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Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering

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A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 January 2018) | Viewed by 46266

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Special Issue Editor

Dr. Bobby Kannan Mathan

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Guest Editor

Biomaterials and Engineering Materials (BEM) Laboratory, College of Science, Technology and Engineering, James Cook University, Townsville, QLD 4811, Australia
Interests: electrochemical engineering; biomaterials; corrosion; wastewater treatment

Special Issue Information

Dear Colleagues,

In today’s society, the use of metallic implants to assist in the repair or replacement of damaged tissue and bone structure has become very common. There are a wide range of specifically designed devices that are intended to be implanted within the body to assist in healing process. Generally, it is a prerequisite for the implant materials to have high biocompatibility. In addition, it is desirable to have load bearing capacity in order to support the weight of the body during service. These implants can be broadly classified into two categories, i.e., permanent implants and temporary implants. Titanium alloys, cobalt-chrome alloys and stainless steels are the commonly used materials for permanent implants in applications such as hip and long-bone replacements. These materials are designed to have high degradation resistance and good mechanical properties. However, long-term exposure of these metallic materials causes degradation and eventually failure of implants. A significant amount of work has been done to improve the degradation resistance of these materials. Minor factures generally require mini-implants in the form of screws, pins and small plates for bone repair. These implants are only required for a short-period of time, hence, they are termed temporary implants. Use of permanent implant materials for this purpose would require an addition surgery to remove the implants after the healing process. Metallic magnesium is an attractive material for this purpose since it is biocompatible and biodegradable. However, the high degradation rate of magnesium is a major issue. Hence, the research focus has been towards improving the degradation performance of metallic magnesium.

For this Special Issue on “Advances in Enhancing Degradation Resistance of Metallic Implant by Surface Engineering”, we are interested in original and review articles on advanced methods, e.g., surface treatments, ceramic and polymer coatings, and ion implantation, for improving the degradation resistance of metallic biomaterials such as titanium-based alloys, stainless steels, cobalt-chromium, and magnesium alloys.

Prof. Dr. M. Bobby Kannan
Guest Editor

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

Biomaterials
Biodegradation
Corrosion
Coatings
Surface Engineering
Calcium Phosphates
Anodisation
Plasma Electrolytic Oxidation
Polymer Coating

Published Papers (10 papers)

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Research

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11 pages, 2689 KiB

Open AccessArticle

TiO₂ Nanotubes on Ti Dental Implant. Part 3: Electrochemical Behavior in Hank’s Solution of Titania Nanotubes Formed in Ethylene Glycol

by Annalisa Acquesta, Anna Carangelo and Tullio Monetta

Metals 2018, 8(7), 489; https://doi.org/10.3390/met8070489 - 27 Jun 2018

Cited by 14 | Viewed by 2686

Abstract

Anodic oxidation is an easy and cheap surface treatment to form nanostructures on the surface of titanium items for improving the interaction between metallic implants and the biological environment. The long-term success of the devices is related to their stability. In this work, titanium nanotubes were formed on a dental screw, made of titanium CP2, through an anodization process using an “organic” solution based on ethylene glycol containing ammonium fluoride and water. Then, the electrochemical stability in the Hank’s solution of these “organic” nanotubes has been investigated for 15 days and compared to that of titanium nanotubes on a similar type of sample grown in an inorganic solution, containing phosphoric and hydrofluoridric acids. Morphological and crystallographic analysis were performed by using scanning electron microscopy (SEM) and X-Ray diffractometry (XRD) tests. Electrochemical measurements were carried out to study the stability of the nanotubes when are in contact with the biological environment. The morphological measurements revealed long nanotubes, small diameters, smooth side walls, and a high density of “organic” nanotubes if compared to the “inorganic” ones. XRD analysis demonstrated the presence of rutile form. An appreciable electrochemical stability has been revealed by Electrochemical Impedance Spectroscopy (EIS) analysis, suggesting that the “organic” nanotubes are more suitable for biomedical devices. Full article

(This article belongs to the Special Issue Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering)

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17 pages, 12911 KiB

Open AccessArticle

Finite Element Analysis of Surface Integrity in Deep Ball-Burnishing of a Biodegradable AZ31B Mg Alloy

by Mohammad Sharif Uddin, Colin Hall, Ryan Hooper, Eric Charrault, Peter Murphy and Vincent Santos

Metals 2018, 8(2), 136; https://doi.org/10.3390/met8020136 - 16 Feb 2018

Cited by 24 | Viewed by 4399

Abstract

As an effective and affordable technique, deep ball-burnishing has been applied to induce the plastic deformation of material, thus resulting in an increased surface hardness, compressive residual stress, and finish quality. Recent research shows that the fast degradation of an Mg alloy implant is a prime limiting factor for its success in in vivo human trials. This paper presents a comprehensive investigation into deep ball-burnishing of a biodegradable AZ31B Mg alloy, in order to improve the alloy’s surface integrity. A series of experiments using an in-house built burnishing tool with a 10-mm steel ball have been conducted, with a key focus of exploring the influence of the major process parameters—e.g., burnishing force (750–2650 N), feed rate (150–500 mm/min), and step-over (0.05–0.15 mm)—on hardness and finish quality. With the aim of performing a parametric sensitivity study, a three-dimensional (3D) finite element (FE) model is developed to predict the deformation mechanics, plastic flow, hardness, and residual stress. The FE model agrees with the experiment, hence validating the reliability of the model. Results show that while burnishing significantly improves surface integrity compared to the untreated surface, burnishing force and step-over are shown to be dominant. The net material movement dictates generated residual stress (tensile or compressive), often negatively affecting the surface integrity (e.g., surface cracks), which may be responsible for the onset of corrosion. An appropriate burnishing strategy must therefore be planned, in order to achieve the intended process outcome. The resulting surface properties, enhanced by the deep ball-burnishing, are expected to potentially increase the corrosion resistance of AZ31B Mg alloy implants. Full article

(This article belongs to the Special Issue Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering)

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13 pages, 2540 KiB

Open AccessArticle

Influence of Heat Treatment and UV Irradiation on the Wettability of Ti35Nb10Ta Nanotubes

by Joan Lario, Vicent Fombuena, Ángel Vicente and Vicente Amigó

Metals 2018, 8(1), 37; https://doi.org/10.3390/met8010037 - 07 Jan 2018

Cited by 2 | Viewed by 3994

Abstract

The implant osseointegration rate depends on the surface’s topography and chemical composition. There is a growing interest in the anodic oxidation process to obtain an oxide layer with a nanotube morphology on beta titanium alloys. This surface treatment presents large surface area, nanoscale rugosity and electrochemical properties that may increase the biocompatibility and osseointegration rate in titanium implants. In this work, an anodic oxidation process was used to modify the surface on the Ti35Nb10Ta alloy to obtain a titanium nanotubes topography. The work focused on analyzing the influence of some variables (voltage, heat treatment and ultraviolet irradiation) on the wettability performance of a titanium alloy. The morphology of the nanotubes surfaces was studied by Field Emission Scanning Electron Microscopy (FESEM), and surface composition was analyzed by Energy Dispersive Spectroscopy (EDS). The measurement of contact angle for the TiO₂ nanotube surfaces was measured by a video contact angle system. The surface with the non photoinduced nanotubes presented the largest contact angles. The post-heat treatment lowered the F/Ti ratio in the nanotubes and decreased the contact angle. Ultraviolet (UV) irradiation of the TiO₂ nanotubes decrease the water contact angle. Full article

(This article belongs to the Special Issue Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering)

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10 pages, 21277 KiB

Open AccessFeature PaperArticle

Ion Implantation of Calcium and Zinc in Magnesium for Biodegradable Implant Applications

by Sahadev Somasundaram, Mihail Ionescu and Bobby Kannan Mathan

Metals 2018, 8(1), 30; https://doi.org/10.3390/met8010030 - 03 Jan 2018

Cited by 14 | Viewed by 4547

Abstract

In this study, magnesium was implanted with calcium-ion and zinc-ion at fluences of 10¹⁵, 10¹⁶, and 10¹⁷ ion·cm⁻², and its in vitro degradation behaviour was evaluated using electrochemical techniques in simulated body fluid (SBF). Rutherford backscattering spectrometry (RBS) revealed that the implanted ions formed layers within the passive magnesium-oxide/hydroxide layers. Electrochemical impedance spectroscopy (EIS) results demonstrated that calcium-ion implantation at a fluence of 10¹⁵ ions·cm⁻² increased the polarisation resistance by 24%, but higher fluences showed no appreciable improvement. In the case of zinc-ion implantation, increase in the fluence decreased the polarisation resistance. A fluence of 10¹⁷ ion·cm⁻² decreased the polarisation resistance by 65%, and fluences of 10¹⁵ and 10¹⁶ showed only marginal effect. Similarly, potentiodynamic polarisation results also suggested that low fluence of calcium-ion decreased the degradation rate by 38% and high fluence of zinc-ion increased the degradation rate by 61%. All the post-polarized ion-implanted samples and the bare metal revealed phosphate and carbonate formation. However, the improved degradative behaviour in calcium-ion implanted samples can be due to a relatively better passivation, whereas the reduction in degradation resistance in zinc-ion implanted samples can be attributed to the micro-galvanic effect. Full article

(This article belongs to the Special Issue Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering)

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3551 KiB

Open AccessArticle

TiO₂ Nanotubes on Ti Dental Implant. Part 2: EIS Characterization in Hank’s Solution

by Tullio Monetta, Annalisa Acquesta, Anna Carangelo and Francesco Bellucci

Metals 2017, 7(6), 220; https://doi.org/10.3390/met7060220 - 14 Jun 2017

Cited by 19 | Viewed by 5198

Abstract

Titania nanotubes are widely studied for their potential applications in several fields. In this paper, the electrochemical characterization of a dental implant, made of commercially pure titanium grade 2, covered by titania nanotubes, when immersed in Hank’s solution, is proposed. Few papers were found in the scientific literature regarding this topic, so a brief review is reported, concerning the use of some equivalent circuits to model experimental data. The analysis of results, obtained by using Electrochemical Impedance Spectroscopy, showed that: (i) a good correlation exists between the variation of E_corr and the estimated values of the charge transfer resistance for both the bare- and the nanotube-covered samples, (ii) the nanostructured surface seems to possess a more active behaviour, while the effect could be over-estimated due to the real extent of the surface covered by nanotubes, (iii) the analysis of the “n” parameter, used to fit the experimental data, confirms the complex nature of nanostructured layer as well as that the nanotubes are partially filled by compounds containing Ca, P and Mg, when immersed in Hank’s solution. The results obtained in this work give a better understanding of the electrochemical behaviour of the nanotubes layer when immersed in Hank’s solution and could help to design a surface able to improve the implant osseointegration. Full article

(This article belongs to the Special Issue Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering)

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6326 KiB

Open AccessArticle

Preparation and Characterization of Aminated Hydroxyethyl Cellulose-Induced Biomimetic Hydroxyapatite Coatings on the AZ31 Magnesium Alloy

by Bowu Zhu, Yimeng Xu, Jing Sun, Lei Yang, Changgang Guo, Jun Liang and Baocheng Cao

Metals 2017, 7(6), 214; https://doi.org/10.3390/met7060214 - 08 Jun 2017

Cited by 19 | Viewed by 5576

Abstract

The purpose of this work is to improve the cytocompatibility and corrosion resistance of magnesium alloy in the hope of preparing a biodegradable medical material. The aminated hydroxyethyl cellulose-induced biomimetic hydroxyapatite coating was successfully prepared on AZ31 magnesium alloy surface with a sol-gel spin coating method and biomimetic mineralization. Potentiodynamic polarization tests and electrochemical impedance spectroscopy showed that the hydroxyapatite/aminated hydroxyethyl cellulose (HA/AHEC) coating can greatly improve the corrosion resistance of AZ31 magnesium alloy and reduce the degradation speed in simulated body fluid (SBF). The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium bromide] method and cell morphology observation results showed that the HA/AHEC coating on AZ31 magnesium alloy has excellent cytocompatibility and biological activity. Full article

(This article belongs to the Special Issue Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering)

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9206 KiB

Open AccessArticle

Investigation of the Effectiveness of Dental Implant Osseointegration Characterized by Different Surface Types

by Natalia Astashina, Alex Lugovskoy, Aleksey Kossenko, Svetlana Lugovskoy, Gennadi Rogozhnikov and Michael Zinigrad

Metals 2017, 7(6), 203; https://doi.org/10.3390/met7060203 - 02 Jun 2017

Cited by 4 | Viewed by 3939

Abstract

Different surfaces were obtained by Plasma Electrolytic Oxidation (PEO) of the Ti–6Al–4V alloy; followed by hydrothermal treatment (HT). The surfaces were studied by scanning electron microscopy (SEM); Energy Dispersive Spectroscopy (EDS); X-ray Diffraction (XRD); Brunauer–Emmett–Teller (BET) absorption and abrasion wear tests. The resulting surface contains hydroxyapatite (HA); which contributes to superior implant osseointegration. Treated implants were introduced into rabbits and their osseointegration was studied after two and six months. It was established that implant surface area increases due to pore formation. Pore formation and hydroxyapatite on the surface of the implant qualitatively change contact osseogenesis processes with reduced duration of osseointegration of implants. The treatment of the surface of the implants by the combination of PEO and HT provided better results in the medico-biological investigations than PEO alone. Abrasion tests demonstrated that the HA will be preserved after the procedure of implantation; ensuring effective osseointegration. Full article

(This article belongs to the Special Issue Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering)

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2235 KiB

Open AccessArticle

TiO₂ Nanotubes on Ti Dental Implant. Part 1: Formation and Aging in Hank’s Solution

by Tullio Monetta, Annalisa Acquesta, Anna Carangelo and Francesco Bellucci

Metals 2017, 7(5), 167; https://doi.org/10.3390/met7050167 - 11 May 2017

Cited by 19 | Viewed by 5867

Abstract

Self-organized TiO₂ nanotube layer has been formed on titanium screws with complex geometry, which are used as dental implants. TiO₂ nanotubes film was grown by potentiostatic anodizing in H₃PO₄ and HF aqueous solution. During anodizing, the titanium screws were mounted on a rotating apparatus to produce a uniform structure both on the peaks and on the valleys of the threads. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) and electrochemical characterization were used to evaluate the layer, chemical composition and electrochemical properties of the samples. Aging in Hank’s solution of both untreated and nanotubes covered screw, showed that: (i) samples are covered by an amorphous oxide layer, (ii) the nanotubes increases the corrosion resistance of the implant, and (iii) the presence of the nanotubes catalyses the formation of chemical compounds containing Ca and P. Full article

(This article belongs to the Special Issue Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering)

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1570 KiB

Open AccessArticle

Primary Stability of Temporary Screws after Dentary and Orthopedic Forces under Static and Dynamic Load Cycles

by Daniel J. Fernandes, Flavia A. Barbosa, Ligia M. Ferreira and Carlos N. Elias

Metals 2017, 7(3), 80; https://doi.org/10.3390/met7030080 - 03 Mar 2017

Viewed by 3808

Abstract

The objective was to analyze the influence of dentary and orthopedic forces under static and dynamic loads in temporary screw stability. Self-drilling titanium (Ti6Al4V) screws (6 × 1.5 mm) were inserted and removed from pig ribs. Screws were loaded by static loads of 2 N and 5 N for 5 weeks. Dynamic force was applied during 56,000 cycles for simulations of a patient’s opening–closing mouth movements. Dynamic applied loads ranged from 2 to 5 N and from 5 to 7 N under a frequency of 1 Hz. Torque peak values at placement and removal were measured before and after static and dynamic cycles. Similarities in torque peaks (p = 0.3139) were identified at placement (12.54 Ncm) and removal (11.2 Ncm) of screws after a static load of 2 N. Statistical comparisons showed significant stability loss after dynamic cycles under loads of 2 N (64.82% at p = 0.0005) and 5 N (64.63% at p = 0.0026). Limited stability loss occurred in temporary screws submitted to 2 N static forces (p = 0.3139). The detrimental effects of dynamic cycles in temporary screws stability was attested after the simulation of dentary and skeletal forces, being intermittent forces more relevant in the loss of mechanical stability. Full article

(This article belongs to the Special Issue Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering)

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Other

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2934 KiB

Open AccessOpinion

Osseoconductive and Corrosion-Inhibiting Plasma-Sprayed Calcium Phosphate Coatings for Metallic Medical Implants

by Robert B. Heimann

Metals 2017, 7(11), 468; https://doi.org/10.3390/met7110468 - 01 Nov 2017

Cited by 27 | Viewed by 5521

Abstract

During the last several decades, research into bioceramic coatings for medical implants has emerged as a hot topic among materials scientists and clinical practitioners alike. In particular, today, calcium phosphate-based bioceramic materials are ubiquitously used in clinical applications to coat the stems of metallic endoprosthetic hips as well as the surfaces of dental root implants. Such implants frequently consist of titanium alloys, CoCrMo alloy, or austenitic surgical stainless steels, and aim at replacing lost body parts or restoring functions to diseased or damaged tissues of the human body. In addition, besides such inherently corrosion-resistant metals, increasingly, biodegradable metals such as magnesium alloys are being researched for osseosynthetic devices and coronary stents both of which are intended to remain in the human body for only a short time. Biocompatible coatings provide not only vital biological functions by supporting osseoconductivity but may serve also to protect the metallic parts of implants from corrosion in the aggressive metabolic environment. Moreover, the essential properties of hydroxylapatite-based bioceramic coatings including their in vitro alteration in contact with simulated body fluids will be addressed in this current review paper. In addition, a paradigmatic shift is suggested towards the development of transition metal-substituted calcium hexa-orthophosphates with the NaSiCON (Na superionic conductor) structure to be used for implant coatings with superior degradation resistance in the corrosive body environment and with pronounced ionic conductivity that might be utilized in novel devices for electrical bone growth stimulation. Full article

(This article belongs to the Special Issue Advances in Enhancing Degradation Resistance of Metallic Implants by Surface Engineering)

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