Use of Titanium–Zirconium Alloy and Titanium Alloy in Dental Implants: A Systematic Review and Meta-Analysis

The aim of this study was to compare the values of bone-implant contact (BIC) and removal torque (RTQ) reported in different animal studies for titanium–zirconium (TiZr) and titanium (Ti) dental implants. This review has been registered at PROSPERO under number CRD42016047745. We undertook an electronic search for data published up until November 2017 using the PubMed/Medline, Embase, and The Cochrane Library databases. Eligibility criteria included in vivo studies, comparisons between Ti and TiZr implants in the same study, and studies published in English that evaluated BIC and RTQ. After inclusion criteria, 8 studies were assessed for eligibility. Of the 8 studies, 7 analyzed BIC outcome and 3 analyzed RTQ outcome. Among such studies, 6 studies were considered for meta-analysis of quantitative for BIC and 2 studies for RTQ. There was no significant difference for BIC analysis (P = .89; random ration [RR]: −0.21; 95% confidence interval [CI]: −3.14 to 2.72). The heterogeneity of the primary outcome studies was considered low (7.19; P = .21; I2: 30%). However, the RTQ analysis showed different results favoring the TiZr dental implants (P = .001; RR: 23.62; 95%CI: 9.15 to 38.10). Low heterogeneity was observed for RTQ (χ2: 1.25; P = .26; I2: 20%). Within the limitations of this study, there was no difference between TiZr and Ti alloys implants in terms of BIC. However, TiZr implants had higher RTQ than Ti alloys.

Wear and Corrosion Interactions at the Titanium/Zirconia Interface: Dental Implant Application

PURPOSE

Dental implants have been shown to have predictable success, but esthetic complications often arise. To reduce tissue shadowing from titanium, zirconia abutments may be used; however, the literature suggests that the use of zirconia leads to greater destruction of the implant interface that may result in biological complications such as titanium tattoos and heavy metal toxicity. Previous studies have examined the mechanical aspects of this implant/abutment relationship, but they have not accounted for the corrosive degradation that also takes place in the dynamic environment of the oral cavity. This study investigated the combined effect of both wear and corrosion on the materials at the implant and abutment interface.

MATERIALS AND METHODS

Using a simulated oral tribocorrosive environment, titanium (Ti) and zirconia (Zr) abutment materials were slid against titanium and Roxolid implant alloys. The four couplings (Ti/Ti, Ti/Rox, Zr/Ti, Zr/Rox) were selected for the tribocorrosion tests (N = 3). The testing was conducted for 25K cycles, and the coefficient of friction (CoF) and voltage evolution were recorded simultaneously. Following the tribocorrosion assays, the wear volume loss was calculated, and surface characterization was performed. Statistical analysis was completed using a one-way ANOVA followed by post-hoc Bonferroni comparisons.

RESULTS

Zr/Ti groups had the highest CoF (1.1647), and Ti/Ti had the lowest (0.5033). The Zr/Ti coupling generated significantly more mechanical damage than the Ti/Ti group (p = 0.021). From the corrosion aspect, the Ti/Ti groups had the highest voltage drop (0.802 V), indicating greater corrosion susceptibility. In comparison, the Zr/Roxolid group had the lowest voltage drop (0.628 V) and significantly less electrochemical degradation (p = 0.019). Overall, the Ti/Ti group had the largest wear volume loss (15.1 × 10⁷ μm³ ), while the Zr/Ti group had the least volume loss (2.26 × 10⁷ μm³ ). Both zirconia couplings had significantly less wear volume than the titanium couplings (p < 0.001).

CONCLUSIONS

This study highlights the synergistic interaction between wear and corrosion, which occurs when masticatory forces combine with the salivary environment of the oral cavity. Overall, the zirconia groups outperformed the titanium groups. In fact, the titanium groups generated 5 to 6 times more wear to the implant alloys as compared with the zirconia counterparts. The best performing group was Zr/Ti, and the worst performing group was Ti/Ti.

Development of binary and ternary titanium alloys for dental implants

OBJECTIVE

The aim of this study was to develop binary and ternary titanium (Ti) alloys containing zirconium (Zr) and niobium (Nb) and to characterize them in terms of microstructural, mechanical, chemical, electrochemical, and biological properties.

METHODS

The experimental alloys - (in wt%) Ti-5Zr, Ti-10Zr, Ti-35Nb-5Zr, and Ti-35Nb-10Zr - were fabricated from pure metals. Commercially pure titanium (cpTi) and Ti-6Al-4V were used as controls. Microstructural analysis was performed by means of X-ray diffraction and scanning electron microscopy. Vickers microhardness, elastic modulus, dispersive energy spectroscopy, X-ray excited photoelectron spectroscopy, atomic force microscopy, surface roughness, and surface free energy were evaluated. The electrochemical behavior analysis was conducted in a body fluid solution (pH 7.4). The albumin adsorption was measured by the bicinchoninic acid method. Data were evaluated through one-way ANOVA and the Tukey test (α=0.05).

RESULTS

The alloying elements proved to modify the alloy microstructure and to enhance the mechanical properties, improving the hardness and decreasing the elastic modulus of the binary and ternary alloys, respectively. Ti-Zr alloys displayed greater electrochemical stability relative to that of controls, presenting higher polarization resistance and lower capacitance. The experimental alloys were not detrimental to albumin adsorption.

SIGNIFICANCE

The experimental alloys are suitable options for dental implant manufacturing, particularly the binary system, which showed a better combination of mechanical and electrochemical properties without the presence of toxic elements.

A review of biocompatible metal injection moulding process parameters for biomedical applications

Biocompatible metals have been revolutionizing the biomedical field, predominantly in human implant applications, where these metals widely used as a substitute to or as function restoration of degenerated tissues or organs. Powder metallurgy techniques, in specific the metal injection moulding (MIM) process, have been employed for the fabrication of controlled porous structures used for dental and orthopaedic surgical implants. The porous metal implant allows bony tissue ingrowth on the implant surface, thereby enhancing fixation and recovery. This paper elaborates a systematic classification of various biocompatible metals from the aspect of MIM process as used in medical industries. In this study, three biocompatible metals are reviewed-stainless steels, cobalt alloys, and titanium alloys. The applications of MIM technology in biomedicine focusing primarily on the MIM process setting parameters discussed thoroughly. This paper should be of value to investigators who are interested in state of the art of metal powder metallurgy, particularly the MIM technology for biocompatible metal implant design and development.

New Ti-Alloys and Surface Modifications to Improve the Mechanical Properties and the Biological Response to Orthopedic and Dental Implants: A Review

Titanium implants are widely used in the orthopedic and dentistry fields for many decades, for joint arthroplasties, spinal and maxillofacial reconstructions, and dental prostheses. However, despite the quite satisfactory survival rates failures still exist. New Ti-alloys and surface treatments have been developed, in an attempt to overcome those failures. This review provides information about new Ti-alloys that provide better mechanical properties to the implants, such as superelasticity, mechanical strength, and corrosion resistance. Furthermore, in vitro and in vivo studies, which investigate the biocompatibility and cytotoxicity of these new biomaterials, are introduced. In addition, data regarding the bioactivity of new surface treatments and surface topographies on Ti-implants is provided. The aim of this paper is to discuss the current trends, advantages, and disadvantages of new titanium-based biomaterials, fabricated to enhance the quality of life of many patients around the world.

Characterization, corrosion behavior, cellular response and in vivo bone tissue compatibility of titanium-niobium alloy with low Young's modulus

β-Type titanium alloys with a low elastic modulus are a potential strategy to enhance bone remodeling and to mitigate the concern over the risks of osteanabrosis and bone resorption caused by stress shielding, when used to substitute irreversibly impaired hard tissue. Hence, in this study, a Ti-45Nb alloy with low Young's modulus and high strength was developed, and microstructure, mechanical properties, corrosion behaviors, cytocompatibility and in vivo osteo-compatibility of the alloy were systematically investigated for the first time. The results of mechanical tests showed that Young's modulus of the Ti-Nb alloy was reduced to about 64.3GPa (close to human cortical bone) accompanied with higher tensile strength and hardness compared with those of pure Ti. Importantly, the Ti-Nb alloy exhibited superior corrosion resistance to Ti in different solutions including SBF, MAS and FAAS (MAS containing NaF) media. In addition, the Ti-Nb alloy produced no deleterious effect to L929 and MG-63 cells, and cells performed excellent cell attachment onto Ti-Nb surface, indicating a good in vitro cytocompatibility. In vivo evaluations indicated that Ti-Nb had comparable bone tissue compatibility to Ti determined from micro-CT and histological evaluations. The Ti-Nb alloy with an elasticity close to human bone, thus, could be suitable for orthopedic/dental applications.

The effect of C content on the mechanical properties of Ti-Zr coatings

In this study, Ti-Zr and Ti-Zr-C coatings were deposited at room temperature via pulsed-DC magnetron sputtering. A 70Ti-30Zr at% target and a 99.99% graphite plate were used to deposit samples. In order to modify C content, coatings were deposited at different target powers such as 50, 75 and 100 W. Changes on the structure, microstructure and mechanical properties due to C addition were studied. Results indicate that the as-deposited coatings were partly crystalline and that an increment on C content stabilized α' phase and inhibited the appearance of ω precipitates. Therefore, Ti-Zr-C alloys with C>1.9 at% showed only α' phase whereas the others alloys exhibited α'+ω structures. Hardness values from 12.94 to 34.31 GPa were obtained, whereas the elastic modulus was found between 181.84 and 298 GPa. Finally, a high elastic recovery ratio (0.69-0.87) was observed as a function of composition. The overall properties of these coatings were improved due to C content increment, martensitic α' phase and nanocrystalline grain size (10-16 nm).

Superelasticity, corrosion resistance and biocompatibility of the Ti-19Zr-10Nb-1Fe alloy

Microstructure, mechanical properties, superelasticity and biocompatibility of a Ti-19Zr-10Nb-1Fe alloy are investigated. X-ray diffraction spectroscopy and transmission electron microscopy observations show that the as-cast Ti-19Zr-10Nb-1Fe alloy is composed of α' and β phases, but only the β phase exists in the as-rolled and as-quenched alloys. The tensile stress-strain tests indicate that the as-quenched alloy exhibits a good combination of mechanical properties with a large elongation of 25%, a low Young's modulus of 59 GPa and a high ultimate tensile stress of 723 MPa. Superelastic recovery behavior is found in the as-quenched alloy during tensile tests, and the corresponding maximum of superelastic strain is 4.7% at the pre-strain of 6%. A superelastic recovery of 4% with high stability is achieved after 10 cyclic loading-unloading training processes. Potentiodynamic polarization and ion release measurements indicate that the as-quenched alloy shows a lower corrosion rate in Hank's solution and a much less ion release rate in 0.9% NaCl solution than those of the NiTi alloys. Cell culture results indicate that the osteoblasts' adhesion and proliferation are similar on both the Ti-19Zr-10Nb-1Fe and NiTi alloys. A better hemocompatibility is confirmed for the as-quenched Ti-19Zr-10Nb-1Fe alloy, attributed to more stable platelet adhesion and small activation degree, and a much lower hemolysis rate compared with the NiTi alloy.

The Influence of Small Quantities of Oxygen in the Structure, Microstructure, Hardness, Elasticity Modulus and Cytocompatibility of Ti-Zr Alloys for Dental Applications

The mechanical properties of Ti alloys are changed significantly with the addition of interstitial elements, such as oxygen. Because oxygen is a strong stabilizer of the α phase and has an effect on hardening in a solid solution, it has aroused great interest in the biomedical area. In this paper, Ti-Zr alloys were subjected to a doping process with small amounts of oxygen. The influence of interstitial oxygen in the structure, microstructure and some selected mechanical properties of interest for use as biomaterial and biocompatibility of the alloys were analyzed. The results showed that in the range of 0.02 wt% to 0.04 wt%, oxygen has no influence on the structure, microstructure or biocompatibility of the studied alloys, but causes hardening of the alloys, increasing the values of the microhardness and causing variation in the elasticity modulus values.

Influence of Oxygen Content and Microstructure on the Mechanical Properties and Biocompatibility of Ti-15 wt%Mo Alloy Used for Biomedical Applications

The Ti-15Mo alloy has its mechanical properties strongly altered by heat treatments and by addition of interstitial elements, such as, oxygen, for example. In this sense, the objective of this paper is to analyze the effect of the introduction of oxygen in selected mechanical properties and the biocompatibility of Ti-15Mo alloy. The samples used in this study were prepared by arc-melting and characterized by density measurements, X-ray diffraction, scanning electron microscopy, microhardness, modulus of elasticity, and biocompatibility tests. Hardness measurements were shown to be sensitive to concentration of oxygen. The modulus results showed interstitial influence in value; this was verified under several conditions to which the samples were exposed. Cytotoxicity tests conducted in vitro showed that the various processing conditions did not alter the biocompatibility of the material.