Enhancement of mineralization on porous titanium surface by filling with nano-hydroxyapatite particles fabricated with a vacuum spray method

Associated effects of blood metal(loid) exposure and impaired glucose metabolism in patients with gastric precancerous lesions or gastric cancer

Exposure to metal(loid)s and glucose metabolism may influence the progression of gastric precancerous lesions (GPLs) or gastric cancer (GC), but their combined effects remain unclear. Our study aimed to elucidate the combined impact of metal (including metalloid and trace element) exposure and disturbances in glucose metabolism on the progression of GPLs and GC. From a prospective observational cohort of 1829 individuals, their metal(loid) levels and blood metabolism were analysed via inductively coupled plasma‒mass spectrometry and targeted metabolomics gas chromatography‒mass spectrometry, respectively. From healthy normal controls (NC) or GPLs to GC, we observed that the aluminum and arsenic levels decreased, whereas the vanadium, titanium and rubidium levels increased, but the iron, copper, zinc and barium levels initially decreased but then increased; these changes were not obvious from the NC to GPL group. With respect to glucose homeostasis, most metabolites decreased, except for phosphoenolpyruvate (PEP), which increased. Multiple logistic regression analysis revealed that titanium and phosphoenolpyruvate might be risk factors for GPLs, that barium is a protective factor for GC, and that D-glucaric acid might be a protective factor for GPLs and GC. Selenium, vanadium, titanium, succinate, maleate, isocitrate, PEP, and the tricarboxylic acid cycle (TCA) had good predictive potential for GPL and GC. Additionally, metal(loid)s such as arsenic, titanium, barium, aluminum, and vanadium were significantly correlated with multiple glucose metabolites involved in the TCA cycle in the GPL and GC groups. Our findings imply that metal(loid) exposure disrupts glucose metabolism, jointly influencing GPL and GC progression.

Preparation, Physicochemical Characterization, and In Vitro and In Vivo Osteogenic Evaluation of Reinforced PLLA-PLCL/HA Resorbable Membranes

This study aimed to develop reinforced poly(L-lactide)-poly(L-lactide-co-ε-caprolactone)/hydroxyapatite (PLLA-PLCL/HA) resorbable membranes for guided bone regeneration (GBR), focusing on optimizing the degradation rate by adjusting PLLA molecular weight. We aimed to achieve a balance between mechanical strength and bioactivity to enhance the efficacy of bone regeneration. PLLA-PLCL/HA membranes with varying degradation rates were fabricated by modifying the molecular weight of PLLA. The membranes were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), andx-ray diffraction (XRD). Mechanical properties were evaluated using three-point bending tests, and in vitro cytocompatibility was assessed through MC3T3-E1 cell adhesion and proliferation. For in vivo experiments, a cranial defect mouse model was used to investigate degradation and osteogenic potential, and bone regeneration was evaluated using micro-CT, histological staining, and immunohistochemistry. The reinforced membranes exhibited superior bending strength compared to collagen membranes. The in vitro studies confirmed excellent cytocompatibility, and in vivo results showed that membranes with slower early stage degradation promoted bone regeneration, emphasizing the importance of degradation control in GBR membranes. The optimized PLLA-PLCL/HA membranes, which combine enhanced mechanical properties and controlled biodegradability, are promising candidates for clinical GBR applications.

Effect of surface pre-treatment with Er: YAG laser on hydroxyapatite coating adhesion and mechanical properties of titanium alloy discs

The use of hydroxyapatite (HAp) as a surface coating enhances the properties of titanium (Ti) by ensuring bioactivity and inducing bone apposition. The coating's limited adhesion to metal surfaces is a challenge, so improving it prevents delamination, inflammatory responses and mechanical failure of implants. The aim of this in vitro study was to evaluate the influence of Erbium-Doped Yttrium Aluminum Garnet (Er: YAG) laser irradiation as a pre-treatment on Ti-6Al-4 V surfaces on the adhesion of HAp coatings. Two groups of Ti-6Al-4 V discs (G1: machined + HAp coated and G2: laser irradiated + HAp coated) were evaluated by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and the crystalline phases of the coating by X-ray Diffraction (XRD). The physical properties were analyzed by microhardness, surface roughness and adhesion according to ASTM-D3359. Microhardness results were subjected to the t-test and surface roughness to the Mann-Whitney test. A 5% significance level was adopted. The characterization analyses were evaluated qualitatively. Laser treatment increased hardness (p = 0.013) and surface roughness (p = 0.002), while the untreated machined surface showed better coating adhesion. XRD, SEM and EDS analysis confirmed the formation of the HAp coating. Using the Er: YAG laser at the parameters determined in this study, no better adhesion of the coating was observed. However, laser irradiation provided greater hardness and roughness compared to films deposited on machined surfaces.

Advancements in nanohydroxyapatite: synthesis, biomedical applications and composite developments

Nanohydroxyapatite (nHA) is distinguished by its exceptional biocompatibility, bioactivity and biodegradability, qualities attributed to its similarity to the mineral component of human bone. This review discusses the synthesis techniques of nHA, highlighting how these methods shape its physicochemical attributes and, in turn, its utility in biomedical applications. The versatility of nHA is further enhanced by doping with biologically significant ions like magnesium or zinc, which can improve its bioactivity and confer therapeutic properties. Notably, nHA-based composites, incorporating metal, polymeric and bioceramic scaffolds, exhibit enhanced osteoconductivity and osteoinductivity. In orthopedic field, nHA and its composites serve effectively as bone graft substitutes, showing exceptional osteointegration and vascularization capabilities. In dentistry, these materials contribute to enamel remineralization, mitigate tooth sensitivity and are employed in surface modification of dental implants. For cancer therapy, nHA composites offer a promising strategy to inhibit tumor growth while sparing healthy tissues. Furthermore, nHA-based composites are emerging as sophisticated platforms with high surface ratio for the delivery of drugs and bioactive substances, gradually releasing therapeutic agents for progressive treatment benefits. Overall, this review delineates the synthesis, modifications and applications of nHA in various biomedical fields, shed light on the future advancements in biomaterials research.

Atomic layer deposited TiO2 nanofilm on titanium implant for reduced the release of particles

Objective: Titanium implants are widely used in surgeries for their biocompatibility and mechanical properties. However, excessive titanium particle release can cause implant failure. This study explores Atomic Layer Deposition (ALD) to coat commercially pure titanium (Cp-Ti) with TiO2, aiming to improve its frictional and corrosion resistance while reducing particle release. By comparing TiO2 films with varying ALD cycle numbers, we assess surface properties, particle release, friction, and corrosion performance, providing insights into mitigating particle release from implants. Methods: Cp-Ti surfaces were prepared and coated with TiO2 films of 100, 300, and 500 ALD cycles. Surface characterization involved SEM, EDX, and XRD. Friction was tested using SEM, nanoindentation, and ICP-MS. Corrosion resistance was evaluated through immersion tests and electrochemical analysis. Cytotoxicity was assessed using BMSCs. Results: Surface characterization revealed smoother surfaces with increased ALD cycles, confirming successful TiO2 deposition. Friction testing showed reduced friction coefficients with higher ALD cycles, supported by nanoindentation results. Corrosion resistance improved with increasing ALD cycles, as evidenced by electrochemical tests and reduced titanium release. Cytotoxicity studies showed no significant cytotoxic effects. Conclusion: ALD-coated TiO2 films significantly enhance frictional and corrosion resistance of titanium implants while reducing particle release. The study underscores the importance of ALD cycle numbers in optimizing film performance, offering insights for designing implants with improved properties.

Caffeic acid phenethyl ester ameliorates titanium particle-induced bone loss and inflammatory reaction in a mouse acute model

With the increasing clinical application of dental and orthopedic implants, the problem of peri-implant osteolysis has attracted attention. The inflammatory response and osteoclast differentiation induced by wear particles play an important role in peri-implant bone loss. However, the treatment of peri-implant osteolysis is still lacking. In the present study, we investigated the effect of caffeic acid phenethyl ester (CAPE) on titanium particles induced bone loss in a mouse model. We found that CAPE significantly suppressed titanium particle-induced bone loss in vivo. CAPE treatment decreased ratio of nuclear factor kappa B receptor activator ligand (RANKL)/osteoprotegerin (OPG) and subsequently reduced osteoclastogenesis in the mouse model. In addition, CAPE downregulated the expression and secretion of interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) stimulated by titanium particles in vivo. In summary, we conclude that CAPE prevent the titanium particles-induced bone loss.

Co-exposure to iron, copper, zinc, selenium and titanium is associated with the prevention of gastric precancerous lesions

Gastric cancer is the third leading cause of cancer death, and gastric precancerous lesions (GPLs) are an important stage in the transformation of normal gastric mucosa to gastric cancer. Matched for age and sex, a total of 316 subjects were eventually included from our prospective observation population (including 1007 patients with GPLs and 762 normal controls), and a questionnaire survey was conducted. In total, 10 plasma elements (iron, copper, zinc, selenium, rubidium, strontium, titanium, aluminum, vanadium and arsenic) were measured by applying inductively coupled plasma‒mass spectrometry (ICP‒MS). A multivariate conditional logistic regression model and Bayesian kernel logistic regression model (BKMR) were used to analyze the association between plasma element concentrations and GPLs. In the multimetal model, plasma titanium concentrations were significantly and positively associated with the prevalence of GPLs, with a fourth-quartile OR of 11.56 ([95% CI]: [2.78-48.13]). Plasma selenium and copper were negatively correlated with GPLs, with the highest quartiles of selenium and copper having an OR of 0.03 ([95% CI]: [0.01-0.15]; P < 0.001) and 0.24 ([95% CI]: [0.07-0.82]), respectively. In the BKMR model, there was a significant negative combined correlation of five metals on GPLs: iron, copper, zinc, selenium, and titanium. The results of this study showed that plasma concentrations of selenium and copper were negatively correlated with GPLs, while plasma concentrations of titanium were positively correlated with GPLs, and the combined action of the five elements was negatively correlated with GPLs.

Synthesis and Characterization of a Titanium-Based Functionally Graded Material-Structured Biocomposite using Powder Metallurgy

This investigation aims at synthesizing and characterizing a biocomposite of hydroxyapatite (HA) and titanium (Ti) as a functionally graded material (FGM) via an economical powder metallurgy route. Ti particles were produced through drilling and chipping, followed by compaction and sintering. Ti foams, so obtained, were then infused with varying volume fractions of HA. The pure Ti foam control sample and the FGM composite samples were then subjected to various characterizations to validate their biocompatibility, structural strength, and integrity. The interface development between the load-bearing Ti implant and living tissue was resolved through an FGM structure, where the base of the implant consisted of load-bearing Ti and the outer periphery changed to HA gradually. HA/Ti specimens of different volume fractions were tested for density measurements, microstructure, hardness, and bioactivity. The bioactive behavior was investigated using the potentiodynamic polarization technique to measure the corrosion rate of the pure Ti foam (0/100 HA/Ti) and the FGM composite (10/90 HA/Ti) samples in a simulated body fluid (SBF). The results showed that the hardness of FGM composites, despite being less than that of 0/100 HA/Ti, was still within safe limits. The corrosion rate, however, was found to be decreased by a significant value of almost 40% for the 10/90 HA/Ti FGM composite sample compared to the pure Ti foam control sample. It was concluded that the optimum composition 10/90 HA/Ti sample offers improved corrosion resistance while maintaining a sufficient allowable hardness level.

Advances and Prospects in Materials for Craniofacial Bone Reconstruction

The craniofacial region is composed of 23 bones, which provide crucial function in keeping the normal position of brain and eyeballs, aesthetics of the craniofacial complex, facial movements, and visual function. Given the complex geometry and architecture, craniofacial bone defects not only affect the normal craniofacial structure but also may result in severe craniofacial dysfunction. Therefore, the exploration of rapid, precise, and effective reconstruction of craniofacial bone defects is urgent. Recently, developments in advanced bone tissue engineering bring new hope for the ideal reconstruction of the craniofacial bone defects. This report, presenting a first-time comprehensive review of recent advances of biomaterials in craniofacial bone tissue engineering, overviews the modification of traditional biomaterials and development of advanced biomaterials applying to craniofacial reconstruction. Challenges and perspectives of biomaterial development in craniofacial fields are discussed in the end.

Effect of the Size of Titanium Particles Released from Dental Implants on Immunological Response

The techniques used in oral implantology to remove bacterial biofilm from the surface of implants by machining the titanium surface (implantoplasty) or by placing rough dental implants through friction with the cortical bone generate a large release of particles. In this work, we performed a simulation of particle generation following clinical protocols. The particles were characterized for commercially pure titanium with particle sizes of 5, 10, 15, and 30 μm. The aim was to determine the effect of particle size and chemical composition of the implant on the immune response. For this purpose, their morphology and possible contamination were characterized by scanning electron microscopy and X-ray microanalysis. In addition, the granulometry, specific surface area, release of metal ions into the medium, and studies of cytocompatibility, gene expression, and cytokine release linked to the inflammatory process were studied. The release of ions for titanium particles showed levels below 800 ppb for all sizes. Smaller particle sizes showed less cytotoxicity, although particles of 15 μm presented higher levels of cytocompatibility. In addition, inflammatory markers (TNFα and Il-1β) were higher compared to larger titanium. Specifically, particles of 15 μm presented a lower proinflammatory and higher anti-inflammatory response as characterized by gene expression and cytokine release, compared to control or smaller particles. Therefore, in general, there is a greater tendency for smaller particles to produce greater toxicity and a greater proinflammatory response.

Synthesis and application of nanometer hydroxyapatite in biomedicine

Nano-hydroxyapatite (nano-HA) has been widely studied as a promising biomaterial because of its potential mechanical and biological properties. In this article, different synthesis methods for nano-HA were summarized. Key factors for the synthesis of nano-HA, including reactant concentration, effects of temperature, PH, additives, aging time, and sintering, were separately investigated. The biological performances of the nano-HA depend strongly on its structures, morphology, and crystallite sizes. Nano-HA with different morphologies may cause different biological effects, such as protein adsorption, cell viability and proliferation, angiogenesis, and vascularization. Recent research progress with respect to the biological functions of the nano-HA in some specific biological applications are summarized and the future development of nano-sized hydroxyapatite is prospected.

Characterization of Porous Titanium-Hydroxyapatite Composite Biological Coating on Polyetheretherketone (PEEK) by Vacuum Plasma Spraying

Titanium powders and hydroxyapatite powders were used to fabricate the titanium and hydroxyapatite composite coating (Ti/Ti/HA) on the Polyetheretherketone (PEEK) by vacuum plasma spraying (VPS). The phase composition and morphology of the Ti/Ti/HA coating were analyzed by XRD, SEM, industrial CT, and three-dimensional contour profiler (DEKTAK XT). The results showed that the phase composition of the Ti/Ti/HA coating was dominated by the HA phase and a small amount of the Ti phase. The Ti/Ti/HA composite coating presented an obvious three-layer structure with different roughness and porosity. The bottom was Ti coating with a porosity less than 10%; the middle was porous Ti coating with a porosity of 35% ± 10%; the surface coating was HA coating with the crystallinity near 95%, a porosity of 32% ± 10%, a roughness Ra = 30 ± 10 μm. Moreover, the TG-DSC and ATR-FTIR results showed that VPS coating has no effect on thermochemical properties of PEEK material. The average bond strength of the composite coating was achieved 32 MPa.

Structural and elemental characterization of glass and ceramic particles for bone surgery

OBJECTIVE

Clinically used bioceramics have been characterized previously with different kinds of methods and comparison of results have proven to be difficult due to varieties of the material properties of interest. Therefore, in this study we compared clinically commonly used bioceramics of hydroxyapatite and carbonate apatite, two bioactive glasses 45S5 and S53P4, and alumina with respect of properties which according to the present knowledge are significant for bone biology.

METHODS

Physicochemical properties of the materials were characterized by various methods. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) was used to analyze the material vibrational features. X-ray Power Diffraction (XRD) was used to characterize the material crystal structure and scanning electron microscopy-energy-dispersive x-ray analysis (SEM-EDXA) was used to evaluate the morphology and size of the materials and to calculate their oxide content. The dissolution behavior of the materials, ion release and pH changes in Tris buffer in a continuous flow-through reaction for 24-hours were determined. The change of the surface of the bioactive glasses by interfacial reaction during the Tris immersion was examined and the thickness of the surface reaction layer of the materials was studied.

RESULTS

SEM examination showed that the particle morphology of BG 45S5, BG S53P4 and alumina particle's surface was smooth. The surface of HAP was porous, but also CAP showed some surface porosity. An increase in the pH of the immersion solution was observed especially for BG 45S5 and BG S53P4. HAP, CAP and alumina caused only a minor increase in pH. BGs 45S5 and S53P4 showed a rapid initial release of sodium and calcium ions, followed by the release of silicon species. Minor release of sodium ions was registered for HAP, CAP and alumina. Calcium ion release was low but constant over the experimental time while only a minor initial dissolution was measured for HAP.

SIGNIFICANCE

The in vitro study showed differences in the materials' properties, which are considered to be important for biological suitability and in clinical applications, such as materials tomography, ion release and pH changes.

The unfavorable role of titanium particles released from dental implants

Titanium is considered to be a metal material with the best biological safety. Studies have proved that the titanium implanted in the bone continuously releases titanium particles (Ti particles), significantly increasing the total titanium content in human body. Generally, Ti particles are released slowly without causing a systemic immune response. However, the continuous increased local concentration may result in damage to the intraepithelial homeostasis, aggravation of inflammatory reaction in the surrounding tissues, bone resorption and implant detachment. They also migrate with blood flow and aggregate in the distal organ. The release of Ti particles is affected by the score of the implant surface structure, microenvironment wear and corrosion, medical operation wear, and so on, but the specific mechanism is not clear. Thus, it difficult to prevent the release completely. This paper reviews the causes of the Ti particles formation, the damage to the surrounding tissue, and its mechanism, in particular, methods for reducing the release and toxicity of the Ti particles.

Nanomaterials in Dentistry: State of the Art and Future Challenges

Nanomaterials are commonly considered as those materials in which the shape and molecular composition at a nanometer scale can be controlled. Subsequently, they present extraordinary properties that are being useful for the development of new and improved applications in many fields, including medicine. In dentistry, several research efforts are being conducted, especially during the last decade, for the improvement of the properties of materials used in dentistry. The objective of the present article is to offer the audience a complete and comprehensive review of the main applications that have been developed in dentistry, by the use of these materials, during the last two decades. It was shown how these materials are improving the treatments in mainly all the important areas of dentistry, such as endodontics, periodontics, implants, tissue engineering and restorative dentistry. The scope of the present review is, subsequently, to revise the main applications regarding nano-shaped materials in dentistry, including nanorods, nanofibers, nanotubes, nanospheres/nanoparticles, and zeolites and other orders porous materials. The results of the bibliographic analysis show that the most explored nanomaterials in dentistry are graphene and carbon nanotubes, and their derivatives. A detailed analysis and a comparative study of their applications show that, although they are quite similar, graphene-based materials seem to be more promising for most of the applications of interest in dentistry. The bibliographic study also demonstrated the potential of zeolite-based materials, although the low number of studies on their applications shows that they have not been totally explored, as well as other porous nanomaterials that have found important applications in medicine, such as metal organic frameworks, have not been explored. Subsequently, it is expected that the research effort will concentrate on graphene and zeolite-based materials in the coming years. Thus, the present review paper presents a detailed bibliographic study, with more than 200 references, in order to briefly describe the main achievements that have been described in dentistry using nanomaterials, compare and analyze them in a critical way, with the aim of predicting the future challenges.

Hydroxyapatite-Incorporated Composite Gels Improve Mechanical Properties and Bioactivity of Bone Scaffolds

Reinforcing polymeric scaffolds with micro/nanoparticles improve their mechanical properties and render them bioactive. In this study, hydroxyapatite (HA) is incorporated into 5% (w/v) gelatin methacrylate (GelMA) hydrogels at 1, 5, and 20 mg mL^-1 concentrations. The material properties of these composite gels are characterized through swelling, degradation, and compression tests. Using 3D cell encapsulation, the cytocompatibility and osteogenic differentiation of preosteoblasts are evaluated to assess the biological properties of the composite scaffolds. The in vitro assays demonstrate increasing cell proliferation and metabolic activity over the course of 14 d in culture. Furthermore, the scaffolds support osteogenic differentiation of the microencapsulated preosteoblasts. For the in vivo study, the composite scaffolds are subcutaneously implanted in rats for 14 d. The histological staining of the explanted in vivo samples exhibits the functional advantages of the scaffold's biocompatibility, biodegradability, and integration into the existing host tissue. This work demonstrates the enhanced mechanical and biological performance of HA-gelatin composite hydrogels for bone tissue engineering applications.