Titanium Specimens Research Articles

Biocompatibility and antibacterial properties of medical stainless steel and titanium modified by alumina and hafnia films prepared by atomic layer deposition.

New methods for producing surfaces with suitable biocompatible properties are desirable due to increasing demands for biomedical devices. Stainless steel 316 L and cp- titanium specimens were coated with thin films of alumina and hafnia deposited using the atomic layer deposition method at two temperatures, 180 and 260 °C. The morphology of the films was analysed using scanning electron microscopy, and their surface energies were determined based on drop contact angle measurements. Biocompatibility assays performed using mesenchymal stem cells were evaluated by incubating the specimens and then exposing their extracts to the cells or directly seeding cells on the specimen surfaces. No detrimental effect was noticed for any of the specimens. Antibacterial properties were tested by directly incubating the specimens with the bacteria Staphylococcus aureus. Overall, our data show that all prepared films were biocompatible. Alumina films deposited on cp-titanium at 260 °C outperform the other prepared and tested surfaces regarding antiadhesive properties, which could be related to their low surface energy.

Optically accessible, 3D-printed flow chamber with integrated sensors for the monitoring of oral multispecies biofilm growth in vitro

The formation of pathogenic multispecies biofilms in the human oral cavity can lead to implant-associated infections, which may ultimately result in implant failure. These infections are neither easily detected nor readily treated. Due to high complexity of oral biofilms, detailed mechanisms of the bacterial dysbiotic shift are not yet even fully understood. In order to study oral biofilms in more detail and develop prevention strategies to fight implant-associated infections, in vitro biofilm models are sorely needed. In this study, we adapted an in vitro biofilm flow chamber model to include miniaturized transparent 3D-printed flow chambers with integrated optical pH sensors – thereby enabling the microscopic evaluation of biofilm growth as well as the monitoring of acidification in close proximity. Two different 3D printing materials were initially characterized with respect to their biocompatibility and surface topography. The functionality of the optically accessible miniaturized flow chambers was then tested using five-species biofilms (featuring the species Streptococcus oralis, Veillonella dispar, Actinomyces naeslundii, Fusobacterium nucleatum, and Porphyromonas gingivalis) and compared to biofilm growth on titanium specimens in the established flow chamber model. As confirmed by live/dead staining and fluorescence in situ hybridization via confocal laser scanning microscopy, the flow chamber setup proved to be suitable for growing reproducible oral biofilms under flow conditions while continuously monitoring biofilm pH. Therefore, the system is suitable for future research use with respect to biofilm dysbiosis and also has great potential for further parallelization and adaptation to achieve higher throughput as well as include additional optical sensors or sample materials.

Innovative 3D-Printed Titanium Specimens Favor a Modulation of Inflammation in Dental Pulp Stem Cells During Liposome-Triggered Mineralization.

developing customized titanium specimens, with innovative surfaces, is a suitable strategy to overcome implant failure. Additionally, a faster and efficient osteogenic commitment assists tissue regeneration. To investigate the interplay between inflammation and differentiation upon implantation, Dental Pulp Stem Cells (DPSCs) were cultured on 3D-printed titanium owning an internal open cell form, administering osteogenic factors by a liposomal formulation (LipoMix) compared to traditional delivery of differentiation medium (DM). osteogenic differentiation was evaluated by western blot, by measuring β1 integrin expression, and by and real-time RT-PCR, by measuring SP7 and Collagen I gene expression; while.angiogenesis was characterized by measuring VEGF secretion levels. Matrix mineralization was assessed by means of Alizarin Red Staining, cell adhesion and inflammation responses through western blot, enzymatic and ELISA assays evaluating Nrf2 expression, catalase activity and Prostaglandin E2 secretion, respectively. LipoMix enhances cell proliferation and adhesion, as revealed by increased integrin β1 expression. Mineralized matrix deposition, SP7 gene expression, Collagen I release and Alkaline Phosphatase activity appear increased in LipoMix condition. Additionally, the redox-sensitive transcription factor Nrf2 is overexpressed at the earliest experimental times, triggering the catalase activity. data reported confirm that internal topography and post-production treatments on titanium surfaces dynamically and positively condition the DPSC progress towards the osteogenic phenotype, moreover, the combination with LipoMix fastens the positive modulation of inflammation under osteogenic conditions. Therefore, the development of customized surfaces along with the administration of differentiating factors enclosed in a liposomal delivery system, could represent a promising and innovative tool in regenerative dentistry.

Enhancing Titanium Osteoconductivity by Alkali-Hot Water Treatment.

Titanium and its alloys are essential in orthopedic and dental treatments owing to their high strength, corrosion resistance, and superior biocompatibility compared with those of other metals. However, titanium alloys are bioinert. Previous studies have indicated that alkali treatment (AT) is a straightforward method to create a surface oxidization layer on titanium, thereby improving its bioactivity. Herein, alkali-hot water pretreatment was used to enhance the osteoconductivity of titanium and to identify a simple and efficient means of enhancing the interaction between osteoblasts and implants for clinical applications. Commercial pure titanium plates were ground (CP Ti) and subjected to alkali solution and hot water treatments (AWT). Single-process CP Ti specimens were prepared via either AT or hot water treatment (WT). Network-like structural features were observed in the AT specimens and were further refined and densified in the AWT specimens. Water contact angle testing revealed that the hydrophilicity of the titanium specimen (80° for CP Ti) increased by 19° for the AT specimens but decreased by 59° for the AWT specimens. Mouse preosteoblasts (MC3T3-E1 cells) were used for in vitro evaluation. After 24 h of culturing, the number of attached MC3T3-E1 cells on the AWT specimens was 1.5 times larger than that on the CP Ti specimens, suggesting that the alkali-hot water treatment enhanced the initial cell attachment. Cell proliferation evaluation indicated that fewer cells were detected in the AT and AWT specimens compared with those in the CP Ti or WT specimens. However, osteogenic differentiation evaluation on day 10 revealed a 1.5-fold higher alkaline phosphatase expression in cells cultured on the AWT specimens than in cells cultured on the CP Ti specimens. These findings demonstrate the good cytocompatibility and osteoconductivity of AWT Ti, highlighting its benefits in orthopedics and dental treatments.

Study on the deep deoxidation mechanism of titanium powder using Y/YOCl/YCl3 and Y/Y2O3 systems

Low-oxygen high-purity titanium (oxygen concentration ≤ 500 ppm) is a critical material for advanced semiconductor and biomedical applications. Current deoxidation methods limit oxygen concentration in titanium to approximately 1000–2000 ppm, failing to meet the demand for ultra-low oxygen levels in high-performance materials. This study investigated the preparation mechanism and conditions for low-oxygen high-purity titanium utilizing a molten salt thermochemical method, employing Y as the deoxidant with a theoretical deoxidation limit below 10 ppm. We experimentally explored the deoxidation mechanisms of titanium using Y/YOCl/YCl3 and Y/Y2O3 systems, successfully reducing the oxygen concentration in titanium to 200 ppm, and proving that the Y/YOCl/YCl3 system is more efficient than the Y/Y2O3 system. Additionally, the titanium samples were analyzed using SEM-EDS, XRD, XPS, and 3D surface profilometry before and after deoxidation. These analyses examined the impact of the deoxidation process using Y on the crystal structure, oxide film, and surface roughness of titanium specimens, which are useful for understanding the deoxidation mechanism. During the sintering process of titanium powder attached to Y, the deoxidation process will produce YOCl or Y2O3. The formation of these deoxidation products leads to local oxygen diffusion, and the crystals of YOCl or Y2O3 are gathered at grain boundaries, which will resolve during the subsequent acid etching process, thus reducing the oxidation concentration of the titanium. The above results provide further theoretical guidance and technical support for the production of ultra-high-purity titanium powder.

Magnetron sputtered ß-Ti coatings for biomedical application: A HiPIMS approach to improve corrosion resistance and mechanical behavior

This work presents the surface modification of commercially pure Ti specimens (c.p.-Ti) prepared by conventional powder metallurgy by depositing a thin film of a ß-Ti alloy (Ti-35Nb-7Zr-5Ta, wt. %, TNZT). Two types of pulsed technologies: conventional (p-DC) and high-power impulse magnetron sputtering (HiPIMS), with and without bias assistance (−60 V) under similar power conditions (250 W) were applied on titanium specimens and silicon substrates leading to different film morphologies and functional properties. Microstructural, X-ray diffraction, nanoindentation, surface wetting, XPS and electrochemical impedance measurements were done to characterize their functionality. All the coatings presented a reduced Young’s Modulus (E ≤ 80GPa) compared to the bulk Ti, representing a reduction of more than 30 %. This decrease can significantly contribute to the reduction of the stress-shielding effect, mitigating the risk of implant loosening and failure. The hardness values of TNZT coatings, slightly lower than c.p.-Ti substrate, range from 4.1 to 4.7 GPa. XPS analysis shows a passivation layer of TiO2, Nb2O5, and ZrO2, which offers high impedance and excellent corrosion resistance. The best compromise between mechanical and corrosion properties is achieved with the HiPIMS technology, thanks to its compact film microstructure with high electrical resistance, despite its limited thickness of about 1 μm.

Influence of Cleaning Procedures and Aging on Shear-Bond- Strength of 3Y, 4Y, and 5Y Zirconia to Titanium.

Lab-side-fabricated abutments and hybrid zirconia crowns, which are bonded to titanium bases with resin-based composites, require disinfection before insertion. This study investigated the effect of cleaning procedures (ultrasonic, autoclaving) and aging methods (24h, 90d, thermocycling) on the shear bond strength between alumina particle air-abraded titanium and zirconia (3Y-, 4Y- and 5Y-TZP) specimens luted with phosphate monomer containing adhesive systems and resin-based composite. Autoclaving significantly improved SBS (F (27,231) &#61; 17.265, p < .001) compared to no cleaning and three-stage disinfection. No differences were identified with regard to zirconia or aging methods. Bond strength initially benefits from autoclaving but continuously approaches the comparative values over longer periods.

Nanoscale niobium coatings including superior conducting and corrosion resistance on titanium foil materials for PEMFC bipolar plates

In this work, the nanoscale Nb coating for titanium is fabricated by high power impulse magnetron sputtering technology to enhance its conductivity and corrosion resistance, which is utilized as bipolar plates material. The surface morphology, composition, corrosion resistance and conductivity of specimens with various deposition times were characterized. The results demonstrate that the thickness and roughness of nanoscale coatings increase with deposition time and all the Nb-coated titanium specimens exhibit superior corrosion resistance in 0.5 M H2SO4 solution with 5 ppm HF at 80 °C. The corrosion current density increases and then decreases with deposition time, reaching its smallest value at 600 s (3.07 μA cm−2), which is reduced by 3 orders of magnitude compared to the substrate (387.98 μA cm−2). After potentiostatic polarization experiment (PP) for 12 h, the polarization current density (ipp) of coatings reduces as deposition time increases, with values of 1.54, 0.58, 0.45 and 0.27 μA cm−2, respectively. Furthermore, a low ICR is obtained for fresh Nb-coated titanium specimens, with values of 8.45, 8.95, 3.62 and 3.04 mΩ cm2, respectively. After PP for 12 h, the ICR slightly increase to values of 9.83, 9.63, 6.76 and 6.15 mΩ cm2, which still satisfy the demand of 2025 DOE requirements (≤10 mΩ cm2).

Influence of anodically grown TiO2 nanotubes on shear strength and fatigue behavior of pure titanium

Titanium and its alloys are among the best materials for metallic biomedical implants owing to their well-established biocompatibility. The effects of surface conditions on the success of implant osseointegration have been investigated previously. Although yet to be applied in clinical practice, the anodic growth of TiO2 nanotubes on implant surfaces has been reported to enhance biocompatibility. However, such a coating increases the roughness of the surface, which can adversely affect the fatigue strength. The cyclical loading mode supported by most bone implants necessitates investigations into the effect of nanostructured coatings on the fatigue life of the implants. This study evaluates the rotating-beam fatigue strength (Fatigue stress ratio = −1, Number of cycles = 107 cycles) of pure titanium specimens coated with TiO2 nanotubes. TiO2 nanotubes are grown via anodization in an HF (0.1% vol.) aqueous solution by applying 20 V for 2 h, thus resulting in nanotubes with diameters and lengths of approximately 100 and 500 nm, respectively. The TiO2 coating, which is initially amorphous, is crystallized via thermal treatment at 370 °C for 3 h, thus resulting in an anatase allotrope, which has been reported to provide better conditions for the integration between the implant and bone. Results of adhesion tests show that the nanotube coating adheres well to the substrate surface and that its integrity is unaffected during fatigue tests. Meanwhile, results of fatigue tests show the insignificant effect of the TiO2 nanotubes on fatigue strength, which indicates that this coating can be used without compromising the implant fatigue life.

Multi-criteria decision making for better quality indicators in µ-EDM using TiN-coated WC electrode

ABSTRACT It is highly essential to enhance the micro EDM process while machining titanium specimens. The utilization of coated electrode and adaptation of optimization algorithms in the process can enhance the material removal mechanism. In the present work, an attempt was made to find the influence of TiN coated tungsten carbide electrode in micro EDM process while machining titanium alloy specimens. It was also attempted to adopt DEAR-based optimization in the process. The TiN coating can produce lower TWR with better surface quality than uncoated tungsten carbide electrode. The capacitance has higher influential nature in µ-EDM since it controls the charging and discharging process during the spark formation across discharge gap. It was found that voltage (Level 3), capacitance (Level 3), and the tool rotation (Level 2) can create better quality measures under the prediction error of 2.3%. The optimal combination can enhance the machining accuracy with tiny craters formation.

Fabrication of a coral-like barium titanate nano-piezoelectric coating and its effect on promoting osteogenic differentiation of rat bone marrow mesenchymal stem cells in vitro

Objective: To investigate the biocompatibility of coral-like barium titanate nano-piezoelectric coatings and the influence of ultrasound-excited piezoelectric effect on the early osteogenic differentiation. Methods: The barium titanate nano-piezoelectric coating (the coating group) was prepared on the surface of titanium metal by anodic oxidation, hydrothermal reaction and high-temperature annealing, and polished titanium specimens were used as control group. The surface morphology, composition, and crystal phase and hydrophilicity of the two groups of titanium specimens were characterized using scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and contact angle meter. The piezoelectric properties of the materials were characterized by piezoresponse force microscopy. Rat bone marrow mesenchymal stem cells (BMSC) were cultured and identified and seeded the surface of titanium specimens in two groups. The cells seeded on blank culture plates were used as blank group. After low intensity pulsed ultrasound intervention, cell proliferation and live/dead staining were detected to evaluate cytocompatibility of the coatings. Alkaline phosphatase (ALP) activity of each group was detected by ALP staining kit, and the expression of osteogenesis-related genes [integrin, bone morphogenetic protein 2 (BMP-2), Runt-related transcription factor 2 (RUNX2)] was detected by real-time fluorescent quantitative PCR (RT-qPCR) to evaluate the effect of the coating on promoting the early osteogenic differentiation of BMSC. Results: The surface of titanium specimens in the coating group showed a uniform coral-like morphology, and the diameter of the coral tentacles was 70-100 nm. The main component was tetragonal barium titanate. The surface hydrophilicity of the coating group (water contact angle 10.12°± 0.93°) was significantly better than that of the control group (water contact angle 78.32°±0.71°) (F= 10 165.91, P<0.001). The coating has a stable piezoelectric property with a piezoelectric constant of about 5 pC/N. Cell experiments showed that, with or without ultrasound, the cell proliferation activity of the coating group was significantly lower than that of the blank group and the control group on the third day (P<0.05). On the fifth day, with or without ultrasound, there was no significant difference in cell proliferation activity between the three groups (P>0.05). After 7 days of culture, the ALP activity of the coating group was significantly higher than that of the blank group and the control group (P<0.05). The results of RT-qPCR showed that the mRNA expression of integrin and BMP-2 in the coating group with ultrasound was significantly higher than that in the other groups with ultrasound, and was higher than that of the coating group without ultrasound (P<0.05). The expression of integrin mRNA in the control group with ultrasound was significantly higher than that in the control group without ultrasound (P<0.05). The expression of RUNX2 mRNA in the coating group with ultrasound was significantly higher than that in the coating group without ultrasound (P<0.05). Conclusions: The coral-like barium titanate nano-piezoelectric coating exhibits favorable biocompatibility and stable piezoelectric property, and facilitates the early osteogenic differentiation of BMSC under the excitation of low-intensity pulsed ultrasound.

Microtexture region segmentation of eddy current testing data using a structural prior

Microtexture regions (MTRs) are collections of grains with similar crystallographic orientation. Because their presence in titanium alloys can significantly impact aerospace component life, a nondestructive method to detect and characterize MTR is needed. In this work, we propose to use data from two nondestructive evaluation methods, eddy current testing (ECT) and scanning acoustic microscopy (SAM), in order to recover the boundary and dominant crystallographic orientation of each MTR in a specimen. ECT is an electromagnetic method that is sensitive to changes in crystallographic orientation associated with MTR; however, its low resolution prevents it from resolving MTR boundaries well. In contrast, SAM is a high frequency ultrasound method that is able to resolve MTR boundaries but is not sensitive to orientation. This paper proposes an algorithm to characterize MTR that makes use of a method known as covariance generalized matching component analysis. This method is used to build a surrogate linear forward model that relates MTR boundaries and orientation to ECT data. The model is inverted using the SAM data as a structural prior. We demonstrate this technique using simulated ECT and experimental SAM data from a large grain titanium specimen.

Fabrication and evaluation of composite hydroxyapatite coating on ordered micro-/nanotextured titanium surface

Objective: To develope a titanium specimen with good osteogenic activity through fabrication of a composite hydroxyapatite coating on ordered micro-/nanotextured titanium surface. Methods: An ordered micro-/nanotextured structure was prepared on the surface of titanium (the control), and then hydroxyapatite was deposited on the as-prepared ordered micro-/nanotextured structure by alternative loop immersion method. The ordered micro-/nanotextured structures before and after hydroxyapatite deposition were denoted as HA and MN, respectively. Surface morphology was observed using a scanning electron microscope. Bone marrow mesenchymal stem cells (BMMSC) were seeded on the surface of three different materials. Cell morphology was observed with a scanning electron microscope. Cell adhesion and cell proliferation were evaluated using 4', 6-diamidino-2-phenylindole staining and cell counting kit-8 assay, respectively. Extracellular matrix mineralization and the expression levels of osteogenesis-related genes were evaluated by alizarin red staining and real-time quantitative PCR, respectively. Each group has three samples in every experiment. Results: After alternative loop immersing, the MN's original microholes (20 μm in diameter) were retained, and the uniform petal-like hydroxyapatite was deposited on the MN's original titania nanotubes (70 nm in diameter). Compared with the control, BMMSC on MN and HA elongated further and intersected along the micron structure with noticeable pseudopodia and pseudoplates, and the trend was more pronounced especially on HA. The number of early adherent cells on HA was remarkably larger than that on the control and MN at each time point (P<0.05). On day 1, the A value of cell proliferation on HA was significantly higher than that on the control and MN (P<0.05). The A value of cell proliferation on HA was significantly lower than that on the control and MN on day 3 (P<0.05). On day 7, the A value of cell proliferation on HA was significantly lower than that on MN (P<0.05), but there was no statistically significant difference in the A value of cell proliferation between HA and the control on day 7 (P>0.05). The Avalue of extracellular matrix mineralization on HA (0.607±0.011) was significantly higher than that on the control and MN (0.268±0.025 and 0.522±0.022, respectively) (t=-0.25, P<0.001; t=-0.34, P<0.001). The expression levels of bone related genes on HA were significantly higher than those on the control and MN (P<0.05). Conclusions: HA could promote the BMMSC adhesion and osteogenic differentiation, support BMMSC proliferation, and demonstrate good osteogenic activity.

TSA and FEM Analysis Applied to CAD/CAM Titanium All-on-Four Prosthesis

Patient with fully edentulous maxillaries often suffer of several disease as an alteration of facial appearance, difficulties in eating, speech, and chews. Fixed and removable prosthesis can be a solution to rehabilitate this issue. The All-on-Four protocol is one of the possible treatment modalities for implant-supported prosthetics. It consists of placing four implants in an intermorainal position, two perpendicular to the occlusal plane and two tilted distally at a 45° angle. This paper aims to assess the stress distribution on an All-on-Four titanium prosthesis by means of a Thermoelastic Stress Analysis (TSA). This full-field non-contact measurement technique allows, through a thermal imaging camera, to observe how the surface temperature of an object changes under the effect of cyclic load. The principle on which thermoelastic analysis is based is the existence of a relationship between deformation, hence applied stress, and temperature change, called the thermoelastic effect. To perform the tests, the prosthesis was fixed to a resin jaw cast that has similar characteristics to the human bone, so that the same damping that would be present under normal working conditions could be accounted for. The distal artificial molar tooth was kept in contact to a narrow screw, which was attached to a Medium-Force (M-Series) Air-Cooled Shakers made by Santek. This shaker generates a sinusoidal load of 800N with a load cell at 10 Hz frequency, which can maintain the temperature variation of the prosthesis constant. A pre-load was applied before starting the tests. To see the change in temperature a Flir A6751SC thermal camera was used, and videos were acquired with a frame rate of 125 Hz and a resolution of 640x512 pixels. From the experimental TSA tests, the trend of the experimental stress concentration on the titanium specimen was detected. The outcomes of the experimental tests were compared to a 3D prosthesis model by Finite Element Analysis (FEM).

Effects of TiO2 Nanotubes and Reduced Graphene Oxide on Streptococcus mutans and Preosteoblastic Cells at an Early Stage.

The effects of TiO2 nanotube (TNT) and reduced graphene oxide (rGO) deposition onto titanium, which is widely used in dental implants, on Streptococcus mutans (S. mutans) and preosteoblastic cells were evaluated. TNTs were formed through anodic oxidation on pure titanium, and rGO was deposited using an atmospheric plasma generator. The specimens used were divided into a control group of titanium specimens and three experimental groups: Group N (specimens with TNT formation), Group G (rGO-deposited specimens), and Group NG (specimens under rGO deposition after TNT formation). Adhesion of S. mutans to the surface was assessed after 24 h of culture using a crystal violet assay, while adhesion and proliferation of MC3T3-E1 cells, a mouse preosteoblastic cell line, were evaluated after 24 and 72 h through a water-soluble tetrazolium salt assay. TNT formation and rGO deposition on titanium decreased S. mutans adhesion (p < 0.05) and increased MC3T3-E1 cell adhesion and proliferation (p < 0.0083). In Group NG, S. mutans adhesion was the lowest (p < 0.05), while MC3T3-E1 cell proliferation was the highest (p < 0.0083). In this study, TNT formation and rGO deposition on a pure titanium surface inhibited the adhesion of S. mutans at an early stage and increased the initial adhesion and proliferation of preosteoblastic cells.

Evaluation of the Color of Zirconia in Different Substrates of Osseointegrated Implants, Thickness of Materials and Types of Resin Cements.

Objectives: To evaluate the impact of surface conditioning of titanium, zirconia thickness, and cement type on the final color of zirconia luted to the titanium. Methods: A total of 192 grade 5 titanium specimens with the final dimensions 10 mm × 10 mm × 2 mm were fabricated and subjected to four different surface conditioning including, that is, sandblasting, etching, and anodization. In addition, 192 zirconia specimens with the same dimensions as the titanium specimens but altered thicknesses of 0.7 (n = 96) and 1.0 (n = 96) mm were fabricated using 5Y-TZP zirconia. Color as expressed by L ∗ (lightness), a ∗ (red-green axis), and b ∗ (blue-yellow axis) of titanium and zirconia specimens as well as the joined titanium-zirconia complex, total assembly (Panavia V5 clear, PC; opaque, PO, each n = 96) were determined under standardized conditions using a spectroradiometer (SpectraScan P-650). Color differences were calculated using the ΔE 00 formula. ANOVA supplemented with post hoc Tukey test for group comparisons was compiled to estimate possible effects of titanium conditioning, zirconia thickness, and type of cement used on the final zirconia color (SPSS Ver. 28; α = 0.05). Results: All investigated factors affected the zirconia color of the total assembly (p < 0.001). Using PO mean values of all groups were still close to baseline colors (ΔE 00 between 5.5 and 6.2). When using PC, the final color was significantly altered, irrespective of the other parameters. Specimens luted with PO appeared lighter, less reddish (a ∗ was affected predominately by sample thickness), and more bluish, while luting with PC resulted in reduced lightness combined with large shifts along the red and yellow axes. Significance: Color changes of zirconia luted to titanium are primarily affected by the color of the substrate if a translucent cement was used. Vice versa, the application of an opaque cement effectively masked the dark substrate color. Substrate color and choice of cement have to be taken into consideration when performing shade selection.

Analysis of Face-Centered Cubic Phase in Additively Manufactured Commercially Pure Ti

Metal additive manufacturing is a developing technique with numerous advantages and challenges to overcome. As with all manufacturing techniques, the specific raw materials and processing parameters used have a profound influence on microstructures and the resulting behavior of materials. It is important to understand the relationship between processing and microstructures of Ti to advance knowledge of Ti-alloys in the additive field. In this study, a face-centered cubic (FCC) phase was found in grade 2 commercially pure titanium specimens, additively manufactured with directed energy deposition in an argon atmosphere. Two scanning speeds (500 and 1000 mm/min) and three scanning patterns (cross-hatched and unidirectional patterns) were investigated. Electron backscatter diffraction and energy-dispersive X-ray spectroscopy were used for microstructural and compositional analysis. Inverse pole figure, phase, and kernel average misorientation (KAM) maps were analyzed in this work. Larger amounts of the FCC phase were found in the unidirectional scanning patterns for the slower scanning speed, while the cross-hatched pattern for both scanning speeds showed a lower amount of FCC. Higher KAM averages were present in the faster scanning speed specimens. According to EDS scans, small amounts of nitrogen were uniformly distributed throughout the specimens, leading to the possibility of interstitial content as a contributing factor for development of the observed FCC phase. However, there is no clear relationship between nitrogen and the FCC phase. The formation of this FCC phase could be connected to high densities of crystalline defects from processing, plastic deformation, or the distribution of interstitials in the AM structure. An unexpected Kurdjumow–Sachs-type orientation relationship between the parent beta phase and FCC phase was found, as 110BCC∥111FCC, 111BCC∥110FCC.

Comparison between mastic gum resin extract and chlorhexidine mouthwash in the prevention of biofilm formation on titanium dental implants.

The biofilm formation around dental implant abutment is considered the main cause of peri-implant infection. The use of antimicrobial mouthwash might potentially reduce biofilm formation and subsequent infection. This study aimed to evaluate the antibiofilm properties of mastic gum resin extract (MGRE) against S. Mutans biofilm on the surface of titanium dental implant discs. This study used grade five (medical grade) titanium dental implant discs measuring 15 mm in diameter. The substances in the MGRE were analyzed by gas chromatography mass spectrometry (GC-MS) which found 12 detectable chemicals in MGRE. In this study, S. mutans was collected around the healing abutment of a recently placed dental implant and then cultured on titanium discs (in vitro). After bacterial growth on the titanium specimens for 24 hours, they were subjected to either chlorhexidine gluconate (CHX), (n = 6) or MGRE (n = 6). The antibacterial activity tests showed that both CHX and MGRE significantly inhibited bacterial growth compared to the negative control, the lactate production and turbidity measurements were significantly lower in MGRE and CHX compared to the control (p ≤ 0.05). Regarding the antibiofilm activity, both treatments showed significantly less turbidity in their biofilm compared to the control. Moreover, scanning electron microscopy (SEM) images showed that there were very limited adherence cells on the titanium implant discs in treatment groups, while there were confluent and attached bacterial cells in the control. The MGRE showed an antimicrobial property against S. mutans indicating that it has a potential for clinical use as a mouthwash.

Effect of thermal oxidation on the dry sliding friction and wear behaviour of CP-Ti on CP-Ti tribopairs

Thermal oxidation (TO) has proven to be a cost-effective and efficient technique to engineer the surfaces of titanium and its alloys to achieve enhanced surface properties. The benefits of TO treatment in enhancing the tribological properties of titanium have been demonstrated by many investigators. However, most of the reported tribological studies have been based on the contact between a TO treated titanium specimen and a counter-body made of other materials, mainly ceramics, steels and polymers. Very few studies have been reported on the friction and wear behaviour of TO treated titanium sliding against TO treated titanium. In this work, the effect of thermal oxidation on the dry sliding friction and wear behaviour of commercially pure Ti (CP-Ti) on CP-Ti tribopairs was investigated under loading conditions ranging from elastic contact to plastic contact. Comparisons were made among three contact pairs: (1) untreated Ti on untreated Ti (Ti–Ti), (2) untreated Ti on TO treated Ti (Ti-TO) and (3) TO treated Ti on TO treated Ti (TO-TO). The results show that the TO-TO contact pair presents an ideal material combination to achieve the best tribological performance in terms of low friction and superior wear resistance. On the other hand, the Ti–Ti pair presents the worst combination in terms of tribological performance. While the Ti-TO pair performs better than the Ti–Ti pair tribologically, it is not as good as the TO-TO pair. It is essential to thermally oxidize both specimens in order to achieve optimal tribological performance. It is the oxide layer-on-oxide layer contact that imparts the excellent tribological performance. Failure of the oxide layer in one of the contact bodies can lead to high and unstable friction and increased wear from both contacting bodies. The tribological performance of the three contact pairs and the failure mechanism of the oxide layer are discussed in the paper. The results of this work suggest that the TO treated Ti on TO treated Ti contact pair would have potential tribological applications in engineering.

Layer-by-Layer Deposition of Regenerated Silk Fibroin─An Approach to the Surface Coating of Biomedical Implant Materials.

Biomaterials and coating techniques unlock major benefits for advanced medical therapies. Here, we explored layer-by-layer (LbL) deposition of silk fibroin (SF) by dip coating to deploy homogeneous films on different materials (titanium, magnesium, and polymers) frequently used for orthopedic and other bone-related implants. Titanium and magnesium specimens underwent preceding plasma electrolytic oxidation (PEO) to increase hydrophilicity. This was determined as surface properties were visualized by scanning electron microscopy and contact angle measurements as well as Fourier transform infrared spectroscopy (FTIR) analysis. Finally, biological in vitro evaluations of hemocompatibility, THP-1 cell culture, and TNF-α assays were conducted. A more hydrophilic surface could be achieved using the PEO surface, and the contact angle for magnesium and titanium showed a reduction from 73 to 18° and from 58 to 17°, respectively. Coating with SF proved successful on all three surfaces, and coating thicknesses of up to 5.14 μm (±SD 0.22 μm) were achieved. Using FTIR analysis, it was shown that the insolubility of the material was achieved by post-treatment with water vapor annealing, although the random coil peak (1640-1649 cm-1) and the α-helix peak (at 1650 cm-1) were still evident. SF did not change hemocompatibility, regardless of the substrate, whereas the PEO-coated materials showed improved hemocompatibility. THP-1 cell culture showed that cells adhered excellently to all of the tested material surfaces. Interestingly, SF coatings induced a significantly higher amount of TNF-α for all materials, indicating an inflammatory response, which plays an important role in a variety of physiological processes, including osteogenesis. LbL coatings of SF are shown to be promising candidates to modulate the body's immune response to implants manufactured from titanium, magnesium, and polymers. They may therefore facilitate future applications for bioactive implant coatings. However, further in vivo studies are needed to confirm the proposed effects on osteogenesis in a physiological environment.