Search Results (101)

Objective: This narrative review synthesizes current evidence on materials and manufacturing technologies for customized dental implants, highlighting their comparative advantages and limitations. Methods: A structured literature search (December 2024–January 2025) was conducted using PubMed, Web of Science, Scopus, and Google Scholar. Peer-reviewed English-language articles (mainly 2015–2025) addressing implant materials, manufacturing methods, and surface modifications were included. Data were critically analyzed and thematically organized without meta-analysis. Results: Digital workflows are advancing implantology toward patient-specific solutions. Subtractive manufacturing (SM) ensures high precision and surface quality but is limited by material waste and geometric constraints. In contrast, additive manufacturing (AM) enables complex, porous, and customized designs, though often requires post-processing. Titanium and its alloys remain the gold standard due to strength and biocompatibility, while TiZr and β-type alloys may reduce stress shielding. Zirconia offers aesthetic benefits but is brittle, whereas PEEK shows favorable elasticity but limited bioactivity. Surface modifications enhance osseointegration and long-term performance. Conclusions: Combining digital workflows with SM and AM supports development of optimized, patient-specific implants. While titanium dominates clinical use, emerging materials offer specific advantages. Further clinical validation and standardization are required. Full article

Titanium alloys, particularly β-type Ti-13Nb-13Zr, are promising biomedical materials due to their low elastic modulus and excellent biocompatibility. However, their bioactivity needs improvement for better bone integration. In this study, a calcium-phosphate (Ca/P) coating was prepared on a Ti-13Nb-13Zr alloy via micro-arc oxidation (MAO) in an electrolyte containing calcium acetate and dipotassium hydrogen phosphate. The effect of applied voltage (300 V, 400 V, and 500 V) on the phase composition, surface morphology, and in vitro bioactivity of the coatings was investigated. Surface characterization was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS). The results show that increasing the voltage increased the surface roughness, average pore size, and rutile TiO₂ content in the coating. The Ca/P ratio in the coating approached 1.67 at 500 V, similar to that of natural bone. After immersion in simulated body fluid (SBF) for 20 days, the coating formed at 500 V induced the highest deposition of hydroxyapatite (HA), completely covering the microporous surface. These findings indicate that MAO treatment at 500 V significantly enhances the bioactivity of the Ti-13Nb-13Zr alloy, making it a promising candidate for orthopedic implants. Full article

This study addressed the poor wear resistance of Ti-7.5Nb-4Mo-2Sn shape memory alloy through the development of Ti-xSn (x = 6, 8, 9, 10, 20 at.%) coatings and laser cladding technology. This β-type titanium alloy is a promising biomaterial for artificial joints and bone fixation implants, and laser cladding is a superior surface modification technology for fabricating metallurgically bonded high-performance coatings. Microstructural characterization revealed that increasing Sn content from 6% to 10% progressively suppressed β-phase formation while enhancing microhardness (peak value: 430.06 HV1) and wear resistance. Conversely, further Sn addition of 20% degraded these properties. The optimal Ti-10Sn alloy was subsequently laser cladded onto a Ti-7.5Nb-4Mo-2Sn substrate in the form of pre-placed thin sheets under varying laser scanning speeds (7–13 mm/s). The results indicated that processing at 10 mm/s produced superior coating features, including complete metallurgical bonding (20 μm transition layer), the maximum surface hardness (494 HV1, 93% increase), and superior wear resistance. Microscopic analysis confirmed a wear mechanism transition from mixed adhesive–abrasive wear (7.5Nb-4Mo-2Sn substrate) to pure abrasive wear (Ti-10Sn coating), resulting in the enhanced wear resistance of the substrate. This study demonstrated that synergistic alloy design combined with a laser cladding approach can significantly enhance biomedical alloy performance. Full article

Damage is inevitably induced in titanium alloy laser-welded (LW) joints after prolonged service, making weld repair an economical and effective restoration method. This study employed gas tungsten arc welding (GTAW) to repair pre-damaged TC4 LW joints, with a systematic investigation on the microstructural and mechanical properties of the repaired joints. The results indicate that both the LW and the GTAW-repaired (GTAW-R) joints exhibit acicular α′ martensite in the fusion zone (FZ). However, the maximum length and width of the α′ phase in the FZ of the GTAW-R joint are 67% and 78% larger than those in the LW joint, respectively. The heat-affected zone (HAZ) of both types of joints comprises α′, α, and β phases. Similarly, due to the higher heat input in GTAW, the α′ phase in the HAZ of the GTAW-R joint is coarser. Differences in acicular martensite size result in an average microhardness of 356.3 HV in the FZ of the GTAW-R joint, which is 15.2 HV lower than that of the LW joint. The higher heat input of GTAW leads to a prolonged duration at elevated temperatures in the HAZ, promoting the formation of acicular α′ phase and, consequently, a slightly higher microhardness compared to the HAZ of the LW joint. The average tensile strength of the GTAW-R joint is 1032 MPa, equivalent to 98.4% of the LW joint strength (1049 MPa) and 96.8% of the BM strength (1066 MPa). Tensile fracture in the LW joint occurs in the BM region, whereas the coarser microstructure in the repair weld leads to fracture in the FZ for the GTAW-R joint. This study demonstrates that when the damage length in an LW joint is less than 20%, GTAW repair can effectively restore the joint strength. Full article

Titanium-based alloys are widely used in dental implantology; however, the mechanical limitations of commercially pure titanium (cpTi) and unresolved concerns regarding stress shielding remain. This study evaluated the structure–property–function relationship of a novel β-type titanium-niobium-zirconium (Ti-Nb-Zr; TNZ) alloy for dental implant applications. Laboratory testing assessed the elemental composition, tensile properties, and fatigue resistance of the cpTi, compared with modified Grade 4 cpTi (MG4T). In parallel, a randomized, single-blind, controlled clinical trial was conducted over 12 months to compare the clinical performance of TNZ and MG4T implants under functional loading. A total of 80 participants (mean age: 54.2 years; 43 females, 37 males) were enrolled, with 77 completing the 12-month follow-up (TNZ: n = 38; MG4T: n = 39). Clinical outcomes included implant success and survival, peri-implant soft tissue parameters, marginal bone levels, fractal dimension (FD) analysis of trabecular bone, and adverse events. TNZ implants demonstrated superior fatigue resistance without an increase in the elastic modulus relative to MG4T. Clinically, both groups achieved 100% implant success and survival, with no implant-related adverse events. FD analysis revealed time-dependent bone remodeling without evidence of pathological adaptation. These findings support the functional viability of TNZ as a mechanically robust, biocompatible implant material. Further long-term, multicenter trials are warranted to confirm sustained clinical benefits and broader applicability. Full article

Background/Objectives: A comparative study of silver (Ag), titanium nitride (TiN), zirconium nitride (ZrN), and copper (Cu) coatings on titanium (Ti) disks, considering the specifications of a microporous skin- and bone-integrated titanium pylon (SBIP), was performed to assess their biocompatibility, osseointegration, and mechanical properties. Methods: To assess cytotoxicity and biocompatibility, Ti disks with various metal coatings were co-cultured with FetMSCs and MG-63 cells for 1, 3, 7, and 14 days and subsequently evaluated using a cell viability assay, as supported by SEM and confocal microscopy studies. The antimicrobial activity of the selected four materials coating the implants was tested against S. aureus by mounting Ti disks onto the surface of LB agar dishes spread with a bacterial suspension and measuring the diameter of the growth inhibition zones. Quantitative Real-Time Polymerase Chain Reaction (RT-PCR) analysis of the relative gene expression of biomarkers that are associated with extracellular matrix components (fibronectin, vitronectin, type I collagen) and cell adhesion (α2, α5, αV integrins), as well as of osteogenic markers (osteopontin, osteonectin, TGF-β1, SMAD), was performed during the 14-day follow-up period. Additionally, the activity of matrix metalloproteinases (MMP-1, -2, -8, -9) was assessed. Results: All samples with metal coatings, except the copper coating, demonstrated a good cytotoxicity profile, as evidenced by the presence of a cellular monolayer on the sample surface on the 14th day of the follow-up period (as shown by SEM and inverted confocal microscopy). All metal coatings enhanced MMP activity, as well as cellular adhesion and osteogenic marker expression; however, TiN showed the highest values of these parameters. Significant inhibition of bacterial growth was observed only in the Ag-coated Ti disks, and it persisted for over 35 days. Conclusions: The silver-based coating, due to its high antibacterial activity, low cytotoxicity, and biointegrative capacity, can be recommended as the coating of choice for microporous titanium implants for further preclinical studies. Full article

This study investigates TNM-type titanium aluminide alloys, representing the third generation of β-stabilized γ-TiAl heat-resistant materials. The aim of this work is to study the combustion characteristics and to produce compact materials via the free SHS compaction method from initial powder reagents taken in the following ratio (wt%): 51.85Ti–43Al–4Nb–1Mo–0.15B, as well as to determine the effect of high-temperature isothermal annealing at 1000 °C on the structure and properties of the obtained materials. Using free SHS compression (self-propagating high-temperature synthesis), we synthesized compact materials from a 51.85Ti–43Al–4Nb–1Mo–0.15B (wt%) powder blend. Key combustion parameters were optimized to maximize the synthesis temperature, employing a chemical ignition system. The as-fabricated materials exhibit a layered macrostructure with wavy interfaces, aligned parallel to material flow during compression. Post-synthesis isothermal annealing at 1000 °C for 3 h promoted further phase transformations, enhancing mechanical properties including microhardness (up to 7.4 GPa), Young’s modulus (up to 200 GPa) and elastic recovery (up to 31.8%). X-ray powder diffraction, SEM, and EDS analyses confirmed solid-state diffusion as the primary mechanism for element interaction during synthesis and annealing. The developed materials show promise as PVD targets for depositing heat-resistant coatings. Full article

Beta (β)-type Ti-29Nb-13Ta-4.6Zr (TNTZ) alloys combine low modulus with biocompatibility but require improved surface properties for long-term implantation. This study aimed to enhance the surface mechanical strength and antibacterial performance of TNTZ by applying TiN and TiAlN coatings via PVD. Notably, TiAlN was deposited on TNTZ for the first time, enabling a direct side-by-side comparison with TiN under identical deposition conditions. Dense TiN (~1.06 μm) and TiAlN (~1.73 μm) coatings were deposited onto solution-treated TNTZ and characterized by X-ray diffraction, scanning probe microscopy, Vickers microhardness, Rockwell indentation test (VDI 3198), static water contact angle measurements, and a Kirby–Bauer disk-diffusion antibacterial assay against Escherichia coli (E. coli). Both coatings formed face-centered cubic (FCC) structures with smooth interfaces (Ra ≤ 5.3 nm) while preserving the single-phase β matrix of the substrate. The hardness increased from 192 HV (uncoated) to 1059 HV (TiN) and 1468 HV (TiAlN), and the adhesion quality was rated as HF2 and HF1, respectively. The surface wettability changed from hydrophilic (48°) to moderately hydrophobic (82°) with TiN and highly hydrophobic (103°) with TiAlN. Similarly, the diameter of the no-growth zones increased to 18.02 mm (TiN) and 19.09 mm (TiAlN) compared to 17.65 mm for uncoated TNTZ. The findings indicate that TiAlN, in particular, provided improved hardness, adhesion, and hydrophobicity. Preliminary bacteriostatic screening under diffusion conditions suggested a modest relative antibacterial response, though the effect was not statistically significant between coated and uncoated TNTZ. Statistical analysis confirmed no significant difference between the groups (p > 0.05), indicating that only a preliminary bacteriostatic trend— rather than a definitive antibacterial effect—was observed. Both nitride coatings strengthened TNTZ without compromising its structural integrity, making TiAlN-coated TNTZ a promising candidate for next-generation orthopedic implants. Full article

Objective: Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), a variant of zirconia (ZrO₂), has attracted interest as a substitute for titanium in dental and orthopedic implants, valued for its biocompatibility and aesthetics that resemble natural teeth. However, its bioinert surface limits osseointegration, making surface modifications such as calcium phosphate (CaP) coatings highly relevant. Materials and methods: The review process adhered to the PRISMA guidelines. Electronic searches of PubMed, Scopus, Web of Science, Embase, and Cochrane Library (July 2025) identified studies evaluating CaP-coated zirconia implants. Eligible studies included in vitro, in vivo, and preclinical investigations with a control group. Data on coating type, deposition method, and biological outcomes were extracted and analyzed. Results: A total of 27 studies were analyzed, featuring different calcium phosphate (CaP) coatings including β-tricalcium phosphate (β-TCP), hydroxyapatite (HA), octacalcium phosphate (OCP), and various composites. These coatings were applied using diverse techniques such as RF magnetron sputtering, sol–gel processing, biomimetic methods, and laser-based approaches. In multiple investigations, calcium phosphate coatings enhanced osteoblast attachment, proliferation, alkaline phosphatase (ALP) expression, and bone-to-implant contact (BIC) relative to unmodified zirconia surfaces. Multifunctional coatings incorporating growth factors, antibiotics, or nanoparticles showed additional benefits. Conclusion: CaP coatings enhance the bioactivity of zirconia implants and represent a promising strategy to overcome their inertness. Further standardized approaches and long-term studies are essential to verify their translational relevance. Full article

The Reformatsky reaction, first reported in 1887, has long been recognized as a fundamental method for carbon–carbon bond construction due to its mild conditions and functional group tolerance. Over the past few decades, this transformation has undergone a notable revival, with modern catalytic variants addressing limitations of stoichiometric protocols and expanding its role in complex molecule synthesis. Yet, despite its versatility, achieving stereoselective control remains a longstanding challenge. Herein we report the use of dichlorocyclopentadienyltitanium(III) (CpTiCl₂), generated in situ from CpTiCl₃ and manganese, as an efficient catalyst for Reformatsky-type couplings of aldehydes with α-haloesters and α-iodonitriles. Under mild conditions, CpTiCl₂ promotes the formation of β-hydroxy esters in high yields and with significant diastereoselective preference for the syn isomer (up to 100:0 syn:anti). This behavior contrasts sharply with the poor or anti-selective outcomes previously observed with titanocene(III) chloride (Cp₂TiCl). Mechanistic analysis suggests that the unique steric and electronic environment of CpTiCl₂—characterized by enhanced Lewis acidity and increased coordination vacancies—favors a Zimmerman–Traxler-type transition state that enforces syn stereocontrol. The methodology tolerates a wide variety of substrates, including aliphatic and aromatic aldehydes as well as α-iodonitriles, extending the scope of titanium-mediated Reformatsky chemistry. These findings establish CpTiCl₂ as a sustainable, selective, and robust organotitanium catalyst for stereoselective carbon–carbon bond formation, providing a promising alternative to the Nugent reagent and paving the way for new applications in complex molecule synthesis. Full article

This study examines the effects of electrolyte composition, specifically the incorporation of dispersed particles, on the properties and formation kinetics of micro-arc oxidation (MAO) coatings on a bioinert titanium alloy. Coatings with particles of β-tricalcium phosphate (CP), wollastonite (CS), and combined coatings containing both types of particles (SP) were obtained. The MAO process was carried out using a Micro-Arc 3.0 unit in pulsed potentiostatic anode mode, with the process voltage ranging from 350 to 500 volts. The surface morphology and internal structure of the coatings were examined using scanning electron microscopy. The elemental composition of the coatings was determined by the EDX method, while the phase composition and fine structure of the coatings were investigated by XRD and TEM methods, respectively. The adhesion properties of the coatings were determined by means of scratch testing. When the MAO process voltage was increased to 500 V, the thickness of CP, CS, and SP coatings increased to 80, 50, and 50 μm, respectively. Notably, SP coatings demonstrated the highest adhesion strength (critical load L_c = 22 N), indicating their potential for use in load-bearing medical implants, where preventing delamination under mechanical stress is critical. Full article

This study investigates the application of the Keyhole–Tungsten Inert Gas Welding (K-TIG) hot-wire filling welding technique with mechanical arc oscillation to weld a 95 mm-thick Ti-6Al-4V titanium alloy plate. The root layer thickness achieved with this technique reaches up to 17 mm, with an average filling thickness of 2.5 mm. The weld bead displays a smooth, shiny appearance, and no significant welding defects are observed in the cross-section of the welded joint. Experimental results show that the welded joint consists of the α phase in different forms, as well as fine α+β microstructures. Compared to the base material, both the weld metal and the heat-affected zone exhibit a lower crystallographic texture strength, with more complex texture types. The impact toughness of the welded joint is excellent, with no significant weaknesses. The impact toughness of the weld metal significantly surpasses that of both the base material and the heat-affected zone. The engagement strengthening effect induced by high-current filling plays a crucial role in enhancing the impact toughness of the weld metal. Full article

This article investigates the precipitation behavior of the phases in metastable β-type titanium alloys (Ti-38644) and their significant impact on the mechanical properties. By manipulating various solid solution aging parameters, the morphology, quantity, and distribution of the αs phase can be optimized. After one hour of solid solution treatment at 760 °C, the alloy is predominantly composed of the β phase, with a higher concentration of aluminum at the grain boundaries compared to the interior of the grains. Subsequently, after ten hours of aging treatment at 450 °C and 470 °C, the needle-shaped αs phase preferentially precipitated at the grain boundaries. As the aging temperature increased to 470 °C, the area percentage of the αs phase rose from 42.36% to 57.34%, while its yield strength (σs) increased from 967 MPa at 450 °C to 1211 MPa at 470 °C. This increase in σs results from the combined effects of dislocation strengthening (${\sigma }_{\rho }$) and precipitation hardening. This article provides a comprehensive theoretical analysis of the various factors that influence σs, offering valuable theoretical support for the development of heat treatment processes for the Ti-38644 titanium alloy. Full article

The Ti-6Al-4V alloy is a typical α + β type titanium alloy and is widely used in the manufacture of aero-engine fans, compressor discs and blades. The working life of modern aero-engine components is usually required to reach more than 10⁸ cycles, which makes the infinite life design based on the traditional fatigue limit unsafe. In this study, through symmetrical loading high-cycle fatigue tests on Ti-6Al-4V titanium alloy, a nonlinear cumulative damage life prediction model was established. Further very-high-cycle fatigue tests of titanium alloys were carried out. The variation law of plastic strain energy in the evolution process of very-high-cycle fatigue damage of titanium alloy materials was described by introducing the internal stress parameter. A prediction model for the very-high-cycle fatigue life of titanium alloys was established, and the sensitivity analysis of model parameters was carried out. The results show that the established high-cycle/very-high-cycle fatigue models can fit the test data well. Moreover, based on the optimized model parameters through sensitivity analysis, the average error of the prediction results has decreased from 59% to 38%. The research aims to provide a model or method for predicting the engineering life of titanium alloys in the high-cycle/very-high-cycle range. Full article

The application fields of high-temperature titanium alloys are mainly concentrated in the aerospace, defense and military industries, such as the high-temperature parts of rocket and aircraft engines, missile cases, tail rudders, etc., which can greatly reduce the weight of aircraft while resisting high temperatures. However, traditional high-temperature titanium alloys containing multiple types of elements (more than six) have a complex impact on the solidification, deformation, and phase transformation processes of the alloys, which greatly increases the difficulty of casting and deformation manufacturing of aerospace and military components. Therefore, developing low-component high-temperature titanium alloys suitable for hot processing and forming is urgent. This study used data augmentation (Gaussian noise) to expedite the development of a novel quinary high-temperature titanium alloy. Utilizing data augmentation, the generalization abilities of four machine learning models (XGBoost, RF, AdaBoost, Lasso) were effectively improved, with the XGBoost model demonstrating superior prediction accuracy (with an R² value of 0.94, an RMSE of 53.31, and an MAE of 42.93 in the test set). Based on this model, a novel Ti-7.2Al-1.8Mo-2.0Nb-0.4Si (wt.%) alloy was designed and experimentally validated. The UTS of the alloy at 600 °C was 629 MPa, closely aligning with the value (649 MPa) predicted by the model, with an error of 3.2%. Compared to as-cast Ti1100 and Ti6242S alloy (both containing six elements), the novel quinary alloy has considerable high-temperature (600 °C) mechanical properties and fewer components. The microstructure analysis revealed that the designed alloy was an α+β type alloy, featuring a typical Widmanstätten structure. The fracture form of the alloy was a mixture of brittle and ductile fracture at both room and high temperatures. Full article