Given realistic applications, a precise portrayal of the implant's mechanical actions is inevitable. Typical designs for custom-made prosthetics are worth considering. The intricate designs of acetabular and hemipelvis implants, incorporating solid and/or trabeculated components, and varied material distributions across scales, impede the creation of highly accurate models of the prostheses. Furthermore, there remain uncertainties in the manufacturing process and material characterization of minuscule components, pushing against the precision boundaries of additive fabrication techniques. Certain processing parameters, according to recent research findings, have an unusual effect on the mechanical properties of thin 3D-printed components. Compared to conventional Ti6Al4V alloy, current numerical models significantly oversimplify the intricate material behavior of each component at various scales, particularly concerning powder grain size, printing orientation, and sample thickness. Two patient-tailored acetabular and hemipelvis prostheses are investigated in this study, with the goal of experimentally and numerically characterizing the mechanical behavior of 3D-printed parts as a function of their particular scale, thereby addressing a critical limitation in current numerical models. Finite element analyses were coupled with experimental procedures by the authors to initially characterize 3D-printed Ti6Al4V dog-bone samples at diverse scales, representative of the material constituents of the prostheses under examination. Following the characterization of material properties, the authors integrated these findings into finite element models to assess the contrasting effects of scale-dependent and conventional, scale-independent approaches on predicting the experimental mechanical performance of the prostheses, specifically focusing on overall stiffness and localized strain patterns. The highlighted material characterization results underscored the necessity of a scale-dependent reduction in elastic modulus for thin samples, contrasting with conventional Ti6Al4V. This reduction is fundamental for accurately describing both the overall stiffness and localized strain distribution within the prostheses. 3D-printed implant finite element models, demanding reliable predictions, are shown to require an appropriate material characterization and a scale-dependent description, as demonstrated by the presented works, which consider the intricate material distribution at multiple scales.
Three-dimensional (3D) scaffolds are a focal point of research and development in bone tissue engineering. However, the task of selecting a material that optimally balances its physical, chemical, and mechanical properties remains a considerable difficulty. For the green synthesis approach to remain sustainable and eco-friendly, while employing textured construction, it is essential to avoid the creation of harmful by-products. Natural, green synthesis of metallic nanoparticles was employed in this study to create composite scaffolds for dental applications. Through a synthetic approach, this study investigated the creation of hybrid scaffolds from polyvinyl alcohol/alginate (PVA/Alg) composites, loaded with diverse concentrations of green palladium nanoparticles (Pd NPs). In order to probe the characteristics of the synthesized composite scaffold, various analytical techniques were applied. Synthesized scaffolds, analyzed by SEM, displayed an impressive microstructure that was demonstrably dependent on the concentration of Pd nanoparticles. Pd NPs doping proved to have a demonstrably positive influence on the sample's long-term stability, according to the results. Scaffolds synthesized exhibited an oriented, lamellar, porous structure. The results affirm the consistent shape, exhibiting no pore breakdown during the drying process's completion. Pd NP incorporation did not alter the degree of crystallinity in the PVA/Alg hybrid scaffolds, as evidenced by XRD analysis. Scaffold mechanical properties, assessed up to 50 MPa, affirmed the remarkable impact of Pd nanoparticle doping and its concentration variations on the developed structures. Cell viability improvements, as measured by the MTT assay, were attributed to the inclusion of Pd NPs in the nanocomposite scaffolds. The SEM results indicated that scaffolds incorporating Pd nanoparticles provided sufficient mechanical support and stability to differentiated osteoblast cells, which displayed a well-defined shape and high density. In brief, the composite scaffolds successfully demonstrated biodegradability, osteoconductivity, and the potential to form 3D structures for bone regeneration, thereby presenting a possible therapeutic strategy for addressing critical bone deficiencies.
Evaluation of micro-displacement in dental prosthetics under electromagnetic excitation is the objective of this paper, using a mathematical model based on a single degree of freedom (SDOF) system. From the literature and employing Finite Element Analysis (FEA), the stiffness and damping values for the mathematical model were ascertained. Liquid Handling A critical factor in the successful implementation of a dental implant system is the continuous monitoring of primary stability, particularly concerning micro-displacement. For quantifying stability, the Frequency Response Analysis (FRA) technique stands out. This technique identifies the resonant frequency of vibration correlated with the maximum micro-displacement (micro-mobility) of the implanted device. From the assortment of FRA techniques, electromagnetic FRA emerges as the most common. Using equations derived from vibrational analysis, the subsequent implant displacement in the bone is calculated. mTOR inhibitor A comparative examination of resonance frequency and micro-displacement was executed, evaluating the influence of input frequencies in the 1-40 Hz band. Using MATLAB, we plotted the micro-displacement alongside its corresponding resonance frequency; the variation in the resonance frequency proved to be negligible. This preliminary mathematical model aims to understand the variation of micro-displacement concerning electromagnetic excitation forces and to ascertain the resonance frequency. This research affirmed the usefulness of input frequency ranges (1-30 Hz), revealing negligible variations in micro-displacement and accompanying resonance frequencies. Nonetheless, input frequencies surpassing 31-40 Hz are not advised, given the considerable variations in micromotion and the resulting resonance frequency.
This study's objective was to investigate the fatigue behavior of strength-graded zirconia polycrystals used in three-unit monolithic implant-supported prostheses; the crystalline phases and micromorphology of the materials were also characterized. Three-unit fixed dental prostheses, anchored by two implants, were constructed using varying materials and techniques. Group 3Y/5Y involved monolithic structures made from a graded 3Y-TZP/5Y-TZP zirconia material (IPS e.max ZirCAD PRIME). Group 4Y/5Y followed a similar design using monolithic graded 4Y-TZP/5Y-TZP zirconia (IPS e.max ZirCAD MT Multi). The bilayer group employed a framework of 3Y-TZP zirconia (Zenostar T) that was subsequently veneered with porcelain (IPS e.max Ceram). Fatigue performance of the samples was assessed via step-stress analysis. The fatigue failure load (FFL), the number of cycles to failure (CFF), and survival rates at each cycle stage were all documented. The fractography analysis was performed, subsequently to the Weibull module calculation. Employing Micro-Raman spectroscopy and Scanning Electron microscopy, the crystalline structural content and crystalline grain size of graded structures were also assessed. In terms of FFL, CFF, survival probability, and reliability, group 3Y/5Y performed at the highest level, measured using the Weibull modulus. Group 4Y/5Y surpassed the bilayer group in both FFL and the likelihood of survival. Fractographic analysis exposed catastrophic flaws within the monolithic structure, revealing cohesive porcelain fracture patterns in bilayer prostheses, all stemming from the occlusal contact point. Graded zirconia displayed a fine grain structure (0.61 micrometers), with the smallest grains located at the cervix. The graded zirconia's principal constituent was grains in the tetragonal crystalline phase. Zirconia, particularly 3Y-TZP and 5Y-TZP grades, demonstrated promising characteristics as a material for monolithic, three-unit, implant-supported prostheses.
Medical imaging modalities focusing on tissue morphology alone are unable to provide immediate insight into the mechanical properties of load-bearing musculoskeletal organs. In vivo, the precise measurement of spine kinematics and intervertebral disc strains provides important data on spinal mechanics, allowing for the exploration of injury impacts and the evaluation of treatment success. Strains also function as a functional biomechanical gauge for distinguishing between normal and diseased tissues. We surmised that the combination of digital volume correlation (DVC) and 3T clinical MRI would offer direct knowledge about the mechanics within the spine. For in vivo displacement and strain measurement within the human lumbar spine, we've designed a novel, non-invasive tool. This tool allowed us to calculate lumbar kinematics and intervertebral disc strains in six healthy subjects during lumbar extension. Spine kinematics and intervertebral disc (IVD) strains were quantifiable by the proposed tool, with measurement errors not exceeding 0.17 mm and 0.5%, respectively. The kinematics study found that, for healthy subjects during spinal extension, 3D translational movements of the lumbar spine varied from a minimum of 1 mm to a maximum of 45 mm, dependent on the specific vertebral level. Hp infection Extension-induced strain analysis of different lumbar levels indicated that the average maximum tensile, compressive, and shear strains spanned from 35% to 72%. Baseline data, obtainable through this tool, elucidates the mechanical characteristics of a healthy lumbar spine, aiding clinicians in the design of preventative therapies, patient-tailored interventions, and the evaluation of surgical and non-surgical treatment efficacy.