Titanium-6 Aluminum-4 Vanadium Research Articles

Evaluation of osseointegration of Ti-6Al-4V alloy orthodontic mini-screws with ibandronate-loaded TiO2 nanotube layer.

Recently, the use of orthodontic mini-screws as an anchorage for orthodontic treatment is increasing, and the degree of osseointegration of the mini-screws affects the performance of orthodontic treatment. This study aimed to evaluate the biocompatibility and osseointegration of Titanium 6Aluminum 4Vanadium (Ti-6Al-4V) alloy orthodontic mini-screws with an ibandronate-loaded TiO2 nanotube (TNT) layer. The TNT layer was formed on the surface of the Ti-6Al-4V alloy orthodontic mini-screws and loaded with ibandronate. The TNT formed by anodic oxidation formed a completely self-organized and compact structure and was stably released for 7 days after loading with ibandronate. Mini-screws loaded with ibandronate were implanted into both tibias of rats, confirming rapid initial bone regeneration. We demonstrate that the release of stable ibandronate from the TNT layer of Ti-6Al-4V alloy orthodontic mini-screws can effectively improve biocompatibility and osseointegration.

Cobalt chromium alloys in fixed prosthodontics: Investigations of mechanical properties and microstructure

Statement of problemCobalt chromium (Co-Cr) alloys possess beneficial mechanical properties because alloys, even in thin sections, can resist high mastication forces and exhibit an acceptable bond to the surface porcelain layer. Traditional manufacturing techniques of Co-Cr alloys such as casting have been replaced with newer fabrication techniques, such as milling, laser melting, and presintered milling. Despite scarce documentation, these new manufacturing techniques are being used to fabricate dental and implant constructions. PurposeThis in vitro study investigates the hardness, yield strength, elastic modulus, and microstructure of the most commonly used Co-Cr alloys for fixed prosthodontics based on manufacturing technique. In addition, this study investigates the effect of heat treatment on the mechanical properties and microstructure of these materials. Material and methodsFive Co-Cr alloys were included (dumbbell and rectangular shaped) based on four manufacturing techniques: cast, milled, laser melted, and presintered milled. Commercially pure titanium grade 4 and titanium-6 aluminum-4 vanadium ELI (extra low interstitial) were included for comparison, and yield strength and elongation after fracture were evaluated. The specimens were tested for hardness using the Vickers test and for elastic modulus using a nondestructive impulse excitation technique. The microstructure of selected specimens was analyzed using focused ion beam-scanning electron microscopy (FIB-SEM) and energy dispersive X-ray spectroscopy (EDS). ResultsThe mechanical properties depend on the manufacturing technique used; the laser-melted and presintered Co-Cr specimens demonstrated the highest mechanical properties, followed by the milled and cast groups. Both the laser-melted and the presintered milled Co-Cr specimens showed smaller grain size compared with the cast and milled Co-Cr specimens. The titanium-6 aluminum-4 vanadium ELI demonstrated higher hardness and yield strength compared to commercially pure titanium grade 4. No major differences were observed for the selected materials regarding the mechanical properties and microstructural appearance after heat treatment. ConclusionsThe laser melting and presintered milling techniques produced higher mechanical properties compared with the cast and milled Co-Cr. These findings were confirmed through microstructural analysis with respect to the grain size, precipitation, and number of pores.

Electron beam manufacturing 3D printed titanium with titanium nitride coating shows favorable overall performance when compared to selective laser sintering cobalt chrome in patient specific talus implants

Background: Selective Laser Sintering (SLS) Cobalt Chrome (CoCr) has been utilized extensively in medical implants. However, Electron Beam Manufacturing (EBM) 3D Printed Titanium-6 Aluminum-4 Vanadium Extra Low Interstitial (Ti6Al4V ELI) is increasingly being utilized due to its higher strength to weight ratio, biocompatibility, resistance to corrosion, and capacity for osseointegration. More recently, Titanium Nitride (TiN) coatings have been applied to Ti6Al4V ELI to improve its long-term durability. While durability and tribology are a critical measure of an implant’s overall performance, no studies comparatively examine these properties in Ti6Al4V ELI TiN and CoCr talar implants. Methods: As a result, two independent laboratories were engaged to test these properties using: ASTM F1978-18 “Standard Test Method for Measuring Abrasion Resistance of Metallic Thermal Spray Coatings by Using the Taber Abraser”, and ISO 22622:2019 “Implants for surgery-Wear of total ankle-joint prostheses”. Results: Testing using method ASTM F1978-18, Ti6Al4V ELI TiN performed 34x more favorably than mirror polished CoCr. Using method ISO 22622:2019, Ti6Al4V ELI TiN and SLS performed similarly, showing only slight wear when tested against Ultra High Molecular Weight Polyethylene (UHMWPE) over 5 million cycles. Conclusion: With density, durability, tribology and ingrowth potential as a combined measure of overall performance, results support Ti6Al4V ELI TiN being favorable to CoCr in certain talar implants.Clinical Relevance: In addition to offering superior abrasion performance and slightly better wear resistance, 3D printed Ti6Al4V ELI TiN coated implants offer physicians and patients a highly customizable implant with a lower strength to weight ratio than existing CoCr SLS implants.Level of Evidence: V.

Polarization of Femtosecond Laser for Titanium Alloy Nanopatterning Influences Osteoblastic Differentiation.

Ultrashort pulse lasers have significant advantages over conventional continuous wave and long pulse lasers for the texturing of metallic surfaces, especially for nanoscale surface structure patterning. Furthermore, ultrafast laser beam polarization allows for the precise control of the spatial alignment of nanotextures imprinted on titanium-based implant surfaces. In this article, we report the biological effect of beam polarization on human mesenchymal stem cell differentiation. We created, on polished titanium-6aluminum-4vanadium (Ti-6Al-4V) plates, a laser-induced periodic surface structure (LIPSS) using linear or azimuthal polarization of infrared beams to generate linear or radial LIPSS, respectively. The main difference between the two surfaces was the microstructural anisotropy of the linear LIPSS and the isotropy of the radial LIPSS. At 7 d post seeding, cells on the radial LIPSS surface showed the highest extracellular fibronectin production. At 14 days, qRT-PCR showed on the same surface an increase in osteogenesis-related genes, such as alkaline phosphatase and osterix. At 21 d, mineralization clusters indicative of final osteoinduction were more abundant on the radial LIPSS. Taken together, we identified that creating more isotropic than linear surfaces enhances cell differentiation, resulting in an improved osseointegration. Thus, the fine tuning of ultrashort pulse lasers may be a promising new route for the functionalization of medical implants.

PEEK as a Potential Material for Dental Implants and its Biomechanical Properties and Osteoblast Cell Response

Proper osseointegration is crucial for the success of dental and orthopedic implants. Titanium-6Aluminum-4Vanadium (TAV) is one of the most popular implant materials; however, polyetheretherketone (PEEK) has gained the interest of implant researchers and manufacturers over the past several years due to its lower modulus of elasticity compared to metallic implant materials. Porosity and patterned surface morphologies are thought to improve mechanical interlocking and play an important role in the differentiation of pre-osteoblasts into mature osteoblasts. This study aimed to determine the effects a macro patterned PEEK surface has on the material’s mechanical properties and the proliferation, differentiation, and maturation of pre-osteoblasts. Mechanical testing data indicated that the macro patterning improved the mechanical interlocking and has no detrimental effect on compression strength. DNA data and live/dead imaging showed that pre-osteoblasts on solid PEEK specimens did not readily differentiate but instead encouraged proliferation only. However, ALP data in comparison to the DNA data showed that cells on patterned PEEK specimens more readily entered the differentiation pathway to mineralization. This is further confirmed by the patterned PEEK specimens showing an overall higher amount of cell mineralization. Clinical significance: This study concludes that surface macro patterning of PEEK material increases the mechanical interlocking and enhances the osseointegration capability without diminishing mechanical properties.

Trueness of removable partial denture frameworks additively manufactured with selective laser melting

Statement of problemAlthough studies have reported on selective laser melting (SLM)-fabricated removable partial dentures (RPDs), research addressing the trueness of SLM-fabricated RPD metal frameworks is sparse. PurposeThe purpose of this in vitro study was to evaluate the trueness of powdered cobalt-chromium (Co-Cr) or titanium-6 aluminum-4 vanadium (Ti-6Al-4V) alloy frameworks for RPDs fabricated by SLM. Material and methodsA digital scan of a Kennedy class II mandible typodont was obtained to design an RPD framework by using a computer-aided design (CAD) software program (denoted as CRF). Two experimental groups of frameworks were fabricated from the CRF by using SLM in alloys of Co-Cr (SLM-Co-Cr, n=6) and in Ti-6Al-4V (SLM-Ti-6Al-4V, n=6) while a control group was fabricated by using traditional lost-wax casting following stereolithography (CA-Co-Cr, n=6). In total, 18 RPD frameworks were digitally scanned (denoted as CRF), with each scan then superimposed on the CRF and evaluated for discrepancies by using a 3D analysis software program. A nonparametric Kruskal-Wallis test was performed to determine differences in trueness among groups (α=.05). ResultsThe CA-Co-Cr group showed the highest discrepancy between CEF and CRF. Statistically significant differences were found between the CA-Co-Cr and SLM-fabricated groups (P=.03 for Co-Cr, and P=.016 for Ti-6Al-4V). However, no significant difference was found between the SLM-Co-Cr and SLM-Ti-6Al-4V groups (P=.787). ConclusionsSLM-fabricated RPD frameworks exhibited higher trueness than CA-Co-Cr fabricated ones, indicating the potential of selective laser melting to produce the geometric shapes required for accurate dental restorations.

Effect of Powder Recycling in Laser-based Powder Bed Fusion of Ti-6Al-4V

Additive manufacturing (AM) has shown promise to process parts for end-use applications, however stringent requirements must be fulfilled in terms of reliability and predictability. The expensiveness of raw materials for AM, especially for metal-based Powder Bed Fusion (PBF), brings about the need for a careful recycling of powder, but the effect of powder reuse on both processing conditions and final part performance is still the focus of intensive research in the open literature. Although ASTM F2924-14 specifies the virgin-to-used powder ratio to be introduced to manufacture titanium-6aluminum-4vanadium (Ti-6Al-4V) components by PBF, a deeper understanding of the effect of powder recycling on the mechanical properties of finished parts is expected to foster a more efficient and safe reuse. The present contribution is therefore addressed to investigate the consequence of Ti-6Al-4V powder recycling on the flowability, particle size distribution and morphology of the feedstock material as well as on the density and tensile performance of built parts. In order to quantify the recyclability of powders, a new average usage (AUT) parameter is defined to account for both the real usage time of the powder and the virgin-to-used powder mixing ratio. The new parameter, whose applicability can be readily extended to any kind of feedstock powder, offers a significant contribution to achieve a more consistent and economical recycling of raw materials for PBF processing.

Effect of Bonding and Rebonding on the Shear Bond Strength of Two-Piece Implant Restorations.

To evaluate the rebonding strength of ceramics to titanium alloy after disassembling by heat treatment. A total of 40 titanium alloy (titanium-6 aluminum-4 vanadium) disks (4.0 × 6.6 mm) and 20 zirconia (Lava Plus) disks were manufactured using computer-aided design and computer-aided manufacturing (CAD/CAM) technology. Twenty heat-pressed lithium disilicate glass-ceramic (IPS e.max Press LT) disks were fabricated and used as controls. Bonding protocol for each specimen surface was performed according to manufacturer's instructions. Specimens (n = 10) of zirconia/titanium alloy (ZR) and lithium disilicate/titanium alloy (LD) were bonded using adhesive resin cement (RelyX Ultimate) and then subjected to a heat treatment (HT, 320°C, 2 minutes) to disassemble the bonding complex, cleaned with aluminum oxide airborne-particle abrasion, and rebonded following the initial protocol, group ZRHT and group LDHT, respectively. After 5000 cycles of thermal cycling, a shear bond test was conducted. A universal testing machine was used at a 5 mm/min crosshead speed. Failed specimens were examined with stereomicroscopy at 10× magnification to identify the mode of failure. One-way ANOVA and Tukey HSD tests were applied for statistical analysis of the shear bond strength data, with statistical significance at α = 0.05. The mean ± SD bond strength values ranged from 28.3 ± 7.2 to 45.9 ± 9.7 MPa. Statistically significant lower shear bond strength values were obtained from the LD group (p = 0.002, F = 5.89), while no statistically significant differences in bond strength were observed between the ZR and ZRHT groups (p > 0.05). Failure mode was predominantly mixed-type failure pattern for all specimens. Heat and abrasion surface treatment increased the bond strength of lithium disilicate glass-ceramics cemented to titanium alloy, but no effect was observed on zirconia/titanium alloy bonding.

Inflammatory cytokine release from human peripheral blood mononuclear cells exposed to polyetheretherketone and titanium-6 aluminum-4 vanadium in vitro.

Objective To investigate the cytokine expression profiles of blood cells exposed to polyetheretherketone and titanium-6 aluminum-4 vanadium materials in vitro. Materials and methods Coin-shaped samples composed of titanium-6 aluminum-4 vanadium, polyetheretherketone, and blasted polyetheretherketone were manufactured. The surfaces of the coins were characterized using optical interferometry, scanning electron microscopy, and contact angle measurements. Peripheral blood mononuclear cells collected from 10 blood donors were cultured for one, three, and six days in the presence or absence of the coins, and then assayed for cytokine production. Quantification of the peripheral blood mononuclear cells attached to the coins was performed using confocal microscopy after immunofluorescence staining. Results The machined titanium-6 aluminum-4 vanadium coins had a smoother surface topography compared to the machined polyetheretherketone and blasted polyetheretherketone. The highest mean contact angle was noted for the blasted polyetheretherketone, followed by the machined polyetheretherketone and titanium-6 aluminum-4 vanadium. The peripheral blood mononuclear cells produced significantly more proinflammatory cytokines when exposed to the polyetheretherketone surface compared to the titanium-6 aluminum-4 vanadium surface, while the blasted polyetheretherketone induced the highest level of proinflammatory cytokine release from the peripheral blood mononuclear cells. Significantly more cells attached to both polyetheretherketone surfaces, as compared to the titanium-6 aluminum-4 vanadium surface. Conclusion Polyetheretherketone induces a stronger inflammatory response from peripheral blood mononuclear cells than does titanium-6 aluminum-4 vanadium. Surface topography has an impact on cytokine release from peripheral blood mononuclear cells.

Clinical outcomes of patient-specific porous titanium endoprostheses in dogs with tumors of the mandible, radius, or tibia: 12 cases (2013-2016).

OBJECTIVE To characterize the processes involved in and outcomes achieved with custom-designed patient-specific implants to provide functional replacement of skeletal structures in dogs with tumors of the mandible, radius, or tibia. DESIGN Prospective case series. ANIMALS 6 dogs with mandibular tumors, 5 with tumors of the distal aspect of the radius, and 1 with a tumor in the distal aspect of the tibia treated from June 2013 to September 2016 at 3 referral centers. PROCEDURES After tumor staging, implants were designed from patients' CT scans by means of various computer-aided design applications and printed by means of selective laser melting in titanium-6 aluminum-4 vanadium alloy. A cutting jig was created in thermoplastic to ensure each osteotomy was performed as planned. Following ostectomy, the implant was secured into the defect with screws of appropriate size and length. RESULTS Initial return to normal clinical function was good to excellent for 11 of the 12 dogs. However, major complications resulted in revision of the implant or amputation of the limb in 5 dogs, and at least 3 of these complications were considered a consequence of faulty implant design or manufacturing. Infection developed in 2 dogs and was successfully treated in 1 dog. The longest-surviving dog maintained good limb function for 2 years. CONCLUSIONS AND CLINICAL RELEVANCE This is the largest reported series of dogs managed with customized 3-D-printed titanium implants. The 3-D printing allowed complex and patient-specific 3-D geometries to be fabricated, enabling function-sparing treatment of bone cancer affecting multiple anatomic sites.

Effect of low-intensity pulsed ultrasound on the biological behavior of osteoblasts on porous titanium alloy scaffolds: An in vitro and in vivo study

Low-intensity pulsed ultrasound (LIPUS) has been used in patients with fresh fractures, delayed union and non-union to enhance bone healing and improve functional outcome. However, there were few studies concerning the effects of LIPUS on the biological behavior of osteoblasts on porous scaffolds. This study aimed to evaluate the effects of LIPUS on the biological behavior of osteoblasts on porous titanium-6aluminum-4vanadium (Ti6Al4V) alloy scaffolds in vitro and in vivo. Scaffolds were randomly divided into an ultrasound group and a control group. Mouse pre-osteoblast cells were cultured with porous Ti6Al4V scaffolds in vitro. The effects of LIPUS on the biological behavior of osteoblasts were evaluated by observing the adhesion, proliferation, differentiation and ingrowth depth on porous Ti6Al4V scaffolds. In addition, scaffolds were implanted into rabbit mandibular defects in vivo. The effects of LIPUS on bone regeneration were evaluated via micro-CT, fluorescent staining and toluidine blue staining. The results revealed that osteoblast adhered well to the scaffolds, and there was no significant difference in the methyl thiazolyl tetrazolium value between the ultrasound group and the control group (p>0.05). Compared with the control group, ultrasound promoted the alkaline phosphatase activity, osteocalcin levels and ingrowth depth of the cells on the scaffolds (p<0.05). In addition, micro-CT and histomorphological analysis showed that the volume and amount of new bone formation were increased and that bone maturity was improved in the ultrasound group compared to the control group. These results indicate that LIPUS promotes osteoblast differentiation as well as enhances bone ingrowth in porous Ti6Al4V scaffolds, and promotes bone formation and maturity in porous Ti6Al4V scaffolds.

Assessment of reliability of CAD-CAM tooth-colored implant custom abutments

Statement of problemInformation is lacking about the fatigue resistance of computer-aided design and computer-aided manufacturing (CAD-CAM) tooth-colored implant custom abutment materials. PurposeThe purpose of this in vitro study was to investigate the reliability of different types of CAD-CAM tooth-colored implant custom abutments. Material and methodsZirconia (Lava Plus), lithium disilicate (IPS e.max CAD), and resin-based composite (Lava Ultimate) abutments were fabricated using CAD-CAM technology and bonded to machined titanium-6 aluminum-4 vanadium (Ti-6Al-4V) alloy inserts for conical connection implants (NobelReplace Conical Connection RP 4.3×10 mm; Nobel Biocare). Three groups (n=19) were assessed: group ZR, CAD-CAM zirconia/Ti-6Al-4V bonded abutments; group RC, CAD-CAM resin-based composite/Ti-6Al-4V bonded abutments; and group LD, CAD-CAM lithium disilicate/Ti-6Al-4V bonded abutments. Fifty-seven implant abutments were secured to implants and embedded in autopolymerizing acrylic resin according to ISO standard 14801. Static failure load (n=5) and fatigue failure load (n=14) were tested. Weibull cumulative damage analysis was used to calculate step-stress reliability at 150-N and 200-N loads with 2-sided 90% confidence limits. Representative fractured specimens were examined using stereomicroscopy and scanning electron microscopy to observe fracture patterns. ResultsWeibull plots revealed β values of 2.59 for group ZR, 0.30 for group RC, and 0.58 for group LD, indicating a wear-out or cumulative fatigue pattern for group ZR and load as the failure accelerating factor for groups RC and LD. Fractographic observation disclosed that failures initiated in the interproximal area where the lingual tensile stresses meet the compressive facial stresses for the early failure specimens. Plastic deformation of titanium inserts with fracture was observed for zirconia abutments in fatigue resistance testing. ConclusionsSignificantly higher reliability was found in group ZR, and no significant differences in reliability were determined between groups RC and LD. Differences were found in the failure characteristics of group ZR between static and fatigue loading.

Bond strength and interactions of machined titanium-based alloy with dental cements

Statement of problemThe most appropriate luting agent for restoring cement-retained implant restorations has yet to be determined. Leachable chemicals from some types of cement designed for teeth may affect metal surfaces. PurposeThe purpose of this in vitro study was to evaluate the shear bond strength and interactions of machined titanium-based alloy with dental luting agents. Material and methodsEight dental luting agents representative of 4 different compositional classes (resin, polycarboxylate, glass ionomer, and zinc oxide-based cements) were used to evaluate their effect on machined titanium-6 aluminum-4 vanadium (Ti-6Al-4V) alloy surfaces. Ninety-six paired disks were cemented together (n=12). After incubation in a 37°C water bath for 7 days, the shear bond strength was measured with a universal testing machine (Instron) and a custom fixture with a crosshead speed of 5 mm/min. Differences were analyzed statistically with 1-way ANOVA and Tukey HSD tests (α=.05). The debonded surfaces of the Ti alloy disks were examined under a light microscope at ×10 magnification to record the failure pattern, and the representative specimens were observed under a scanning electron microscope. ResultsThe mean ±SD of shear failure loads ranged from 3.4 ±0.5 to 15.2 ±2.6 MPa. The retention provided by both polycarboxylate cements was significantly greater than that of all other groups (P<.05). The scanning electron microscope examination revealed surface pits only on the bonded surface cemented with the polycarboxylate cements. ConclusionsCementation with polycarboxylate cement obtained higher shear bond strength. Some chemical interactions occurred between the machined Ti-6Al-4V alloy surface and polycarboxylate cements during cementation.

The influence of cathodic polarization and simulated inflammation on titanium electrochemistry

This study evaluated the influence of simulated inflammation and cathodic polarization on the electrochemical properties of commercially pure titanium (CpTi) and titanium-6%aluminum-4%vanadium (Ti6Al4V). Normal conditions immersed the metals in phosphate buffered saline at open circuit potential (OCP). Inflammatory conditions immersed the metals in a 150 mM hydrogen peroxide titrated to pH = 5.0 at OCP. Cathodic inflammatory conditions immersed the metals in the inflammatory electrolyte at -1 V versus Ag/AgCl. Cathodic polarization scans revealed a more electropositive corrosion potential (Ecorr ) and an increased corrosion current density (Icorr ) for both metals after incubation at inflammatory conditions (CpTi: Ecorr = 171 mV, Icorr = 147 nA/cm(2) and Ti6Al4V: Ecorr = 241 mV and Icorr = 413 nA/cm(2) ) as compared to normal conditions (CpTi: Ecorr = -249 mV, Icorr = 19 nA/cm(2) and Ti6Al4V: Ecorr = -263 mV and Icorr = 11 nA/cm(2) ). Electrochemical impedance spectroscopy showed the polarization resistance (Rp ) decreases and constant phase element (CPE) magnitude increases for both metals when comparing normal (CpTi: Rp = 3.5 MΩ cm(2) , CPE = 35 µS s(α) /cm(2) and Ti6Al4V: Rp = 6.5 MΩ cm(2) and CPE = 30 µS s(α) /cm(2) ) to inflammatory (CpTi: Rp = 79 kΩ cm(2) , CPE = 55 µS s(α) /cm(2) and Ti6Al4V: Rp = 230 kΩ cm(2) and CPE = 56 µS s(α) /cm(2) ) to cathodic inflammatory (CpTi: Rp =24 kΩ cm(2) , CPE = 290 µS s(α) /cm(2) and Ti6Al4V: Rp = 12 kΩ cm(2) and CPE = 250 µS s(α) /cm(2) ) conditions. These observed changes are consistent with the formation of a thin and defective oxide film. Inductively coupled plasma mass spectroscopy revealed that inflammatory conditions increased dissolution of both metals and that the addition of cathodic potential significantly increased the dissolution of the beta phase elements of Ti6Al4V.

Low elastic modulus contributes to the osteointegration of titanium alloy plug

Resurfacing of cartilage defect with mini titanium plug is considered a promising alternative for the treatment of focal chondral defects. Elastic modulus of the metal implant plays a significant role in force transmission which influences the stability of plug. This study assessed the effects of two kinds of titanium alloy plug with different elastic modulus, that is, titanium 2448 (Ti2448) plug and titanium-6 aluminum-4 vanadium (TAV) plug on osteointegration. The full-thickness chondral defects were created in bilateral knees of dogs and then TAV and Ti2448 plugs were implanted, respectively. After 12 weeks, radiographic evaluation did not reveal any signs of disassembly, subsidence, or periprosthetic radiolucency in both groups. Microcomputed tomography analysis revealed that bone histomorphometric parameters in Ti2448 group were all significantly better than those of TAV group. Furthermore, the value of pullout force in Ti2448 group was also significantly higher. Histology showed that the screw threads of Ti2448 plug were well integrated into the newly formed bone. In contrast, the trabecular bone was sparsely distributed around TAV plug. In conclusion, Ti2448 plug with low elastic modulus showed more favorable characteristics in osteointegration. Ti2448 may be a promising biomaterial for fabricating mini plug applied for cartilage resurfacing.

In vitro biocompatibility of titanium alloy discs made using direct metal fabrication

Custom orthopedic implants may be generated using free-form fabrication methods (FFF) such as electron beam melting (EBM). EBM FFF may be used to make solid metal implants whose surface is often polished using CNC machining and porous scaffolds that are usually left unpolished. We assessed the in vitro biocompatibility of EBM titanium–6 aluminum–4 vanadium (Ti6Al4V) structures by comparing the cellular response to solid polished, solid unpolished, and porous EBM discs to the cellular response to discs made of commercially produced Ti6Al4V. The discs were seeded with 20,000 human adipose-derived adult stem cells (hASCs) and assessed for cell viability, proliferation, and release of the proinflammatory cytokines interleukin-6 (IL-6) and interleukin-8 (IL-8). Cell viability was assessed with Live/Dead staining 8 days after seeding. Cell proliferation was assessed using alamarBlue assays at days 0, 1, 2, 3, and 7. The hASCs were alive on all discs after 8 days. Cellular proliferation on porous EBM discs was increased at days 2, 3, and 7 compared to discs made of commercial Ti6Al4V. Cellular proliferation on porous EBM discs was also increased compared to solid polished and unpolished EBM discs. IL-6 and IL-8 releases at day 7 were lower for porous EBM discs than for other discs. Solid polished, unpolished, and porous EBM Ti6Al4V discs exhibited an acceptable biocompatibility profile compared to solid Ti6Al4V discs from a commercial source. EBM FFF may be considered as an option for the fabrication of custom orthopedic implants.

Peri-implant and systemic release of metallic elements following insertion of a mandibular modular endoprosthesis in Macaca fascicularis

Background and Objectives: Metal elements from biologic devices have been found in surrounding tissues and distant organs. The aim of this study was to assess the release of metal elements from titanium-6 aluminum-4 vanadium (Ti6Al4V) modular endoprostheses, in segmental mandibular defects.

The effect of temperature on gross slip fretting wear of cold-sprayed nickel coatings on Ti6Al4V interfaces

Fretting wear is an accumulation of damage that occurs at component interfaces that are subjected to high contact stresses coupled with low-amplitude oscillation. In metallic contacts, surface oxides, adhesion, and material transfer play a primary role in the initial stages of fretting wear degradation. Given these behaviors, the focus of this study was to determine the effect of temperature on inter-metallic fretting wear between Ti6Al4V (titanium, 6% aluminum, 4% vanadium) and cold-sprayed, commercially pure nickel coatings. The results presented herein show that increased temperature decreases friction through the formation of a uniform NiO layer, and by a reduction of Ni 2O 3 in contacts. In addition, it was found that a localized minimum friction coefficient is achieved at approximately 300 °C, above which friction increases slightly due to annealing of the cold-sprayed coatings.

Evaluations of Bone Tissue Integration to Pure and Alloyed Titanium Implants

This study was performed for comparisons of tissue integration to commercially pure (CP) and titanium-6-aluminum-4 vanadium (Ti-6-Al-4V) implants using various existing three-dimensional biomechanical and two-dimensional histomorphometrical techniques, and to monitor the loosening torque during in vivo removal torque (RTQ) test with a novel unit not used before in a pilot study in rabbits. The implants were topographically characterized and inserted in femurs and tibiae of five rabbits (in total 40 implants, 20 per group). After 16 weeks, the implant integration was biomechanically evaluated by: (1) resonance frequency test, and (2) peak RTQ test and the graph from the monitoring curve. Biopsies of the implants in situ were processed to undecalcified cut and ground sections followed by light microscopical quantifications. Shear strength calculations were performed. Significantly higher mean value of RTQ (p = .01) and shear strength tests (p = .03) were observed for the CP titanium implants compared to Ti-6-Al-4V implants. The monitoring curve from the RTQ test demonstrated no differences in the shape or form that could provide further information about the differences in the implant-to-bone attachment. The CP titanium implants showed increased RTQ and shear strength values compared to the Ti-6-Al-4V implants. The new tool of monitoring the RTQ curve could not demonstrate differences between the two materials. The exact influence of the implant materials on the surrounding tissues needs to be further investigated.

Gross slip fretting wear of CrCN, TiAlN, Ni, and CuNiIn coatings on Ti6Al4V interfaces

Fretting is a low amplitude oscillatory wear that occurs at component interfaces and can accelerate crack initiation as well as interfacial degradation. Prevalent in Ti-alloy contacts, fretting wear often occurs at the blade/disk interfaces of fan and compressor stages in turbine engines, causing premature component failure. In many cases, plasma sprayed CuNiIn (copper–nickel–indium) coatings and solid lubricants are applied to blade roots to mitigate the fretting problem. However, the CuNiIn coatings can cause severe damage to the uncoated Ti-alloy counter parts once the solid lubricants wear out. In this study, bench level gross slip fretting wear tests were conducted at room temperature on unlubricated Ti6Al4V (titanium, 6% aluminum, 4% vanadium) surfaces mated with CuNiIn and commercially pure Ni plasma sprayed surfaces. Upon analysis, it was determined that the uncoated Ti6Al4V surfaces initially gall. Then the resulting adherent wear particles break up causing a transition into a third body type wear mode over time. This leads to an accumulation of wear that is similar to that of uncoated Ti6Al4V mating surfaces. Additional tests were conducted after applying 2-μm thick PVD deposited TiAlN (titanium–aluminium–nitride) and CrCN (chrome–carbon–nitride) coatings to the surfaces of a second set of Ti6Al4V mating pairs. When worn against the unlubricated CuNiIn and Ni coatings, the thin TiAlN and CrCN coatings wore gradually without delaminating or cracking and were able to mitigate galling and extend test life. The application of the hard coatings lead to a reduction in wear in all of the tests except with the combination of TiAlN worn against CuNiIn.