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26 pages, 7227 KiB  
Article
Uncertainty-Based Scale Identification and Process–Topography Interaction Analysis via Bootstrap: Application to Grit Blasting
by François Berkmans, Julie Lemesle, Robin Guibert, Michal Wieczorowski, Christopher Brown and Maxence Bigerelle
Fractal Fract. 2025, 9(1), 48; https://doi.org/10.3390/fractalfract9010048 - 17 Jan 2025
Viewed by 276
Abstract
Finding the relevant scale to observe the influence of a process is one of the most important purposes of multiscale surface characterization. This study investigates various methods to determine a pertinent scale for evaluating the relationship between the relative area and grit blasting [...] Read more.
Finding the relevant scale to observe the influence of a process is one of the most important purposes of multiscale surface characterization. This study investigates various methods to determine a pertinent scale for evaluating the relationship between the relative area and grit blasting pressure. Several media types were tested alongside two different methods for calculating the relative area and three bootstrapping approaches for scale determination through regression. Comparison with the existing literature highlights innovations in roughness parameter characterization, particularly the advantages of relative area over traditional parameters like Sa. This study also discusses the relevance of different media types in influencing surface topography. Additionally, insights from a similar study on the multiscale Sdq parameter and blasting pressure correlation are integrated, emphasizing a scale relevance akin to our Sdr method’s 120 µm cut-off length. Overall, our findings suggest a pertinent scale of 10,000 µm2 for the Patchwork method and a 120 µm cut-off length for the Sdr method, derived from bootstrapping on residual regression across all media. At the relevant scale, every value of R2 inferior to 0.83 is not significant with the threshold of 5% for the two methods of calculation of the relative area. This study enhances the understanding of how media types and blasting pressures impact surface topography, offering insights for refining material processing and surface treatment strategies. Full article
(This article belongs to the Special Issue Fractal Analysis and Its Applications in Materials Science)
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Figure 1

Figure 1
<p>Comparison of two methods, Sdr (ISO 25178-2) and Patchwork, for calculating relative areas of surface topographies created by blasting with glass beads. The points represent the median of the relative area values, categorized by calculation method and pressure. Blue symbols indicate the median points for the Patchwork method, while red symbols correspond to the Sdr method. The scale refers to the cut-off length of the low-pass Gaussian filter applied in the Sdr calculation. For the Patchwork method, the tile size in µm<sup>2</sup> is equal to half the square of the cut-off length.</p> Full article ">Figure 2
<p>Surface topographies of TA6V surfaces grit-blasted at 2 bar (<b>a</b>), 4 bar (<b>b</b>), and 8 bar (<b>c</b>) with the C300 medium. The aggressiveness of the medium can make it difficult to assess visually the gradation in blasting intensity. More surface topographies are shown in <a href="#app1-fractalfract-09-00048" class="html-app">Appendix A</a>.</p> Full article ">Figure 3
<p>Diagram of the two calculation methods used in this study, shown in terms of relative length. The blue continuous line represents a real surface. The green line, a linear interpolation between measured height points, represents our measured profile (the Sdr method calculates the relative length at the sampling scale). The red line illustrates the profile obtained by the Patchwork method.</p> Full article ">Figure 4
<p>Results of the linear regressions of the relative area as a function of pressure for the two calculation methods. Simulations from 0 to 9 are obtained from bootstrapping replication of the real data and then averaged. The results come from measurements performed on surfaces blasted with the C 300 medium (corundum). Each simulation corresponds to an R<sup>2</sup> value, which is then averaged.</p> Full article ">Figure 5
<p>Analysis of the R<sup>2</sup> distributions according to the scale of calculation for relative area under hypotheses H1 (<b>a</b>) and H0 (<b>b</b>) for the three bootstrapping methods: simple bootstrap (<b>i</b>), bootstrap based on pairs (<b>ii</b>), and bootstrap based on residuals (<b>iii</b>). The tile size of the Patchwork method (in µm<sup>2</sup>) is equal to half the square of the cut-off length of the Sdr method. Two plots are proposed for each bootstrapping method: the first one based on the media (<b>c</b>,<b>e</b>,<b>g</b>) and the second one based on the method of the relative area calculation, Sdr or Patchwork (<b>d</b>,<b>f</b>,<b>h</b>).</p> Full article ">Figure 5 Cont.
<p>Analysis of the R<sup>2</sup> distributions according to the scale of calculation for relative area under hypotheses H1 (<b>a</b>) and H0 (<b>b</b>) for the three bootstrapping methods: simple bootstrap (<b>i</b>), bootstrap based on pairs (<b>ii</b>), and bootstrap based on residuals (<b>iii</b>). The tile size of the Patchwork method (in µm<sup>2</sup>) is equal to half the square of the cut-off length of the Sdr method. Two plots are proposed for each bootstrapping method: the first one based on the media (<b>c</b>,<b>e</b>,<b>g</b>) and the second one based on the method of the relative area calculation, Sdr or Patchwork (<b>d</b>,<b>f</b>,<b>h</b>).</p> Full article ">Figure 6
<p>Surface topographies of TA6V samples grit-blasted at 2 bar (<b>a</b>), 4 bar (<b>b</b>), and 8 bar (<b>c</b>) with the C300 medium. The range of height varies significantly. The surfaces are the same as those presented in <a href="#fractalfract-09-00048-f002" class="html-fig">Figure 2</a> but this time filtered with a low-pass Gaussian filter at a 120 µm cut off (the relevance scale).</p> Full article ">Figure 7
<p>Distributions of the R<sup>2</sup> values at all scales under H1 (<b>a</b>) and H0 (<b>b</b>) for every method of bootstrapping computation: simple bootstrap (<b>i</b>), paired bootstrap (<b>ii</b>), and bootstrap based on residuals (<b>iii</b>). The black lines on the H0 plots are the threshold value at 95% of the R<sup>2</sup> distribution: 0.59 (<b>bi</b>), 0.91 (<b>bii</b>), and 0.83 (<b>biii</b>).</p> Full article ">Figure 8
<p>Evolution of the slope (<b>i</b>) and intercept (<b>ii</b>) as a function of scale for H1 (<b>a</b>) and H0 (<b>b</b>) using bootstrap based on residuals.</p> Full article ">Figure 9
<p>Distribution of the R<sup>2</sup> values by medium at the relevant scale for the Patchwork (<b>i</b>) and Sdr (<b>ii</b>) methods and for H1 (<b>a</b>) and H0 (<b>b</b>). The digits after 250 indicate the blasting series (e.g., G 250-1 = first series of the G250 medium).</p> Full article ">Figure 10
<p>Box plots of the relative area values by pressure at the relevance scale (tile size between 10,000 µm<sup>2</sup> and 14,000 µm<sup>2</sup> for the Patchwork method and cut-off length of 120 µm for the Sdr method). The results are presented by medium (<b>a</b>–<b>e</b>) and calculation method (<b>i</b>,<b>ii</b>).</p> Full article ">Figure 10 Cont.
<p>Box plots of the relative area values by pressure at the relevance scale (tile size between 10,000 µm<sup>2</sup> and 14,000 µm<sup>2</sup> for the Patchwork method and cut-off length of 120 µm for the Sdr method). The results are presented by medium (<b>a</b>–<b>e</b>) and calculation method (<b>i</b>,<b>ii</b>).</p> Full article ">Figure 11
<p>Bivariate density (intercept, slope) of the linear regression at the relevant scale between relative area for the three media of grit blasting and the two methods of relative area calculation (Patchwork, Sdr) obtained by bootstrap on residuals. The red frame is a zoom with ellipses of confidence at 95%.</p> Full article ">Figure A1
<p>Surface topographies of blasted surface using the medium G 100 at (<b>a</b>) 2 bar of pressure, (<b>b</b>) 4 bar of pressure, and (<b>c</b>) 8 bar of pressure.</p> Full article ">Figure A2
<p>Surface topographies of blasted surface using the medium G 250 at (<b>a</b>) 2 bar of pressure, (<b>b</b>) 4 bar of pressure, and (<b>c</b>) 8 bar of pressure.</p> Full article ">Figure A3
<p>Surface topographies of blasted surface using the medium C 300 at (<b>a</b>) 2 bar of pressure, (<b>b</b>) 4 bar of pressure, and (<b>c</b>) 8 bar of pressure.</p> Full article ">
15 pages, 5848 KiB  
Article
Adhesion-Related Phenomena of Stellite 6 HVOF Sprayed Coating Deposited on Laser-Textured Substrates
by Žaneta Dlouhá, Josef Duliškovič, Marie Frank Netrvalová, Jana Naďová, Marek Vostřák, Sebastian Kraft, Udo Löschner, Jiří Martan and Šárka Houdková
Materials 2024, 17(20), 5069; https://doi.org/10.3390/ma17205069 - 17 Oct 2024
Viewed by 773
Abstract
The focus of this research is to examine the feasibility of using laser texturing as a method for surface preparation prior to thermal spraying. The experimental part includes the thermal spraying of a Stellite 6 coating by High Velocity Oxygen Fuel (HVOF) technology [...] Read more.
The focus of this research is to examine the feasibility of using laser texturing as a method for surface preparation prior to thermal spraying. The experimental part includes the thermal spraying of a Stellite 6 coating by High Velocity Oxygen Fuel (HVOF) technology on laser-textured substrates. The thermal spraying of this coating was deposited both on conventional substrate material (low carbon steel) and on substrates that had been previously heat treated (nitrided steel). The properties of the coatings were analysed using scanning electron microscopy (SEM), optical microscopy (OM) and Raman spectroscopy. Adhesion was assessed through a tensile adhesion test. The results showed the usability of laser texturing in the case of carbon steel, which was comparable or even better than traditional grit blasting. For nitrided steel, the problem remains with the hardness and brittleness of the nitrided layer, which allows for the propagation of brittle cracks near the interface and thus reduces the adhesion strength. Full article
(This article belongs to the Special Issue Advances in Metal Coatings for Wear and Corrosion Applications)
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Figure 1

Figure 1
<p>Laser texturing patterns.</p> Full article ">Figure 2
<p>Examples of laser texturing geometries: (<b>a</b>) CSD4; (<b>b</b>) CST1; (<b>c</b>) CSC2.</p> Full article ">Figure 3
<p>Measurement positions and measured Raman spectra on the surface of 3 types of substrates on 5 differently placed measurements.</p> Full article ">Figure 4
<p>The dimple structure of (<b>a</b>) CSD1 and (<b>b</b>) NSD1.</p> Full article ">Figure 5
<p>Examples of Stellite 6 coating, deposited on carbon steel substrate with various texture geometry: (<b>a</b>) CSD1, (<b>b</b>) CSC2 and (<b>c</b>) CST3.</p> Full article ">Figure 6
<p>The interface between Stellite 6 coating and (<b>a</b>) carbon steel substrate CSD1 and (<b>b</b>) nitride steel NSD1. The red arrows indicate multiple cracks in the thin layer beneath the surface of the nitrided substrate.</p> Full article ">Figure 7
<p>Graph of the EDX analysis on (<b>a</b>) NSD1 and (<b>b</b>) NSC3. The numbers 23 and 25 in the figure represent the total number of measurements taken.</p> Full article ">Figure 8
<p>HV0.3 distribution for nitride (NS—2 measurements), laser-textured (NSC4 without coating—2 measurements), and laser-textured and sprayed samples (NSC4 with coating—3 measurements).</p> Full article ">
13 pages, 35411 KiB  
Article
The Effect of Shot Blasting Abrasive Particles on the Microstructure of Thermal Barrier Coatings Containing Ni-Based Superalloy
by Jianping Lai, Xin Shen, Xiaohu Yuan, Dingjun Li, Xiufang Gong, Fei Zhao, Xiaobo Liao and Jiaxin Yu
Coatings 2024, 14(10), 1312; https://doi.org/10.3390/coatings14101312 - 14 Oct 2024
Viewed by 764
Abstract
Grit particles remaining on the substrate surface after grit blasting are generally considered to impair the thermal performance of thermal barrier coatings (TBCs). However, the specific mechanisms by which these particles degrade the multilayer structure of TBCs during thermal cycling have not yet [...] Read more.
Grit particles remaining on the substrate surface after grit blasting are generally considered to impair the thermal performance of thermal barrier coatings (TBCs). However, the specific mechanisms by which these particles degrade the multilayer structure of TBCs during thermal cycling have not yet been fully elucidated. In this study, the superalloy substrate was grit-blasted using various processing parameters, followed by the deposition of thermal barrier coatings (TBCs) consisting of a metallic bond coat (BC) and a ceramic top coat (TC). After thermal shock tests, local thinning or discontinuities in the thermally grown oxide (TGO) layer were observed in TBCs where large grit particles were embedded at the BC/substrate interface. Moreover, cracks originated at the concave positions of the TGO layer and propagated vertically towards BC; these cracks may be associated with additional stress imposed by the foreign grit particles during thermal cycling. At the BC/substrate interface, crack origins were observed in the vicinity of large grit particles (~50 μm). Full article
(This article belongs to the Special Issue Additive Manufacturing of Metallic Components for Hard Coatings)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>(<b>a</b>,<b>b</b>) Backscattered electron and (<b>c</b>,<b>d</b>) corresponding software-processed images of grit-blasted surfaces for (<b>a</b>,<b>c</b>) sample A and (<b>b</b>,<b>d</b>) sample B.</p> Full article ">Figure 2
<p>(<b>a</b>,<b>c</b>) Backscattered electron and corresponding (<b>b</b>,<b>d</b>) secondary electron images of grit-blasted surfaces for (<b>a</b>,<b>b</b>) sample A and (<b>c</b>,<b>d</b>) sample B.</p> Full article ">Figure 3
<p>The coating spallation degree of the samples A and B subjected to 300 thermal cycles.</p> Full article ">Figure 4
<p>The cross-sectional SEM images of the (<b>a</b>,<b>b</b>) as-deposited TBCs and the (<b>c</b>,<b>d</b>) TBCs after 300 thermal shocking cycles: (<b>a</b>,<b>c</b>) sample A and (<b>b</b>,<b>d</b>) sample B.</p> Full article ">Figure 5
<p>(<b>a</b>) The cross-sectional SEM SEM image of TBCs for sample A after thermal shocking cycles. (<b>b</b>–<b>f</b>) Elemental mapping of interfacial microstructure of the TBCs.</p> Full article ">Figure 6
<p>(<b>a</b>) The cross-sectional SEM image of TBCs for sample B after thermal shocking cycles. (<b>b</b>–<b>f</b>) Elemental mapping of interfacial microstructure of the TBCs.</p> Full article ">Figure 7
<p>High magnified cross-sectional SEM elemental mapping of oxide scale regions inside BC in sample B after thermal cycles. (<b>a</b>) Cross-sectional SEM image of TBCs for sample B after thermal cycles. (<b>b</b>) A high-magnified rectangle in (<b>a</b>) shows the microstructure of the oxide scale inside BC. Elemental mapping of the oxide scale region. (<b>c</b>–<b>f</b>) Elemental mapping of the oxide scale in BC.</p> Full article ">Figure 8
<p>(<b>a</b>) Cross-sectional SEM image of TBCs for sample B after thermal cycles. (<b>b</b>) A magnified rectangle in (<b>a</b>) shows the microstructure around the large alumina particle. (<b>c</b>–<b>f</b>) Elemental mapping of alumina particle region embedded at BC/substrate surface.</p> Full article ">Figure 9
<p>Nanoindentation array on alumina particles with different sizes. (<b>a</b>,<b>c</b>,<b>e</b>) optical metallurgical images showing the microstructure around the particles. (<b>b</b>,<b>d</b>,<b>f</b>) The nanohardness map around the large medium and small particles shows the substrate hardening due to the impact of the particles, respectively.</p> Full article ">
14 pages, 2965 KiB  
Article
Bonding Effectiveness of Veneering Ceramic to Zirconia after Different Grit-Blasting Treatments
by Francesca Zicari, Carlo Monaco, Marcio Vivan Cardoso, Davide Silvestri and Bart Van Meerbeek
Dent. J. 2024, 12(7), 219; https://doi.org/10.3390/dj12070219 - 15 Jul 2024
Viewed by 1101
Abstract
Objective: To determine the effect of grit-blasting before and after sintering on the surface roughness of zirconia and the micro-tensile bond strength of a pressable veneering ceramic to zirconia. Methods: Pre-sintered zirconia blocks (IPS e.max ZirCAD, Ivoclar) were divided into four test groups [...] Read more.
Objective: To determine the effect of grit-blasting before and after sintering on the surface roughness of zirconia and the micro-tensile bond strength of a pressable veneering ceramic to zirconia. Methods: Pre-sintered zirconia blocks (IPS e.max ZirCAD, Ivoclar) were divided into four test groups of three specimens each and a control group (‘CTR’; no surface treatment). Pre-S-30, Pre-S-50, and Pre-S-110 were grit-blasted with 30-µm SiO2-coated Al2O3, 50-µm Al2O3 and 110-µm Al2O3 particles, respectively, before sintering. Post-S-30 was grit-blasted with 30-µm SiO2-coated Al2O3 after sintering. For each treatment, the surface roughness was measured (Ra, Perthometer M4P, Mahr Perthen). After sintering the zirconia blocks, a liner was applied and a pressable ceramic (IPS e.max ZirPress, Ivoclar) was heat-pressed. Sixteen microbars were obtained from each block and submitted to micro-tensile bond-strength (µTBS) testing. Data were analyzed with one-way ANOVA. Any correlation between Ra and µTBS was evaluated (Sperman test). Results: Grit-blasting before sintering with 110-µm Al2O3 (RaPre-S-110 = 3.4 ± 0.4 µm), 50-µm Al2O3 (RaPre-S-50 = 2.3 ± 0.5 µm), and 30-µm SiO2-coated Al2O3 (RaPre-S-30 = 1.2 ± 0.2 µm) resulted in significantly higher roughness than grit-blasting after sintering with 30-µm SiO2-coated Al2O3 (RaPost-S-30 = 0.5 ± 0.1 µm). The highest µTBS was measured when the sintered zirconia was grit-blasted with 30-μm SiO2-coated Al2O3 (µTBSPost-S-30 = 28.5 ± 12.6 MPa), which was significantly different from that of specimens that were grit-blasted before sintering (µTBSPre-S-30 = 21.8 ± 10.4; µTBSPre-S-50 = 24.1 ± 12.6; µTBSPre-S-110 = 26.4 ± 14.1) or were not grit-blasted (µTBSCTR = 20.2 ± 11.2). Conclusions: Grit-blasting zirconia before sintering enhanced the surface roughness proportionally to the particle size of the sand used. Grit-blasting with 30-µm SiO2-coated Al2O3 after sintering improved bonding of the veneering ceramic to zirconia. Clinical Significance: As grit-blasting with 30-µm SiO2-coated Al2O3 after sintering improved bonding of the veneering ceramic to zirconia, it may reduce veneering ceramic fractures/chipping. Full article
(This article belongs to the Topic Advances in Materials and Concepts in Fixed Prosthodontics and Implant Therapy)
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Figure 1

Figure 1
<p>Specimen preparation.</p> Full article ">Figure 2
<p>Graph showing means and standard deviation of surface roughness (Ra) for all surface treatments tested (One-way ANOVA with Tukey-HSD for post-hoc comparison). Different capital letters indicate statistically significant differences.</p> Full article ">Figure 3
<p>SEM photomicrographs of grit-blasted specimens. (<b>a</b>) Zirconia surface grit-blasted with 30-µm SiO<sub>2</sub>-coated Al<sub>2</sub>O<sub>3</sub> before sintering. (<b>b</b>) Zirconia surface grit-blasted with 110-µm Al<sub>2</sub>O<sub>3</sub> before sintering. The pointers indicate darker alumina particles fractured at grit-blasting impact and melted onto the zirconia surface. (<b>c</b>) Zirconia surface grit-blasted with 30-µm SiO<sub>2</sub>-coated Al<sub>2</sub>O<sub>3</sub> after sintering. The tiny particles represent silica deposited on the surface.</p> Full article ">Figure 4
<p>Graph showing the mean micro-tensile bond strength (µTBS) with standard deviation for all experimental groups. Connected lines indicate absence of significant difference. Different lines refer to the different strategies for dealing with pretesting failures (PTF). The continuous black lines refer to the analysis conducted by including PTF with the lowest measured value (‘PTF = MIN VALUE’). The dotted black line refers to the analysis conducted by excluding PTF (‘PTF = /’). The dashed black line refers to the analysis conducted by including PTF as 0 MPa (‘PTF = 0’).</p> Full article ">Figure 5
<p>Failure analysis. A prevalence of mixed failures was observed in all experimental groups.</p> Full article ">Figure 6
<p>SEM photomicrographs showing a typical mixed failure at the veneering ceramic-zirconia interface (left side) and inner void defects within the heat-pressed ceramic layer (right side).</p> Full article ">Figure 7
<p>SEM photomicrograph of a pre-sintered specimen grit-blasted with 30-µm Cojet (3M Oral Care) powder (Post-S-30) and the corresponding EDS spectrum at the contact area. Peaks representing several elements of the veneering ceramic layer, among which Zr, Si, and Al, have been detected.</p> Full article ">
17 pages, 2996 KiB  
Article
Influence of the Surface Topography of Titanium Dental Implants on the Behavior of Human Amniotic Stem Cells
by Rodrigo Riedel, Soledad Pérez-Amodio, Laura Cabo-Zabala, Eugenio Velasco-Ortega, Julieta Maymó, Javier Gil, Loreto Monsalve-Guil, Iván Ortiz-Garcia, Antonio Pérez-Pérez, Victor Sánchez-Margalet and Alvaro Jiménez-Guerra
Int. J. Mol. Sci. 2024, 25(13), 7416; https://doi.org/10.3390/ijms25137416 - 6 Jul 2024
Cited by 1 | Viewed by 1147
Abstract
The dental implant surface plays a crucial role in osseointegration. The topography and physicochemical properties will affect the cellular functions. In this research, four distinct titanium surfaces have been studied: machined acting (MACH), acid etched (AE), grit blasting (GBLAST), and a combination of [...] Read more.
The dental implant surface plays a crucial role in osseointegration. The topography and physicochemical properties will affect the cellular functions. In this research, four distinct titanium surfaces have been studied: machined acting (MACH), acid etched (AE), grit blasting (GBLAST), and a combination of grit blasting and subsequent acid etching (GBLAST + AE). Human amniotic mesenchymal (hAMSCs) and epithelial stem cells (hAECs) isolated from the amniotic membrane have attractive stem-cell properties. They were cultured on titanium surfaces to analyze their impact on biological behavior. The surface roughness, microhardness, wettability, and surface energy were analyzed using interferometric microscopy, Vickers indentation, and drop-sessile techniques. The GBLAST and GBLAST + AE surfaces showed higher roughness, reduced hydrophilicity, and lower surface energy with significant differences. Increased microhardness values for GBLAST and GBLAST + AE implants were attributed to surface compression. Cell viability was higher for hAMSCs, particularly on GBLAST and GBLAST + AE surfaces. Alkaline phosphatase activity enhanced in hAMSCs cultured on GBLAST and GBLAST + AE surfaces, while hAECs showed no mineralization signals. Osteogenic gene expression was upregulated in hAMSCs on GBLAST surfaces. Moreover, α2 and β1 integrin expression enhanced in hAMSCs, suggesting a surface−integrin interaction. Consequently, hAMSCs would tend toward osteoblastic differentiation on grit-blasted surfaces conducive to osseointegration, a phenomenon not observed in hAECs. Full article
(This article belongs to the Collection Feature Papers in Materials Science)
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Figure 1

Figure 1
<p>Different surfaces observed by Scanning Electron Microscope. (<b>A</b>) Machined (MACH), (<b>B</b>) Grit Blasting (GBLAST), (<b>C</b>) Grit Blasting and Acid Etching (GBLAST + AE), (<b>D</b>) Acid Etched (AE).</p> Full article ">Figure 2
<p>Surfaces of the different treatments observed by Confocal Laser Scanning Microscopy images. (<b>A</b>) Machined (MACH), (<b>B</b>) Grit Blasting (GBLAST), (<b>C</b>) Grit Blasting and Acid Etching (GBLAST + AE), (<b>D</b>) Acid Etched (AE).</p> Full article ">Figure 3
<p>Cell viability of (<b>A</b>) hAMSCs and (<b>B</b>) hAECs cultured on different titanium surfaces. Data are presented as mean ± SD. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, *** <span class="html-italic">p</span> &lt; 0.001 vs. control day 1.</p> Full article ">Figure 4
<p>ALP activity in (<b>A</b>) hAMSCs and (<b>B</b>) hAECs cultured on different surfaces for 1, 7 and 14 days. Data are presented as mean ± SD. * <span class="html-italic">p</span> &lt; 0.05 vs. control day 1.</p> Full article ">Figure 5
<p>Calcium intake from (<b>A</b>) hAMSCs and (<b>B</b>) hAECs cultured on different surfaces for 1, 7 and 14 days. Data are presented as mean ± SD. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01 vs. control day 1.</p> Full article ">Figure 6
<p>Quantitative RT-PCR results of mRNA osteogenic gene expression in hAMSCs, (<b>A</b>) OSTERIX, (<b>B</b>), RUNX2, (<b>C</b>) ALP and (<b>D</b>) OPN. Data are presented as mean ± SD. ** <span class="html-italic">p</span> &lt; 0.01, *** <span class="html-italic">p</span> &lt; 0.001 vs. respective control.</p> Full article ">Figure 7
<p>Quantitative RT-PCR results of mRNA integrin α and β subunit gene expression in hAMCs, (<b>A</b>) α1, (<b>B</b>) α5, (<b>C</b>) αv, (<b>D</b>) β2, (<b>E</b>) β3, and (<b>F</b>) β5. Data are presented as mean ± SD. * <span class="html-italic">p</span> &lt; 0.05, *** <span class="html-italic">p</span> &lt; 0.001 vs. respective control.</p> Full article ">Figure 8
<p>Flowchart of the experiments realized.</p> Full article ">
30 pages, 22061 KiB  
Article
Durability Analysis of Cold Spray Repairs: Phase I—Effect of Surface Grit Blasting
by Daren Peng, Caixian Tang, Jarrod Watts, Andrew Ang, R. K. Singh Raman, Michael Nicholas, Nam Phan and Rhys Jones
Materials 2024, 17(11), 2656; https://doi.org/10.3390/ma17112656 - 31 May 2024
Cited by 1 | Viewed by 734
Abstract
This paper presents the results of an extensive investigation into the durability of cold spray repairs to corrosion damage in AA7075-T7351 aluminium alloy specimens where, prior to powder deposition, the surface preparation involved grit blasting. In this context, it is shown that the [...] Read more.
This paper presents the results of an extensive investigation into the durability of cold spray repairs to corrosion damage in AA7075-T7351 aluminium alloy specimens where, prior to powder deposition, the surface preparation involved grit blasting. In this context, it is shown that the growth of small naturally occurring cracks in cold spray repairs to simulated corrosion damage can be accurately computed using the Hartman–Schijve crack growth equation in a fashion that is consistent with the requirements delineated in USAF Structures Bulletin EZ-SB-19-01, MIL-STD-1530D, and the US Joint Services Structural Guidelines JSSG2006. The relatively large variation in the da/dN versus ΔK curves associated with low values of da/dN highlights the fact that, before any durability assessment of a cold spray repair to an operational airframe is attempted, it is first necessary to perform a sufficient number of tests so that the worst-case small crack growth curve needed to perform the mandated airworthiness certification analysis can be determined. Full article
(This article belongs to the Special Issue Artificial Intelligence in Materials Science and Engineering)
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<p>Dimensions of the test specimen geometry.</p> Full article ">Figure 2
<p>A schematic diagram of marker block load spectrum 3.</p> Full article ">Figure 3
<p>The maximum principal stress in the specimen at a remote load of 30 kN. Only one half of the specimen is shown.</p> Full article ">Figure 4
<p>Failure in the 75_1_NC_1_#1 specimen (failed 368,528 cycles).</p> Full article ">Figure 5
<p>SEM of Crack 1, which was the fastest-growing (i.e., the lead) crack in specimen 75_1_NC_1_#1.</p> Full article ">Figure 6
<p>The measured and computed crack depth histories for specimen 75_1_NC_1_#1.</p> Full article ">Figure 7
<p>Failure in the 75_1_NC_2_#2 specimen (failed 354,393 cycles).</p> Full article ">Figure 8
<p>SEM of crack in specimen 75_1_NC_2_#2.</p> Full article ">Figure 9
<p>The measured and computed crack depth histories for specimen 75_1_NC_2_#2.</p> Full article ">Figure 10
<p>Failure in the 75_1_NC_1_#2 specimen (failed 378,932 cycles).</p> Full article ">Figure 11
<p>SEM of the lead crack (Crack 1) in specimen 75_1_NC_1_#2.</p> Full article ">Figure 12
<p>The measured and computed crack depth histories for specimen 75_1_NC_1_#2.</p> Full article ">Figure 13
<p>Failure in the 75_1_NC_2_#3 specimen (failed 365,534 cycles).</p> Full article ">Figure 14
<p>SEM of the lead crack (Crack 1) in specimen 75_1_NC_2_#3.</p> Full article ">Figure 15
<p>The measured and computed crack depth for specimen 75_1_NC_2_#3.</p> Full article ">Figure 16
<p>Failure in the B_1_1_#1 specimen (failed 555,619 cycles).</p> Full article ">Figure 17
<p>SEM of the lead crack (Crack 1) in specimen B_1_1_#1.</p> Full article ">Figure 18
<p>The measured and computed crack depth histories for specimen B_1_1_#1.</p> Full article ">Figure 19
<p>Failure in the 75_1_NC_1_#3 specimen (failed 629,120 cycles).</p> Full article ">Figure 20
<p>SEM of the lead crack (Crack 1) in specimen 75_1_NC_1_#3.</p> Full article ">Figure 21
<p>The measured and computed crack depth histories for specimen 75_1_NC_1_#3.</p> Full article ">Figure 22
<p>Failure in the 75_1_NC_1_#4 specimen (failed 670,905 cycles).</p> Full article ">Figure 23
<p>SEM of the lead crack (Crack 1) in specimen 75_1_NC_1_#4.</p> Full article ">Figure 24
<p>The measured and computed crack depth histories for specimen 75_1_NC_1_#4.</p> Full article ">Figure 25
<p>Failure in the 75_1_NC_2_#4 specimen (failed 360,543 cycles).</p> Full article ">Figure 26
<p>SEM of the lead crack in specimen 75_1_NC_2_#4.</p> Full article ">Figure 27
<p>The measured and computed crack depth histories for specimen 75_1_NC_2_#4.</p> Full article ">Figure 28
<p>Failure in the 75_1_NC_2_#5 specimen (failed 373,397 cycles).</p> Full article ">Figure 29
<p>SEM of the lead crack (Crack 1) in specimen 75_1_NC_2_#5.</p> Full article ">Figure 30
<p>The measured and computed crack depth histories for specimen 75_1_NC_2_#5.</p> Full article ">Figure 31
<p>Failure in the B_1_1_#2 specimen (failed 1,117,056 cycles).</p> Full article ">Figure 32
<p>SEM of the lead crack in specimen B_1_1_#2.</p> Full article ">Figure 33
<p>The measured and computed crack depth histories for specimen B_1_1_#2.</p> Full article ">Figure 34
<p>Failure in the B_1_1_#3 specimen (failed 765,288 cycles).</p> Full article ">Figure 35
<p>SEM of the lead crack (Crack 2) in specimen B_1_1_#3.</p> Full article ">Figure 36
<p>The measured and computed crack depth histories for specimen B_1_1_#3.</p> Full article ">Figure 37
<p>Failure in the 75_1_NC_1_#5 specimen (failed 899,480 cycles).</p> Full article ">Figure 38
<p>SEM of the lead crack in specimen 75_1_NC_1_#5.</p> Full article ">Figure 39
<p>The measured and computed crack depth histories for specimen 75_1_NC_1_#5.</p> Full article ">Figure 40
<p>The variability in the crack growth curves seen by the twenty-five cracks examined in the present study.</p> Full article ">
20 pages, 7387 KiB  
Article
Press-Fit Placement of a Rectangular Block Implant in the Resorbed Alveolar Ridge: Surgical and Biomechanical Considerations
by Efthimios Gazelakis, Roy B. Judge, Joseph E. A. Palamara, Shiva Subramanian and Mohsin Nazir
Bioengineering 2024, 11(6), 532; https://doi.org/10.3390/bioengineering11060532 - 23 May 2024
Viewed by 1314
Abstract
Rectangular Block Implant (RBIs) were manufactured, using computer-aided-design lathe turning, surface roughened with grit blasting and gamma irradiated. Implants were surgically placed into the resorbed edentulous mandibular ridges of both greyhound dogs (ex vivo and in vivo) and humans; the pooled total was [...] Read more.
Rectangular Block Implant (RBIs) were manufactured, using computer-aided-design lathe turning, surface roughened with grit blasting and gamma irradiated. Implants were surgically placed into the resorbed edentulous mandibular ridges of both greyhound dogs (ex vivo and in vivo) and humans; the pooled total was 17 placements. The aim was to achieve mechanical stability and full implant submergence without damage to the mandibular canal and without bone fracture: fulfilment of all of these criteria was deemed to be a successful surgical outcome. Rectangular osteotomy sites were prepared with piezo surgical instrumentation. Sixteen implants were fully submerged and achieved good primary stability without bone fracture and without evidence of impingement of the mandibular canal. One implant placement was deemed a failure due to bone fracture: the event of a random successful outcome was rejected (p < 0.01 confidence, binomial analysis). Technique of placement yielded excellent mechanical retention: key biomechanical factors that emerged in this process included under preparation of the osteotomy site with the use of specifically designed trial-fit gauges, the viscoelastic property of the peri-implant bone, the flat faces and cornered edges of the block surfaces which enhance stress distribution and mechanical retention, respectively. It was concluded that the surgical protocol for the RBI placement in the resorbed alveolus is a predictable clinical procedure tailored to its specific, unique biomechanical profile. Full article
(This article belongs to the Special Issue Translational Advances in Dental Implants)
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<p>RBI dimensions: 6 mm in “horizontal” mesiodistal length (L), 5.25 mm in “vertical” crestal-apical height (H), and 4 mm in “horizontal” bucco-lingual width (W). Mesial and distal crestal surface depressions (red arrows) facilitate the press action fit with the use of centre punch action [<a href="#B24-bioengineering-11-00532" class="html-bibr">24</a>].</p> Full article ">Figure 2
<p>Corresponding anatomical axes X, Y, Z. Where the “horizontal” axes are X and Y, while the “vertical” axis is Z.</p> Full article ">Figure 3
<p>Surgical Protocol: Incision Design. Vertical, V; Horizontal, H; incisions (blue dashed lines). Raised soft tissue flap overlying the crest (red arrow dashed outline). X, Y, and Z-axes and the position of the inferior alveolar nerve (IAN) (green arrow) are depicted.</p> Full article ">Figure 4
<p>Bespoke Rectangular Piezotomes. Two such designs were manufactured: (<b>a</b>) where the action is in a buccolingual direction (Y-axis) and (<b>b</b>) the other in a mesiodistal direction (X-axis). The aim of these tools was to facilitate the final flat rectangular osteotomy at the full depth (5.25 mm). Yellow arrows represent relative 5 mm lengths.</p> Full article ">Figure 5
<p>Trial-fit Gauges with 20% depth markings and stems attached. Black arrows represent relative 3.0 cm lengths.</p> Full article ">Figure 6
<p>The developed RBI surgical protocol in the assessment of final biomechanical successful press-fit placement.</p> Full article ">Figure 7
<p>Successful Insertion: Ex vivo. These cases highlighted the elasticity of the bone. (<b>a</b>) The cortical plate here overlapped the crestal aspect of the inserted block implant. Instead of fracturing on tapping into place, the bone expanded and accommodated the implant (white arrow). (<b>b</b>) There was excellent primary retention, as felt by attempting to move the implant through its attached abutment (white arrow). (<b>c</b>) Complete seating of the RBI and evidence of the undamaged underlying inferior alveolar nerve (yellow arrow). (<b>d</b>) Incomplete passive seating: Less than 75%. This level of initial passive seating was deemed inadequate, resulting in fracture. Black arrows represent relative 6 mm lengths.</p> Full article ">Figure 8
<p>(<b>a</b>) Examples of Seated Implants. (<b>b</b>) Note the crestally overlapping bony buccal margins (yellow arrows). Black arrows represent relative 6 mm lengths.</p> Full article ">Figure 9
<p>Examples of CBCT bucco-lingual views (<b>a</b>,<b>b</b>). CBCT confirmed good crestal bony coverage (red arrows). These bucco-lingual views highlighted the proximity (yellow arrows) of the “apical” base and the superior aspect of the inferior alveolar nerve canal (red ellipses). Given that the length of this implant is 5.25 mm, it emerged that a longer implant would be anatomically precluded. White arrows represent relative 6 mm lengths. Buccal orientation in these cross sections: “b”.</p> Full article ">Figure 10
<p>CBCT images Patients 1 (<b>a</b>,<b>b</b>), Patient 2 (<b>c</b>,<b>d</b>). (<b>a</b>,<b>c</b>): Extensive alveolar resorption at the planned sites (yellow arrows). (<b>b</b>,<b>d</b>): Cross-sectional views of the proposed positions of the planned RBIs where there was little crestal clearance (approximately 5 mm) above the inferior alveolar nerve (red).</p> Full article ">Figure 11
<p>Patient 1. (<b>a</b>) The rectangular osteotomy. (<b>b</b>) The trial-fit gauge was tested repeatedly to achieve complete seating. (<b>c</b>) The RBI was inserted to full depth without bony fracture and achieved primary stability. This was visualised radiographically. Black arrows represent relative 6 mm lengths.</p> Full article ">Figure 12
<p>Patient 2. (<b>a</b>) Placement of the RBI into the osteotomy with a stem attached. Finger pressure on the stem confirmed excellent stability. (<b>b</b>) Radiographic image of the fully seated and well-stabilised RBI. Yellow arrows represent relative 6 mm lengths.</p> Full article ">Figure 13
<p>Schematic of the Horizontal (Fh) and Vertical (Fv) Components of the Applied Force (F):—as expressed through the centre of the RBI, which will also contain the centroid of the block-bone complex (Cc). The centroid will be apically positioned with respect to a normally free-bodied block centroid (Cb) due to the unison with the bone. These are depicted (<b>a</b>) from the buccolingual cross-sectional perspective and (<b>b</b>) from the mesiodistal cross-sectional perspective, as both aspects would have off-centred forces applied. X, Y and Z axes are depicted.</p> Full article ">Figure 14
<p>Load Intensity Schematic of the Horizontal (orange arrows) and Vertical Force (red arrows) Components: the crestal buccal (orange: compression [C]) and crestal lingual (green: tension [T]) equal and opposite reactions. Proceeding apically, these directions will be reversed below the centroid of the block–bone complex [Cc]. These are depicted (<b>a</b>) from the buccolingual cross-sectional perspective and (<b>b</b>) from the mesiodistal cross-sectional perspective. X, Y and Z axes are depicted.</p> Full article ">Figure 14 Cont.
<p>Load Intensity Schematic of the Horizontal (orange arrows) and Vertical Force (red arrows) Components: the crestal buccal (orange: compression [C]) and crestal lingual (green: tension [T]) equal and opposite reactions. Proceeding apically, these directions will be reversed below the centroid of the block–bone complex [Cc]. These are depicted (<b>a</b>) from the buccolingual cross-sectional perspective and (<b>b</b>) from the mesiodistal cross-sectional perspective. X, Y and Z axes are depicted.</p> Full article ">Figure 15
<p>Schematic Outline of Crestal “Horizontal” Stress Patterns Generated Upon Complete RBI Placement. From the crestal perspective, the internal stresses generated on all four surfaces of the block resulting from the insertion load of the obliquely applied forces can be summarised as predominantly buccal and lingual plate compression (orange arrows). Stress concentrations will be maximal at the corners (red arrows) and approximal torsion. X and Y axes are depicted.</p> Full article ">Figure 16
<p>Cylindrical Implant Load Intensity Schematic. The applied load (F: Purple Arrow) generates Horizontal (compressive: orange arrows) and apical vertical (compressive: red arrows, (Fv)) force components. Compression (C) and Tension (T: green arrows) are in opposite directions and invert beyond the centroid of the implant–bone complex (Cc). X and Y axes would be symmetrical in the cylindrical geometry. X/Y and Z axes are depicted.</p> Full article ">Figure 17
<p>Cylindrical Implant Cross Sectional Schematic of the Horizontal Compressive Force Distribution. In any horizontal cross-section along the axial length of the cylindrical implant, the interfacial horizontal force distribution will be unevenly distributed. This distribution will be in an elliptical form (blue arrows), with a maximum at the radial position aligned with the direction of the applied force (F: red arrow), tangentially normal to the surface (hashed red line). X and Y axes are depicted.</p> Full article ">Figure 18
<p>Apical Vertical Force Distribution (red arrows): Cylindrical (left) and Rectangular (right) Implants. It is seen that a cylindrical counterpart also has an analogous force intensity distribution, assuming the same uni-lateral and uni-directional applied force. The vertical component of the cylindrical implant will be concentrated along the apically directed axis and exhibit unequal distribution at the apex, approximating zero in the horizontal direction. The flat-faced counterpart will exhibit even apical distribution. X and Z axes are depicted.</p> Full article ">
19 pages, 13822 KiB  
Article
Two 3D Fractal-Based Approaches for Topographical Characterization: Richardson Patchwork versus Sdr
by François Berkmans, Julie Lemesle, Robin Guibert, Michał Wieczorowski, Christopher Brown and Maxence Bigerelle
Materials 2024, 17(10), 2386; https://doi.org/10.3390/ma17102386 - 16 May 2024
Cited by 2 | Viewed by 794
Abstract
Various methods exist for multiscale characterization of surface topographies, each offering unique insights and applications. The study focuses on fractal-based approaches, distinguishing themselves by leveraging fractals to analyze surface complexity. Specifically, the Richardson Patchwork method, used in the ASME B46.1 and ISO 25178 [...] Read more.
Various methods exist for multiscale characterization of surface topographies, each offering unique insights and applications. The study focuses on fractal-based approaches, distinguishing themselves by leveraging fractals to analyze surface complexity. Specifically, the Richardson Patchwork method, used in the ASME B46.1 and ISO 25178 standards, is compared to the Sdr parameter derived from ISO 25178-2, with a low-pass Gaussian filter for multiscale characterization. The comparison is performed from the relative area calculated on topographies of TA6V samples grit blasted with different pressures and blasting materials (media). The surfaces obtained by grit blasting have fractal-like characteristics over the scales studied, enabling the analysis of area development at multiple levels based on pressure and media. The relative area is similar for both methods, regardless of the complexity of the topographies. The relevance scale for each calculation method that significantly represents the effect of grit blasting pressure on the increased value of the relative area is a tiling of 7657.64 µm² of triangle area for the Patchwork method and a 124.6 µm cut-off for the low-pass Gaussian filter of the Sdr method. These results could facilitate a standard, friendly, new fractal method for multiscale characterization of the relative area. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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<p>Two calculations of the relative length for two different scales. (<b>a</b>) Calculation from a profile view with 4 steps. (<b>b</b>) Calculation from a profile view with 12 steps. The calculated length is the sum of the step length multiplied by the number of steps. The nominal length is 230 µm.</p> Full article ">Figure 1 Cont.
<p>Two calculations of the relative length for two different scales. (<b>a</b>) Calculation from a profile view with 4 steps. (<b>b</b>) Calculation from a profile view with 12 steps. The calculated length is the sum of the step length multiplied by the number of steps. The nominal length is 230 µm.</p> Full article ">Figure 2
<p>Length–scale plot. The self-similarity over some range of scales is emphasized by the regression line in green. According to ASME B.46, the fractal dimension based on the length scale is 1.095 (no unit). The blue line is the interpolation between the values for the calculation of the relative length on every scale. The dashed green corresponds to the fractal domain, which is the range where the surface is self-similar on different scales.</p> Full article ">Figure 3
<p>Selection of surface topographies classified by pressure of grit blasting (<b>a</b>–<b>c</b>) and blasting material (<b>i</b>–<b>iii</b>). The topographies for the media G 100 (<b>i</b>) and G 250 (<b>ii</b>) have more circular features considering the spherical nature of the glass beads. The topographies of the C 300 medium (<b>iii</b>) have more sharply edged indents due to the angular nature of the corundum.</p> Full article ">Figure 4
<p>Triangular tiling at three different scales of a TA6V surface grit blasted with the C300 medium and a pressure 8 bar. The scale is the area of the triangular tiles, which have the same area but different projected areas, depending on the inclination.</p> Full article ">Figure 5
<p>Representation of the four neighboring pixels (Z<sub>1</sub> to Z<sub>4</sub>) of the surface topography used to create two triangular areas (A<sub>1</sub> in green and A<sub>2</sub> in orange) with segments (S<sub>12</sub>, S<sub>23</sub>, S<sub>34</sub>, S<sub>13</sub>, S<sub>41</sub>) and a comparison on the projected area (A<sub>n</sub> in blue).</p> Full article ">Figure 6
<p>Actual surface area as topography on a given scale (color) on the projected surface area (black). The topography is represented as squares of 4 pixels. The magnification is representing the calculation of the area between four adjacent points (A–D) calculated from the mean value of two triangulations (blue triangles) [<a href="#B25-materials-17-02386" class="html-bibr">25</a>].</p> Full article ">Figure 7
<p>Diagrams of the two calculation methods used in this study for the developed length. The blue line is a representation of a real surface. The orange line is a linear interpolation between measured height points which is our measured profile (the Sdr method was used for computing the relative length at the sampling scale). The green line is a representation of the Patchwork method following the measured profile using the same length steps and sometimes interpolating between measured height points.</p> Full article ">Figure 8
<p>Comparison of the two methods, Sdr and Patchwork, for the calculation of the relative area on the surface topographies created with the C 300 grit-blasting material and a pressure of 8 bar (these are the most aggressive conditions of our material/pressure experimentation). The blue rings represent the values of the relative area calculated by the Patchwork method depending on the size of the triangle tiling (patch area). The red dots represent the calculation of the relative area related to one of the 24 cut-off lengths of the low-pass filter.</p> Full article ">Figure 9
<p>Density probability distributions obtained after applying the bootstrapping protocol to the relative area measurement data. The area of the tiling triangles corresponds to (<b>a</b>) 0.02 µm<sup>2</sup>, (<b>b</b>) 5.124 µm<sup>2</sup> and (<b>c</b>) 10,845 µm<sup>2</sup>.</p> Full article ">Figure 10
<p>Distributions of the relative area values calculated by the Patchwork method from the 50 measurements of the sample sandblasted at 8 bar with C 300: (<b>a</b>) the lines of the 50 sample measurements, (<b>b</b>) the values after resampling by bootstrapping, (<b>c</b>) the averages of the original measurements and (<b>d</b>) the averages of the bootstrapped values.</p> Full article ">Figure 11
<p>Comparison of the two methods, Sdr and Patchwork, for the calculation of the relative area of the surface topographies created with the grit-blasting materials G 100 (<b>a</b>), G 250 (<b>b</b>) and C 300 (<b>c</b>). The points represent the medians of the distribution of the relative area values, categorized by the calculation method and pressure. The blue symbols represent the median points for the Patchwork method and the red symbols correspond to the Sdr method. The scale references the cut-off length for the low-pass Gaussian filter applied for the Sdr calculation. In this scale, the tiling size in µm<sup>2</sup> for the Patchwork method is equal to the square of the cut-off length divided by 2.</p> Full article ">Figure 12
<p>Distributions of the relative area values by method of calculation (Patchwork (<b>a</b>,<b>c</b>,<b>e</b>) and Sdr (<b>b</b>,<b>d</b>,<b>f</b>)), media (G 100 (<b>a</b>,<b>b</b>), G 250 (<b>c</b>,<b>d</b>) and C 300 (<b>e</b>,<b>f</b>)) and pressure.</p> Full article ">Figure A1
<p>Original and filtered surfaces grit blasted by C 300 at 8 bar. The surfaces were, respectively, unfiltered (<b>a</b>) and filtered at 8.4 µm (<b>b</b>), 73.4 µm (<b>c</b>) and 603.8 µm (<b>d</b>). The relative area was calculated after filtering.</p> Full article ">Figure A2
<p>Original and filtered surfaces grit blasted by G 100 at 8 bar. The surfaces were, respectively, unfiltered (<b>a</b>) and filtered at 8.4 µm (<b>b</b>), 73.4 µm (<b>c</b>) and 603.8 µm (<b>d</b>). The relative area was calculated after filtering.</p> Full article ">Figure A3
<p>Original and filtered surfaces grit blasted by G 250 at 8 bar. The surfaces were, respectively, unfiltered (<b>a</b>) and filtered at 8.4 µm (<b>b</b>), 73.4 µm (<b>c</b>) and 603.8 µm (<b>d</b>). The relative area was calculated after filtering.</p> Full article ">
18 pages, 3209 KiB  
Article
Different Methods to Modify the Hydrophilicity of Titanium Implants with Biomimetic Surface Topography to Induce Variable Responses in Bone Marrow Stromal Cells
by Thomas W. Jacobs, Jonathan T. Dillon, David J. Cohen, Barbara D. Boyan and Zvi Schwartz
Biomimetics 2024, 9(4), 227; https://doi.org/10.3390/biomimetics9040227 - 10 Apr 2024
Cited by 4 | Viewed by 1799
Abstract
The osteoblastic differentiation of bone marrow stromal cells (bMSCs), critical to the osseointegration of titanium implants, is enhanced on titanium surfaces with biomimetic topography, and this is further enhanced when the surfaces are hydrophilic. This is a result of changing the surface free [...] Read more.
The osteoblastic differentiation of bone marrow stromal cells (bMSCs), critical to the osseointegration of titanium implants, is enhanced on titanium surfaces with biomimetic topography, and this is further enhanced when the surfaces are hydrophilic. This is a result of changing the surface free energy to change protein adsorption, improving cell attachment and differentiation, and improving bone-to-implant contact in patients. In this study, we examined different methods of plasma treatment, a well-accepted method of increasing hydrophilicity, and evaluated changes in surface properties as well as the response of bMSCs in vitro. Commercially pure Ti and titanium–aluminum–vanadium (Ti6Al4V) disks were sand-blasted and acid-etched to impart microscale and nanoscale roughness, followed by treatment with various post-processing surface modification methods, including ultraviolet light (UV), dielectric barrier discharge (DBD)-generated plasma, and plasma treatment under an argon or oxygen atmosphere. Surface wettability was based on a sessile water drop measurement of contact angle; the elemental composition was analyzed using XPS, and changes in topography were characterized using scanning electron microscopy (SEM) and confocal imaging. The cell response was evaluated using bMSCs; outcome measures included the production of osteogenic markers, paracrine signaling factors, and immunomodulatory cytokines. All plasma treatments were effective in inducing superhydrophilic surfaces. Small but significant increases in surface roughness were observed following UV, DBD and argon plasma treatment. No other modifications to surface topography were noted. However, the relative composition of Ti, O, and C varied with the treatment method. The cell response to these hydrophilic surfaces depended on the plasma treatment method used. DBD plasma treatment significantly enhanced the osteogenic response of the bMSCs. In contrast, the bMSC response to argon plasma-treated surfaces was varied, with an increase in OPG production but a decrease in OCN production. These results indicate that post-packaging methods that increased hydrophilicity as measured by contact angle did not change the surface free energy in the same way, and accordingly, cells responded differently. Wettability and surface chemistry alone are not enough to declare whether an implant has an improved osteogenic effect and do not fully explain how surface free energy affects cell response. Full article
(This article belongs to the Special Issue Bioinspired Interfacial Materials)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>UV treatment effect on surface properties. Implant surface characterization shows increased wettability following treatment with UV–plasma-based cleaner. Sessile water droplet test of Ti6Al4V surface (<b>A</b>) and Ti6Al4V surface treated with UV–plasma cleaner (<b>B</b>). Contact angle measurements of water droplets for treated and untreated surfaces (<b>C</b>); measures were taken at 6 different locations on the implant surface. Optical profilometry measurements of surface micro-roughness (<b>D</b>) and peak-to-valley height (<b>E</b>). X-ray photoelectron spectroscopy to assess concentrations of elements present on the surface (<b>F</b>). Results are the means of 6 measurements taken at different points on 2 surfaces (<span class="html-italic">n</span> = 12) with bars showing SEM. Groups labeled with “*” are statistically significant compared to untreated Ti6Al4V using a Student’s unpaired <span class="html-italic">t</span>-test. (* = α &lt; 0.05, *** = α &lt; 0.0005, **** = α &lt; 0.0001).</p> Full article ">Figure 2
<p>UV treatment effect on cell response. In vitro assessment of bMSCs cultured on UV–plasma-treated and untreated Ti6Al4V surfaces. Total DNA content measured at 7 days of culture (<b>A</b>). ELISA quantification of osteoblast maturation markers osteocalcin (<b>B</b>) and osteopontin (<b>C</b>), and paracrine signaling factors osteoprotegerin (<b>D</b>) and vascular endothelial growth factor (<b>E</b>) in response to UV–plasma-treated surfaces. Immunomodulatory cytokine production of IL-6 (<b>F</b>) and IL-10 (<b>G</b>). Groups are means of 6 cultures/variables, with errors bars representing SEM. Factor production in the conditioned media was normalized to total DNA and statistics were determined by ANOVA with Tukey post-test. Groups labeled with “*” are statistically significant compared to TCPS at <span class="html-italic">p</span>-value equal to or less than 0.05.</p> Full article ">Figure 3
<p>DBD treatment effect on surface properties. Implant surface characterization shows increased wettability following treatment with argon-based plasma cleaning method. Sessile water droplet test of Ti6Al4V surface (<b>A</b>) and Ti6Al4V surface treated with argon plasma cleaner (<b>B</b>). Contact angle measurements of water droplets for treated and untreated surfaces (<b>C</b>); measures were taken at 6 different locations on the implant surface. Optical profilometry measurements of surface micro-roughness (<b>D</b>) and peak-to-valley height (<b>E</b>). X-ray photoelectron spectroscopy to assess concentrations of elements present on the surface (<b>F</b>). Results are the means of 6 measurements taken at different points on 2 surfaces (<span class="html-italic">n</span> = 12) with bars showing SEM. Groups labeled with “*” are statistically significant compared to untreated Ti6Al4V using a Student’s unpaired <span class="html-italic">t</span>-test (* = α &lt; 0.05, **** = α &lt; 0.0001).</p> Full article ">Figure 4
<p>DBD treatment effect on cell response. In vitro assessment of bMSCs cultured on argon plasma-treated and untreated Ti6Al4V surfaces. Total DNA content measured at 7 days of culture (<b>A</b>). ELISA quantification of osteoblast maturation markers osteocalcin (<b>B</b>) and osteopontin (<b>C</b>), and paracrine signaling factors osteoprotegerin (<b>D</b>) and vascular endothelial growth factor (<b>E</b>) in response to argon plasma-treated surfaces. Immunomodulatory cytokine production of IL-6 (<b>F</b>) and IL-10 (<b>G</b>). Groups are the means of 6 independent cultures/variables, with error bars representing SEM. Factor production in the conditioned media was normalized to total DNA, and stats were determined using a Student’s unpaired <span class="html-italic">t</span>-test. Groups labeled with “*” are statistically significant compared to untreated Ti6Al4V at <span class="html-italic">p</span>-value equal to or less than 0.05.</p> Full article ">Figure 5
<p>Argon treatment effect on surface properties. Implant surface characterization shows increased wettability following treatment with oxygen plasma-based cleaner under vacuum conditions. Sessile water droplet test of Ti6Al4V surface (<b>A</b>) and Ti6Al4V surface treated with UV–plasma cleaner (<b>B</b>). Contact angle measurements of water droplets for treated and untreated surfaces (<b>C</b>); measures were taken at 6 different locations on the implant surface. Optical profilometry measurements of surface micro-roughness (<b>D</b>) and peak-to-valley height (<b>E</b>). X-ray photoelectron spectroscopy to assess concentrations of elements present on the surface (<b>F</b>). Results are the means of 6 measurements taken at different points on 2 surfaces (<span class="html-italic">n</span> = 12), with bars showing SEM. Groups labeled with “*” are statistically significant compared to untreated Ti6Al4V using a Student’s unpaired <span class="html-italic">t</span>-test (* = α &lt; 0.05, **** = α &lt; 0.0001).</p> Full article ">Figure 6
<p>Argon treatment effect on cell response. In vitro assessment of bMSCs cultured on oxygen plasma under vacuum-treated and untreated Ti6Al4V surfaces. Total DNA content measured at 7 days of culture (<b>A</b>). ELISA quantification of osteoblast maturation markers osteocalcin (<b>B</b>) and osteopontin (<b>C</b>), and paracrine signaling factors osteoprotegerin (<b>D</b>) and vascular endothelial growth factor (<b>E</b>) in response to oxygen plasma vacuum-treated surfaces. Immunomodulatory cytokine production of IL-6 (<b>F</b>) and IL-10 (<b>G</b>). Groups are the means of 6 independent cultures/variables, with error bars representing SEM. Factor production in the conditioned media was normalized to total DNA, and stats were determined using a Student’s unpaired <span class="html-italic">t</span>-test. Groups labeled with “*” are statistically significant compared to untreated Ti6Al4V at <span class="html-italic">p</span>-value equal to or less than 0.05.</p> Full article ">Figure 7
<p>Argon and oxygen plasma treatment effect on surface properties of SLA surfaces. Surface characterization of SLA and modSLA surfaces that were treated with argon or oxygen plasma. Contact angle measurements of water droplets for treated and untreated SLA (<b>A</b>) and modSLA (<b>B</b>) surfaces; measures were taken at 6 different locations on the implant surface. Analysis of SLA surface micro-roughness (<b>C</b>) and peak-to-valley height (<b>D</b>) using optical profilometry. Optical profilometry measurements of surface micro-roughness (<b>E</b>) and peak-to-valley height (<b>F</b>) of modSLA-treated and untreated surfaces. X-ray photoelectron spectroscopy to assess concentrations of elements on untreated SLA and modSLA surfaces and plasma-treated SLA surfaces (<b>G</b>). Results are the means of 6 measurements taken at different points on 2 surfaces (<span class="html-italic">n</span> = 12), with bars showing SEM. Groups labeled with “*” are statistically significant compared to untreated SLA at <span class="html-italic">p</span>-value equal to or less than 0.05.</p> Full article ">Figure 8
<p>Argon and oxygen plasma treatment effect on cell response of SLA surfaces. In vitro assessment of bMSCs cultured on SLA surfaces treated with or without plasma and compared to modSLA. Total DNA content measured at 7 days of culture (<b>A</b>). ELISA quantification of osteoblast maturation markers osteocalcin (<b>B</b>) and osteopontin (<b>C</b>), paracrine signaling factor osteoprotegerin (<b>D</b>), and immunomodulatory cytokines Il-6 (<b>E</b>) and Il-10 (<b>F</b>) in response to SLA surfaces that were treated with either argon or oxygen plasma cleaner and compared to modSLA surfaces. Groups are the means of 6 independent cultures/variables with error bars representing SEM. Factor production in the conditioned media was normalized to total DNA, and stats were determined by ANOVA with Tukey post-test. Groups labeled with “*” are statistically significant compared to SLA at <span class="html-italic">p</span>-value equal to or less than 0.05. Groups labeled with a “#” are statistically significant compared to SLA-AR at <span class="html-italic">p</span>-value equal to or less than 0.05. Groups labeled with a “<span>$</span>” are statistically significant compared to SLA-O<sub>2</sub> at <span class="html-italic">p</span>-value equal to or less than 0.05.</p> Full article ">Figure 9
<p>Argon plasma treatment effect on cell response of SLA and modSLA surfaces. In vitro assessment of bMSCs cultured on SLA and modSLA surfaces and treated with argon plasma. Total DNA content (<b>A</b>) and production of osteogenic markers osteocalcin (<b>B</b>), osteopontin (<b>C</b>), and osteoprotegerin (<b>D</b>) were measured. Production of cytokines Il-6 (<b>E</b>) and Il-10 (<b>F</b>) were measured. Groups are means of 6 independent cultures/variables, with error bars representing SEM. Factor production in the conditioned media was normalized to total DNA and stats were determined by ANOVA with Tukey post-test. Groups labeled with “*” are statistically significant compared to SLA at <span class="html-italic">p</span>-value equal to or less than 0.05. Groups labeled with a “#” are statistically significant compared to SLA AR at <span class="html-italic">p</span>-value equal to or less than 0.05. Groups labeled with a “<span>$</span>” are statistically significant compared to mSLA at <span class="html-italic">p</span>-value equal to or less than 0.05.</p> Full article ">
13 pages, 2025 KiB  
Article
Influence of Titanium Surface Residual Stresses on Osteoblastic Response and Bacteria Colonization
by Rita Pereira, Paulo Maia, Jose Vicente Rios-Santos, Mariano Herrero-Climent, Blanca Rios-Carrasco, Conrado Aparicio and Javier Gil
Materials 2024, 17(7), 1626; https://doi.org/10.3390/ma17071626 - 2 Apr 2024
Cited by 4 | Viewed by 1176
Abstract
Grit basting is the most common process applied to titanium dental implants to give them a roughness that favors bone colonization. There are numerous studies on the influence of roughness on osseointegration, but the influence of the compressive residual stress associated with this [...] Read more.
Grit basting is the most common process applied to titanium dental implants to give them a roughness that favors bone colonization. There are numerous studies on the influence of roughness on osseointegration, but the influence of the compressive residual stress associated with this treatment on biological behavior has not been determined. For this purpose, four types of surfaces have been studied using 60 titanium discs: smooth, smooth with residual stress, rough without stress, and rough with residual stress. Roughness was studied by optic interferometry; wettability and surface energy (polar and dispersive components) by contact angle equipment using three solvents; and residual stresses by Bragg–Bentano X-ray diffraction. The adhesion and alkaline phosphatase (ALP) levels on the different surfaces were studied using Saos-2 osteoblastic cultures. The bacterial strains Streptococcus sanguinis and Lactobacillus salivarius were cultured on different surfaces, determining the adhesion. The results showed that residual stresses lead to increased hydrophilicity on the surfaces, as well as an increase in surface energy, especially on the polar component. From the culture results, higher adhesion and higher ALP levels were observed in the discs with residual stresses when compared between smooth and roughened discs. It was also found that roughness was the property that mostly influenced osteoblasts’ response. Bacteria colonize rough surfaces better than smooth surfaces, but no changes are observed due to residual surface tension. Full article
(This article belongs to the Special Issue Advances in Dental Implants, Tissue Engineering and Prosthetic Materials)
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<p>Roughness parameters scheme. Sa expresses, as an absolute value, the difference in height of each point compared to the arithmetical mean of the surface. This parameter is generally used to evaluate surface roughness. The maximum height Sz is equivalent to the sum of the maximum peak height Sp and maximum valley depth Sv. The colors in the scheme represent different heights. From the red color with the highest height to the blue color with the lowest depression.</p> Full article ">Figure 2
<p>Proliferation of Saos-2 cells on surfaces: (<b>A</b>) after 3 days and (<b>B</b>) after 14 days of incubation. The results marked with one asterisk show statistically significant differences with respect to those marked with two asterisks and those marked with three asterisks show statistically significant differences with respect to those marked with two asterisks. The differences present at <span class="html-italic">p</span> &lt; 0.001.</p> Full article ">Figure 3
<p>Production of ALP by Saos-2 cells on different surfaces. The results marked with one asterisk show statistically significant differences with respect to those marked with two asterisks and those marked with three asterisks show statistically significant differences with respect to those marked with two asterisks. The differences present at <span class="html-italic">p</span> &lt; 0.001.</p> Full article ">Figure 4
<p>Bacterial colonies adhered on the different surfaces studied. Samples with the same symbol show no statistically significant differences between them. The results marked with one asterisk show statistically significant differences with respect to those marked with two asterisks. The differences present at <span class="html-italic">p</span> &lt; 0.001.</p> Full article ">Figure 5
<p>Fractures on the neck of the implant produced by fatigue in dental implants made of commercially pure titanium.</p> Full article ">
13 pages, 2428 KiB  
Article
Vacuum Plasma Treatment Device for Enhancing Fibroblast Activity on Machined and Rough Titanium Surfaces
by Luigi Canullo, Tullio Genova, Giorgia Chinigò, Roberta Iacono, Paolo Pesce, Maria Menini and Federico Mussano
Dent. J. 2024, 12(3), 71; https://doi.org/10.3390/dj12030071 - 7 Mar 2024
Cited by 2 | Viewed by 2022
Abstract
This study was conducted to compare the effects of an innovative plasma surface treatment device that does not need a gas supply for titanium disks with two different surface topographies: the prototypical machined surface (MAC) and one of the most diffused roughened ones [...] Read more.
This study was conducted to compare the effects of an innovative plasma surface treatment device that does not need a gas supply for titanium disks with two different surface topographies: the prototypical machined surface (MAC) and one of the most diffused roughened ones (SL) obtained through grit blasting and acid etching. A total of 200-MAC and 200-SL titanium disks were used. Each group of disks was divided into four sub-groups of 40 samples each that were subjected to five different tests. Among these, 150-MAC and 150-SL were considered the test group, and they were treated with plasma for 15, 30, and 60 s after being removed from the sterile packaging. On the other hand, 50-MAC and 50-SL were considered the control group, and they were only removed from sterile plastic vials. The samples were analyzed to evaluate the capability of the plasma treatment in influencing protein adsorption, cell adhesion, proliferation, and microbial growth on the test group disks when compared to the untreated disks. Protein adsorption was significantly enhanced after 20 min of plasma treatment for 15 and 30 s on the MAC and SL disks. Plasma treatment for 15 and 30 s significantly increased the level of adhesion in both treated samples after 30 min. Furthermore, the MAC samples showed a significant increase in cell adhesion 4 h after plasma treatment for 15 s. The SEM analysis highlighted that, on the treated samples (especially on the MAC disks), the cells with a polygonal and flat shape prevailed, while the fusiform- and globular-shaped cells were rare. The encouraging results obtained further confirm the effectiveness of plasma treatments on cell adhesion and fibroblast activity. Full article
(This article belongs to the Special Issue Feature Papers in Digital Dentistry)
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<p>Flow diagram of the study experiments.</p> Full article ">Figure 2
<p>The assessment of the sample contaminations involved quantifying the number of colony-forming units per milliliter (CFU/mL) of the LB Broth medium, a medium that was incubated with the tested disks following exposure to controlled environmental conditions for post-plasma treatment durations ranging from 15 to 100 s. * indicates statistical significance vs. the CTRL surface (where a <span class="html-italic">p</span> value of &lt; 0.05 is considered statistically significant).</p> Full article ">Figure 3
<p>The protein adsorption was evaluated on MAC and SL samples at 20 min and 4 h, as well as on the plasma treatments for 15, 30, and 60 s. The level of protein adsorption was evaluated using a BAC assay. Values represent the mean ± SEM. * indicates statistical significance vs. the CTRL surface (where a <span class="html-italic">p</span> value of &lt; 0.05 is considered statistically significant).</p> Full article ">Figure 4
<p>The cell adhesion was assessed on the MAC and SL samples at 30 min, as well as on the 4 h post-plasma treatment durations of 15, 30, and 60 s. The extent of the cell adhesion was quantified by enumerating the number of adherent cells per field. The reported values represent the mean ± standard error of the mean (SEM). Statistical significance compared to the control (CTRL) surface is denoted by * for <span class="html-italic">p</span> values less than 0.05.</p> Full article ">Figure 5
<p>The cell proliferation was assessed on the MAC and SL samples at 24 h post the plasma treatment durations of 15, 30, and 60 s. Evaluation of the proliferation levels was conducted using a luminometric cell titer glo assay. Values are presented as the mean ± SEM.</p> Full article ">Figure 6
<p>Representative images depicting the morphology of the cells. The fluorescence photomicrographs captured the cells seeded on the MAC and SL samples at 1, 4, and 24 h post the plasma treatment durations of 15, 30, and 60 s. The cells were stained to visualize the nucleus (DAPI, blue), actin filaments (rhodamine-phalloidin, red), and focal adhesions (paxillin, green).</p> Full article ">Figure 7
<p>Representative pictures of the post-op conditions of the discs with cell growths at different time points. Quantitatively significant differences can be detected between the control and bio-active surfaces.</p> Full article ">Figure 8
<p>Representative pictures of the cell growth at different time points. Globous cells can be detected on the control machined surface, while spread arrangement can be seen on the bioactivated surfaces at different time points.</p> Full article ">
14 pages, 5164 KiB  
Article
Osteoblast Attachment on Bioactive Glass Air Particle Abrasion-Induced Calcium Phosphate Coating
by Faleh Abushahba, Elina Kylmäoja, Nagat Areid, Leena Hupa, Pekka K. Vallittu, Juha Tuukkanen and Timo Närhi
Bioengineering 2024, 11(1), 74; https://doi.org/10.3390/bioengineering11010074 - 12 Jan 2024
Viewed by 1787
Abstract
Air particle abrasion (APA) using bioactive glass (BG) effectively decontaminates titanium (Ti) surface biofilms and the retained glass particles on the abraded surfaces impart potent antibacterial properties against various clinically significant pathogens. The objective of this study was to investigate the effect of [...] Read more.
Air particle abrasion (APA) using bioactive glass (BG) effectively decontaminates titanium (Ti) surface biofilms and the retained glass particles on the abraded surfaces impart potent antibacterial properties against various clinically significant pathogens. The objective of this study was to investigate the effect of BG APA and simulated body fluid (SBF) immersion of sandblasted and acid-etched (SA) Ti surfaces on osteoblast cell viability. Another goal was to study the antibacterial effect against Streptococcus mutans. Square-shaped 10 mm diameter Ti substrates (n = 136) were SA by grit blasting with aluminum oxide particles, then acid-etching in an HCl-H2SO4 mixture. The SA substrates (n = 68) were used as non-coated controls (NC-SA). The test group (n = 68) was further subjected to APA using experimental zinc-containing BG (Zn4) and then mineralized in SBF for 14 d (Zn4-CaP). Surface roughness, contact angle, and surface free energy (SFE) were calculated on test and control surfaces. In addition, the topography and chemistry of substrate surfaces were also characterized. Osteoblastic cell viability and focal adhesion were also evaluated and compared to glass slides as an additional control. The antibacterial effect of Zn4-CaP was also assessed against S. mutans. After immersion in SBF, a mineralized zinc-containing Ca-P coating was formed on the SA substrates. The Zn4-CaP coating resulted in a significantly lower Ra surface roughness value (2.565 μm; p < 0.001), higher wettability (13.35°; p < 0.001), and higher total SFE (71.13; p < 0.001) compared to 3.695 μm, 77.19° and 40.43 for the NC-SA, respectively. APA using Zn4 can produce a zinc-containing calcium phosphate coating that demonstrates osteoblast cell viability and focal adhesion comparable to that on NC-SA or glass slides. Nevertheless, the coating had no antibacterial effect against S. mutans. Full article
(This article belongs to the Special Issue Titanium Implant and Its Cleaning/Decontamination Techniques)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Typical surface profiles of the NC-SA (<b>A</b>), Zn4-APA (<b>B</b>), and Zn4-CaP (<b>C</b>) surfaces. The images were acquired with a 5× objective lens and utilizing a field of view multiplier of 0.5×.</p> Full article ">Figure 2
<p>SEM images of NC-SA (<b>A</b>,<b>D</b>,<b>G</b>), Zn4-APA (<b>B</b>,<b>E</b>,<b>H</b>), and Zn4-CaP (<b>C</b>,<b>F</b>,<b>I</b>). Magnifications 250× (<b>A</b>–<b>C</b>), 2500× (<b>D</b>–<b>F</b>) and (<b>C</b>,<b>F</b>,<b>I</b>) 5000×. Arrows in (<b>H</b>) show some of the attached glass particles. The window in (<b>I</b>) shows the same picture in 25,000× magnification, illustrating the possible HA crystals.</p> Full article ">Figure 3
<p>Viable <span class="html-italic">S. mutans</span> on the Zn4-CaP and NC-SA substrates.</p> Full article ">Figure 4
<p>Localization of focal adhesion in MC3T3-E1 cells. Focal adhesion staining of the cells on cover glass, Zn4-CaP, and NC-SA after 48 h culture (images presented here represent one culture). Hoechst 33258 was used for nucleus staining (blue), anti-vinculin was employed for focal adhesion labeling (green), and TRITC-phalloidin was utilized for visualizing the actin cytoskeleton (red). A fluorescence microscope was used to capture the images with 20× objective (with or without 4× zoom). The focal adhesion-like structures were observed at the peripheries of cells on all surfaces. On cover glasses, these structures were thin dash-like structures (arrowheads), whereas, on Zn4-CaP and NC-SA, the structures were more spread over the surface of the substrate (arrows). On cover glass and Zn4-CaP, the actin cytoskeleton of the cells is normal, but on NC-SA, actin localizes mainly in nuclei, and only a small amount is visible in the cytoplasm.</p> Full article ">Figure 5
<p>MTT assay results of MC3T3-E1 cells cultured on cover glass, Zn4-CaP, and NC-SA. Cell viability on Zn4-CaP and NC-SA substrates was assessed relative to cover glasses, serving as controls with their viability set to 100%. The data represent the mean (SD) pooled from three independent cell cultures.</p> Full article ">
17 pages, 7395 KiB  
Article
Influence of Surface Preparation on the Microstructure and Mechanical Properties of Cold-Sprayed Nickel Coatings on Al 7075 Alloy
by Wojciech Żórawski, Anna Góral, Medard Makrenek, Lidia Lityńska-Dobrzyńska and Paweł Czaja
Materials 2023, 16(21), 7002; https://doi.org/10.3390/ma16217002 - 1 Nov 2023
Cited by 1 | Viewed by 1211
Abstract
This work presents the effect of surface roughness (Al 7075) on the microstructure and mechanical properties of cold-sprayed nickel coatings. Coating analysis included substrate surfaces and coating geometry, microstructure characterization, microhardness, nanohardness, elastic modulus, and adhesion. The results show that the surface preparation [...] Read more.
This work presents the effect of surface roughness (Al 7075) on the microstructure and mechanical properties of cold-sprayed nickel coatings. Coating analysis included substrate surfaces and coating geometry, microstructure characterization, microhardness, nanohardness, elastic modulus, and adhesion. The results show that the surface preparation had a significant effect on coating adhesion and microstructure. The coating deposited at the highest gas temperature revealed a dense microstructure, showing very good adhesion of the impacting powder particles to the substrate and good bonding between deposited layers. The Ni grains with different shapes (elongated, equiaxed) and sizes of a few dozen to several hundred nanometres were present in the splats. An increase in temperature caused significant growth in coating thickness as a result of the powder grains’ higher velocity. Moreover, higher gas temperature resulted in the enhancement of micro- and nanohardness, elastic modulus, and adhesion. The adhesive bond strength of Ni coatings in the tested temperature ranges from 500 °C to 800 °C increased with the increase in the surface roughness of the substrate. For the Al 7075 coarse grit-blasted (CG) substrate with the highest roughness, the adhesion reached the highest value of 44.6 MPa when the working gas was at a temperature of 800 °C. There were no distinct dependencies of surface roughness and thickness on the mechanical properties of the cold-sprayed nickel coating. Full article
(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys (Second Volume))
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<p>Ni powder: (<b>a</b>) morphology of grains, (<b>b</b>) surface morphology of grains, (<b>c</b>) cross-section of grains, (<b>d</b>) high magnification of grain cross-section.</p> Full article ">Figure 2
<p>Geometry of Al 7075 substrate surface: (<b>a</b>) NG, (<b>b</b>) MG, (<b>c</b>) CG, (<b>d</b>) CG cross-section.</p> Full article ">Figure 3
<p>Microstructure of CS Ni coatings sprayed on the CG surface with nitrogen at (<b>a</b>) 500 °C, (<b>b</b>) 600 °C, (<b>c</b>) 700 °C, (<b>d</b>) 800 °C, white arrows indicate coating discontinuities.</p> Full article ">Figure 4
<p>Microstructure of CS Ni coatings sprayed on the surface with nitrogen at (<b>a</b>) NG/500 °C, (<b>b</b>) NG/600 °C, (<b>c</b>) MG/600 °C.</p> Full article ">Figure 5
<p>Morphology of CS Ni coating surface sprayed on the NG surface with nitrogen at (<b>a</b>) 500 °C, (<b>b</b>) 600 °C, (<b>c</b>) 700 °C, (<b>d</b>) 800 °C.</p> Full article ">Figure 6
<p>(<b>a</b>) BF TEM image of part of the Ni coating/7075 Al alloy substrate system, (<b>b</b>) SAD pattern corresponds to the Ni coating, (<b>c</b>) SAD pattern corresponds to the aluminium alloy substrate.</p> Full article ">Figure 7
<p>STEM images of (<b>a</b>) Ni coating, (<b>b</b>) area showing coating/substrate interface.</p> Full article ">Figure 8
<p>(<b>a</b>) BF TEM image and (<b>b</b>) STEM image of the sample cut out from the region lying in the upper part of the Ni coating—near the coating surface. The white-filled arrows indicate twin grains, while the white hollow arrows show a boundary of Ni splat.</p> Full article ">Figure 9
<p>X-ray diffraction patterns obtained for both the Ni powder feedstock and coatings cold sprayed at various nitrogen temperatures: 500 °C, 600 °C, 700 °C, 800 °C.</p> Full article ">Figure 10
<p>HV microhardness imprints: (<b>a</b>) across the CS Ni coating (CG/600 °C), (<b>b</b>) inter-plat cracks on the CS Ni coating near to the Al 7075 substrate, (<b>c</b>) Ni bulk material, (<b>d</b>) high magnification of inter-splat cracks in the middle of the CS Ni coating.</p> Full article ">Figure 11
<p>Microhardness of CS Ni coatings with nitrogen gas at: (<b>a</b>) 600 °C, (<b>b</b>) 700 °C, (<b>c</b>) 800 °C, (<b>d</b>) collected results.</p> Full article ">Figure 12
<p>Cross-section of CS Ni coatings: (<b>a</b>) square array of nanoindentations, (<b>b</b>) a contour plot of nanohardness versus position within the coating.</p> Full article ">Figure 13
<p>CS Ni coatings: (<b>a</b>) nanohardness, (<b>b</b>) elastic modulus.</p> Full article ">Figure 14
<p>The adhesion of cold-sprayed Ni coatings vs. nitrogen.</p> Full article ">
17 pages, 16592 KiB  
Article
The Impact of Al2O3 Particles from Grit-Blasted Ti6Al7Nb (Alloy) Implant Surfaces on Biocompatibility, Aseptic Loosening, and Infection
by Boštjan Kocjančič, Klemen Avsec, Barbara Šetina Batič, Darja Feizpour, Matjaž Godec, Veronika Kralj-Iglič, Rok Podlipec, Andrej Cör, Mojca Debeljak, John T. Grant, Monika Jenko and Drago Dolinar
Materials 2023, 16(21), 6867; https://doi.org/10.3390/ma16216867 - 26 Oct 2023
Cited by 1 | Viewed by 1865
Abstract
For the improvement of surface roughness, titanium joint arthroplasty (TJA) components are grit-blasted with Al2O3 (corundum) particles during manufacturing. There is an acute concern, particularly with uncemented implants, about polymeric, metallic, and corundum debris generation and accumulation in TJA, and [...] Read more.
For the improvement of surface roughness, titanium joint arthroplasty (TJA) components are grit-blasted with Al2O3 (corundum) particles during manufacturing. There is an acute concern, particularly with uncemented implants, about polymeric, metallic, and corundum debris generation and accumulation in TJA, and its association with osteolysis and implant loosening. The surface morphology, chemistry, phase analysis, and surface chemistry of retrieved and new Al2O3 grit-blasted titanium alloy were determined with scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and confocal laser fluorescence microscopy, respectively. Peri-prosthetic soft tissue was studied with histopathology. Blasted retrieved and new stems were exposed to human mesenchymal stromal stem cells (BMSCs) for 7 days to test biocompatibility and cytotoxicity. We found metallic particles in the peri-prosthetic soft tissue. Ti6Al7Nb with the residual Al2O3 particles exhibited a low cytotoxic effect while polished titanium and ceramic disks exhibited no cytotoxic effect. None of the tested materials caused cell death or even a zone of inhibition. Our results indicate a possible biological effect of the blasting debris; however, we found no significant toxicity with these materials. Further studies on the optimal size and properties of the blasting particles are indicated for minimizing their adverse biological effects. Full article
(This article belongs to the Special Issue Current Progress in Surface, Micromorphology and Mechanical Properties of Implants)
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<p>(<b>a</b>) SE image of rough surface (S<sub>a</sub> 6 μm); (<b>b</b>) cementless femoral component of a new ZM hip endoprosthesis stem; the retrieved stems after being cleaned and sterilized appear the same; the red box indicates the region investigated; (<b>c</b>) EDS spectrum of a representative sample indicating that the dark grey region in SE image (<b>d</b>) and green in (<b>e</b>) is corundum Al<sub>2</sub>O<sub>3</sub>; (<b>d</b>) SE image of a cross-section of new Ti6Al7Nb stem indicating residual Al<sub>2</sub>O<sub>3</sub> surface contamination (dark grey) in the subsurface up to 20μm from an Al<sub>2</sub>O<sub>3</sub> grit blasting; (<b>e</b>) EDS mapping showing the Ti6Al7Nb matrix (red) and Al<sub>2</sub>O<sub>3</sub> contamination (green). Different colors correspond to different materials.</p> Full article ">Figure 2
<p>(<b>a</b>) SE image of commercial white fused alumina WFA 40 of irregular granulation 300–400 μM for surface roughening of implants; (<b>b</b>) Bright-field (BF) TEM image of highly purified white corundum particle with marked TEM profile analysis and inset of electron diffraction; (<b>c</b>) TEM profile analysis shows Al, O, and Fe traces in the corundum particle; (<b>d</b>) TEM mapping analysis with Al, O, and Fe elements; and (<b>e</b>) XRD spectrum of highly purified white corundum milled powder.</p> Full article ">Figure 3
<p>(<b>a</b>) XPS depth profile of a new Ti6Al7Nb alloy covered with native oxide after polishing. The thickness of the oxide was estimated to be 6 ± 2 nm. (<b>b</b>) XPS depth profile of a retrieved Ti6Al7Nb alloy covered with a native oxide after polishing. The thickness of the oxide was estimated to be 5 ± 2 nm.</p> Full article ">Figure 4
<p>The results of daily monitoring of cytotoxicity testing. The photos represent the cells, grown in immediate vicinity of the materials. The Al<sub>2</sub>O<sub>3</sub> disc shows no sign of cytotoxicity. Corundum small particles, except for the + control, exhibit the most obvious cytotoxic effect. The Ti6Al7Nb alloy with a modified surface via grit blasting and with residual debris particles on the surface and subsurface exhibited a small level of cytotoxicity but only on the surface where a corundum cover was present. When those samples were polished, there was no cytotoxic effect (not shown).</p> Full article ">Figure 5
<p>Signs of stress in the vicinity of corundum small particles: inclusion bodies (arrows), overspread cells (stars), and overspread cells (triangles) on a Ti6Al7Nb alloy with a modified surface via grit blasting and with residual debris particles on the surface and subsurface.</p> Full article ">Figure 6
<p>The effect of residual Al<sub>2</sub>O<sub>3</sub> particles on the morphology of BMSC cells. (<b>A</b>–<b>D</b>) Corundum particles on the glass surface, (<b>E</b>–<b>H</b>) cells growing one week on corundum ceramic disc, (<b>I</b>–<b>L</b>): cells growing on glass with added toxic compound (positive control), and (<b>M</b>–<b>P</b>) cells growing on glass (negative control).</p> Full article ">Figure 7
<p>Confocal fluorescence images of live BSMCs grown on Ti6Al7Nb alloys with different surface finishing. (<b>A</b>–<b>C</b>) BMSCs on a polished (mirror-like) surface with non-oriented growth; (<b>D</b>–<b>F</b>) BMSCs on a ground surface with oriented growth; (<b>G</b>–<b>I</b>) BMSCs on a rough, Al<sub>2</sub>O<sub>3</sub> contaminated surface with non-oriented poor growth, mostly only partially attached to the surface via anchoring points (see the arrows).</p> Full article ">Figure 8
<p>Confocal 2D/3D fluorescence microscopy of locally adhered live BSMCs on the rough Ti6Al7Nb surface with remaining Al<sub>2</sub>O<sub>3</sub> particles embedded. The material surface (gray color) is observed through the backscatter detection of the laser source. In this example, cells are adhered to the surface through four anchoring sites (red arrows), where the gaps between the surface and the cell are denoted with a white arrow and dashed rectangle. The gaps could be a possible place for bacteria adherence and consequently premature failure due to periprosthetic infection.</p> Full article ">Figure 9
<p>Photomicrographs of granulomatous tissue from a periprosthetic membrane filled with macrophages containing metal wear particles. (<b>A</b>) Gray-blue macrophage cytoplasm (obj. mag. 20×); (<b>B</b>) Black, needle-shaped to polygonal, sharp-edged metal microparticles different in size (obj. mag. 20×); (<b>C</b>) Cytoplasm filled with black particles (obj. mag. 40×); (<b>D</b>) Severe metallosis with metal particles in macrophages and extracellular space (obj. mag. 20×). Black bar = 50 μm and white bars = 100 μm.</p> Full article ">Figure 10
<p>Photomicrograph illustrations of lymphocytic infiltrate in periprosthetic membrane. (<b>A</b>) Diffuse distributed lymphocytes (obj. mag. 40×) and (<b>B</b>) small perivascular lymphocytic cuff (obj. mag. 20×). Black bar = 50 μm and white bar = 100 μm.</p> Full article ">Figure A1
<p>Retrieved prostheses/stems.</p> Full article ">
8 pages, 2803 KiB  
Case Report
Human Histological Analysis of Early Bone Response to Immediately Loaded Narrow Dental Implants with Biphasic Calcium Phosphate® Grid-Blasted Surface Treatment: A Case Report
by Tárcio Hiroshi Ishimine Skiba, Eduardo C. Kalil, Adriano Piattelli and Jamil Awad Shibli
Dent. J. 2023, 11(7), 177; https://doi.org/10.3390/dj11070177 - 19 Jul 2023
Cited by 2 | Viewed by 1665
Abstract
Implant surface topography using bioactive material provides faster bone-to-implant healing. This histological report described the analysis of human bone tissue around an immediately loaded implant, with BPC® (Biphasic Calcium Phosphate) grit-blasted surface treatment, after two months of healing. Two temporary mini-implants (2.8 [...] Read more.
Implant surface topography using bioactive material provides faster bone-to-implant healing. This histological report described the analysis of human bone tissue around an immediately loaded implant, with BPC® (Biphasic Calcium Phosphate) grit-blasted surface treatment, after two months of healing. Two temporary mini-implants (2.8 × 10 mm) with BPC® grit-blasting surfaces were placed and immediately loaded to retain a complete interim denture. After a 60-day healing period, one mini-implant was removed for histologic analysis. The ground section showed the whole implant surrounded by healthy peri-implant tissues. Implant surface presented a close contact with newly formed bone, showing some areas of osteoblasts secreting mineral matrix. The ground section depicted a bone contact of 60.3 + 8.5%. The BPC® grit-blasted surface was biocompatible and enabled the osseointegration process after a short-term period. Full article
(This article belongs to the Topic Medical and Dental Care, Photobiomodulation and Photomedicine)
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Figure 1

Figure 1
<p>Clinical view of the temporary implant placement.</p> Full article ">Figure 2
<p>(<b>A</b>) Clinical aspect of the temporary implants after 60 days of healing; (<b>B</b>) radiographic aspect of the temporary implants (arrows) and the conventional type. Note that the conventional implants were submerged and will receive the 2nd stage of surgery.</p> Full article ">Figure 3
<p>Temporary implant retrieved after 60-day healing period. Note the presence of attached bone tissue around the implant.</p> Full article ">Figure 4
<p>Ground section—15× original magnification; Stevenel’s blue and alizarin red stain. The implant is surrounded by newly formed bone along the entire perimeter with some areas of woven bone.</p> Full article ">Figure 5
<p>Ground section—200× original magnification; Stevenel’s blue and alizarin red stain. The implant (I) is surrounded by new bone (NB) with areas of ongoing bone formation. Woven bone (WB) and some areas with connective tissue are also seen with vessels (*) and some particles of pristine bone (PB).</p> Full article ">Figure 6
<p>Ground section—200× original magnification; Stevenel’s blue and alizarin red stain. The implant (I) is in close contact with osteoblasts (white arrowheads), suggesting ongoing bone formation or osseointegration. New bone (NB) is also present with areas of bone matrix formation with several osteoblasts (arrows) and a large area of woven bone (WB), usually seen in the regions with type IV bone (maxillae).</p> Full article ">
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