The Effect of Ti-6Al-4V Alloy Surface Structure on the Adhesion and Morphology of Unidirectional Freeze-Coated Gelatin

The modification of a metal implant surface with a biomimetic coating of bone-like anisotropic and graded porosity structures to improve its biological anchorage with the surrounding bone tissue at implanting, is still a high challenge. In this paper, we present an innovative way of a gelatin (GEL) dip-coating on Ti-6Al-4V substrates of different square-net surface textures by the unidirectional deep-freezing process at simultaneous cross-linking using carbodiimide chemistry. Different concentrations of GEL solution were used to study the changes in morphology, density, and mechanical properties of the coatings. In addition, the surface free energy and polarity of Ti-6Al-4V substrate surfaces and GEL solutions have been evaluated to assess the wetting properties at the substrate interfaces, and to describe the adhesion of GEL macromolecules with their surfaces, being supported by mechanical pull-out testing. The results indicate that the coating’s morphology depends primarily on the Ti-6Al-4V substrate’s surface texture and second, on the concentration of GEL, which further influences their adhesion properties, orientation, morphological arrangement, as well as compression strength. The substrate with a 300 × 300 μm2 texture resulted in a highly adhered GEL coating with ≥80% porosity, interconnected and well-aligned pores of 75–200 μm, required to stimulate the bone ingrowth, mechanically and histologically.

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Optimizing Manufacturing and Osseointegration of Ti6Al4V Implants through Precision Casting and Calcium and Phosphorus Ion Implantation? In Vivo Results of a Large-Scale Animal Trial

Materials ◽

10.3390/ma13071670 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1670 ◽

Cited By ~ 2

Author(s):

Wölfle-Roos JV ◽

Katmer Amet B ◽

Fiedler J ◽

Michels H ◽

Kappelt G ◽

...

Keyword(s):

Ion Implantation ◽

Large Scale ◽

In Vivo Studies ◽

Control Group ◽

Implant Surface ◽

Precision Casting ◽

Pull Out ◽

Significant Difference ◽

Calcium And Phosphorus

Background: Uncemented implants are still associated with several major challenges, especially with regard to their manufacturing and their osseointegration. In this study, a novel manufacturing technique—an optimized form of precision casting—and a novel surface modification to promote osseointegration—calcium and phosphorus ion implantation into the implant surface—were tested in vivo. Methods: Cylindrical Ti6Al4V implants were inserted bilaterally into the tibia of 110 rats. We compared two generations of cast Ti6Al4V implants (CAST 1st GEN, n = 22, and CAST 2nd GEN, n = 22) as well as cast 2nd GEN Ti6Al4V implants with calcium (CAST + CA, n = 22) and phosphorus (CAST + P, n = 22) ion implantation to standard machined Ti6Al4V implants (control, n = 22). After 4 and 12 weeks, maximal pull-out force and bone-to-implant contact rate (BIC) were measured and compared between all five groups. Results: There was no significant difference between all five groups after 4 weeks or 12 weeks with regard to pull-out force (p > 0.05, Kruskal Wallis test). Histomorphometric analysis showed no significant difference of BIC after 4 weeks (p > 0.05, Kruskal–Wallis test), whereas there was a trend towards a higher BIC in the CAST + P group (54.8% ± 15.2%), especially compared to the control group (38.6% ± 12.8%) after 12 weeks (p = 0.053, Kruskal–Wallis test). Conclusion: In this study, we found no indication of inferiority of Ti6Al4V implants cast with the optimized centrifugal precision casting technique of the second generation compared to standard Ti6Al4V implants. As the employed manufacturing process holds considerable economic potential, mainly due to a significantly decreased material demand per implant by casting near net-shape instead of milling away most of the starting ingot, its application in manufacturing uncemented implants seems promising. However, no significant advantages of calcium or phosphorus ion implantation could be observed in this study. Due to the promising results of ion implantation in previous in vitro and in vivo studies, further in vivo studies with different ion implantation conditions should be considered.

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Bone Ingrowth Around an Uncemented Femoral Implant Using Mechanoregulatory Algorithm: A Multiscale Finite Element Analysis

Journal of Biomechanical Engineering ◽

10.1115/1.4052227 ◽

2021 ◽

Author(s):

Basil Mathai ◽

Sanjay Gupta

Keyword(s):

Finite Element ◽

Bone Tissue ◽

Bone Ingrowth ◽

Progressive Increase ◽

Stair Climbing ◽

Porous Coating ◽

Fe Model ◽

Implant Surface ◽

Element Analysis ◽

Medial Side

Abstract The primary fixation and long-term stability of a cementless femoral implant depend on bone ingrowth within the porous coating. Although attempts were made to quantify the peri-implant bone ingrowth using the finite element (FE) analysis and mechanoregulatory principles, the tissue differentiation patterns on a porous-coated hip stem have scarcely been investigated. The objective of this study is to predict the spatial distribution of evolutionary bone ingrowth around an uncemented hip stem, using a 3D multiscale mechanobiology based numerical framework. Multiple load cases representing a variety of daily living activities, including walking, stair climbing, sitting down and standing up from a chair, were used as applied loading conditions. The study accounted for the local variations in host bone material properties and implant-bone relative displacements of the macroscale implanted FE model, in order to predict bone ingrowth in microscale representative volume elements (RVEs) of twelve interfacial regions. In majority RVEs, 20-70% bone tissue (immature and mature) was predicted after two months, contributing towards a progressive increase in average Young's modulus (1200-3000 MPa) of the inter-bead tissue layer. Higher bone ingrowth (mostly greater than 60%) was predicted in the antero-lateral regions of the implant, as compared to the postero-medial side (20-50%). New bone tissue was formed deeper inside the inter-bead spacing, adhering to the implant surface. The study helps to gain an insight into the degree of osseointegration of a porous-coated femoral implant.

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Hard Quasicrystalline Coatings Deposited by HVOF Thermal Spray to Reduce Ice Accretion in Aero-Structures Components

Coatings ◽

10.3390/coatings10030290 ◽

2020 ◽

Vol 10 (3) ◽

pp. 290

Author(s):

J. Mora ◽

P. García ◽

R. Muelas ◽

A. Agüero

Keyword(s):

Thermal Spray ◽

Surface Engineering ◽

High Hardness ◽

Ceramic Materials ◽

Ice Accretion ◽

Adhesion Properties ◽

Wetting Properties ◽

Lap Shear ◽

Hvof Thermal Spray ◽

Ice Adhesion

Weather hazards, in particular icing conditions, are an important contributing factor in aviation accidents and incidents worldwide. Many different anti-icing strategies are currently being explored to find suitable long-lasting solutions, such as surface engineering, which can contribute to reduce ice accumulation. Quasicrystals (QCs) are metallic materials, but with similar properties to those of ceramic materials, such as low thermal and electrical conductivities, and high hardness. In particular, QCs that have low surface energy are commercially used as coatings to replace polytetrafluoroethylene (PTFE), also known as Teflon, on frying pans, as they do not scratch easily. PTFE exhibits excellent anti-wetting and anti-icing properties and therefore QCs appear as good candidates to be employed as ice-phobic coatings. Al-based QCs have been applied by High Velocity Oxyfuel (HVOF) thermal spray on typically used aeronautic materials, such as Ti and Al alloys, as well as steels. The coatings have been characterized and evaluated, including the measurement of hardness, roughness, wetting properties, ice accretion behavior in an icing wind tunnel (IWT), and ice adhesion by a double lap shear test. The coatings were studied, both as-deposited, as well as after grinding, in order to study the effect of the surface roughness and morphology on the ice accretion and adhesion properties. The QC coating was compared with PTFE and two polyurethane (PU)-based commercial paints, one of them known to have anti-icing properties, and the results indicate an ice accretion reduction relative to these two materials, and ice adhesion lower than bare AA6061-T6, or the PU paint in the ground version of one of the two QCs. Since the QC coatings are hard (GPa Vickers hardness > 5), a durable behavior is expected.

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Comparison and Impact of Different Fiber Debond Techniques on Fiber Reinforced Flexible Composites

Polymers ◽

10.3390/polym12020472 ◽

2020 ◽

Vol 12 (2) ◽

pp. 472 ◽

Cited By ~ 3

Author(s):

Julia Beter ◽

Bernd Schrittesser ◽

Boris Maroh ◽

Essi Sarlin ◽

Peter Filipp Fuchs ◽

...

Keyword(s):

Single Fiber ◽

Fiber Bundles ◽

Testing Device ◽

Adhesion Properties ◽

Test Setup ◽

Flexible Composites ◽

Pull Out ◽

Specimen Holder ◽

Microbond Test ◽

Modified Test

The focus of this paper is the realization and verification of a modified fiber bundle pull-out test setup to estimate the adhesion properties between threads and elastic matrix materials with a more realistic failure mode than single fiber debond techniques. This testing device including a modified specimen holder provides the basis for an adequate estimation of the interlaminar adhesion of fiber bundles including the opportunity of a faster, easier, and more economic handling compared to single fiber tests. The verification was done with the single-fiber and microbond test. Overall, the modified test setup showed the typical pull-out behavior, and the relative comparability between different test scales is given.

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Novel Method for Hydroxyapatite Coating by Hydrothermal Hot-Pressing via Double Layered Capsule

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.309-311.647 ◽

2006 ◽

Vol 309-311 ◽

pp. 647-650 ◽

Cited By ~ 1

Author(s):

Takamasa Onoki ◽

Toshiyuki Hashida

Keyword(s):

Coating Layer ◽

Hydrothermal Condition ◽

Confining Pressure ◽

Ceramic Coatings ◽

Coating Materials ◽

Adhesion Properties ◽

Pull Out ◽

Ha Coating ◽

Outer Capsule ◽

Novel Method

A new hydrothermal method is proposed which enables us to prepare thin hydroxyapatite (HA) ceramic coatings on Ti substrates with a curved surface at low temperatures. The method uses double layered capsules in order to produce a suitable hydrothermal condition; the inner capsule encapsulates the coating materials and a Ti substrate, and the outer capsule is subjected to isostatic pressing under the hydrothermal condition. In this study, it is demonstrated that a pure HA ceramic layer with the thickness of 50 µm could be coated to a Ti cylindrical rod at the low temperature as low as 135°C under the confining pressure of 40 MPa. Pull-out tests were conducted to obtain an estimate for the adhesion properties of the HA coating prepared by the double layered capsule method. The shear strength obtained from the pull-out tests was in the range of 4.0-5.5 MPa. It was also shown that the crack propagation occurred within the HA coating layer, not along the HA/Ti interface in the pull-out tests.

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TiO2/PCL Hybrid Layers Prepared via Sol-Gel Dip Coating for the Surface Modification of Titanium Implants: Characterization and Bioactivity Evaluation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.760.353 ◽

2015 ◽

Vol 760 ◽

pp. 353-358 ◽

Cited By ~ 2

Author(s):

Michelina Catauro ◽

Flavia Bollino ◽

Ferdinando Papale ◽

Giuseppe Lamanna

Keyword(s):

Sol Gel ◽

Pure Titanium ◽

Dip Coating ◽

Biological Properties ◽

Titanium Implants ◽

Human Blood Plasma ◽

Commercially Pure Titanium ◽

Implant Surface ◽

Titanium Grade ◽

Dip Coating Technique

When bioactive coatings are applied to medical implants by means of sol-gel dip coating technique, the biological proprieties of the implant surface can be modified to match the properties of the surrounding tissues. In this study, sol-gel method is used to synthesized organic-inorganic nanocomposites materials consisting of an inorganic titania matrix in which 10 wt% of a biodegradable polymer, the poly-ε-caprolactone (PCL), was incorporated. The synthesized materials, in sol phase, were used to dip-coat a commercially pure titanium grade 4 substrate in order to improve its surface biological properties. Materials were characterized using Fourier transform infrared spectroscopy (FT-IR) and a morphological analysis of the obtained films was performed via scanning electron microscopy (SEM). Coating bioactivity was investigated by soaking coated substrates in a fluid simulating the human blood plasma (SBF) and successively evaluating the formation of a hydroxyapatite layer on their surface by means of SEM/EDX (energy dispersive X-ray).

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Nano Hydroxyapatite-coated Implants Improve Bone Nanomechanical Properties

Journal of Dental Research ◽

10.1177/0022034512463240 ◽

2012 ◽

Vol 91 (12) ◽

pp. 1172-1177 ◽

Cited By ~ 58

Author(s):

R. Jimbo ◽

P.G. Coelho ◽

M. Bryington ◽

M. Baldassarri ◽

N. Tovar ◽

...

Keyword(s):

Titanium Alloy ◽

Dental Implants ◽

Tissue Quality ◽

Implant Surface ◽

Nanomechanical Properties ◽

Nanoparticle Surface ◽

Heat Treated ◽

Coated Implant ◽

Bone To Implant Contact ◽

Surrounding Bone

Nanostructure modification of dental implants has long been sought as a means to improve osseointegration through enhanced biomimicry of host structures. Several methods have been proposed and demonstrated for creating nanotopographic features; here we describe a nanoscale hydroxyapatite (HA)-coated implant surface and hypothesize that it will hasten osseointegration and improve its quality relative to that of non-coated implants. Twenty threaded titanium alloy implants, half prepared with a stable HA nanoparticle surface and half grit-blasted, acid-etched, and heat-treated (HT), were inserted into rabbit femurs. Pre-operatively, the implants were morphologically and topographically characterized. After 3 weeks of healing, the samples were retrieved for histomorphometry. The nanomechanical properties of the surrounding bone were evaluated by nanoindentation. While both implants revealed similar bone-to-implant contact, the nanoindentation demonstrated that the tissue quality was significantly enhanced around the HA-coated implants, validating the postulated hypothesis.

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Nontraumatic Implant Explantation: A Biomechanical and Biological Analysis in Sheep Tibia

Journal of Oral Implantology ◽

10.1563/aaid-joi-d-14-00193 ◽

2016 ◽

Vol 42 (1) ◽

pp. 3-11

Author(s):

Eduardo Anitua ◽

Alia Murias-Freijo ◽

Laura Piñas ◽

Ricardo Tejero ◽

Roberto Prado ◽

...

Keyword(s):

Bone Structure ◽

Angular Displacement ◽

Primary Stability ◽

Preclinical Research ◽

Implant Surface ◽

Minimal Damage ◽

Conventional Microscopy ◽

Underlying Mechanisms ◽

Surrounding Bone ◽

Angle Of Rotation

Preclinical research in a sheep tibia model has been conducted to evaluate the underlying mechanisms of the nontraumatic implant explantation of failed implants, which allow placing a new one in the bone bed. Twelve dental implants were placed in sheep diaphysis tibia and once osseointegrated they were explanted using a nontraumatic implant explantation approach. Implant osseointegration and explantation were monitored by means of frequency resonance, removal torque, and angle of rotation measurement. The host bone bed and the explanted implant surface were analyzed by conventional microscopy and scanning electron microscope. Results show that osseointegration was broken with an angular displacement of less than 20°. In this situation the implant returns to implant stability quotient values in the same range of their primary stability. Moreover, the explantation technique causes minimal damage to the surrounding bone structure and cellularity. This nontraumatic approach allows the straightforward replacement of failed implants and emerges as a promising strategy to resolve clinically challenging situations.

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Evaluation of Chemical Mechanical Polishing-Based Surface Modification on 3D Dental Implants Compared to Alternative Methods

Materials ◽

10.3390/ma11112286 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2286 ◽

Cited By ~ 4

Author(s):

Riaid Alsaeedi ◽

Z. Ozdemir

Keyword(s):

Surface Modification ◽

Surface Chemistry ◽

Dental Implants ◽

Chemical Mechanical Polishing ◽

Mechanical Performance ◽

Roughness Parameter ◽

Mechanical Polishing ◽

Alternative Methods ◽

Implant Surface ◽

Pull Out

Chemical mechanical polishing (CMP) has been introduced in previous studies as a synergistic technique to modify the surface chemistry and topography of titanium-based implants to control their biocompatibility. In this study, the effectiveness of CMP implementation on titanium-based implant surface modification was compared to machined implants, such as baseline and etching and biphasic calcium phosphate (BCP) particle-based sand blasting treatments, in terms of the surface chemical and mechanical performance. Initially, a lab-scale 3D CMP technique was developed and optimized on commercial dental implant samples. The mechanical competitiveness of the dental implants treated with the selected methods was examined with the Vickers microhardness test as well as pull-out force and removal torque force measurements. Furthermore, the surface structures were quantified through evaluation of the arithmetic mean roughness parameter (Ra). Subsequently, the surface chemistry changes on the treated implants were studied as wettability by contact angle measurement, and surface passivation was evaluated through electrochemical methods. In each evaluation, the CMP treated samples were observed to perform equal or better than the baseline machined implants as well as the current method of choice, the BCP treatment. The ability to control the surface topography and chemistry simultaneously by the use of CMP technique is believed to be the motivation for its adaptation for the modification of implant surfaces in the near future.

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Polyamide 12/E-glass Fabric Composite Production with Dip-coating

MATEC Web of Conferences ◽

10.1051/matecconf/201818801022 ◽

2018 ◽

Vol 188 ◽

pp. 01022

Author(s):

Aylin Bekem ◽

Ahmet Unal

Keyword(s):

Mechanical Properties ◽

Dip Coating ◽

Woven Fabric ◽

Fibre Failure ◽

Polyamide 12 ◽

Impact Tests ◽

Pull Out ◽

Fabric Composite ◽

Composite Production ◽

Coated Fabrics

In this study PA12 was reinforced with E-glass woven fabric by dip-coating. PA12 powder and ethanol suspensions were prepared with ratios at 30, 40 and 50% of powder to obtain different fibre contents. Coated fabrics were laid-up and kept in oven at 60°C to evaporate ethanol. Then it was placed in a compression mould and pressed. Obtained laminates were subjected to tensile, bending and impact tests. Fractured surfaces were observed. It was found that mechanical properties were highest when 40% PA powder used in suspension with dip-coating with additional lamination. Fibre failure and fibre pull-out were observed on fractured surfaces.

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