Journal of Materials Science: Materials in Medicine最新文献

Objectives

This study evaluated the mechanical and surface characteristics of the transition zone of multilayered translucent zirconia (TZ) after aging and analyzed the correlation between the 4-point bending flexural strength (4PBFS) and biaxial flexural strength (BFS) in each zone.

Methods

Traditional (3Y-TZP of LT; L, 4Y-TZP of MT; M) and multilayered TZ (5Y-TZP of MT Multi; T, 3Y/5Y-TZP of Prime; P, 4Y/5Y-TZP of Prime esthetic; E) IPS E.max ZirCAD blocks were used to fabricate 525 disk-shaped and 300 bar-shaped specimens. Specimens were separated into three groups, aged in an autoclave at 134 °C under 0.2 MPa for 0 h, 5 h, and 10 h. The mechanical and surface characteristics of the transition zone in multilayered TZ were analyzed, following statistical analyses (α = 0.05).

Results

L showed the highest 4PBFS and BFS, irrespective of aging. Consistent correlations between the 4PBFS and BFS were found in all groups. L showed the highest Weibull characteristic strength under all conditions. T showed the highest nanoindentation hardness and Young’s modulus, and the Vickers hardness of L and P were lower than other groups. Aging led to surface uplifts and microcracks caused by phase transformation, particularly in L and P.

Conclusions

The flexural strength of 3Y/5Y-TZP and 4Y/5Y-TZP was comparable to that of 3Y-TZP and 4Y, 5Y-TZP respectively, regardless of aging. Surface roughness showed a marked increase after aging in 3Y-TZP and 3Y/5Y-TZP. Furthermore, the interaction between yttria content and aging was evident across all mechanical and surface characteristics, except for flexural strength.

Graphical Abstract

Opacification of intraocular lenses (IOLs) due to the formation of calcium phosphate occurs because of their contact with the aqueous humor (AH), which is supersaturated with respect to calcium phosphate. Calcification of IOLs was simulated in vitro using a batch reactor in which the IOLs were exposed to solutions simulating AH. Based on the precise and reproducible measurement of the rates of formation of mineral deposits on the IOLs, it is possible to develop reliable screening tests of different types of IOL materials. Depending on their material composition, IOLs are expected to present different active sites for the growth of deposits. Measurements of the kinetics of formation of hydroxyapatite (Ca₅(PO₄)₃OH; HAP) were used to compare the relative tendency of IOL towards calcification. The trend the IOLs tested showed towards calcification was found to correlate with contact angle values. In the case of hydrophobic IOLs, the surface charge calculated from the corresponding zeta potential measurements was low in comparison with the respective high (absolute) values of the mineralizing hydrophilic IOLs, suggesting strong correlation between surface charge and tendency to calcify. The in vitro results align with the in vivo tests, suggesting that in vivo tests can be safely substituted or at least significantly reduced by the in vitro model.

Graphical Abstract

Intrauterine adhesions pose a significant challenge to female fertility, with current treatments showing limited efficacy and safety concerns, including poor biocompatibility and secondary trauma risks. In this work, we present a novel biodegradable bacterial nanocellulose (BC)-based physical barrier that integrates controlled drug release capabilities for preventing intrauterine adhesions. Through TEMPO-mediated oxidation and N-vinyl pyrrolidone grafting, we developed BC membranes exhibiting superior biocompatibility (cell death rate <5%) and selective fibroblast inhibition. The system achieves controlled biodegradation over 14 days while maintaining mechanical integrity (tensile strength >2.0 MPa) and providing sustained β-estradiol release. This approach represents a significant advancement in intrauterine adhesion prevention strategies.

When measured in vitro, the release of metal ions from orthodontic alloys is typically carried out in artificial saliva (AS), a medium with many advantages but lacking the biological complexity of natural human saliva. In this study, we measured ion release profiles from the complete orthodontic fixed appliance, comprising stainless steel and NiTi parts, in a proteinaceous media (yeast extract peptone dextrose, YPD) and compared it to AS. Two immersion models were used, differing in medium replenishment dynamics. To elucidate the metal release results, surface chemistry and topography were analysed using atomic force microscopy (AFM) followed by roughness analysis, and elemental analysis of the top micrometric and nanometric layer (SEM/EDX and XPS analyses).The results showed that proteinaceous media promoted the leaching of Fe, Cu, and Al while suppressing Ni and Cr. Ni²⁺ and Cr³⁺ ions were detected in the top layer on NiTi in AS, but not in YPD. A rough “wavy” surface layer was formed in AS, as opposed to smaller sharper entities formed in YPD. Cu(I) compounds on orthodontic bands were detected in both media. The replenishment of the media during immersion influenced the development of surface chemistry and ion leaching for both types of media, AS and YPD. The results obtained in this study are expected to provide a significant advancement over previous studies using artificial saliva (only).

Graphical Abstract

This study evaluates how next-generation silicone impression materials intended for dental use behave during polymerization, as well as their dimensional stability, mechanical properties, degradation patterns, and in silico toxicity levels. Silicone materials are preferred for dental applications because of their outstanding mechanical properties and compatibility with biological tissues. The performance of these materials is susceptible to environmental conditions including temperature changes, humidity levels, and exposure to oral fluids. Patient safety requires evaluation of degradation product toxicity concerns. It is crucial to examine these properties at the molecular level to enhance material durability and safety during clinical use. The structural, mechanical, and stability properties of silicone materials were modeled through molecular dynamics (MD) simulations using BIOVIA Materials Studio 2020. Material characterization and evaluation of mechanical properties were performed with the Forcite module using the COMPASSIII force field. The study simulated polymerization dynamics to understand the reaction mechanisms while employing the Kinetix and DMol3 modules to analyze dimensional stability under various environmental stresses. The CASTEP and DMol3 modules, along with the OSIRIS DataWarrior, were employed to forecast degradation pathways and potential toxicity. The combination of an elastic modulus of 2.533 GPa and tensile strength of 5.387 MPa allows Polydimethylsiloxane (PDMS) to show superior flexibility and rigidity, which qualifies it as the best choice for dental impression materials. Methacryloxypropyltrimethoxysilane (3.248 GPa) and hexaphenylcyclotrisiloxane (3.017 GPa) exhibited enhanced stiffness, suggesting their usefulness in load-bearing scenarios. In silico toxicity predictions indicated that most silicone derivatives demonstrated acceptable biocompatibility, although some silane compounds showed potential risks requiring further experimental validation. Under simulated conditions, the materials maintained stable configurations and exhibited positive polymerization dynamics, indicating that they could provide high durability along with dimensional stability for dental usage. This study highlights the superior balance of flexibility, rigidity, and safety exhibited by PDMS, while also identifying Methacryloxypropyltrimethoxysilane and hexaphenylcyclotrisiloxane as candidates for specialized load-bearing dental applications. Promising in silico findings require experimental validation and clinical testing to establish their practical applications.

Ceramic-Titanium matrix composites have recently attracted significant interest as a new type of biomaterials protecting the brain from external force and infections of cranial defects due to its biocompatibility and good mechanical and corrosion properties matched with the bone tissue. Spark plasma sintering (SPS) is one of powder technology techniques that can be utilised in the fabrication of final net complex and irregular shape parts used for cranial reconstruction and maxillofacial trauma by reconstruction and cranioplasty. The present work studies the effect of alumina (Al₂O₃) short fibers reinforcement addition on the nanomechanical properties estimated by the nanoindentation measurements of the Ti-12Mo-6Zr and its correlation with the microstructure. Al₂O₃ short fibers/Ti-12Mo-6Zr of different Al₂O₃ reinforcement short fibers content up to 5 wt.% were fabricated by Spark Plasma Sintering technique. Powders of Ti, Mo, and Zr powders were mechanically wet milled with different wt.% of Al₂O₃ reinforced short fibers. The mechanically mixed Al₂O₃ short fibers/Ti-12Mo-6Zr samples of different compositions were consolidated by SPS at 1000 ^oC for 5 min under vacuum and 50 Mpa compaction pressure. Optical microscopy (OM), high-resolution scanning electronic microscopy (HRSEM) conducted with Electron dispersive spectroscopy (EDAX) unite and X-Ray Diffraction (XRD) are used to evaluate the particle size and shape, surface morphology, microstructure, the chemical compositions and the phase identifications for the investigated samples. The samples were determined by the rule of mixture (ROM) as well as the Archimedes’ principle. The nanomechanical properties were estimated by measuring the nanoindentation of the produced Al₂O₃ short fibers/Ti-12Mo-6Zr sintered samples using a Berkovich indenter with continuous stiffness measurement (CSM) method. The hardness and the Young modulus were estimated from the obtained data of the applied load-displacement in the depth curves. The obtained Al₂O₃ short fibers/Ti-12Mo-6Zr composites have good mechanical properties which revealed the efficiency of the sintering process by spark plasma sintering. Also, the estimated hardness and Young’s modulus are increased by increasing the content of the Al₂O₃ reinforcement nanoparticles from 1 to 5 wt.% in the Ti-12Mo-6Zr metal matrix. Based on our findings of the nanoindentation studies; it was expected that the produced Al₂O₃ short fibers/Ti-12Mo-6Zr new composites have appropriate physical and mechanical properties for cranial reconstruction applications.

In this study, vancomycin, bone cement (PMMA) and mineralized collagen (MC) were mixed in order to obtain a new composite drug-carrying biomaterial, which has good results in both drug slow release, good biocompatibility, and good growth of osteoblasts, osteoclasts, and mesenchymal stem cells on the surface of the biomaterial, which provides a new therapeutic idea for the clinical treatment of bone defect infections. In this study, the drug retardation system of vancomycin and mineralized collagen composite bone cement-carrying biomaterials was prepared in proportion to the drug retardation system, and the experimental studies were carried out using electron microscope scanning, HPLC drug retardation analysis, in vitro antimicrobials, and co-cultivation of osteoclasts, osteoblasts, and mesenchymal stem cells. We found that the composite drug-carrying material of vancomycin, bone cement and mineralized collagen had good slow-release effect and antimicrobial properties, and the addition of vancomycin and bone cement to mineralized collagen material had even better drug-release efficiency than that of bone cement plus vancomycin alone. In vitro antimicrobial showed that the composite material has excellent antimicrobial effect against Staphylococcus aureus. Co-culture of osteoblasts, osteoclasts and mesenchymal stem cells with the material showed that the cells were morphologically complete on the surface of the composites with good growth status. Vancomycin, bone cement and mineralized collagen composite drug-carrying biomaterials have excellent slow-release effect and antimicrobial properties with good biocompatibility, which is a new therapeutic idea for the future clinical treatment of bone defect infections.

Calcium-phosphate cement (CPC), a paste-like artificial bone, is a material form that allows minimally invasive treatment. However, CPC is not infection resistant, which may lead to surgical site infections. We recently developed a paste-like organic/inorganic hybrid artificial bone that is compatible with the bone remodeling cycle. In this study, we added silver-loaded tricalcium phosphate, which has antibacterial properties, to the hybrid CPC and fabricated a prototype “antibacterial CPC”. Antibacterial and non-antibacterial CPCs were implanted into a rabbit jaw defect model in which infection could occur, and the in vivo responses were compared. In cement specimens retrieved from rabbit jaws, residual material was observed with the non-antibacterial CPC, whereas with the antibacterial CPC, almost all of the material was resorbed and replaced with host bone. These results suggest that placement of antibacterial CPC in a rabbit jaw bone defect model susceptible to bacterial infection promotes material resorption and bone formation. The antibacterial CPC developed in this study is thus a novel paste artificial bone exhibiting good bioresorption and osteogenic potential in biological hard tissues.

Bone infections are common and difficult to treat, and secondary bone defects, which are often observed, may require a bone allograft. In this case, the surgeon will add antibiotics (usually vancomycin) in direct contact with the bone graft during the procedure, in order to allow in-situ release after implantation in the operating site. Dalbavancin is a novel antibiotic indicated for treating acute bacterial infections resistant to vancomycin. Its modified chemical structure grants it an increased half-life that could modify its release kinetics from the bone allograft. The aim of this study was to determine the release kinetics of dalbavancin from bone grafts after they were immersed in a dalbavancin solution. The study was conducted using a Design of Experiments (DoE) protocol. Decellularized and delipidated allograft bone cubes were preliminarily characterized and put into contact with dalbavancin solutions. The parameters that were studied where the allograft mass, initial dalbavancin concentration and contact time. The samples were then transferred into the release media, which was sampled over time and dalbavancin was quantified using a high pressure liquid chromatography with diode array detector method that was developed for the occasion. Our results showed that on average, dalbavancin was fully released after 5 min for the lower mass bone grafts, but after 60 min for the high mass and high concentration conditions. Contact time had no impact, thus indicating a fast loading process of dalbavancin into the allograft. Although our study revealed the possible benefits of using dalbavancin in bone grafting, an in-vivo study is required to confirm our hypotheses.

Graphical Abstract

Bioactive glass particles have previously been found to stimulate new bone growth in vivo and have a long clinical track record. The effect of bioactive glasses on human bone marrow derived stromal cells (hBMSCs) has not been clearly ascertained previously. Recently, 3D printed scaffolds of the ICIE16 glass composition (49.46 mol% SiO₂, 36.6 mol% CaO, 6.6 mol% Na₂O, 6.6 mol% K₂O, 1.07 mol% P₂O₅) were found to produce high quality bone ingrowth in vivo in a rabbit model. This composition was chosen because it can be sintered into scaffolds without crystallisation. Here, we cultured hBMSCs on the 3D printed ICIE16 scaffolds to determine whether the scaffolds can support cell growth and osteogenic differentiation in vitro, with and without the presence of osteogenic supplements. This was compared to a control of culture media containing dissolution products of the bioactive glass scaffold. Our hypothesis was that the cells cultured on the scaffolds would undergo more osteogenic differentiation than cells cultured in media containing only the dissolution ions of the scaffolds, even without osteogenic supplements. hBMSCs cultured on ICIE16 scaffolds significantly increased expression of osteogenic differentiation and matrix formation markers, including Runx 2, Col1a1, Osteopontin, Osteocalcin and Alkaline Phosphatase, in comparison to monolayer cultures in basal conditions with bioactive glass dissolution products, at all time points up to 6 weeks. Six weeks was chosen as it is the time scale for bone fracture healing. The presence of osteogenic supplements appeared to have synergetic effects with 3D scaffolds, especially during early stages of osteogenic differentiation (week 2 and 4). By week 6, there was no significant difference in the expression of osteogenic markers by hBMSCs cultured on ICE16 scaffolds with and without osteogenic supplements. These findings support our hypothesis and highlight that the 3D structure and the dissolution of ICIE16 bioactive glass ionic products both independently influence osteogenic differentiation of hBMSCs.

Graphical Abstract