Submit to Metals Review for Metals Propose a Special Issue

Journal Browser

Titanium Alloys for Biomedical Implants and Devices

Print Special Issue Flyer
Special Issue Editors
Special Issue Information
Keywords
Published Papers

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Biobased and Biodegradable Metals".

Deadline for manuscript submissions: closed (30 June 2019) | Viewed by 46281

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special issue Titanium Alloys for Biomedical Implants and Devices book cover image

Share This Special Issue

Special Issue Editors

Dr. Hooyar Attar

E-Mail Website
Guest Editor

Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), The University of Queensland, St. Lucia 4072, Australia
Interests: metal matrix composites; additive manufacturing; tribology; powder metallurgy
Special Issues, Collections and Topics in MDPI journals

Dr. Damon Kent

E-Mail Website
Guest Editor

1. School of Science, Technology and Engineering, University of the Sunshine Coast, Maroochydore DC, QLD 4558, Australia
2. Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), University of Queensland, Brisbane, QLD 4072, Australia
Interests: light metals; powder metallurgy; additive manufacturing; phase transformations; composites
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

A range of materials may be used in the human body including metals, ceramics, and polymers. Among them, titanium alloys have received significant interest leading to widespread successful adoption in the biomedical field due to their unique combination of outstanding properties. Over the past decades, a large amount of research has focused on various aspects of titanium alloys leading to the design, production, and commercialization of a series of alloys specifically tailored to biomedical applications. Despite the outstanding properties afforded by current titanium alloys, there is a need to continue to enhance their performance through developing further understanding of important aspects of their processing and structure. This is necessary to enhance performance and reliability of titanium implants and devices and, consequently, improve patient health outcomes and reduce the need for painful and costly revisionary surgery. This Special Issue seeks to collect expert views and article contributions on various aspects of a wide range of titanium alloys to highlight challenges and recent advances relevant to the biomedical area. This issue is dedicated to all aspects of titanium biomedical alloys which include, but are not limited to:

New alloy design
Chemical, physical, and toxicological properties
Microstructures, phase analysis, and mechanical properties
Mechanical behavior, damage, and failure
Simulation and modeling techniques
Corrosion and tribology properties
Net shape and additive manufacturing
Surface functionalization and modification
Biological tests
Porous and complex hierarchical structures

This Special Issue looks forward to receiving submissions in any form, including review articles, regular research articles, and short communications. Both experimental and theoretical studies are of interest.

Kind regards,

Dr. Hooyar Attar
Dr. Damon Kent
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Titanium alloys
Microstructures
Mechanical characterization
Modeling
Additive manufacturing
Surface treatment
Corrosion
Tribology
Biology

Published Papers (10 papers)

Download All Papers

Research

Jump to: Review

14 pages, 7386 KiB

Open AccessArticle

Fatigue Behavior of Non-Optimized Laser-Cut Medical Grade Ti-6Al-4V-ELI Sheets and the Effects of Mechanical Post-Processing

by André Reck, André Till Zeuner and Martina Zimmermann

Metals 2019, 9(8), 843; https://doi.org/10.3390/met9080843 - 30 Jul 2019

Cited by 9 | Viewed by 3505

Abstract

The study presented investigates the fatigue strength of the (α+β) Ti-6Al-4V-ELI titanium alloy processed by laser cutting with and without mechanical post-processing. The surface quality and possible notch effects as a consequence of non-optimized intermediate cutting parameters are characterized and evaluated. The microstructural changes in the heat-affected zone (HAZ) are documented in detail and compared to samples with a mechanically post-processed (barrel grinding, mechanical polishing) surface condition. The obtained results show a significant increase (≈50%) in fatigue strength due to mechanical post-processing correlating with decreased surface roughness and minimized notch effects when compared to the surface quality of the non-optimized laser cutting. The martensitic α’-phase is detected in the HAZ with the formation of distinctive zones compared to the initial equiaxial α+β microstructure. The HAZ could be removed up to 50% by means of barrel grinding and up to 100% through mechanical polishing. A fracture analysis revealed that the fatigue cracks always initiate on the laser-cut edges in the as-cut surface condition, which could be assigned to an irregular macro and micro-notch relief. However, the typical characteristics of the non-optimized laser cutting process (melting drops and significant higher surface roughness) lead to early fatigue failure. The fatigue cracks solely started from the micro-notches of the surface relief and not from the dross. As a consequence, the fatigue properties are dominated by these notches, which lead to significant scatter, as well as decreased fatigue strength compared to the surface conditions with mechanical finishing and better surface quality. With optimized laser-cutting conditions, HAZ will be minimized, and surface roughness strongly decreased, which will lead to significantly improved fatigue strength. Full article

(This article belongs to the Special Issue Titanium Alloys for Biomedical Implants and Devices)

► Show Figures

Graphical abstract

20 pages, 7948 KiB

Open AccessArticle

Digital Design, Analysis and 3D Printing of Prosthesis Scaffolds for Mandibular Reconstruction

by Khaja Moiduddin, Syed Hammad Mian, Hisham Alkhalefah and Usama Umer

Metals 2019, 9(5), 569; https://doi.org/10.3390/met9050569 - 16 May 2019

Cited by 17 | Viewed by 4756

Abstract

Segmental mandibular reconstruction has been a challenge for medical practitioners, despite significant advances in medical technology. There is a recent trend in relation to customized implants, made up of porous structures. These lightweight prosthesis scaffolds present a new direction in the evolution of mandibular restoration. Indeed, the design and properties of porous implants for mandibular reconstruction should be able to recover the anatomy and contour of the missing region as well as restore the functions, including mastication, swallowing, etc. In this work, two different designs for customized prosthesis scaffold have been assessed for mandibular continuity. These designs have been evaluated for functional and aesthetic aspects along with effective osseointegration. The two designs classified as top and bottom porous plate and inner porous plate were designed and realized through the integration of imaging technology (computer tomography), processing software and additive manufacturing (Electron Beam Melting). In addition, the proposed designs for prosthesis scaffolds were analyzed for their biomechanical properties, structural integrity, fitting accuracy and heaviness. The simulation of biomechanical activity revealed that the scaffold with top and bottom porous plate design inherited lower Von Mises stress (214.77 MPa) as compared to scaffold design with inner porous plate design (360.22 MPa). Moreover, the top and bottom porous plate design resulted in a better fit with an average deviation of 0.8274 mm and its structure was more efficiently interconnected through the network of channels without any cracks or powder material. Verily, this study has demonstrated the feasibility and effectiveness of the customized porous titanium implants in mandibular reconstruction. Notice that the design and formation of the porous implant play a crucial role in restoring the desired mandibular performance. Full article

(This article belongs to the Special Issue Titanium Alloys for Biomedical Implants and Devices)

► Show Figures

Figure 1

16 pages, 4605 KiB

Open AccessArticle

Corrosion Study of Implanted TiN Electrodes Using Excessive Electrical Stimulation in Minipigs

by Suzan Meijs, Kristian Rechendorff, Søren Sørensen and Nico J.M. Rijkhoff

Metals 2019, 9(4), 389; https://doi.org/10.3390/met9040389 - 28 Mar 2019

Cited by 1 | Viewed by 3035

Abstract

(1) Background: Titanium nitride (TiN) electrodes have been used for implantable stimulation and sensing electrodes for decades. Nevertheless, there still is a discrepancy between the in vitro and in vivo determined safe charge injection limits. This study investigated the consequences of pulsing implanted electrodes beyond the in vivo safe charge injection limits. (2) Methods: The electrodes were implanted for a month and then pulsed at 20 mA and 50 mA and 200 Hz and 400 Hz. Afterwards, the electrodes were investigated using electrochemical and analytical methods to evaluate whether electrode degradation had occurred. (3) Results: Electrochemical tests showed that electrodes that pulsed at 20 mA and 200 Hz (lowest electrical dose) had a significantly lower charge injection capacity and higher impedance than the other used and unused electrodes. (4) Conclusions: The electrodes pulsed at the lowest electrical dose, for which no tissue damage was found, appeared to have degraded. Electrodes pulsed at higher electrical doses for which tissue damage did occur, on the other hand, show no significant degradation in electrochemical tests compared to unused implanted and not implanted electrodes. It is thus clear that the tissue surrounding the electrode has an influence on the charge injection properties of the electrodes and vice versa. Full article

(This article belongs to the Special Issue Titanium Alloys for Biomedical Implants and Devices)

► Show Figures

Figure 1

13 pages, 3057 KiB

Open AccessFeature PaperArticle

Diffraction Line Profile Analysis of 3D Wedge Samples of Ti-6Al-4V Fabricated Using Four Different Additive Manufacturing Processes

by Ryan Cottam, Suresh Palanisamy, Maxim Avdeev, Tom Jarvis, Chad Henry, Dominic Cuiuri, Levente Balogh and Rizwan Abdul Rahman Rashid

Metals 2019, 9(1), 60; https://doi.org/10.3390/met9010060 - 09 Jan 2019

Cited by 23 | Viewed by 3755

Abstract

Wedge-shaped samples were manufactured by four different Additive Manufacturing (AM) processes, namely selective laser melting (SLM), electron beam melting (EBM), direct metal deposition (DMD), and wire and arc additive manufacturing (WAAM), using Ti-6Al-4V as the feed material. A high-resolution powder diffractometer was used to measure the diffraction patterns of the samples whilst rotated about two axes to collect detected neutrons from all possible lattice planes. The diffraction pattern of a LaB₆ standard powder sample was also measured to characterize the instrumental broadening and peak shapes necessary for the Diffraction Line Profile Analysis. The line profile analysis was conducted using the extended Convolution Multiple Whole Profile (eCMWP) procedure. Once analyzed, it was found that there was significant variation in the dislocation densities between the SLMed and the EBMed samples, although having a similar manufacturing technique. While the samples fabricated via WAAM and the DMD processes showed almost similar dislocation densities, they were, however, different in comparison to the other two AM processes, as expected. The hexagonal (HCP) crystal structure of the predominant α-Ti phase allowed a breakdown of the percentage of the Burgers’ vectors possible for this crystal structure. All four techniques exhibited different combinations of the three possible Burgers’ vectors, and these differences were attributed to the variation in the cooling rates experienced by the parts fabricated using these AM processes. Full article

(This article belongs to the Special Issue Titanium Alloys for Biomedical Implants and Devices)

► Show Figures

Figure 1

21 pages, 5666 KiB

Open AccessArticle

Experimental Characterization of the Primary Stability of Acetabular Press-Fit Cups with Open-Porous Load-Bearing Structures on the Surface Layer

by Volker Weißmann, Christian Boss, Christian Schulze, Harald Hansmann and Rainer Bader

Metals 2018, 8(10), 839; https://doi.org/10.3390/met8100839 - 17 Oct 2018

Cited by 8 | Viewed by 3680

Abstract

Background: Nowadays, hip cups are being used in a wide range of design versions and in an increasing number of units. Their development is progressing steadily. In contrast to conventional methods of manufacturing acetabular cups, additive methods play an increasingly central role in the development progress. Method: A series of eight modified cups were developed on the basis of a standard press-fit cup with a pole flattening and in a reduced version. The surface structures consist of repetitive open-pore load-bearing textural elements aligned right-angled to the cup surface. We used three different types of unit cells (twisted, combined and combined open structures) for constructing of the surface structure. All cups were manufactured using selective laser melting (SLM) of titanium powder (Ti6Al4V). To evaluate the primary stability of the press fit cups in the artificial bone cavity, pull-out and lever-out tests were conducted. All tests were carried out under exact fit conditions. The closed-cell polyurethane (PU) foam, which was used as an artificial bone cavity, was characterized mechanically in order to preempt any potential impact on the test results. Results and conclusions: The pull-out forces as well as the lever moments of the examined cups differ significantly depending on the elementary cells used. The best results in pull-out forces and lever-out moments are shown by the press-fit cups with a combined structure. The results for the assessment of primary stability are related to the geometry used (unit cell), the dimensions of the unit cell, and the volume and porosity responsible for the press fit. Corresponding functional relationships could be identified. The findings show that the implementation of reduced cups in a press-fit design makes sense as part of the development work. Full article

(This article belongs to the Special Issue Titanium Alloys for Biomedical Implants and Devices)

► Show Figures

Figure 1

12 pages, 3331 KiB

Open AccessArticle

Insights into Machining of a β Titanium Biomedical Alloy from Chip Microstructures

by Damon Kent, Rizwan Rahman Rashid, Michael Bermingham, Hooyar Attar, Shoujin Sun and Matthew Dargusch

Metals 2018, 8(9), 710; https://doi.org/10.3390/met8090710 - 11 Sep 2018

Cited by 12 | Viewed by 3417

Abstract

New metastable β titanium alloys are receiving increasing attention due to their excellent biomechanical properties and machinability is critical to their uptake. In this study, machining chip microstructure has been investigated to gain an understanding of strain and temperature fields during cutting. For higher cutting speeds, ≥60 m/min, the chips have segmented morphologies characterised by a serrated appearance. High levels of strain in the primary shear zone promote formation of expanded shear band regions between segments which exhibit intensive refinement of the β phase down to grain sizes below 100 nm. The presence of both α and β phases across the expanded shear band suggests that temperatures during cutting are in the range of 400–600 °C. For the secondary shear zone, very large strains at the cutting interface result in heavily refined and approximately equiaxed nanocrystalline β grains with sizes around 20–50 nm, while further from the interface the β grains become highly elongated in the shear direction. An absence of the α phase in the region immediately adjacent to the cutting interface indicates recrystallization during cutting and temperatures in excess of the 720 °C β transus temperature. Full article

(This article belongs to the Special Issue Titanium Alloys for Biomedical Implants and Devices)

► Show Figures

Graphical abstract

30 pages, 26053 KiB

Open AccessArticle

Incremental Forming of Titanium Ti6Al4V Alloy for Cranioplasty Plates—Decision-Making Process and Technological Approaches

by Sever Gabriel Racz, Radu Eugen Breaz, Melania Tera, Claudia Gîrjob, Cristina Biriș, Anca Lucia Chicea and Octavian Bologa

Metals 2018, 8(8), 626; https://doi.org/10.3390/met8080626 - 09 Aug 2018

Cited by 22 | Viewed by 5412

Abstract

Ti6Al4V titanium alloy is considered a biocompatible material, suitable to be used for manufacturing medical devices, particularly cranioplasty plates. Several methods for processing titanium alloys are reported in the literature, each one presenting both advantages and drawbacks. A decision-making method based upon AHP (analytic hierarchy process) was used in this paper for choosing the most recommended manufacturing process among some alternatives. The result of AHP indicated that single-point incremental forming (SPIF) at room temperature could be considered the best approach when manufacturing medical devices. However, Ti6Al4V titanium alloy is known as a low-plasticity material when subjected to plastic deformation at room temperature, so special measures had to be taken. The experimental results of processing parts from Ti6Al4V titanium alloy by means of SPIF and technological aspects are considered. Full article

(This article belongs to the Special Issue Titanium Alloys for Biomedical Implants and Devices)

► Show Figures

Graphical abstract

15 pages, 6438 KiB

Open AccessArticle

Implant Treatment in Atrophic Maxilla by Titanium Hybrid-Plates: A Finite Element Study to Evaluate the Biomechanical Behavior of Plates

by María Prados-Privado, Henri Diederich and Juan Carlos Prados-Frutos

Metals 2018, 8(8), 573; https://doi.org/10.3390/met8080573 - 25 Jul 2018

Cited by 2 | Viewed by 4929

Abstract

A severely atrophied maxilla presents serious limitations for rehabilitation with osseointegrated implants. This study evaluated the biomechanical and long-term behavior of titanium hybrid-plates in atrophic maxilla rehabilitation with finite elements and probabilistic methodology. A three-dimensional finite element model based on a real clinical case was built to simulate an entirely edentulous maxilla with four plates. Each plate was deformed to become accustomed to the maxilla’s curvature. An axial force of 100 N was applied in the area where the prosthesis was adjusted in each plate. The von Mises stresses were obtained on the plates and principal stresses on maxilla. The difference in stress between the right and left HENGG-1 plates was 3%, while between the two HENGG-2 plates it was 2%, where HENGG means Highly Efficient No Graft Gear. A mean maximum value of 80 MPa in the plates’ region was obtained, which is a lower value than bone resorption stress. A probability cumulative function was computed. Mean fatigue life was 1,819,235 cycles. According to the results of this study, it was possible to conclude that this technique based on titanium hybrid-plates can be considered a viable alternative for atrophic maxilla rehabilitation, although more studies are necessary to corroborate the clinical results. Full article

(This article belongs to the Special Issue Titanium Alloys for Biomedical Implants and Devices)

► Show Figures

Figure 1

21 pages, 4273 KiB

Open AccessArticle

Mechanical Properties and In Vitro Behavior of Additively Manufactured and Functionally Graded Ti6Al4V Porous Scaffolds

by Ezgi Onal, Jessica E. Frith, Marten Jurg, Xinhua Wu and Andrey Molotnikov

Metals 2018, 8(4), 200; https://doi.org/10.3390/met8040200 - 21 Mar 2018

Cited by 107 | Viewed by 8644

Abstract

Functionally graded lattice structures produced by additive manufacturing are promising for bone tissue engineering. Spatial variations in their porosity are reported to vary the stiffness and make it comparable to cortical or trabecular bone. However, the interplay between the mechanical properties and biological response of functionally graded lattices is less clear. Here we show that by designing continuous gradient structures and studying their mechanical and biological properties simultaneously, orthopedic implant design can be improved and guidelines can be established. Our continuous gradient structures were generated by gradually changing the strut diameter of a body centered cubic (BCC) unit cell. This approach enables a smooth transition between unit cell layers and minimizes the effect of stress discontinuity within the scaffold. Scaffolds were fabricated using selective laser melting (SLM) and underwent mechanical and in vitro biological testing. Our results indicate that optimal gradient structures should possess small pores in their core (~900 µm) to increase their mechanical strength whilst large pores (~1100 µm) should be utilized in their outer surface to enhance cell penetration and proliferation. We suggest this approach could be widely used in the design of orthopedic implants to maximize both the mechanical and biological properties of the implant. Full article

(This article belongs to the Special Issue Titanium Alloys for Biomedical Implants and Devices)

► Show Figures

Graphical abstract

Review

Jump to: Research

16 pages, 2161 KiB

Open AccessReview

Evaluation of Fatigue Behavior in Dental Implants from In Vitro Clinical Tests: A Systematic Review

by Rosa Rojo, María Prados-Privado, Antonio José Reinoso and Juan Carlos Prados-Frutos

Metals 2018, 8(5), 313; https://doi.org/10.3390/met8050313 - 03 May 2018

Cited by 8 | Viewed by 3947

Abstract

In the area of dentistry, there is a wide variety of designs of dental implant and materials, especially titanium, which aims to avoid failures and increase their clinical durability. The purpose of this review was to evaluate fatigue behavior in different connections and implant materials, as well as their loading conditions and response to failure. In vitro tests under normal and dynamic loading conditions evaluating fatigue at implant and abutment connection were included. A search was conducted in PubMed, Scopus, and Science Direct. Data extraction was performed independently by two reviewers. The quality of selected studies was assessed using the Cochrane Handbook proposed by the tool for clinical trials. Nineteen studies were included. Fourteen studies had an unclear risk and five had high risk of bias. Due to the heterogeneity of the data and the evaluation of the quality of the studies, meta-analysis could not be performed. Evidence from this study suggests that both internal and morse taper connections presented a better behavior to failure. However, it is necessary to unify criteria in the methodological design of in vitro studies, following methodological guidelines and establishing conditions that allow the homogenization of designs in ISO (International Organization for Standardization) standards. Full article

(This article belongs to the Special Issue Titanium Alloys for Biomedical Implants and Devices)

► Show Figures