No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Formation and characterization of anodic titanium oxide films containing Ca and P
Abstract
Commercially pure titanium was anodized in an electrolytic solution that was dissolved calcium and phosphorus compounds in water, and an AOFCP (anodic titanium oxide film containing Ca and P) was formed. It was found that sodium beta-glycerophosphate (beta-GP) and calcium acetate (CA) were suitable for the electrolytes to form the AOFCP having an equivalent Ca/P ratio to hydroxyapatite (HA). The AOFCP was characterized by scanning electron microscopy (SEM), an energy-dispersive X-ray microanalysis (EDX), and X-ray diffraction (XRD). Numerous micropores and microprojections were observed on the AOFCP by SEM. The composition of the AOFCP, which was measured by EDX, changed according to beta-GP and CA concentration, and the electrolytic voltage. Ca and P in the AOFCP seem to be incorporated into the TiO2 matrix from CA and beta-GP in the electrolyte during the anodic oxidation. Despite the existence of Ca and P in the AOFCP, no calcium phosphate peak was detected by XRD, and the AOFCP consisted of anatase and only a little rutile. The AOFCP, whose contents of Ca and P were low, had a high adhesive strength after soaking in a simulated body fluid for 300 days. When the AOFCP having an equivalent Ca/P ratio to HA was hydrothermally heated at 300 degrees C, HA crystals were precipitated on the AOFCP and completely covered the surface.
... AO in an electrolyte mixture of β-glycerolphosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA) allows for the embedding of phosphate and calcium ions into the oxide layer [4]. The resultant oxide layer displayed larger interconnectivity of pores and greater pore diameters (with increasing β-GP molarity [5]), rougher anodised surface (with increase in CA concentration [6]), and improved tribocorrosion (with increase in β-GP and CA composition [7]). ...
... The resultant oxide layer displayed larger interconnectivity of pores and greater pore diameters (with increasing β-GP molarity [5]), rougher anodised surface (with increase in CA concentration [6]), and improved tribocorrosion (with increase in β-GP and CA composition [7]). Studies by Abdullah et al. [2,[8][9][10] have showed that the titanium anodised in an electrolyte mixture of 0.4 M CA + 0.04 M β-GP adsorbs more Ca 2+ and PO 4 3− ions during anodisation into its crystalline and exceedingly porous mixed rutile and anatase layer. However, the bioactivity results for this oxide layer were poor when assessed in terms of precipitation of bone-like apatite in SBF; this was attributed to the lower extent of functionality of the surface as groups such as hydroxyl ions are known to enhance the nucleation of bone-like apatite [2,4,11]. ...
... Studies by Abdullah et al. [2,[8][9][10] have showed that the titanium anodised in an electrolyte mixture of 0.4 M CA + 0.04 M β-GP adsorbs more Ca 2+ and PO 4 3− ions during anodisation into its crystalline and exceedingly porous mixed rutile and anatase layer. However, the bioactivity results for this oxide layer were poor when assessed in terms of precipitation of bone-like apatite in SBF; this was attributed to the lower extent of functionality of the surface as groups such as hydroxyl ions are known to enhance the nucleation of bone-like apatite [2,4,11]. With regard to the obtained surface structures of anodised Ti-oxides in the CaP-based electrolyte, the resultant coatings have shown strong similarities in terms of morphology and mineralogy; and there was been limited the exploration of other kinds of surface morphology of coating [12]. ...
Anodic oxidation (AO) of titanium is a common electrochemical process for surface modification of metallic surfaces and is conducted in an electrolyte solution. Anodisation of titanium implants can generate a coating with optimal characteristics to accelerate the growth of bone-like apatite. The present work aims to develop a novel AO electrolyte formulation of a CaP base solution containing three different alteration agents. The characteristics of the anodised coating were modified by varying the volume fractions of the alteration agents, namely sulphuric acid, hydrogen peroxide, and acetic acid in a base solution of β-glycerolphosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA). The surface morphology, mineralogy, wettability, and bioactivity of these coatings were analysed using scanning electron microscopy (SEM), X-ray diffraction (XRD), contact angle analysis, and in vitro testing using simulated body fluid (SBF). Anodisation in a mixture of β-GP + CA electrolyte resulted in the formation of CaP rich oxide coating (with surface features with a donut-like shape) and when altered with 12.5 vol% sulphuric acid, highly defined spiky needle-like morphology was seen on the surface. These coatings were composed of hydroxyapatite, tricalcium phosphate, and calcium diphosphate. After 7 days of SBF immersion, the surface was observed to contain a dense layer of bone-like apatite. However, alteration using acetic acid did not result in any significant changes to the surface characteristics and no bone-like apatite formation was observed even after soaking in SBF for 7 days. Alteration using hydrogen peroxide resulted in an anodised coating that assisted the growth of bone-like apatite layer on the coating surfaces after soaking in SBF for 7 days. The differences in coating performance are linked to the presence of different functional ions with hydronium groups (from sulphuric acid) being superior compared to the carboxyl ions (from acetic acid). The coating produced by sulphuric acid alteration demonstrated super hydrophilicity and rougher topographies which are ideal characteristics for cell attachment and proliferation in implant applications.
... Previous studies have shown that discharge anodic oxidation followed by hydrothermal treatment (spark-discharged anodic oxidation [SA]) coats c.p.Ti implants (SA-treated c.p.Ti) with a highly crystalline, thin hydroxyapatite (HA) layer of an anodic titanium oxide film that provides a suitable nanotopographic structure for clinical oral implants [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Previous in vivo and in vitro studies confirmed that SA treatment induced a coating that promoted good bone conduction, early bone matrix mineralization, and high adhesive strength when paired with a c.p.Ti substratum [20,22,24,26,27,29]. ...
... SA treatment was completed by washing with distilled water, drying, and then hydrothermally heating the AO c.p.Ti disks using high-pressure steam at 300 ℃ for 2 h in an autoclave (1.3 L; Nitto Kouatsu Co., Ltd., Tsukuba, Japan). This resulted in HA crystal precipitation on the disk surface (0.75 ± 0.03 µm Ra) [15,28,29,32]. The surface morphologies of the AO c.p.Ti and SA-treated c.p.Ti disks were confirmed by scanning electron microscopy (SEM; XM170007-0007; JEOL, Ltd., Tokyo, Japan) after coating with carbon by chemical vapor deposition. ...
... The surface morphologies of the AO c.p.Ti and SA-treated c.p.Ti disks were confirmed by scanning electron microscopy (SEM; XM170007-0007; JEOL, Ltd., Tokyo, Japan) after coating with carbon by chemical vapor deposition. The AO c.p.Ti surface was coated with an anodic titanium oxide film characterized by a porous microstructure with numerous craters and micropores with a diameter of 1-3 µm [15][16][17][18]. Conversely, the HA crystal layer of the anodic titanium oxide film containing calcium and phosphoric acid (AOFCP ) were observed on the AO film of SA-treated c.p.Ti, characterized by a typical single hexagonal columnar shape, highly crystallized [15][16][17][18]23,24,27,29], and covering more than 60% of the AOFCP on SA-treated c.p.Ti [15][16][17]. ...
Purpose: Implants made of anodized-hydrothermally treated commercially pure titanium with a nanotopographic surface structure (SA-treated c.p.Ti) may advantageously promote contact osteogenesis during the early stages of healing. We hypothesized that utilizing SA-treated c.p.Ti with dental pulp stem cells (DPSCs) might improve osteoconduction during the process of osseointegration. This in vitro study investigated the effect of initial adhesion of DPSCs to SA-treated c.p.Ti compared with conventional c.p.Ti and anodic oxide (AO) c.p.Ti.
Methods: DPSCs were obtained from the mandibular incisors of Sprague-Dawley rats and cultured without osteogenic induction medium on c.p.Ti, AO c.p.Ti, and SA-treated c.p.Ti disks for up to 14 days. The morphology, proliferation, and differentiation of DPSCs were assessed by scanning electron microscopy, an MTT assay, and Alizarin Red S staining, respectively. A real-time quantitative polymerase chain reaction was used to quantify the mRNA expression of osteocalcin, osteopontin, and bone sialoprotein.
Results: On all disks, the DPSCs appeared flattened with the formation of extensions over time. The filopodium-like extensions were closely bound to the SA-treated c.p.Ti surface. The proliferation of DPSCs was not significantly different among the c.p.Ti treatments. However, DPSCs on SA-treated c.p.Ti showed the greatest mRNA levels of osteopontin, osteocalcin, and bone sialoprotein, as well as increased Alizarin Red S staining.
Conclusions: The results of the present in vitro study demonstrate that the surface properties of SA-treated c.p.Ti disks enhance osteogenic differentiation of DPSCs and may facilitate mineralized matrix formation on SA-treated c.p.Ti implant surfaces, which can enhance early bone regeneration.
... Although Ti is the most biocompatible metallic material, it is also bioinert thus, it cannot induce bone growth. With the aim of addressing this issue, several surface modification approaches have been developed such as micro-arc oxidation (MAO) [24][25][26][27][28][29][30][31][32][33][34]. MAO does not only lead to a better corrosion behaviour but also can improve the bioactivity of Ti through the creation of tailored surfaces in terms of chemical composition, nano/micro porosity and topography [24][25][26][28][29][30][31][32][33][34][35][36]. ...
... With the aim of addressing this issue, several surface modification approaches have been developed such as micro-arc oxidation (MAO) [24][25][26][27][28][29][30][31][32][33][34]. MAO does not only lead to a better corrosion behaviour but also can improve the bioactivity of Ti through the creation of tailored surfaces in terms of chemical composition, nano/micro porosity and topography [24][25][26][28][29][30][31][32][33][34][35][36]. Furthermore, during MAO treatment it is possible to incorporate https://doi.org/10.1016/j.surfcoat.2020.125487 ...
... Also, from the cross sections obtained for the samples from each group, it was not possible to observe any visible effects in the compactness of the oxide. On the other hand, micro-pores were formed at high voltages (exceeding the electrochemical breakdown potential) and the species present in the electrolyte were incorporated into the porous oxide layer [27][28][29][30][31]38]. Consequently, MAO process resulted in porous surfaces with a wide range of pore sizes [33,37] presenting the well-known volcano-like structures. ...
Ti foams are attractive for orthopaedic applications due to reduced Young's modulus and ability of bone in-growth. However, poor corrosion behaviour and lack of bioactivity are yet to be overcome. In the present work, highly porous Ti samples were processed by powder metallurgy with space holder technique and bio-functionalized by micro-arc oxidation, resulting in nano/micro structured TiO2 surfaces containing bioactive elements. The electrochemical behaviour of these bio-functionalized highly porous Ti surfaces was evaluated through potentiodynamic polarization and EIS in physiological solution at body temperature. Results showed that bio-functionalization improved the corrosion behaviour of highly porous Ti. However, increased macro-porosity led to an increased corrosion rate.
... Plasma electrolytic oxidation (PEO) is one of the techniques for this purpose to enhance the mechanical properties, wear resistance, and the good adhesion with the substrate exhibited by the coatings. Also, PEO allows easily ions incorporation in the electrolytic plasma solution and an easy technological development of the technique [7,8]. ...
... These different pore sizes will stimulate fluid exchange and cells signaling and will make possible the occurrence of high surface energy sites [1]. Pore sizes described are related to the spark discharges produced by the high electrolytic and dielectric breakdown voltage, which can be controlled with the corresponding variables in the electrolyte assembly [6,8]. ...
... In addition, the coating thickness had a relation with the voltage reached during PEO, for 270 V similar coating thickness had been reported with a tendency to increase until 10 µm with 600 V [9]. The coating thickness increased proportionally to the electrolytic voltage [8]. ...
Ti6Al4V ELI (ASTM F136) alloy is one of the most used alloys in devices for osteosynthesis and joint replacement. However, the properties of this alloy can be improved regarding biocompatibility and the osteointegration with the bone tissue through coatings. The aim of this study was the evaluation of the electrochemical behavior of a coating obtained by plasma electrolytic oxidation on Ti6Al4V ELI, using electrolyte solutions enriched with PO4²-, Ca⁺², Si⁺⁴ ions and various concentrations of Ag⁺¹. The coatings were characterized by electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) in a three-electrode cell with a simulated physiological solution. The electrochemical behavior was compared with electrostatic force microscopy (EFM). The EIS results showed improved stability properties in corrosion for Ca-P-Ag coatings, compared with Ca-P-Si-Ag. Nyquist and Bode Spectra showed relaxations related to charge transference to the double electrochemical layer and the reflex of the microstructural changes and conductivity of the coating given by its composition. According to with M-S results, all the samples showed an n-type conductivity increased with silver inclusion. The potential, the phase, and amplitude of the coatings with silver inclusion compared to uncoated Ti6Al4V were observed by EFM.
... Hence, there is the need for a comprehensive study that summarises the mechanical stability, bioactivity, cytocompatibility, and antibacterial properties of MAO coating and this will provide a comprehensive overview of the potential design of anodised titanium and its varying micromorphologies for use as an implant surface [61][62][63][64][65][66][67]. Thus, in the present work, MAT was formed using a relatively higher molarity of CA+β-GP electrolyte (0.4 M CA+0.04 M β-GP) [68], with longer anodisation period of 10 min [69,70] at different voltages (150 to 450 V) to obseve the transition in morphologies from donut-shape anodised surface to needle-shape morphology. The oxidation was performed solely through MAO without pre-or post-treatment for the development of CaP-based coatings on the surface of the underlying TiO 2 -matrix. ...
... In this study, however, at a voltage > 350 V, the structure of flakes was retained even though they became thicker (Fig. 4). These flake layers as found on 450 V sample are covered by another CaP layer in form of needle-like structures ( Fig. 2(f)), similar to that observed elsewhere [5,31,[68][69][70]88]. As they get thicker, the CaP stucture appears to take a different form, namely 'segmented dome-shape' (Fig. 2(e)). ...
This study examined the effect of changes to the surface of CaP-based anodised titanium on osteogenesis and antimicrobial activity in vitro. The present work is proposed to investigate the mechanical stability of two different CaP/TiO2 micromorphology-based coatings, namely donut-shaped (350 V) and needle-shaped (450 V), that are fabricated by single-step micro-arc anodic oxidation at different conditions alongside with their cytocompatibility and antibacterial properties. The microhardness of the sample anodised at 450 V is ~100 MPa lower than that seen in the sample fabricated at 350 V, but both resultant coatings were strongly adhere to the substrate. However, the coating at 450 V was observed to suffer from delamination, indicating the needle-like structure is mechanically unstable. After 7 days of SBF immersion, the 450 V sample was highly bioactive relative to the 350 V sample. However, MTT assays showed that the 450 V coatings showed lower growth rate of hFOB 1.19 at day 14, which indicates that although the structure does have a superior ability to form apatite, it has long-term negative implications possibly from the toxicity of the structure to bone growth. The Alizarin-red staining shows that 450 V sample shows a negative trend of osteogenic mineralisation, thus qualitatively validating the toxicity. For antimicrobial effects, the donut-shaped microstructures were shown to have adequate antibacterial properties compared to the needle-like structures. Overall, this study suggest that the donut-shaped TiO2 morphology is the best cementless interface for bone cell anchorage.
... Titanium systems are widely used for body implant applications (failed hard tissue) due to their (i) high corrosion resistance and (ii) good bone compatibility [1][2][3][4]. This excellent level of biocompatibility is due to the presence of stable and protective oxide formed on titanium naturally [4]. ...
... The release of even a small quantity of these ions causes irritation in the localized region of the implant [2]. Additionally, these cell and tissue responses are influenced by the implant surface topography or roughness [1]. ...
Ti6Al4V substrates were electrochemically deposited with nano-crystalline hydroxyapatite (HA) from aqueous electrolytes. Cathodic HA coatings were obtained when the electrolyte was stirred using ultrasonic vibration. Two current densities of 20 mA/cm2 and 50 mA/cm2 were employed. Polarization and electrochemical impedance spectroscopy (EIS) were the techniques used to estimate the corrosion of coatings in simulated body fluid (SBF). The results indicate good corrosion resistance for the coating obtained at 50 mA/cm2 from ultrasonic stirring of the electrolyte.
... 15 As reported in literature, in order to improve the bioactivity of Ti and Ti alloys, and thus the HA growth, a possible strategy is to grow a thick porous anodic layer on the metal surface, using an electrolyte consisting of calcium acetate and β-glycerophosphate disodium salt pentahydrate. [16][17][18][19] Anodizing of Ti and Ti alloys has been widely studied with special interest on anodic layers composition and microstructure, 17,[20][21][22] but there is no information about electronic properties of such films. Since it sounds counterintuitive that the presence of thick ceramic material on the metal surface improves the bioactivity, in this work we want to study the electronic properties of TiO 2 layers grown by anodizing or hard anodizing on Ti and Ti6Al4V alloys with the aim to understand how they affect the corrosion resistance and thus the reactivity of these materials. ...
... 15 As reported in literature, in order to improve the bioactivity of Ti and Ti alloys, and thus the HA growth, a possible strategy is to grow a thick porous anodic layer on the metal surface, using an electrolyte consisting of calcium acetate and β-glycerophosphate disodium salt pentahydrate. [16][17][18][19] Anodizing of Ti and Ti alloys has been widely studied with special interest on anodic layers composition and microstructure, 17,[20][21][22] but there is no information about electronic properties of such films. Since it sounds counterintuitive that the presence of thick ceramic material on the metal surface improves the bioactivity, in this work we want to study the electronic properties of TiO 2 layers grown by anodizing or hard anodizing on Ti and Ti6Al4V alloys with the aim to understand how they affect the corrosion resistance and thus the reactivity of these materials. ...
The electronic properties of barrier and porous layers on Ti and Ti6Al4V were studied. Barrier anodic oxides grown to 40 V on Ti and on Ti6Al4V are both n-type semiconductors with a band gap of 3.3 and 3.4 eV, respectively, in agreement with the formation of amorphous TiO2. Anodizing to 200 V at 20 mA cm-2 in calcium acetate and β-glycerol phosphate disodium pentahydrate leads to the formation of Ca and P containing porous films with a photoelectrochemical behaviour dependent on the metallic substrate. A band gap of 3.2 eV and the flat band potential of -0.5 V vs. Ag/AgCl were measured for the porous oxide on Ti, while optical transitions at 2.15 eV and a significantly more positive flat band potential were revealed for the porous oxide on the alloy. The different electronic properties were rationalized by taking into account the presence of localized states inside the gap, induced by incorporation of Al and V from the underlaying alloy during the hard anodizing process. These electronic properties are responsible of the reactivity of porous layer grown on Ti6Al4V alloy in simulated body fluid.
... In addition, recently the fabrication of anodised titanium topography has focussed on the growth of self-ordered nanotubes (TNTs) [46,47,48,49,50], which has allowed their use as a structure with good osseointegration capabilities [51,52,53] to drug nanocontainers for localised therapeutics [46,47,54,55]. Such diverse possibilities for the use of anodised titanium as implant coating material has motivated this current review. ...
... Traditionally, this compact oxide surface morphology provides high energy interaction of bone-to-implant contact (BIC) [18,120]. In 1995, Ishizawa and Ogino introduced the calcium-phosphorous (CaP) based electrolyte which is able to produce microporous TiO 2 and incorporate Ca 2þ and PO 4 3-ions into the oxide layer [51]. The advantages of CaP based electrolyte lies in its ability to form a thick (1-10 μm), rough, and porous oxide layer integrated with calcium and phosphate ions, which have beneficial effects on the growth of bone tissue and enhanced anchorage of the implants to the bone [62]. ...
Anodised titanium has a long history as a coating structure for implants due to its bioactive and ossified surface, which promotes rapid bone integration. In response to the growing literature on anodised titanium, this article is the first to revisit the evolution of anodised titanium as an implant coating. The review reports the process and mechanisms for the engineering of distinctive anodised titanium structures, the significant factors influencing the mechanisms of its formation, bioactivity, as well as recent pre- and post-surface treatments proposed to improve the performance of anodised titanium. The review then broadens the discussion to include future functional trends of anodised titanium, ranging from the provision of higher surface energy interactions in the design of biocomposite coatings (template stencil interface for mechanical interlock) to techniques for measuring the bone-to-implant contact (BIC), each with their own challenges. Overall, this paper provides up-to-date information on the impacts of the structure and function of anodised titanium as an implant coating in vitro and in/ex vivo tests, as well as the four key future challenges that are important for its clinical translations, namely (i) techniques to enhance the mechanical stability and (ii) testing techniques to measure the mechanical stability of anodised titanium, (iii) real-time/in-situ detection methods for surface reactions, and (iv) cost-effectiveness for anodised titanium and its safety as a bone implant coating.
... 9,10,14,15 This method also promotes assimilation of calcium and phosphorus into the laminating layer of titanium alloy, which induces bone ongrowth via osteoblastlike cell responses. [16][17][18] Use of MAO coating has been successful in the dental field, but it has been difficult to apply to the orthopaedic field. This is because MAO process surface-treated Ti-Alloy's average surface roughness is too smooth to employ a cementless femoral stem. ...
... However, in theory, MAO is known to incorporate calcium and phosphorus into the laminating layer of titanium alloy and form thick oxide coatings and nanoporous pits on the metal surface. 9,10,14,15 This MAO coating on titanium alloy surface may improve bone ongrowth over cementless stems through osteoblast-like cell responses, [16][17][18] even though its usefulness has not been clinically proven. ...
Background: Recently, a femoral stem treated with grit-blasting and micro-arc oxidation (MAO) coating has commercialised but medium-term follow-up studies are lacking. The aim of this study was to report the outcome of a grit-blasted and MAO-coated femoral component designed as a straight, double-wedged, tapered stem with a rectangular cross-section with minimum 10 years follow-up.
Methods: Between March 2006 and December 2008, 309 primary total hip arthroplasties using a grit-blasted and MAO-coated femoral component were performed by 3 experienced hip surgeons in 3 hospitals. At minimum 10 years after index THA, 299 hips were living, 10 hips were deceased, and 65 hips were lost to follow-up or had a follow-up period <10 years. Finally, 234 hips were enrolled in this study.
Results: Mean duration of clinical follow-up was 129.6 months. The mean Harris Hip Score was improved from 46.9 to 88.4 at the final follow-up. 4 hips were revised for 2 aseptic femoral loosening, 1 aseptic acetabular cup loosening and 1 late infection. 3 hips were revised for a periprosthetic femoral fracture requiring a femoral component revision. The average time to revision was 51.6 (range 0-148) months. Kaplan-Meier survivorship analysis with an end point of revision for any reason demonstrated a survival rate of 97.4% at 10 years. Survival was 98.7% with revision for aseptic loosening as the endpoint.
Conclusions: The outcomes of a cementless grit-blasted and MAO-coated tapered-wedge stem of THA were excellent to satisfactory after a follow-up of at least 10 years.
... The oxide layer with strong barrier properties protects titanium surface against corrosion [7]. Electrochemical surface modification of titanium is able to modify the layer of the titanium oxide film, making it more adherent and porous, with better biological properties [14]. The mechanism for modifying the oxide layer under anodizing conditions is well known [15]. ...
... The mechanism for modifying the oxide layer under anodizing conditions is well known [15]. Implant surfaces subjected to anodic oxidation, have morphological characteristics that facilitate adhesion, orientation and bone formation more quickly, allowing the insertion of implants in regions with low densities, accelerating the loading of implants [14]. ...
Objectives
Development of a new generation of stable β alloy, free of aluminum or vanadium and with better biological and mechanical compatibility and evaluate the surface properties of Ti–6Al–4V and Ti–35Nb–7Zr–5Ta after anodization in hydrofluoric acid, followed by deposition of different electrolyte concentrations of magnesium particles by micro arc-oxidation treatment.
Methods
Disks were anodized in hydrofluoric acid. After this first anodization, the specimens received the deposition of magnesium using different concentration (8.5% and 12.5%) and times (30s and 60s). The surface morphology was assessed using scanning electron microscopy, and the chemical composition was assessed using energy dispersive x ray spectroscopy. The surface free energy was measured from the contact angle, and the mean roughness was measured using a digital profilometer.
Results
Anodization in hydrofluoric acid provided the formation of nanotubes in both alloys, and the best concentration of magnesium considered was 8.5%, as it was the condition where the magnesium was incorporated without covering the morphology of the nanotubes. X-ray dispersive energy spectroscopy showed magnesium incorporation in all conditions. The average roughness was increased in the Ti–35Nb–7Zr–5Ta alloy.
Conclusions
It was concluded that anodizing could be used to deposit magnesium on the surfaces of Ti–6Al–4V and Ti–35Nb–7Zr–5Ta nanotubes, with better results obtained in samples with magnesium concentration in 8.5% and the process favored the roughness in the Ti–35Nb–7Zr–5Ta group.
... The decrease of the pore size could be caused by lower electrolyte concentration (GP and CA). The increase in the size of the pores with increasing electrolyte concentration was also reported by Ishizawa et al. [45] for anodic titanium oxide films containing Ca and P. ...
... This phenomenon has been previously observed [52] and can be correlated with an increase in the intensity and temperature of the microarc discharges leading to the increase of the reactive capacity of all electrolyte components. It was also found [45] that sodium glycerophosphate and calcium acetate were suitable for the electrolytes to form a coating possessing the Ca/P ratio as that of hydroxyapatite (1.67). In this study, with the increasing voltage, the Ca/P ratio also increased; however, the value was smaller than that of boneapatite. ...
Titania-based films on selective laser melted Ti13Zr13Nb have been formed by micro-arc oxidation (MAO) at different process parameters (voltage, current, processing time) in order to evaluate the impact of MAO process parameters in calcium and phosphate (Ca + P) containing electrolyte on surface characteristic, early-stage bioactivity, nanomechanical properties, and adhesion between the oxide coatings and substrate. The surface topography, surface roughness, pore diameter, elemental composition, crystal structure, surface wettability, and the early stage-bioactivity in Hank’s solution were evaluated for all coatings. Hardness, maximum indent depth, Young’s modulus, and Ecoating/Esubstrate, H/E, H3/E2 ratios were determined in the case of nanomechanical evaluation while the MAO coating adhesion properties were estimated by the scratch test. The study indicated that the most important parameter of MAO process influencing the coating characteristic is voltage. Due to the good ratio of structural and nanomechanical properties of the coatings, the optimal conditions of MAO process were found at 300 V during 15 min, at 32 mA or 50 mA of current, which resulted in the predictable structure, high Ca/P ratio, high hydrophilicity, the highest demonstrated early-stage bioactivity, better nanomechanical properties, the elastic modulus and hardness well close to the values characteristic for bones, as compared to specimens treated at a lower voltage (200 V) and uncoated substrate, as well as a higher critical load of adhesion and total delamination.
... In response, there has evolved the development of new prospective surface modification technologies. This fact provides the opportunity for introduction of new advanced methods for obtaining modified surface layers with unique properties and they successfully eliminate the existing disadvantages [4,7,13]. ...
... This surface layer composition can be explained with the specific processes running through the experimental procedure conduction. The following interactions in the Ti-6Al-7Nb samples, during the anodizing process in sulphuric acid solution are conducted [4,5,7,9,10,11]: ...
Titanium alloys possess unique combination of good mechanical properties and excellent corrosion resistance which make them an attractive material for application in many engineering areas. Along with these properties there are some disadvantages which can be eliminated successfully using different surface treatment methods. One of the most commonly used among them is anodizing. This article presents investigation of the results obtained from anodizing titanium alloy Ti-6Al-7Nb using sulphuric acid. The quality assessment and morphology of the anodized layer is made using a micro structural analysis, EDS analysis, XRD analysis and microhardness measurements.
... Diversas técnicas podem ser utilizadas para a oxidação da superfície dos implantes, dentre elas a "oxidação por microarco" (MAO). Este processo consiste na oxidação anódica da superfície do implante usando altas tensões para obter uma superfície com óxidos [22]. ...
... The improvement of surfaces is carried out by various techniques, such as acid etching, hydrothermal treatment, sandblasting, laser, plasma electrolytic oxidation (PEO), and anodizing, among others. PEO is capable of modifying the titanium oxide film layer using high voltages, making it more adherent and porous, with better biological properties [9], in addition to enabling the incorporation of ions into the oxide layer. ...
High implant survival rates have been achieved in recent decades due to continual modifications in implant design and surface topography, however there is still an ongoing quest to control peri-implant bone loss. The objective of this work was to develop Ti-35Nb-7Zr-5Ta (TNZT) alloys, perform physicochemical and morphological characterization of their surface modified by electrolytic oxidative plasma technique with ions related to osseointegration and lastly evaluate bacterial colonization in vitro. Three groups were evaluated: C group (polished TNZT), CaP group (sodium β glycerophosphate + calcium acetate) and Mg group (magnesium acetate). Before and after anodizing the surfaces, physicochemical and morphological analyses were performed: scanning electron microscopy with field emission gun (FEG-SEM), energy dispersion spectroscopy (EDS), X-ray diffraction (DRX), wettability (goniometer) and roughness (rugometer). Controlled and treated specimens were contaminated with unstimulated saliva collected from 10 healthy volunteers. Then, biofilm samples were collected and up to 35 microbial species, including commensal and pathogenic microorganisms, were identified and quantified by the Checkerboard DNA-DNA Hybridization method. The CaP group modified the surface morphology in the form of pores, while the Mg group modified it in the form of flakes. The contact angle was significantly smaller in the CaP group. The average roughness was higher in the CaP and Mg groups. A smaller total amount of bacteria was identified in the Mg group and relevant differences were found in the microbial profile associated with different surface treatments. Therefore, considering the microbiological profile and for the prevention of peri-implantitis, the Mg group presented more satisfactory and encouraging results for the manufacture of dental implants
Graphical Abstract
... High performance of bone growth and cell adhesions were noticed when amino film available over the titanium alloy. Ishizawa and Ogino 145 Anodization Effect of coating (oxygen consisting of calcium and phosphorus) on the titanium alloy was discussed. ...
Titanium and its alloys are belonging to the class of biomedical materials and have amazing characteristic features, including high corrosion protection, incredible wear resistance, superb hardness, and extraordinary bio-degradability and activity. Due to these remarkable qualities, titanium materials are considerably treated in medical applications like bone implantation, surgical devices and prosthesis, dental implants, and fracture bone fixation by screws, plates, nails and abutments. However, there is a property of titanium alloys that it holds layers of oxygen over the surface, but the
atmospheric reactions/changes at extremely high temperature alter the morphology of the films, resulting in the loss of biological performance. In order to cover up this barrier, surface treatments are performed through different mechanical, chemical, and physical means. The treatments over the surface enhance the micro-features, improve the biocompatibility, and extend the life of coatings on titanium substrate. These modifications allow the various titanium alloys to be principally used in medical and dental applications. Considering the significance and applications of these alloys, this article is mainly conducted to scrutinize the various aspects, that is, biomedical applications and surface modification techniques, of titanium-based materials.
... By changing the electrolyte concentration, the dielectric breakdown that occurs during the MAO treatment changes, and thus the pore size is different. On the other hand, by increasing the calcium acetate concentration, the conductivity of the electrolyte increases; this is the main reason for the enlargement of pore size [16,[25][26][27]. Figure 1e presents the evolution of current during the MAO treatments, which can be divided into two distinct zones, i.e., the galvanostatic and potentiostatic zones. ...
Ti-based materials are widely used for dental and orthopaedic implant applications due to their adequate mechanical properties, corrosion behaviour and biocompatibility. However, these materials are biologically inert and display poor wear resistance. In one of the most studied processes that aims to overcome these drawbacks, Ti surfaces are often covered by anodic oxide films with the incorporation of bioactive agents such as Ca and P. Although there are several works on the tribocorrosion behaviour of MAO-treated Ti surfaces, the influence of electrolyte composition on the corrosion kinetics under sliding is yet to be fully understood. In the present work, anodic oxide films were produced on cp-Ti surfaces with different calcium acetate concentrations in the electrolyte. Tribocorrosion behaviour was investigated by reciprocating sliding tests performed in 8 g/L NaCl solution at body temperature, under potentiostatic conditions. The results showed that higher concentrations of calcium acetate had a detrimental effect on tribocorrosion kinetics, however, they resulted in less mechanical damage due to alterations in the topography and structure of the MAO layer.
... In particular, the anatase fraction drops more significantly for duty cycles above 50%, while the Ti content drops going from 10% to 50% duty, regardless of frequency. Overall, a high anatase content can be positive for hydroxyapatite nucleation, thus enhancing bone tissue growth and implant integration [38,39]. ...
In this work, copper and zinc co-doped coatings were successfully produced on commercially pure titanium samples by plasma electrolytic oxidation (PEO) using a sodium borate-based electrolyte. The effect of different duty cycles and frequencies on the treatment process was assessed, showing a significant influence of these parameters on the morphology and physical-chemical properties of the produced coatings. In particular, the coatings formed by applying duty cycles above 50% and 100 Hz frequency showed the highest thickness, surface homogeneity and porosity among all the treatment conditions. Moreover, the treatment significantly increased the wettability of all the samples, leading to a superhydrophilic behavior. The undoped PEO surface showed a clear bacteriostatic capability, given by its tuned morphology (high homogeneity and controlled pore size) and chemical-physical properties (high wettability), while the doping ions conferred antibacterial properties to the specimens, significantly reducing the number and the metabolic activity of the typical pathogens responsible for bone infections upon surgery (S. aureus, S. epidermidis, E. coli). Furthermore, the same ions did not induce any cytotoxic effect on Saos-2 osteoblasts, while the release of the early osteogenic marker alkaline phosphatase (ALP) suggested a pro-osteogenic activity of the surfaces.
... The EDS results showed that combining the MAO and sol-gel processes resulted in surfaces containing Ca, P, and Zn. The incorporation of Ca or P ions into the surface layer can improve osteoblast cell responses and support osseointegration, as has been confirmed by several previous researchers 25,26) , and anatase TiO2 supports important biological activities such as mineralization and protein adsorption 27) . Characteristic HA peaks and Ca3(PO4)2 peaks were observed in groups MAO-Ti+HA, MAO-Ti+HA+Zn(Low), and MAO-Ti+HA+Zn(High). ...
The aim of this study was to assess the biological and antibacterial properties of composite coatings on titanium surfaces modified by microarc oxidation and sol-gel processing. A layer of hydroxyapatite (HA) with different concentrations of zinc (Zn) ions, prepared by the sol-gel method, was coated on microarc oxidized Ti (MAO-Ti) substrates. Five groups of specimens were tested. The microstructures, elemental compositions, and chemical phases of the composite coatings were investigated, and the biological and antibacterial properties of specimens were evaluated in vitro. The EDS and XRD results confirmed the composite coatings contained HA and Zn ions which was formed on titanium surfaces. The proliferation and ALP activity of BMSCs was significantly higher in group MAO-Ti+HA and MAO-Ti+HA+Zn(High), but MAO-Ti+HA+Zn(High) showed better antibacterial performance. The MAO-Ti substrate coated with the higher Zn concentration in the HA coating exhibited not only favorable biocompatibility, but also antibacterial action against Gram-negative anaerobic bacteria.
... lasted surface group is parallel with the literature [Kiel-Jamrozik et. al., 2015]. Within anodization groups, Blasted 350 V anodized specimen showed higher deviation than Blasted 280 V anodized group and deviation was similar with the blasted group. This result was attributed to the irregularly distributed macro-sized pores on the surface (Fig 2) [Ishizawa et. al., 1995]. In the literature there are similar results for the pore size and roughness increase with increase of the anodization voltage [Jain et. al., 2018;Cirak et. al., 2017, Park et. al., 2006. ...
... TiO 2 has these properties [30] and can be increased in thickness by thermal treatment [31], sol-gel coatings [32], and the physical-vapor-deposition (PVD) of titanium oxide [33]. Different techniques have been used to enhance the TiO 2 layer, thermal, anodix [34], anodic oxidation [35], heat, enhancing bone formation, and improving initial stability [36][37][38]. Earlier research has demonstrated that this coating on the transmucosal part of the abutment minimizes the bacterial amount bound to the metal surface and creates healthy peri-implant tissues [39]. ...
High bone-implant contact is a crucial factor in the achievement of osseointegration and long time clinical success of dental implants. Micro, nano, microtopography, and oxide layer of dental implants influence tissue response. The lasers were used for achieving an implant surface with homogeneous micro texturing and uncontaminated surface. The present study aimed to characterize the implant surfaces treated by Nd: DPSS Q-sw Laser treatment compared to machined implants. A total of 10 machined implants and 10 lasered surface implants were evaluated in this study. The implant surfaces were evaluated by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES), and metallography to characterize and measure the thickness of the oxide layer on the implant titanium surface. The machined surfaces showed a non-homogeneous oxide layer ranging between 20 and 30 nm. The lasered implant surfaces showed a homogeneous oxide layer ranging between 400 nm and 460 nm in the area of the laser holes, while outside the layer, thickness ranged between 200 nm and 400 nm without microcracks or evidence of damage. Another exciting result after this laser treatment is a topographically controlled, repeatable, homogeneous, and clean surface. This technique can obtain the implant surface without leaving residues of foreign substances on it. The study results indicate that the use of Nd: DPSS Q-sw laser produces a predictable and reproducible treatment able to improve the titanium oxide layer on the dental implant surface.
... The use of titanium (Ti) as a substrate leads to the formation of a titanium dioxide (TiO 2 ) layer, which can improve its surface properties such as decorativeness 1,2) and biocompatibility. 3,4) In recent years, the TiO 2 layer is used as a photocatalyst for pollution control, due to its strong oxidative capability under light illumination, 5,6) and anodic oxidation of Ti substrate has gained attention as a fabrication process of photocatalytic TiO 2 . The photocatalytic properties of an intact TiO 2 layer are only activated by ultraviolet (UV) light. ...
Anodizing Ti substrates in an ammonium nitrate/ethylene glycol electrolyte is an innovative process capable of fabricating nitrogen-doped photocatalytic titanium oxide (TiO2) layer in one step. This fabricated layer comprises both rutile and anatase TiO2 phases; however, a major phase contributing to its excellent visible-light responsive photocatalytic performance is still unknown. In the present work, the crystallographic phase of an anodic layer was controlled by exploiting a post-thermal treatment and relationship between the phase variation and photocatalytic performance was then investigated to determine the major phase contributing to this performance. Post-thermal treatment to the anodic TiO2 layer had little influence on the surface morphology and nitrogen doping, but the crystallographic phase, more specifically the ratio of anatase to rutile phases, changed with the heating temperature. The photocatalytic activity, evaluated by methylene blue decolorization and ethylene decomposition, increased with an increase in the ratio of anatase phase, while the correlation with the rutile phase was not observed. X-ray diffraction (XRD) analysis using a grazing incidence geometry showed that the anatase phase was concentrated in the topmost surface region when compared with the rutile phase. In conclusion, the variation of the photocatalytic performance was related to the growth of the anatase TiO2 phase in the layer, with the treatment temperature of 723 K showing the highest photocatalytic activity.
Fig. 3 N 1s XPS spectra obtained from the sample surfaces treated at 523 K, 723 K, and 923 K. Fullsize Image
... 12 Besides increasing oxide-layer thickness, anodization leads to the formation of a highly crystalline oxide 11 with an increased number of hydroxyl groups, 13 which can incorporate specific molecules, such as magnesium, calcium, or phosphates, depending on the electrolyte. 14,15 Although implants with optimized surface properties show promising clinical outcomes, it is a challenge to standardize and control implant design properties over the shelf life. 16 Most commercial implants can be stored for up to 5 years in sterile packaging. ...
Background
Long‐term success and patient satisfaction of dental implant systems can only be achieved by fulfilling clinical as well as biological needs related to maintenance, aesthetics, soft tissue sealing, and osseointegration, among others. Surface properties largely contribute to the biological and clinical performance of implants and abutments.
Purpose
To decipher the clinical and biological needs in implant dentistry. To address identified needs, next‐generation dental implant and abutment surfaces are designed and characterized in vitro.
Materials and Methods
Novel implant and abutment surface designs were produced and characterized using surface chemical analysis, surface topography analysis, scanning electron microscopy, contact‐angle measurements, and cell‐culture experiments.
Results
The novel anodized implant surface was gradually anodized, increasing the surface roughness, surface enlargement, and oxide‐layer thickness from platform to apex. The surface was phosphorus enriched, nonporous, and nanostructured at the collar, and showed micropores elsewhere. The novel anodized abutment surface was smooth, nanostructured, nonporous, and yellow. Pristine surfaces with high density of hydroxyl‐groups were protected during storage using a removable cell‐friendly layer that allowed dry packaging.
Conclusions
A novel anodized implant system was developed with surface chemistry, topography, nanostructure, color, and surface energy designed to balance the clinical and biological needs at every tissue level.
... Moreover, UV irradiation on titanium implant enhances bone integration and increases the TiO 2 layer thickness [35]. Several techniques, including anodic oxidation [36][37][38][39] and thermal treatment [40][41][42][43], were used to achieve the deposition of the titanium oxide for improving osseointegration or prevent bacterial adhesion. The TiO 2 layer on the transmucosal portion of the abutment reduces the quantity of bacteria that attach to the metal surface and produces more healthy peri-implant tissues [43]. ...
Background
Pure titanium continues to be the first choice for dental implants and represents the gold standard for their biocompatibility and physical and mechanical characteristics, while the titanium alloy (Ti6Al4V) has good mechanical properties. The surface structure of the titanium oxide layer formation on the surface influences and improves the bone response around dental implants.
Purpose
The purpose of this study is to evaluate the influence of a thermal treatment of Ti6Al4V implant surfaces and the bone healing response in a rabbit model.
Methods
Altogether sixteen implants with same design were inserted into the distal femoral metaphysis. A screw (13 mm long, 4 mm in diameter) was inserted in an implant bed. Each rabbit received two implants, one in the left femur and one in the right femur. The samples were histologically and histomorphometrically evaluated at 8 weeks.
Results
A statistically significant difference (p = 0.000034) was present histologically in the percentages of bone-implant contact (BIC) between the test group (BIC = 69.25±4.49%.) and control group (BIC = 56.25 ± 4.8%) by one-way analysis of variance (ANOVA). Significance was set at p ≤ 0.05.
Conclusions
The outcome of the present study indicates a novel approach to improving bone healing around titanium implants.
... This electrochemical technique allows the incorporation of bactericidal elements along with Ca and P on titanium surface. Ishizawa et al. showed for the first time the possibility to incorporate Ca and P on the TiO 2 structure by PEO; those coatings reduce the Ti 4+ ion release, increase osteoblast adhesion and proliferation in vitro, and improve the osseointegration in vivo [8][9][10][11]. ...
Metallic implants are susceptible to bacterial colonization even years after the implantation impairing the osseointegration process. The treatment of a colonized implant is highly demanding, and in most cases implant replacement is the only effective solution. To avoid the bacterial attachment and proliferation, bactericidal coatings are proposed as a long-term prevention tool. Those coatings must assure a bactericidal activity for a long period and cannot induce cytotoxic responses in eukaryotic cells. Among all the bactericidal agents, Zinc is one of the most investigated due to its broad bactericidal activity spectrum and its stimulatory effect on bone formation. The aim of this study is to obtain a titanium oxide coating containing Zinc and evaluate its bactericidal activity, cytotoxicity and ion release profile. The coating was obtained by Plasma Electrolytic Oxidation (PEO) on commercially pure titanium grade 4 at 350 V for 60 s. Samples were divided in two groups; the reference group was obtained in a base electrolyte containing calcium acetate and calcium glycerophosphate (called CaP group). The experimental group had Zinc acetate added as a Zinc source to the base electrolyte (called Zn-CaP group). The surface was characterized by Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS), while the ion dissolution was evaluated by Inductively Coupled Plasma - Atomic Emission Spectroscopy (ICP-AES). The bactericidal activity was determined against Staphylococcus aureus by fluorescence microscopy using a live/dead viability kit. The cytotoxicity against eukaryotic cells was evaluated using adipose derived stem cells (ADSC) using the lactate dehydrogenase (LDH) assay. Zinc, Calcium and Phosphorous were incorporated to the titanium oxide coating and no changes on the coating structure and morphology were observed by the addition of Zn to the electrolyte. ICP-AES results show the coatings released Ca, P and Z ions after 28 days of immersion in DI water. The ICP-AES profile suggests the ion release reach an equilibrium state after 7 days of immersion. The Zn-CaP coating presented bactericidal activity against S. aureus, showing a higher number of dead bacteria after 6 h of incubation and a lower number of living bacteria after 24 h compared to the CaP group. No cytotoxic effect was observed against ADSC by the presence of Zn on the coating, indicating the Zn-CaP coating has a potential to prevent bacterial colonization in metallic implants.
... It can be seen that no bone-like apatite was observed on the surface of the untreated anodised titanium. This effect is because the oxide layer formed by anodic oxidation in a mixture of β-GP and CA tends to have insufficient nucleation sites for the growth of bone-like apatite [30,31]. In contrast, large-sized agglomerates of bone-like apatite were observed on the surfaces of the sample UVA-treated in solutions of pH 1, 4, and 11. ...
Photocatalytic TiO 2 layers were deposited by anodic oxidation on high purity titanium substrates followed by ultraviolet light A (UVA) irradiation in solutions of varying pH (1, 4, 7, and 11) for 12 h. Afterwards, the UVA-treated anodised titanium foils were soaked in simulated body fluid (SBF) for 7 days. The morphological, mi-neralogical, surface wettability, and in vitro synthesis of the anodised samples were determined. The work showed that the surface morphology and crystallinity of the anodised coating was unchanged after UVA treatment in solutions of varying pH. However, the water contact angle decreased remarkably after UVA treatment, with the sample irradiated in a solution of pH 1 showing the lowest angle (31.8°). After soaking in SBF and with UVA irradiation for 7 days, highly crystallised bone-like apatite layer fully covered the surfaces of the anodised samples. Cross-sectional images revealed that the optimal condition for UVA treatment was at pH 1 (acidic) since it resulted in the thickest layer (2.8 μm) of bone-like apatite formation after soaking in SBF. The results clearly showed that UVA irradiation assisted the growth of bone-like apatite layer on anodised surfaces.
... The coatings presented a volcano shape porous morphology (Figure 1), characteristic of coatings obtained by PEO process in calcium and phosphorous containing electrolyte [40,41]. The coatings are 6.2 ± 1.2 µm thick, composed by two layers: a compact inner layer and an external porous layer, region 1 and 2 in Figure 1, respectively. ...
Implant centered infections remain as one of the main complications associated with the use of biomedical
implants. These infections can be avoided with the development of bactericidal coatings that prevent bacterial
contamination since the very early stage of implantation. However, a multifunctional coating should inhibit bacterial
contamination without generating cytotoxic responses. To achieve this purpose, this work presents a comparative
evaluation of coatings with different concentrations of Ag. Coatings containing silver, calcium and phosphorous were
obtained by plasma electrolytic oxidation (PEO) and its bactericidal activity and cytotoxicity were evaluated against
Staphylococcus aureus and adipose derived stem cells (ADSC), respectively. Silver, calcium and phosphorous were
successfully incorporated in the coatings and silver has not affected the coating morphology nor the crystalline structure.
ADSC viability was unaltered by cell growth over the surfaces, despite the observation of thinner cells on coatings with
higher silver content. After 24 h of incubation, bactericidal activity was observed in coatings with more than 0.6 % at. Ag
incorporated, while coatings with 0.2 % at. Ag presented an increased bacterial proliferation indicating a hormetic
response. Thus, Ag-CaP-TiO2 coating could be a potential solution for the prevention of implant infections.
... 16,17 MAO is an electrochemical surface modification technique using high voltages (several hundred volts) to fabricate porous and thick oxide coatings on metals 18 and to incorporate phosphorus (P) and calcium (Ca) ions into the surface layer. 19 One attractive property of MAO is its ability to create a macro-porous and firmly adherent TiO 2 film on Ti surfaces and consequently to modify the surface chemistry and topography. 20 Morphology observations have revealed that implants treated with MAO could form a porous multipore topography because of the discharges occurring under high potentials and adequate hydroxyl groups, resulting in a hydrophilic surface. ...
Microarc oxidation (MAO) has become a promising technique for the surface modification of implants. Therefore, the aims of this study were to further quantitatively and qualitatively evaluate the osteointegration abilities of MAO-treated and smooth surface (SF) implants in vivo and to investigate the areas in which the superiority of MAO-treated implants are displayed. In a rabbit model, a comprehensive histomorphological, osteogenic, mineralizational, and integrative assessment was performed using light microscopy, fluorescence microscopy, confocal laser scanning microscopy, and radiographic analyses. Compared with the SF groups, the MAO-treated groups exhibited more active contact osteogenesis, as well as distant osteogenesis, under fluorescence examination, the mineral apposition rate was found to be greater for all of the MAO-treated implants, and the osteointegration index (OI) value was greater in the MAO-treated groups at different times. In conclusion, the calcium-rich amorphous layer created by MAO provided a better environment for osteointegration, with more active contact osteogenesis, a more rapid mineral apposition rate and greater OI values.
... It is been reported that osteoconductivity of Ca-and P-rich anodic oxide films is induced by the presence of HAP crystals. [45][46][47][48][49] According to Carr e and Lacarriè re, 50 cell adhesion process consists of four steps: protein adsorption; cell-substrate contact; cell-substrate attachment; and cell-cell interaction. These steps are influenced by several factors, such as roughness, porosity, wettability, surface energy, topography, polarity, charge, chemical composition, among others. ...
Highly porous Ti implant materials are being used in order to overcome the stress shielding effect on orthopedic implants. However, the lack of bioactivity on Ti surfaces is still a major concern regarding the osseointegration process. It is known that the rapid recruitment of osteoblasts in bone defects is an essential prerequisite for efficient bone repair. Conventionally, osteoblast recruitment to bone defects and subsequent bone repair has been achieved using growth factors. Thus, in this study highly porous Ti samples were processed by powder metallurgy using space holder technique followed by the bio-functionalization through microarc oxidation using a Ca- and P-rich electrolyte. The biological response in terms of early cell response, namely, adhesion, spreading, viability, and proliferation of the novel biofunctionalized highly porous Ti was carried out with NIH/3T3 fibroblasts and MC3T3-E1 preosteoblasts in terms of viability, adhesion, proliferation, and alkaline phosphatase activity. Results showed that bio-functionalization did not affect the cell viability. However, bio-functionalized highly porous Ti (22% porosity) enhanced the cell proliferation and activity. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018.
... 27,28 To solve these problems, several studies have been conducted, such as micro arc TiO 2 and anodic Al 2 O 3 between bioactive HA coating and metal substrate, which led to some helpful results. [29][30][31] The problems caused by the shrinkage of ceramics during sintering can be solved by a reaction bonding process. When sintering process performs in an oxidizing air atmosphere, the metal phase changes to the metal oxide phase which is sintered and bonded to the substrate. ...
In this research work, HA-Al2O3 bio nano-composite coatings were coated on titanium substrate by electrophoretic deposition (EPD) and reaction bonding process. The reaction bonding process densifies the coating and creates small uniform porosities. HA -Al2O3 bio nano-composite coatings were analyzed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). For the coatings sintered for 2h at 850°C, XRD results demonstrated no significant Hydroxyapatite (HA) decomposition. The adhesion strength increased from 10.2 MPa to 25 MPa. It was determined that 50wt.% of Al is the optimum content for producing free-of-crack composite coatings on the titanium surface as shown by SEM examination
... In our previous study, we applied anodic oxidation (AO) on titanium sheets because it is an easily controlled method of surface-roughening which can be readily applied to the implant surface at room temperatures. [16][17][18] We found that when the voltage reached 180 V, the anodized titanium dioxide (TiO 2 ) films (Ra = 1.3383 ± 0.1839) promoted protein adsorption, enhanced fibroblast growth and inhibited bacterial adhesion. 19 However, the inorganic anodized structure could not form a direct biochemical bond with the organic collagen fibers in the periimplant connective tissue. ...
Background and objective:
Nowadays, most designs for the transmucosal surface of implants are machined-smooth. However, connective tissue adhered to the smooth surface of an implant has poor mechanical resistance, which can render separation of tissue from the implant interface and induce epithelial downgrowth. Modification of the transmucosal surface of implants, which can help form a good seal of connective tissue, is therefore desired. We hypothesized that anodic oxidation (AO) and polydopamine (PD) deposition could be used to enhance the attachment between an implant and peri-implant connective tissue. We tested this hypothesis in the mandibles of Beagle dogs.
Material and methods:
AO and PD were used to modify the transmucosal region of transmucosal implants (implant neck). The surface microstructure, surface roughness and elemental composition were investigated in vitro. L929 mouse fibroblasts were cultured to test the effect of PD on cell adhesion. Six Beagle dogs were used for the in vivo experiment (n = 6 dogs per group). Three months after building the edentulous animal model, four groups of implants (control, AO, PD and AO + PD) were inserted. After 4 months of healing, samples were harvested for histometric analyses.
Results:
The surfaces of anodized implant necks were overlaid with densely distributed pores, 2-7 μm in size. On the PD-modified surfaces, N1s, the chemical bond of nitrogen in PD, was detected using X-ray photoelectron spectroscopy. L929 developed pseudopods more quickly on the PD-modified surfaces than on the surfaces of the control group. The in vivo experiment showed a longer connective tissue seal and a more coronally located peri-implant soft-tissue attachment in the AO + PD group than in the control group (P < .05).
Conclusion:
The modification of AO + PD on the implant neck yielded better attachment between the implant and peri-implant connective tissue.
... The application of PEO has been recently expanded into the biomedical area due to its micro-porous and adherent layer formation on the metallic substrate. Ishizawa et al. [141,142] were the first research group to make use of PEO process for the preparation of HA layer on titanium substrate. But unfortunately they are not successful using only PEO process. ...
Recently, there has been an increasing trend in researches focusing on improving the performance of the
biomedical implants. The clinicians used metallic implants to treat bone imperfections and fractures. The
commonly used metals (Stainless steel, Ti-alloys and Co-alloy) failed to prove long-term durability and
did not build sufficient bond with human bone. Since the invention of bioactive materials, which can
generate chemical bond with bones, the researchers proposed combining the superior mechanical
properties of metals and bioactivity of bioactive materials. This can be achieved by cladding bioactive
material on metallic substrate. Different techniques, like thermal spraying, electron magnetron sputtering,
laser cladding, etc., were proposed to successfully deposit bioactive materials on metallic substrates.
In this article, we will discuss the potential of available metallic alloys and bioactive materials in
biomedical implants including different techniques used in depositing bioactive materials on metallic
implants.
Titanium was anodically oxidized in aqueous electrolyte containing dissolved 1 M Na2SO4 and 0.5 wt% NaF. This oxidation was performed for 0.5 and 1 h at 20 and 30 V in unstirred and magnetic pellet stirred baths. Irrespective of the stirring conditions, amorphous, nanotubular oxide was formed at 20 V. Compared to the unstirred condition, the tubular length was increased upon stirring at 20 V. However, flat, anatase layers were produced at 30 V in both stirring conditions. The nanotube network was formed probably in first 5 min and disturbed later, so that the oxidation proceeds laterally and perpendicular to the longitudinal tubular axis. Among the oxides tested, the oxide films obtained by oxidation for 0.5 h at 20 and 30 V under stirring condition (M20, 0.5 and M30, 0.5) have higher impedance and lower corrosion current density in simulated body fluid (SBF). The SBF represents the actual conditions of fluid inside the body.
Graphical abstract
A three‐step electrochemical process is developed to grow a coating on Ti6Al4V alloy for biomedical applications aimed to enhance its bioactivity. The coating is composed by a porous titanium oxide filled with Ag, alginic acid, and hydroxyapatite to provide antibacterial properties and, at the same time, osteointegration capability. Anodized and treated with the electrochemical process samples are characterized by Scanning Electron Microscopy (SEM), Energy‐Dispersive X‐ray Spectroscopy (EDX), X‐Ray Diffraction, and Raman Spectroscopy to have information about morphology and composition soon after the fabrication and after immersion in Hanks’ solution. Bioactivity of the samples is also proved by electrochemical tests through Electrochemical Impedance Spectroscopy (EIS) measurements. Antibacterial properties, cytocompatibility and hemocompatibility of the samples are successfully demonstrated by in vitro tests. A novel three‐step electrochemical process is developed to grow a coating on Ti6Al4V alloy for biomedical applications aimed to enhance its bioactivity. The coating is composed by a porous TiO2 filled with Ag, alginic acid and hydroxyapatite to provide antibacterial properties and, at the same time, osteointegration capability.
The plasma electrolytic oxidation is an innovative method for the surface treatment of titanium and its alloys. This review provides an overview of the historical development of the process and summarizes the current state of the art. The chemical as well as the electro- and plasma-chemical basics of the layer forming mechanisms, which comprises the substrate/electrolyte interface before discharge initiation and the different types and stages of plasma electrolytic discharge phenomena are explained within the context of titanium-based materials. How these phenomena can be influenced by the use of suitable electrolytes and controlled by the electrical regime is described. Subsequently, the microstructures and composition of the layers are described in detail, and the properties for specific applications are then discussed. The resistance of a PEO coating to corrosive environments, tribological factors, and alternating mechanical stress is viewed critically, and the extensive functional properties such as physiological compatibility, photocatalytic activity, and decorative properties are revealed. Finally, examples of various practical applications in the medical engineering, aviation, automotive, and environmental technology fields, as well as other branches of industry, are presented.
Nanomaterials have unique surface properties. The surface modification of nanomaterials through appropriate surface modification technology can improve the properties of nanomaterials to a certain extent. Nanomaterials include nano-metal materials, nano-nonmetallic materials, nano-polymer materials and nanocomposites, and different nanomaterials have different modification methods. According to the formation mechanism of surface modification layer, the surface modification methods of nanomaterials can be divided into chemical methods and physical methods. In this paper, the surface modification methods of various nanomaterials and their wide applications in drug delivery, antibacterial, bone tissue engineering, tumor imaging, diagnosis, and therapy are reviewed, which reflects the important role of surface modification of nanomaterials in the field of biomedicine.
Electrical discharge coating (EDC) has been applied to prepare a Ca and P-containing layer on Ti as implant applications. This study aimed to enhance Ca and P incorporation in the coating by absorbing HA on gas using gas-assisted perforated electrodes. The effects of gas flow rate and electrode rotational speed on the coating composition and coating thickness were investigated. Using the gas-assisted perforated electrodes at an appropriate gas flow rate (0.02 L/min) enhanced the Ca and P amount in the coating. In addition, an increase in the rotational speed of the electrode decreased the Ca and P amount in the coating. The coating thickness decreased with increasing electrode rotational speed. The EDC-treated Ti exhibits higher surface hardness and corrosion resistance than Ti. After hydrothermal treatment, the needle and prism HA crystals precipitated on the coating surface, exhibiting hydrophilic property. Furthermore, the hydrothermal treatment slightly improves the corrosion resistance of the EDC-treated Ti.
There has been a constant requirement from the clinic to develop biomedical titanium (Ti) implants with high osteogenic ability. In this study, we clarified a novel mechanism of how MAO (microarc oxidation) coating of Ti implants facilitates osteogenic differentiation of human bone marrow mesenchymal stem cells (hB-MSCs) by activating ERK1/2-miR-1827-Osterix signaling pathway in vitro. MAO surface of titanium implant was more favorable to promote osteogenic differentiation than SLA and AOS coating. Besides, titanium implants regulated hB-MSCs osteogenesis through the p38 MAPK pathway and ERK1/2 might be the most efficient target. Furthermore, MAO coating induced osteogenic differentiation though ERK1/2-miR-1827 pathway. Finally, we verified miR-1827 regulated osteogenic differentiation partially through Osterix. Our study reveals novel insights that MAO surface of titanium implant is a prior choice for biomedical trial and for its use in periprosthetic osteolysis (PIO) treatment in an evidence-based rationale.
The purpose of this study was to coat thin stable calcium phosphates on titanium substrates using a discharging method in an electrolyte. A titanium plate was connected to the cathode with a platinum anode in phosphoric acid and citric acid solution with oversaturated tri-calcium phosphate powder using a pulsed battery and was treated under discharging. The surface of titanium plates was coated by a calcium phosphate layer with treatment. The surface and the sectioned surface of the coated titanium plates were observed by SEM.
The coated layer was also analyzed by EDX, X-ray diffractory (XRD) analysis, and IR analysis. SEM observation on the sectioned surface revealed that the coated layer with a thickness of 5-10 μm adhered to the mother metal tightly. The results indicated that the composition of the coated layer was hydroxyapatite when the electrolyte contained 2 wt% phosphoric acid with citric acid. On the other hand, that of the coated layer was β-TCP when the electrolyte contained 4 wt% phosphoric acid with citric acid.
Therefore, thin stable calcium phosphate coating without secondary components on titanium could be obtained by discharging in an electrolyte when adjusting the composition and content of the electrolyte.
The aim of this study was to prepare thin hydroxyapatite (HAP) coatings on titanium (Ti) surface using a 2-stage discharging method in an electrolyte. First, a Ti plate was anodic oxidized by discharging in a phosphoric and citric acid solution with supersaturated tri-calcium phosphates. Then, components in the solution were coated to the Ti plate by discharging with a reversed polarity. XRD, FT-IR, XRF and XMA analysis were performed on both anodic oxidized and coated Ti plates to find suitable discharging conditions. Anodic oxide films contained amorphous calcium phosphate ceramics and calcium titanium phosphate. These elements were important to produce HAP coatings without by-products when Ti plates were cathodic treated under discharging. HAP coatings with a thikcness of 5-10 μm adhered tightly to the surface of the Ti plates and were still stable after 28 days in pH 5.0 NaCl solution. These findings suggest that these coatings may be useful to apply osseous implant materials.
Thanks to a considerable number of fascinating properties, titanium (Ti) and Ti alloys play important roles in a variety of industrial sectors. However, Ti and Ti alloys could not satisfy all industrial requirements; the degradation of Ti and Ti alloys always commences on their surfaces in service, which declines the performances of Ti workpieces. Therefore, with aim to further improve their mechanical, corrosion and biological properties, surface modification is often required for Ti and Ti alloys. This article reviews the technologies and recent developments of surface‐modification methods with respect to Ti and Ti alloys, including mechanical, physical, chemical, and biochemical technologies. Conventional methods have limited improvement in the properties and/or restriction on the geometry of workpieces. Therefore, many advanced surface‐modification technologies have emerged in recent decades. New methods make Ti and Ti alloys have better performance and extended applications. With requirement of high surface properties in future. Understanding the mechanism in various surface‐modification methods, combining the advantages of current technologies and developing new coating materials with high performance are required urgently. As such, incorporation of different surface‐modification technologies with high‐performance modified layers may be the mainstream of surface modifications for Ti and Ti alloys.
مواد پایه تیتانیومی از جمله مهمترین مواد مورد استفاده در مهندسی پزشکی بهشمار میروند. امروزه تیتانیوم خالص تجاری بهدلیل زیست سازگاری بالا با بدن انسان، بهطور فزایندهای مورد توجه پژوهشگران قرار گرفته است. بهمنظور دستیابی به خواص مکانیکی بهتر، بدون بهخطر انداختن دیگر خواص مفید تیتانیوم، همچنین بهجهت رسیدن به ساختار ریزدانه از روش تغییر شکل پلاستیک شدید استفاده میشود. اصلاح اندازة دانه توسط این روش به بهبود خواص مکانیکی و کاربردی تیتانیوم منجر خواهد شد. در این مقاله به مرور تکنیکهای مورد استفاده در تغییر شکل پلاستیک شدید به منظور ساخت تیتانیوم خالص ریزدانه پرداخته شده است. همچنین طیف وسیعی از خواص تیتانیوم خالص تجاری که با ریزدانه کردن ساختار آن به روش تغییر شکل پلاستیک شدید بهدست آمده است، از قبیل ریزساختاری، خواص مکانیکی، عملکرد در برابر خوردگی و زیستسازگاری مورد مطالعه قرار گرفته است.
The fracture toughness of brittle biofilms prepared through the microarc oxidation process on the Ti–13Nb–13Zr alloy needs to be improved. The ultrasonic technology was successfully incorporated into the process. The indentation test and its analysis method were adopted to measure the film fracture toughness. The properties of the film such as surface morphology and phase composition were compared with those of a film prepared without using the ultrasonic technology, and the toughening factors were analyzed and a calculation model of fracture mechanics was established. The results show that the composite-process film has higher fracture toughness than the single-process film with a different film porosity, and the toughness of the former can reach 2·65 MPa m 1/2 for higher duty cycles. Parts of titanium dioxide (TiO 2 ) phase transformation toughening, reduction of the main-crack stress concentration by microcracks and the densification of the microstructure caused by ultrasonic cavitation effect are the main reasons that fracture toughness improved. Similar results for measurement and calculations obviously indicate the validity of the model. The composite process can achieve the purpose of toughening titanium alloy biofilms.
The bioactivity of anodized near-β TiNbSn alloy with low Young's modulus prepared in sulfuric acid electrolytes was examined to explore the osseointegration mechanism with a focus on the role of anodic oxide. Hydroxyapatite (HA) precipitated on the surface of anodic oxide following immersion in Hank's solution, and precipitation accelerated with increase in the sulfuric acid concentration of the electrolyte. HA is formed on the surface of as-anodized oxide without subsequent annealing or hot water (HW) treatment. This outcome differs from that of a previous study using anodized TiNbSn alloy prepared in acetic acid electrolytes requiring for subsequent HW treatment. It was found that the oxide anodized in sulfuric acid electrolyte contains a large amount of internal pores and is highly crystallized thick TiO2, whereas the same prepared in the acetic acid electrolyte is low crystalline thin TiO2 containing a small amount of pores. The present anodized TiNbSn alloy is preferred for maintaining the low Young's modulus of the alloy and eliminating the subsequent treatment to increase the Young's modulus. A model to rationalize the bioactivity of the present anodic oxide is proposed based on the series of studies. It is concluded that the sulfuric acid electrolyte is favorable for both HA formation and low Young's modulus, and the bioactivity is attributed to the anodic TiO2 that facilitates incorporation of bone ingredients.
Titanium and platinum samples as components of bimetallic implants for the osteoregeneration process have been modified in solutions modeling biological systems and studied by means of cyclic voltammetry, electrochemical impedance spectroscopy and scanning probe microscopy. While aspartic and glutamic acids did not adsorb significantly on platinum in the potential region investigated, the presence of the amino acids affects oxide layer growth on the titanium surface under anodic polarization. The two studied amino acids behave differently on the titanium electrode surface due to differences in adsorption modes of these substances. The adsorption of the glutamic acid depends on the polarization potential to a large extent, and most of quantitative adsorption characteristics (EIS data, the surface roughness) undergo drastic change at the polarization potential value of 750 mV (vs. Ag/AgCl) in the presence of this substance. Equivalent circuit modeling of the surface processes has been carried out, and a scheme for aspartic and glutamic acid adsorption onto the titanium surface has proposed.
Oxide coatings were produced on Ti-6Al-4V alloy by anodization process using two different aqueous electrolytes. The electrolytes contained calcium and phosphorus in the molar ratios of 5 and 15, respectively. Coatings were obtained by applying 250 and 300 V and were characterized by XRD and TEM. Properties like chemical composition, thickness and surface roughness were obtained. All the coatings contained TiO2 along with calcium and phosphorus. Electrochemical polarization and AC impedance studies were done in Simulated Body Fluid medium. The coating obtained by oxidation at 250 V from the bath maintained at Ca/P ratio of 5 had better corrosion properties. Improvement in corrosion resistance was attributed to the presence of phosphorus in the coatings.
This study aimed to confer esthetic appearance on ash gray-colored titanium-based implant materials. Binary Ti alloys were prepared by arc-melting of titanium and one of the transition metals (Au, Cr, Cu, Mn, Mo, Nb, V, and Zr). Ti alloys containing 1, 2.5, 5 and 10 wt% alloying elements were microarc-oxidized in an electrolyte containing Ca and P ions under a constant current using a DC power supply. During the microarc oxidation (MAO) treatment, the potential vs. time curves were strongly affected by the alloying element type and content. The pore size, thickness, and crystallinity of the oxide layer increased as the final potential was increased. Colored oxide layers were obtained for the Ti alloys containing 3d (Cr, Cu, Mn, and V) and 5d (Au) transition metals. Their colors were dependent on the alloying metal type and content. In the L*a*b coordinate for color measurement adopted by the Commission Internationale d’Eclairage (CIE), the oxide layer of Ti-5Cr/MAO exhibited the highest average b* value of 19.81 (p < 0.05). The oxide layer of Ti-2.5Cu/MAO showed the next highest average b* value of 16.73. The oxidation state of 3d transition metals contributed to colorization of the microarc-oxidized Ti alloys. The characteristic colors of MAO-treated Ti alloys were rendered by the chemical binding state of alloying elements: yellow color for Cr³⁺, red color for Cu⁺, yellow color for Mn⁴⁺ and yellow color for V⁵⁺. The purple color of the MAO-treated Ti-Au alloy surface originated from Au nanoparticles. The 4d transition metals (Zr, Nb, and Mo) did not affect color revelation of the MAO-treated Ti alloys.
In order to prepare functional films containing a predetermined ratio of calcium (Ca) and phosphorus (P) and guide the rational allocation of chemical reagents on a titanium (Ti) alloy surface, calcium/phosphorus biological films were fabricated by using the microarc oxidation (MAO) process. The films' morphology and elemental composition were observed and analyzed. Moreover, a wear resistance test was performed on the film surface. The influence of different concentrations and calcium/phosphorus molar ratios of the films and the MAO system were researched. The effects of electrolyte concentration on the calcium/phosphorus molar ratio of the films were also investigated. The experimental results show that with an increase in electrolyte concentration, the calcium and phosphorus contents of the films all decreased, but the calcium/phosphorus ratio increased. Similarly, the values of the calcium/phosphorus molar ratio and the calcium and phosphorus contents in the films all became lower. Furthermore, a proper electrolyte concentration is helpful in improving the surface properties of the films. If preparation of a film with a certain calcium/phosphorus molar ratio is wanted, this certain ratio can determine the different electrolyte molar concentrations of calcium/ phosphorus and it can roughly determine the ratio of the compound reagent and improve the test efficiency.
Oxide films with different thicknesses and electrochemical properties can be anodically formed on titanium and titanium alloys. In this work the resistance, and particularly, the passivity currents of a Ti6Al4V alloy anodized under different conditions were evaluated. The tests were performed in a physiological solution simulating the environment of the human body. A significant reduction in the passivity current and an increase of the range of passive potentials have been observed on anodized specimens. Consequently the anodic oxidation of the Ti6Al4V alloy to obtain an high thickness oxide film can be considered an important improvement in the finishing of prosthetic devices.
The surface of titanium specimens was treated by anodic oxidation and immersion in aqueous solutions containing phosphate ions and calcium ions, in order to obtain a more biocompatible surface of titanium.The surfaces treated by the above methods were characterized using scanning electron microscopy, x-ray photoelectron spectroscopy, and Fourier transformed infrared absorption spectroscopy with reflection absorption spectroscopy.In addition, the specimens treated were immersed in Hanks' solution at 37℃ for 30 days and then the surfaces were analyzed using the above methods.The results indicated that the treatments accelerated the formation of calcium phosphate during immersion in Hanks' solution.Some treatments produced a calcium phosphate surface resembling apatite on the titanium in Hanks' solution.
Although the mechanical properties of dental alloys have been studied by static tests including tensile tests and hardness tests, the measurements of endurance strength in which the fatigue properties of the dental alloys are considered have not yet been performed. It has been reported that fatigue fracture occurs in these alloys even when recurring stresses are lower than their yield strength. The purpose of this study is to measure several different fatigue properties in five varieties of wrought gold alloys. The relationships between stress amplitude (σa) and number of stress cycles (N) were studied using a four point bending testing machine at a frequency of 30Hz. After the fatigue tests, the fracture surfaces were observed by SEM. The alloys with small elongation and comparatively high tensile or yield strength showed high fatigue strength. Gold alloys having such high fatigue strength cracked through a striation process named stage II from their crack inception. We conclude that it is indispensable to consider the mechanical properties of dental alloys as measured by dynamic tests as well as by static ones. © 1991, The Japanese Society for Dental Materials and Devices. All rights reserved.
Titanium was anodized utilizing the D. C. -constant voltage method to form an anodic oxide film with the thickness of an order of magnitude of a micrometer on titanium. Single baths of 25 g/l of phosphoric acid and 35 g/l of sulfuric acid and a mixed bath of these acids were mainly used as the electrolytic bath. Size of the counter electrode was the same as that of the working electrode of titanium.
Spark discharge is more easily emitted with the increase of electrolytic voltage in the anodic oxidation process using those electrolytic baths. The spark-discharging voltages in the single baths of sulfuric acid and phosphoric acid and the mixed bath were approximately 115,220 and 130 V, respectively. Only a thin film, so-called interference film, was produced in the anodic oxidation under a voltage lower than those spark-discharging voltages, while a thick gray film composed of anatase- or rutile-type titanium oxide was produced in the anodic oxidation under a voltage higher than those voltages. The thickest film of approximately 8 μm was produced under 300 V in the anodic oxidation using the mixed bath. Such a thick film was porous. The pores began to be clearly observed approaching the spark-discharging voltage and the pore diameter increased with the increase of the electrolytic voltage. The pores ranging from 1 μm to several micrometers in diameter were widely distributed on the film produced under 300 V in the anodic oxidation using the mixed bath.
The widespread use of pure Ti in biomedical applications and in basic biomaterials research has led to an increasing interest in the properties of its surface oxides, and how they can be modified. In this work, which was part of a broad surface characterization of oxide films on pure Ti and Ti-6A1-4V, the chemical composition of anodic oxide films formed on pure Ti during electropolishing and anodic oxidation was investigated using multi-technique surface analysis (XPS, AES/SAM, SIMS, RBS and NRA). XPS and AES Ti line shapes show that the oxide formed is mainly TiO2, but the chemical composition can be modified by anion adsorption and/or incorporation when H2SO4 or H3PO4 electrolytes are used. Modification of the anodic oxide film composition also occurs during sterilization; increased Ca and H levels are observed by SIMS and NRA after autoclaving. AES and XPS depth profiles, together with RBS measurements, show that the oxide thickness depends linearly on the anodizing potential in the range 5–80 V, with a growth constant αm≈ 1.1 × 1016 oxygen atoms/V⋯ cm2. The present results are compared with parallel studies of the composition and microstructure of thermal and anodic oxides on pure Ti and Ti-6A1-4V. The demonstrated systematic variation of oxide properties opens up the possibility to study the influence of specific surface properties on the biological response to Ti materials.
The development of a post operative infection following the implantation of a foreign material, such as a total joint prosthesis, is one of the most feared complications in orthopedic surgery. Prevention of such bacterial infections is best accomplished through the delivery of antibiotics as close to the implant as possible. A novel method has been developed to attach, retain and release antibiotics from titanium based materials. This technique consists of forming porous surface coatings by anodizing and using the surface chemical properties of the oxide coatings to attach antibiotics. Coatings with pores in the size range 0.1 to 10 urn have been formed in acid as well as basic solutions. The thickness, stoichiometry and morphology of the coatings have been characterized by Rutherford backscattering spectrometry and electron spectroscopy techniques. The isoelectric point of the coatings has been measured by a streaming potential technique. The attachment and retainment of gentamicin sulfate, a cationic antibiotic, to the coatings has been investigated using microbiological and streaming potential methods. In vitro test results have shown that the duration of antimicrobial activity on the surface of anodized materials is dependent on the porosity and isoelectric point of the coatings. Using microporous oxide coatings, it has been found that antimicrobial activity could be retained for almost two weeks.
Thermal and anodic oxides on Ti6A14V were investigated by XPS, scanning AES, and SIMS, including depth profiling. The oxide layers on the alloy are predominantly TiO2 but have considerable concentrations of the alloying elements included in the oxide. Al, but not V, is observed in the outermost atomic layers of the oxide. Both A1 and V are present at relatively high maximum atomic concentrations (Al/Ti ≈ 0.17 and V/Ti ≈ 0.07) inside anodic oxides. The V concentration varies laterally over the surface, reflecting the variation of the V concentration in the underlying metal due to its two phases. The results are compared with the corresponding results for pure Ti. The implications of these results for the use of Ti6A14V as a biomaterial in surgical implants are discussed shortly.
This paper reports a novel electrochemical method for the preparation of protective titanium oxide coatings to improve the corrosion resistance and biocompatibility of the Ti6A14V surgical alloy. Scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), Auger electron spectroscopy (AES), and the X-ray diffraction technique were used to characterize the structure and the chemical composition of the oxide coatings.In vitro electrochemical corrosion studies were also conducted to assess the effectiveness of the oxide coatings in reducing the metal-ion release from Ti6A14V. The results suggest that the coating process may provide an effective means for improving the corrosion resistance and biocompatibility of titanium surgical alloys under physiological conditions.
On examine une technique electrochimique pour l'obtention de revetements ceramiques bioactifs de phosphate de calcium a des temperatures relativement basses. On utilise des solutions aqueuses d'electrolytes contenant des ions Ca et P.
Incluye bibliografía e índice
In vitro cellular responses of osteoblast-like cells were studied on titanium surfaces with different surface morphologies. Surface profilometry was used to determine whether rough or smooth surfaces with regular or irregular morphologies can be produced by conventional fabrication techniques. Significantly higher levels of cellular attachment were found using rough, sandblasted surfaces with irregular morphologies. These results correlate with recent in vivo findings and suggest that implants should be prepared with roughened surfaces at bony contact areas.
In order to study the interaction of calcium phosphate coatings with bone tissue, coated titanium cylinders with a standard size were implanted in dog femora. Coatings were made by plasma spraying powders of hydroxylapatite, beta-whitlockite, and tetracalciumphosphate particles. The plasma spraying process turns beta-whitlockite into alpha-TCP. Bone bonding and bone formation were evaluated by mechanical push-out tests and histological observations. Hydroxylapatite and tetracalciumphosphate coatings show an interface strength after 3 months of implantation of 34.3 +/- 6.5 MPa and 26.8 +/- 3.9 MPa, respectively, while alpha-TCP and blanco titanium lead to an interface strength of 10.0 +/- 3.5 MPa and 9.7 +/- 1.3 MPa, respectively. Histological examinations revealed that hydroxylapatite and tetracalciumphosphate give rise to an excellent bone formation, while alpha-TCP and blanco titanium evoked remodeling and less bone contact.
Osseointegration has been defined as the direct structural and functional connection between ordered, living bone and the surface of a load-carrying implant. To date, this concept has been described by descriptive histological and ultrastructural criteria but not by biochemical means. This review evaluates the basic science work performed on this concept and then applies the concept to the principle of osseous healing. Specific studies are cited where alterations in the healing response are due to clinical management of implant placement and how studies of surface properties may lead to further insights on implant design and prognosis. In addition, a review of bone expression as a function of in vitro stress applications is given. This is followed by an indepth review of the collagens and noncollagenous proteins, described to date, within isolated bone matrix. It is this collagenous matrix (especially type I) that is described as being close to and oriented with a glycoprotein component next to the implant surface. In turn, the large family of noncollagenous proteins are important in mediating bone proliferation, matrix accumulation, orientation, mineralization, and turnover. This section is followed by a discussion of specific growth factors as they may relate to osseous healing around an implant.
The purpose of the present study was to evaluate the influence of different surface characteristics on bone integration of titanium implants. Hollow-cylinder implants with six different surfaces were placed in the metaphyses of the tibia and femur in six miniature pigs. After 3 and 6 weeks, the implants with surrounding bone were removed and analyzed in undecalcified transverse sections. The histologic examination revealed direct bone-implant contact for all implants. However, the morphometric analyses demonstrated significant differences in the percentage of bone-implant contact, when measured in cancellous bone. Electropolished as well as the sandblasted and acid pickled (medium grit; HF/HNO3) implant surfaces had the lowest percentage of bone contact with mean values ranging between 20 and 25%. Sandblasted implants with a large grit and titanium plasma-sprayed implants demonstrated 30-40% mean bone contact. The highest extent of bone-implant interface was observed in sandblasted and acid attacked surfaces (large grit; HCl/H2SO4) with mean values of 50-60%, and hydroxylapatite (HA)-coated implants with 60-70%. However, the HA coating consistently revealed signs of resorption. It can be concluded that the extent of bone-implant interface is positively correlated with an increasing roughness of the implant surface.
Bioactive calcium phosphate ceramics (CPC) guide bone formation along their surface. This property is conceptually attractive from the viewpoint of enhancing early bone tissue formation in porous metal coatings. The various studies conducted to exploit this idea, however, reveal a considerable variability of the effect. This suggests material- and processing-induced parametric influences. Thus this study focuses on the formulation of model porous metal-CPC materials for use in one-parametric analyses of material factors. Easily reproducible, porous metals with a uniform porous structure and CPC coating are made with orderly oriented wire mesh (OOWM) porous metal coatings and electrophoretically deposited CPC films. The deposition of the ceramic can be hampered by adsorbed water. Subsequent vacuum sintering leads to several phase transformations: hydroxyapatite is transformed to a mixture of oxyhydroxyapatite and tetracalcium phosphate; the underlying titanium promotes the beta- to alpha-tricalcium phosphate transformation; and Ca-deficient hydroxyapatite is transformed to a mixture containing oxyhydroxyapatite and alpha- and beta-tricalcium phosphate. These phase transformations provoke a considerable increase of in vitro dissolution in 0.05 M tris buffered physiological solution.
Hydroxyapatite from two sources was electrophoretically deposited onto flat titanium plate material. Depending upon the deposition conditions various changes in the structure of the ceramic were identified. A well-adhering Ti-P compound was present at the interface. Hydroxyapatite oxygenated to various degrees and tetracalcium phosphate were reproducibly formed in the coating.
Dental implants vary markedly in the topography of the surfaces that contact cells. Four principles of cell behavior first observed in cell culture explain to some extent the interactions of cells and implants. (1) Contact guidance aligns cells and collagen fibers with fine grooves, such as those produced by machining. (2) Rugophilia describes the tendency of macrophages to prefer rough surfaces. (3) The two-center effect can explain the orientation of soft connective tissue cells and fibers attached to porous surfaces. (4) Haptotaxis may be involved in the formation of capsules around implants with low-energy surfaces.
When a biological system encounters an implant, reactions are induced at the implant-tissue interface. This article deals with various surface properties that are expected to influence tissue-implant reactions and methods available for implant surface characterization. Surface properties of interest are chemical composition, contamination and cleanliness, microarchitecture and structure, etc. Surface science offers a range of methods for surface characterization, eg, x-ray photoemission spectroscopy (XPS or ESCA) and Auger electron spectroscopy (AES), and preparation, which may be used to optimize implant fabrication with molecular level control. Examples are given from analytical and preparative work by XPS, AES, and electron microscopy on pure and alloyed titanium, with focus on surface oxides on these materials. Results of this type are valuable for basic research concerning implant-tissue reactions as well as production control and implant standardization.
A novel method has been developed to attach, retain, and release antibiotics from titanium based materials. This technique consists of forming porous surface coatings by anodizing and using the surface chemical properties of the oxide coatings to attach antibiotics. Coatings with pores in the size range 0.1-0.5 micron have been formed in acid solutions. The attachment and retainment of gentamicin sulfate, a cationic antibiotic, to the coatings has been investigated using microbiological methods. In vitro test results have shown that the duration of antimicrobial activity on the surface of anodized materials is dependent on the porosity and isoelectric point of the coatings. Using microporous oxide coatings formed in phosphoric acid solutions, it has been found that antimicrobial activity could be retained for more than 2 weeks.
Os-seointegration on titanium surfaces in vitroAnodic oxidation of tita-nium in phosphoric acid-sulfate acid system electro-lytic bath
- K D Chesmel
- D Mazur
- R S Tuan
K. D. Chesmel, D. Mazur, and R. S. Tuan, "Os-seointegration on titanium surfaces in vitro," In Trans-actions of the 4th World Biomaterials Congress, Ber-lin, 1992, p. 226. S. Ito, K. Koizuka, M. Hirochi, T. Onaka, H. Mat-sunaga, and T. Hanada, "Anodic oxidation of tita-nium in phosphoric acid-sulfate acid system electro-lytic bath," Shikizai, 61, 599-605 (1988).
CRC Critical Reviews in Biocompatibility
- T. Albrektsson
Osseointegration on titanium surfaces in vitro
- K D Chesmel
- D Mazur Andr
- . S Tuan
Bone healing around titanium implants with different surface oxide properties
- Larsson P Thomsen
- J Lausmaa
- B Kasemo
- . E Ericson
Surface analysis and biocompatibility test of hydroxyapatite coating on titanium
- Miyazaki S Fujimori
- Suzuki
Surface treatment of titanium (part 4): In vitro biocompatibility of titanium treated by the anodic spark oxidation
- T. Suzuki
- S. Fujimori
- A. Fujishima
- T. Miyazaki
- E. Suzuki
- S. Ibe
Bioceramics 5, Proceedings of the 5th International Symposium on Ceramics in Medicine
- S. Ban
- S. Maruno
Surface treatment of titanium (part 4): In vitro biocompatibility of titanium treated by the anodic spark oxidation
- Suzuki T.