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The aim of this work was to study, using the finite element method (FEM), the distribution of thermal residual stresses arising in metal–ceramic dental restorations after cooling from the processing temperature. Three different interface configurations were studied: with conventional sharp transition; one with a 50% metal–50% ceramic interlayer; and one with a compositionally functionally gradated material (FGM) interlayer. The FE analysis was performed based on experimental data obtained from Dynamic Mechanical Analysis (DMA) and Dilatometry (DIL) studies of the monolithic materials and metal/ceramic composites. Results have shown significant benefits of using the 50% metal–50% ceramic interlayer and the FGM interlayer over the conventional sharp transition interface configuration in reduction of the thermal residual stress and improvement of stress profiles. Maximum stresses magnitudes were reduced by 10% for the crowns with 50% metal–50% ceramic interlayer and by 20% with FGM interlayer. The reduction in stress magnitude and smoothness of the stress distribution profile due to the gradated architectures might explain the improved behavior of these novel dental restorative systems relative to the conventional one, demonstrated by in-vitro studies already reported in literature. [ABSTRACT FROM AUTHOR]

In this study, Selective Laser Melting (SLM) was used to produce mono-material Ti64Al4V- and NiTi-cubic cellular structures with an open-cell size and wall thickness of 500 μm and 100 μm, respectively. Bioactive beta-tricalcium phosphate (βTCP) and polymer poly-ether-ether ketone (PEEK) were used to fill the produced structures open-cells, thus creating multi-material components. These structures were characterized in vitro in terms of cell viability, adhesion, differentiation and mineralization. Also, bio-tribological experiments were performed against bovine plate to mimic the moment of implant insertion. Results revealed that metabolic activity and mineralization were improved on SLM mono-material groups, when compared to the control group. All cell metrics were improved with the addition of PEEK, conversely to βTCP where no significant differences were found. These results suggest that the proposed solutions can be used to improve implants performance. [Display omitted] • Ti- and NiTi-based structures were produced by SLM and pressure-assisted methods. • In vitro and bio-tribological tests were made and benchmarked against Ti64 SLA. • Ti and NiTi structures showed improved biological response when compared with SLA. • PEEK-filled structures show positive cellular response, conversely to βTCP. • These solutions ensure adequate in vitro response, while keeping primary stability. [ABSTRACT FROM AUTHOR]

Abstract: In this study, mechanical and thermal properties of CoCrMo–porcelain composites for dental restorations have been evaluated. These metal–ceramic composites were produced by powder metallurgy and hot pressing techniques from the mixtures of metal and ceramic powders with different volume fractions. Young's moduli and the coefficient of thermal expansion of materials were evaluated by dynamic mechanical analysis (DMA) and dilatometry (DIL) tests, respectively. The strength in flexion and shear was measured with a universal test machine and hardness with a respective tester. The microstructures and fracture surfaces were inspected by the means of optical microscopy and Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS). Shear strength, Flexural strength and Young' moduli of ceramic and metal-matrix composites were found to increase with higher metal particles content. The DMA tests performed at different frequencies showed no frequency-dependent features of the materials studied, indicating no viscoelastic behavior. The fracture surfaces analysis suggests the load-transfer mechanism be possibly responsible for this behavior, as the differences in CTE are low enough to cause significant thermal stresses in these materials. The results might be included in a materials properties database for further use for design and optimization of dental restorations. [Copyright &y& Elsevier]

Abstract: Objectives: The purpose of this study was to evaluate the shear bond strength between CoCrMo dental alloy and porcelain restorations by application of different metal–ceramic transitional interfaces aiming at improvement of the bond strength and fracture tolerances. Methods: Several metal–ceramic specimens with different composite interlayers were produced. The interlayers consisted of metal/ceramic composites with different metal volume fractions (20M; 40M; 60M; 80M). The metal–ceramic bond strength as well as the fracture strength of the composites and monolithic base materials were assessed by the means of a shear test performed in a universal test machine. The interfaces of fractured and untested specimens were examined by the means of optical microscopy. The microstructures of monolithic base materials were analyzed using SEM/EDS. The elastic and inelastic properties of the homogeneous compositions were additionally evaluated using dynamic mechanical analysis. Results: The bond strength results obtained for metal–ceramic gradated specimens were the highest (261±38MPa) for 40vol% metal in the interlayer [40M] vs. 109±27MPa for a direct metal–ceramic joint. The Young''s moduli and the fracture resistance of the composites revealed an increasing trend for increasing metal contents. Significance: This study shows that a graded transition between metal and ceramic, provided by a metal/ceramic composite interlayer, is regarded for an increase by 2.5 times in the bond strength between the two materials relative to conventional sharp transitions. The elastic modulus of the composites used as interlayers might be very reasonably approximated by a micromechanical model. [Copyright &y& Elsevier]

Abstract: Objectives: The aim of this study was to evaluate the effect of thermo-mechanical cycling on the metal–ceramic bond strength of conventional porcelain fused to metal restorations (PFM) and new functionally graded metal–ceramic dental restorations (FGMR). Methods: Two types of specimens were produced: PFM and FGMR specimens. PFM specimens were produced by conventional PFM technique. FGMR specimens were hot pressed and prepared with a metal/ceramic composite interlayer (50M, vol%) at the metal–ceramic interface. They were manufactured and standardized in cylindrical format and then submitted to thermal (3000, 6000 and 12,000 cycles; between 5°C and 60°C; dwell time: 30s) and mechanical (25,000, 50,000 and 100,000 cycles under a load of 50N; 1.6Hz) cycling. The shear bond strength tests were performed in a universal testing machine (crosshead speed: 0.5mm/min), using a special device to concentrate the tension at the metal–ceramic interface and the load was applied until fracture. The metal–ceramic interfaces were examined with SEM/EDS prior to and after shear tests. The Young''s modulus and hardness were measured across the interfaces of both types of specimens using nanoindentation tests. Data was analyzed with Shapiro–Wilk test to test the assumption of normality. The 2-way ANOVA was used to compare shear bond strength results (p<0.05). Results: FGMR specimens showed significantly (p<0.001) higher shear bond strength results than PFM specimens, irrespective of fatigue conditions. Fatigue conditions significantly (p<0.05) affected the shear bond strength results. The analysis of surface fracture revealed adhesive fracture type for PFM specimens and mixed fracture type for FGMR specimens. Nanoindentation tests showed differences in mechanical properties measured across the metal–ceramic interface for the two types of specimens, namely Young''s Modulus and hardness. Significance: This study showed significantly better performance of the new functionally graded restorations relative to conventional PFM restorations, under fatigue testing conditions and for the materials tested. [Copyright &y& Elsevier]

In this work the cold gas spray (CGS) technique was used to produce anti-biofilm and biocompatibility copper surfaces. Copper was deposited onto carbon steel and the phase composition, morphology, porosity, and adherence of the coating were investigated. Methicillin-susceptible Staphylococcus aureus (MSSA-ATCC 25923), Escherichia coli (ATCC 25922) and Candida albicans (SC 5314) biofilms were used in the antimicrobial tests, and the biocompatibility of the coatings was tested in human monocytes (THP-1 cell line). The main physical characteristics of the copper coating were thickness (640 ± 5) μm, porosity 0.4% and adherence 30 MPa. The X-ray diffraction pattern of the coatings showed only crystalline phase of copper. The plate spreading method, XTT assay, confocal fluorescence microscopy and scanning electron microscopy images showed that copper coatings were effective as an antimicrobial agent by blocking the adhesion and viability of C. albicans and killing the surface adhered bacterial strains, significantly reducing the biofilm survival. The viability rate of THP-1 cells for 24 h was 95% and the confocal microscopy showed the same labeling as the standard culture conditions. [Display omitted] • Copper powders were sprayed on carbon steel using Cold Gas Spray (CGS). • Copper coatings are dense with low porosity and high adhesion. • CGS copper coatings showed antibacterial and fungicidal activity. • CGS copper coatings showed biocompatibility for THP-1 cells. [ABSTRACT FROM AUTHOR]

Ti6Al4V sub-millimetric cellular structures arise as promising solutions concerning the progress of conventional orthopedic implants due to its ability to address a combination of mechanical, physical and topological properties. Such ability can improve the interaction between implant materials and surrounding bone leading to long-term successful orthopedic implants. Selective Laser Melting (SLM) capability to produce high quality Ti6Al4V porous implants is in great demand towards orthopedic biomaterials. In this study, Ti6Al4V cellular structures were designed, modeled, SLM produced and characterized targeting orthopedic implants. For that purpose, a set of tools is proposed to overcome SLM limited accuracy to produce porous biomaterials with desired dimensions and mechanical properties. Morphological analyses were performed to evaluate the dimensional deviations noticed between the model CAD and the SLM produced structures. Tensile tests were carried out to estimate the elastic modulus of the Ti6Al4V cellular structures. The present work proposes a design methodology showing the linear correlations found for the dimensions, the porosity and the elastic modulus when comparing the model CAD designs with Ti6Al4V structures by SLM. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a novel design for implants surface functionalization through the production of HAp-coated zirconia structured surfaces by means of hybrid laser technique. The HAp-rich structured surfaces were designed to avoid hydroxyapatite (HAp) coating detachment from the zirconia surface during implant insertion, thus guaranteeing an effective osseointegration. The functionalization process of zirconia surface started by creating micro-textures using a Nd:YAG laser and subsequent deposition of a HAp coating on the designated locations by dip-coating process. Afterwards, a CO 2 laser was used to sinter the HAp coating. The potential of the HAp-coated zirconia structured surfaces was inspected concerning HAp bioactivity preservation, surface wettability, HAp coating adhesion to the textured surfaces and mechanical resistance of zirconia, as assessed by different approaches. The functionalized surfaces exhibited a superhydrophilic behavior (2.30 ± 0.81°) and the remaining results showed that through the hybrid strategy, it is possible to maintain the HAp bioactivity as well as promote a strong adhesion of HAp coating to the textured surfaces even after high energy ultrasonic cavitation tests and friction tests against bovine bone. It was also verified that the flexural strength of zirconia (503 ± 24 MPa) fulfills the strict requirements of the ISO 13356:2008 standard and as such is expectable to be enough for biomedical applications. The promising results of this study indicate that the proposed surface design can open the window for manufacturing zirconia-based implants with improved bioactivity required for an effective osseointegration as it avoids the coating detachment problem during the implant insertion. [ABSTRACT FROM AUTHOR]

Bone is a dynamic tissue with an amazing but yet limited capacity of self-healing. Bone is the second most transplanted tissue in the world and there is a huge need for bone grafts and substitutes which lead to a decrease in bone banks donors. In this study, we developed three-dimensional scaffolds based on Ti 6 Al 4 V, ZrO 2 and PEEK targeting bone tissue engineering applications. Experimental mechanical compressive tests and finite element analyses were carried out to study the mechanical performance of the scaffolds. Overall, the scaffolds presented different hydrophilicity properties and a reduced elastic modulus when compared with the corresponding solid materials which can in some extension minimize the phenomenon of stress shielding. The ability as a scaffold material for bone tissue regeneration applications was evaluated in vitro by seeding human osteosarcoma (SaOS-2) cells onto the scaffolds. Then, the successful culture of SaOS-2 cells on developed scaffolds was monitored by assessment of cell's viability, proliferation and alkaline phosphatase (ALP) activity up to 14 days of culturing. The in vitro results revealed that Ti 6 Al 4 V, ZrO 2 and PEEK scaffolds were cytocompatible allowing the successful culture of an osteoblastic cell line, suggesting their potential application in bone tissue engineering. Statement of Significance. The work presented is timely and relevant since it gathers both the mechanical and cellular study of non-degradable cellular structures with the potential to be used as bone scaffolds. This work allow to investigate three possible bone scaffolds solutions which exhibit a significantly reduced elastic modulus when compared with conventional solid materials. While it is generally accepted that the Ti 6 Al 4 V, ZrO 2 and PEEK are candidates for such applications a further study of their features and their comparison is extremely important for a better understanding of their potential. [ABSTRACT FROM AUTHOR]

Nickel-titanium (NiTi) cellular structures are a very promising solution to some issues related to orthopaedic implant failure. These structures can be designed and fabricated to simultaneously address a combination of mechanical and physical properties, such as elastic modulus, porosity, wear and corrosion resistance, biocompatibility and appropriate biological environment. This ability can enhance the modest interaction currently existing between metallic dense implants and surrounding bone tissue, allowing long-term successful orthopaedic implants. For that purpose, NiTi cellular structures with different levels of porosity intended to reduce the elastic modulus were designed, modelled, selective laser melting (SLM) fabricated and characterized. Significant differences were found between the CAD design and the SLM-produced NiTi structures by performing systematic image analysis. This work proposes designing guidelines to anticipate and correct the systematic differences between CAD and produced structures. Compressive tests were carried out to estimate the elastic modulus of the produced structures and finite element analyses were performed, for comparison purposes. Linear correlations were found for the dimensions, porosity, and elastic modulus when comparing the CAD design with the SLM structures. The produced NiTi structures exhibit elastic moduli that match that of bone tissue, which is a good indication of the potential of these structures in orthopaedic implants. Image 1 [ABSTRACT FROM AUTHOR]

Tooth loss is a problem that affects both old and young people. It may be caused by several conditions, such as poor oral hygiene, lifestyle choices or even diseases like periodontal disease, tooth grinding or diabetes. Nowadays, replacing a missing tooth by an implant is a very common process. However, many limitations regarding the actual strategies can be enumerated. Conventional screwed implants tend to induce high levels of stress in the peri-implant bone area, leading to bone loss, bacterial bio-film formation, and subsequent implant failure. In this sense, root-analogue dental implants are becoming promising solutions for immediate implantation due to their minimally invasive nature, improved bone stress distribution and because they do not require bone drilling, sinus lift, bone augmentation nor other traumatic procedures. The aim of this study was to analyse and compare, by means of FEA, the stress fields of peri-implant bone around root-analogue and screwed conventional zirconia implants. For that purpose, one root-analogue implant, one root-analogue implant with flaps, two conventional implants (with different threads) and a replica of a natural tooth were modelled. COMSOL was used to perform the analysis and implants were subjected to two simultaneous loads: 100 N axially and 100 N oblique (45°). revealed that root-analogue implants, namely with flaps, should be considered as promising alternatives for dental implant solutions since they promote a better stress distribution in the cortical bone when compared with conventional implants. Image 1 • In this study 4 different implant geometries were modelled: 2 conventional threaded implants and 2 root-analogue implants. • Implant displacement, von Mises stresses, hydrostatic pressure and shear strain were assessed. • Results showed that root-analogue implants induce a better distribution of the von Mises stresses along the cortical bone. • The five tested models were mainly subjected to shear strain values within the physiological parameters. • Root-analogue implants seem to be a promising solution, overcoming the limitations of the threaded conventional implants. [ABSTRACT FROM AUTHOR]

Despite the reported high success of dental implants, problems related to biofilm formation and peri-implantitis due to the entrance and proliferation of bacteria on the peri-implant zone have increasing attention. In this sense, this work proposes a new zirconia surface with micro-grooves aiming to develop an effective tight seal between artificial soft tissue and implant surface and thus, to protect from bacterial invasion. In this study, different laser and design parameters were tested to produce successive micro-grooves with different and variated depth, width and wall. The micro-grooves were produced by a Nd:YAG laser and were morphologically characterized by SEM. Higher marked depths were obtained for a high number of laser passages under low scan speed as a result of a high amount of laser energy density. The most adequate conditions were mechanically tested regarding their capacity to retain artificial soft tissue (mimicking natural gingiva) by mechanical tensile strength test. The strength of adhesion between soft tissue and the micro-grooved surface revealed to be strongly dependent on the depth and width. The obtained results showed that the production of successive micro-grooves on the zirconia surface increased the adhesion of artificial soft tissue to its surface, proving that laser technology is a promising approach for the manufacturing of implants with micro-grooves sites that can protect from bacterial invasion. [ABSTRACT FROM AUTHOR]

The purpose of this study was to characterize the wear behavior of dental glass–ceramic composites reinforced with different contents of zirconia particles (10–50%). The tests were carried out using a ball-on-plate configuration, in artificial saliva at body temperature (37 °C). The worn surfaces were characterized by field emission guns scanning electron microscope. The results demonstrated that zirconia plays a relevant role on wear behavior of zirconia reinforced glass–ceramic composites. The optimal wear properties were obtained for the glass–ceramic reinforced with 30% (vol%) of zirconia particles. The improvement on wear resistance was mainly attributed to the good dispersion of the reinforcement phase, which allowed the load transfer reinforcing mechanism to effectively occur from the matrix to the reinforcement. [ABSTRACT FROM AUTHOR]

This work proposes the design of laser-textured patterns for the development of surfaces with high anchor densities capable of promoting solid mechanical bonding of highly abrasive sintered diamond/carbide-reinforced. Cu-based composite coatings with excellent wear resistance. The results show the development of dense and well-adhered coatings onto the patterns and how the higher nucleation of TiC/Fe 3 C on the diamond surfaces favours its greater bonding within the matrix, preventing its graphitization, and detachment. Reductions above 40% and 60% in the CoF were observed, under dry conditions, for coatings reinforced with 10 & 30 wt% of diamonds, respectively. Depending on the percentage of diamond used, the best glass/coating and alumina/coating wear volume ratios were around 20 and 6. These values would indicate that these composite coatings show high performance and therefore could be used to make tools for grinding and/or cutting glass and ceramic materials. [Display omitted] • A novel composite coating with high cutting/grinding performance is proposed. • TiC nucleation on diamonds promotes increased bonding with the composite matrix. • Fe3C nucleation promotes strengthening of diamond-reinforced alloyed powder blends. • The CoF values in the composite coatings are much lower than the CuBeCo substrate. • Coatings with 10 & 30% of diamond HIPped at 60 MPa/glass pairs have the lowest Kw. [ABSTRACT FROM AUTHOR]

Different materials have been used for dental restorations, and, like a natural tooth, they are subject to wear due to abrasion produced by toothbrushing during oral hygiene routine. The purpose of the present study was to evaluate the toothbrush abrasion resistance of four restorative dental CAD/CAM materials available on the market: an acrylic polymer - PMMA (DD TempMED HI, Dental Direkt), a composite resin (BRILLIANT CRIOS cerec HT A1 14, Coltene, CH) and two ceramics (polychromatic feldspathic porcelain (VITABLOCS RealLife 1M1C, Vita Zahnfabrik) and 3Y-TZP zirconia (DD Bio ZW iso color, Dental Direkt), under the same conditions. The specimens were immersed in a mixture of toothpaste and deionized water and subjected to simulated toothbrushing tests following ISO/TR14569–1:2007. Tests were performed under 3.5 N load, 5 Hz frequency, and 10 mm stroke length. The toothbrush abrasion resistance of each tested material was evaluated through the specific wear rate. The surface roughness and color difference were assessed for all materials before and after 16 years of simulated toothbrushing tests. Statistical analysis was performed by applying one-way ANOVA. The results revealed that the surface characteristics of restorative dental materials were modified by the toothbrushing, except for zirconia. The polymer was the material more susceptible to toothbrushing wear, presenting the highest surface roughness, specific wear rate, and surface change. On the other hand, zirconia showed to be about 10 times more resistant to abrasion than feldspathic porcelain and composite and about 100 times more resistant than polymer. Thus, it is a promising solution for the promotion of longevity restorations. [Display omitted] • The aim of this study was to evaluate the toothbrush abrasion resistance of 4 commercial restorative dental materials under the same conditions. • The toothbrush abrasion resistance of each tested material was evaluated through the specific wear rate; • Color differences and lightness caused by toothbrushing were verified. However, the obtained values are below the perceptibility threshold • The polymer was the most affected by toothbrushing, the one with the greatest color change and highest lightness. • Zirconia is about 10 times more resistant to abrasion than feldspathic porcelain and composite and about 100 times more resistant than polymer. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the tribological behaviour of a dental glass-ceramic (GC) reinforced by 20% (vol.) Yttria-Stabilized Zirconia. Two types of particles were tested: zirconia agglomerates (ZA) and pre-sintered zirconia particles (ZP). The wear tests were carried out using a ball-on-plate configuration. The wear mechanisms were characterized by field emission guns scanning electron microscope. Results revealed an improvement of wear behaviour for GC reinforced by ZP. The improvement on wear resistance was attributed to the effect of reinforcement, by the action of the uniformly distributed ZP that allowed the load transfer reinforcing mechanism through the matrix and reinforcement phase. Dental glass-ceramic reinforced by ZP can constitute a promising alternative to conventional glass-ceramics to produce prosthetic restorations. [ABSTRACT FROM AUTHOR]

3Y-TZP discs were coated using 5Y-PSZ and 12Ce-TZP suspensions. Samples were evaluated in terms of roughness (Ra, Rq, Rz and Rsk), B3B flexural resistance, hardness, Young's modulus by instrumented indentation and surface damage resistance and Vickers hardness by impress Vickers measurements. Coatings with thickness of ~7 μm were obtained. 3Y-TZP uncoated discs showed similar hardness and Young's modulus when compared to those coated with 5Y-PSZ. Discs coated with 12Ce-TZP had opposite behavior. Vickers and Berkovich hardness showed the same trend, with almost no difference observed between monolithic and the 5Y-PSZ coated samples, and with the 12Ce-TZP coated samples exhibiting lower hardness values. Coated samples presented lower flexural strength than uncoated ones. Correlation between roughness and B3B flexural strength was also performed, showing that surface quality achieved by the coating process is the one that rules the final resistance of the component, instead of the coating material. [ABSTRACT FROM AUTHOR]

In this work a textured diamond-reinforced copper-beryllium composite was produced and its tribological behavior was evaluated. In a first stage, a Cu–Be matrix was textured by laser and diamond particles were functionalized with a Cu–Sn–Ti eutectic alloy by mechanical alloying. The second stage consisted on the incorporation and consolidation of the functionalized diamond particles to the matrix by laser sintering. The results showed that despite some heterogeneity of the powders/matrix interface, the textured diamond-reinforced copper-beryllium materials exhibited a much better tribological performance than the unreinforced Cu–Be ones. Such behavior was attributed to the presence of diamond and formation of oxides, like TiO 2 , that act as solid lubricant. No graphitization was observed during laser sintering process. Image 1 • New approach for producing diamond-reinforced Cu–Be composites. • Laser sintering of functionalized diamond particles on a textured Cu–Be matrix. • Reduction of around 30% of the COF for the diamond-reinforced Cu–Be composite. [ABSTRACT FROM AUTHOR]

In this work 3 mol.% yttria-stabilized zirconia (Y-TZP) disks were pressed and subsequently coated, aiming at producing reliable protective coatings to avoid Low Temperature Degradation (LTD) of Y-TZP. Suspensions of 12Ce-TZP or 5Y-PSZ (5 mol.% yttria stabilized zirconia) powders with different solid contents were used as coatings. Accelerated aging was conducted for times of 2, 6 and 18 hours at 134 °C. Specimens were analyzed using XRD, SEM and Colorimetry. Suspensions with solid content of 23 wt% prepared with 12 mol% ceria stabilized zirconia showed coarsening porosity, while all other suspensions achieved acceptable results for this property. Suspensions with 28 wt% Ce-TZP and 23 wt% Y-PSZ were the selected conditions for the LTD studies. They were selected among the remaining conditions, based on their enhanced color properties and surface density, displaying layers with ∼7 μm and 5-10 μm, respectively. Coatings enhanced resistance to LTD. [ABSTRACT FROM AUTHOR]

Zirconia is becoming a promising solution for biomedical applications, namely for dental implants, due to its biocompatibility, and mechanical and aesthetical properties. Despite the constant developments in the dentistry field, strategies to promote an effective vascularization at the implant's surface and consequently improved osseointegration are still not enough.In this sense, with the aim of promoting the vascularization at the implant's surface, zirconia surfaces with micro-channels were designed and evaluated regarding their hydrophilicity and capillarity. A CAD/CAM system was used to design and produce the specimens and different techniques were used to characterize the surfaces. The obtained average surface roughnesses are in accordance with the literature for similar materials. Results revealed that the produced materials present high levels of hydrophilicity, whether in contact with water or FBS - Fetal Bovine Serum. Additionally, micro-channels with 200 μm of width and 100 μm of depth were the ones that presented higher capillarity, thus being promising solutions for the promotion of implants vascularization, and consequently improved osseointegration. [ABSTRACT FROM AUTHOR]

Abstract A new family of bioceramic scaffolds consisting of zirconia foam-like structures with 58S bioactive glass (BG) coating was developed. Three open-cell structures fabricated by the foam replica method were coated via immersion in a sol-gel solution. The coating technique was optimised controlling the sol viscosity, condensation time, and the number of immersions in order to increase the coating thickness. The scaffolds chemical and structural characteristics were evaluated before in vitro tests, including the Ca/P ratio, crystalline phase composition, pH change, pore diameter and microporosity of the scaffolds struts. In vitro tests were performed by culturing MG-63 human osteoblast-like cells. An increase in cell proliferation of 100% was found with the decrease in pore size from 700 to 120 μm. Also, with the presence of the 58S-BG coating, an increase of cell proliferation was reached, which indicates the positive effect of the BG coating on the otherwise bioinert ceramic scaffold. [ABSTRACT FROM AUTHOR]

Abstract Load-bearing implants success is strongly dependent on several physical and chemical properties that are known to drive cellular response. In this work, multi-material β-TCP-Ti6Al4V cellular structures were designed to combine Ti6Al4V mechanical properties and β-Tricalcium Phosphate bioactivity, in order to promote bone ingrowth as the bioactive material is being absorbed and replaced by newly formed bone. In this sense, the produced structures were characterized regarding roughness, wettability, β-TCP quantity and quality inside the structures after fabrication and the pH measured during cell culture (as consequence of β-TCP dissolution) and those aspects were correlated with cellular viability, distribution, morphology and proliferation. These structures displayed a hydrophilic behavior and results showed that the addition of β-TCP to these cellular structures led to an alkalization of the medium, aspect that significantly influences the cellular response. Higher impregnation ratios were found more adequate for lowering the media pH and toxicity, and thus enhance cell adhesion and proliferation. Highlights • β-TCP-Ti6Al4V cellular structures were designed and manufactured by combining AM technique (SLM) with Press and Sintering. • This structure design will allow bone ingrowth while the bioactive material is being absorbed and replaced by new bone. • Structures physical and chemical aspects were assessed and correlated with cell viability, adhesion and proliferation. • β-TCP amount inside these cellular structures has a significant impact on medium pH and thus on the cellular response. [ABSTRACT FROM AUTHOR]

Abstract Contrarily to conventional sintering (CS) method where longer cycles and high temperature (1400–1500 °C) are applied to sinter yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramics, this work presents a faster and low temperature (1175 °C) way through hot pressing (HP) to produce full densified zirconia with good mechanical and tribological properties. This work is concerned with the influence of sintering pressure on the microstructure and tribological properties of hot-pressed Y-TZP. For this purpose, four sintering pressures 5, 20, 60 and 100 MPa were tested. The wear tests were carried out by reciprocating ball-on-plate as a simplified test for tooth-to-restorative material contact under 37 °C using artificial saliva to mimic oral conditions. The results demonstrated that density, hardness and tribological properties are strongly influenced by the sintering pressure, namely an improvement with pressure increase was achieved. The highest density, hardness values and wear resistance were achieved for Y-TZP samples produced at P = 100 MPa. Furthermore, it was revealed that a smaller grain size for Z100 samples (full densification condition) was achieved comparatively to conventional-sintered Y-TZP. This work proves that it is possible to produce dense Y-TZP materials under low sintering temperature and faster cycles with reduced grain size without compromise mechanical and tribological properties. [ABSTRACT FROM AUTHOR]

Abstract A multi-material concept that gathers Ti6Al4V and PEEK properties in a cellular structured component was designed, fabricated and investigated targeting hip implants. SLM and pressure assisted injection techniques were used to obtain Ti6Al4V-PEEK multi-material structures. Aiming to reproduce to some extension the tribological phenomena occurring during and after hip implant insertion, five tribological tests were outlined and performed. The obtained results showed that the presence of PEEK on the Ti6Al4V-PEEK cellular structures led to a substantial improvement on the wear resistance (62% reduction in the mass loss) when compared to the material currently available on market for hip implants. The multi-material solution here investigated shows a good compromise between the primary stability after implant insertion and the wear performance. Graphical abstract Image 1 Highlights • Ti6Al4V-PEEK multi-material structures were produced by SLM and pressure assisted injection. • The multi-material structures displayed 40% lower mass loss than cast/forged Ti6Al4V. • The multi-material structures displayed 62% lower mass loss than Ti6Al4V cellular structures. • Ti6Al4V-PEEK structures displayed the best wear performance due to PEEK auto-lubrication effect. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study was to investigate the influence of the matrix properties, number of the carbon and aramid layers and fiber orientation on low velocity impact behavior of the fabric reinforced hybrid composites with stratified filled epoxy matrix. The impact tests were performed with the drop weight impact system at 90.629 J of energy level. The damage areas were analyzed by the visual inspection and tomographic images. The results showed that the matrix properties have a great influence over the fracture mode of the hybrid composites, while the fault degree of the damaged areas depends on the fiber orientation. The highest impact resistance was obtained in the case of hybrid composites with 0° ply orientation. [ABSTRACT FROM AUTHOR]

Highlights • New implant surface functionalization: Ti6Al4V laser machining & HAP laser sintering. • The HAP laser sintering inside the machined spots was optimized using a CO 2 laser. • Laser technology was proven effective for producing Ti6Al4V-hydroxyapatite implants. • An effective retention and non-degradation of hydroxyapatite was achieved. • Validating this design for the production of implants with improved bioactivity. Abstract Although hydroxyapatite coatings have been proven effective for obtaining uniform and continuous coatings on metallic endosseous implants, the detachment of these coatings during implantation can critically compromise the hydroxyapatite bioactive role. In order to overcome this problem, this work proposes a new integrated approach, starting with the laser machining of the Ti6Al4V implant, followed by the allocation of the hydroxyapatite and its subsequent laser sintering. In this study two different powder compaction/laser sintering methods were tested. Hydroxyapatite sinterability and adhesion to the metal was assessed for both methods, considering several conditions. Hydroxyapatite possible degradation due to the temperatures achieved during this process was also evaluated by means of Energy Dispersive Spectrometry (EDS) and X-ray diffraction (XRD). The better solution assured a significant retained volume of non-degraded hydroxyapatite. This work proves that laser technology is a promising approach for the manufacturing of implants with improved bioactivity sites that can overcome the detachment problems of coating-based solutions. [ABSTRACT FROM AUTHOR]

Abstract Focusing on implant surface design, aiming to improve implant primary stability, SLM technology was explored to produce dense and cellular structured Ti6Al4V specimens. The SLM specimens and also a commercial casted/forged Ti6Al4V group, were sandblasted and acid-etched to obtain a moderate surface roughness topography, typically used in implant manufacturing. Ti6Al4V-bone interaction and tribological performance were assessed by performing sliding tests aiming to replicate in some extension the insertion of a hip implant. The results shown a 24 and 32% higher kinetic friction coefficient values when comparing the cellular structures with the conventional casted/forged Ti6Al4V. These friction results together with a high amount of adhered bone are promising evidences of a higher efficiency of Ti6Al4V cellular structures for enhancing implant stability. Graphical abstract Image 1 Highlights • In this work an implant surface design for improving implants primary stability is proposed. • Selective Laser Melting technology was used to produce Ti6Al4V dense and cellular structured components. • The implant-bone interaction during insertion was simulated by a sliding test of Ti6Al4V structures against bone. • Cellular structures displayed a higher kinetic friction coefficient when compared to dense materials produced by SLM or casting. • Cellular structures with 400 μm open-cell size evidenced a higher efficiency on implant primary fixation when compared to dense materials. [ABSTRACT FROM AUTHOR]

Abstract Multi-material Ti6Al4V cellular structures impregnated with 45S5 bioactive glass were designed and produced using Selective Laser Melting (SLM), an additive manufacturing technique, combined with Press and Sintering focusing on load bearing components like hip implants. These structures were designed to combine Ti6Al4V mechanical properties and promote bone ingrowth into the structure as the bioactive material (45S5) is being absorbed and replaced by newly formed bone. The influence of these structures design on some of the physical and chemical aspects that drive cellular response was assessed. Roughness, wettability, bioactive glass quantity and quality on the structures after processing and the pH measured during cell culture (as a consequence of bioactive glass dissolution) were evaluated and correlated with cellular viability, cellular distribution, morphology and proliferation on the surface and inside the structures. Graphical abstract Unlabelled Image Highlights • Ti6Al4V cellular structures were produced by additive manufacturing and bioactive glass impregnated by press and sintering • This design promotes bone ingrowth into the structure as the bioactive is absorbed and replaced by newly formed bone • The bioactive glass quantity on these structures had influenced the medium pH, greatly influencing the cellular viability • The influence of these structures design on physical/chemical aspects was determined and biologically validated in vitro [ABSTRACT FROM AUTHOR]

Scheme. While humans are vulnerable to slipping on ice and snow, many animals have the intrinsic ability to resist slips and fall on these slippery surfaces. [Display omitted] • This comprehensive review addressing slips and falls on icy/snowy surfaces during winters and their repercussions. • The reasons, physics, and mechanisms of slipping on ice especially formation of quasi liquid layer are discussed in detail. • The mechanisms and designs on anti-slipping nature-inspired surfaces based on different adhesion/deadhesion are presented. • Eight animals that do not slip are presented revealing the materials, mechanism, and structural designs of their anti-slipping. • The review provides new insight into developing advanced nature-inspired shoe-sole by addressing current challenges and research gaps. Slip and Fall (SF) on slippery icy/snowy surfaces during winters is evident worldwide, especially in Nordic regions. Every year millions of people slip and fall due to ice accretion on the roads, streets, and pavements causing traumatic injuries, loss of limbs, and sometime loss of lives, costing billions in hospitals and recovery. An efficient anti-slipping winter shoe-sole could prevent these accidents and save lives. Footwear industries came up with solutions such like crampons, cleats, anti-skidding materials and tread pattern designs, but with limited success because of their ineffectiveness on wet ice, quick rate of wearing. The inspiration from nature like polar bear, seal, arctic fox, penguin, snake, octopus, frog, and gecko where this problem is elegantly solved through evolution process can address these limitations and design advanced anti-slippery surfaces. The review presents a comprehensive understanding of biological designs of the footpads (polar bear, penguin, arctic fox, frog, gecko) and skins (seal, snake, octopus' suction cups) and recent progress on their translation for practical applications. The review emphasises on the mechanisms of icy slippery surfaces and the contact surfaces (shoe-sole and ice/snow) to mimic anti-slipping mechanism of animals and their movement on ice enabling to design the finest anti-slipping winter shoe-soles. [ABSTRACT FROM AUTHOR]

The development of new approaches to improve the implant integration and subsequently its long-term maintenance is an actual challenge. In this way and trying to mimic natural bone composition, HAp-functionalized zirconia surfaces were produced by means of hybrid laser technique combining additive (laser sintering) and subtractive (laser machining) processes. Nd:YAG laser-generated textures were created to improve mechanical interlocking of hydroxyapatite (HAp) powder and consequently enhance its adhesion to zirconia surface. Different laser parameters and also different approaches were tested to optimize the textured line-patterning of zirconia surface. The created microtextures were characterized by Scanning Electron Microscopy (SEM). Furthermore, textured zirconia surfaces were functionalized with HAp by means of CO 2 laser. Different power and scan speed laser parameters were tested to promote HAp retention inside of line-patterning. The results showed that it is possible to design the textured surface by changing energy density and atmosphere. Furthermore, high amount of retained and sintered bioactive material was found when high laser power and low scan speed were performed. [ABSTRACT FROM AUTHOR]

The interest in zirconia as an excellent technical material is growing for a huge field of engineering and research applications, where some of them include rough and/or porous surfaces. Nevertheless, the wear resistance of yttria-stabilized zirconia coated with a porous layer is poorly documented. The aim of this work was to produce porous layers (powder with different average sizes – 40 μm, 70 μm, 100 μm) over a dense zirconia substrate and assess their tribological behaviour against an Al 2 O 3 ball. The porous layers were removed from the substrate during the wear tests. No significant differences were found for the coefficient of friction and the wear rate of the different groups (p > 0.05). [ABSTRACT FROM AUTHOR]

The tribocorrosion behavior of Ti-6Al-4V alloy as produced using different manufacturing/processing methods is experimentally investigated. Various Ti-6Al-4V specimens sourced from either casting, hot pressing (HP) or Laser Engineered Net Shaping (LENS) processes were analyzed via reciprocating sliding alumina contact tests under open circuit potential (OCP). Results indicate that the tribocorrosion behavior of Ti-6Al-4V parts depends on its manufacturing method. The additive manufactured, LENS Ti-6Al-4V samples showed better wear and corrosion resistance as compared to the Ti-6Al-4V samples produced by either casting or HP. This unique characteristic is attributed to the very high, localized cooling rates experienced during LENS resulting in the Ti-6Al-4V material having higher hardness and slight chemistry variation. [ABSTRACT FROM AUTHOR]