From a realistic perspective, a comprehensive analysis of the implant's mechanical response is required. Considering the typical design of custom prostheses. Complex designs, such as those found in acetabular and hemipelvis implants, encompassing both solid and trabeculated parts, and material distributions at different scales, obstruct the creation of a precise model of the prosthesis. In addition, ambiguities persist regarding the production and material properties of small parts at the cutting edge of additive manufacturing precision. Specific processing parameters, as exemplified in recent studies, appear to have a unique impact on the mechanical properties of 3D-printed thin parts. Current numerical models significantly simplify the complex material behavior of each part, particularly at varying scales, as compared to conventional Ti6Al4V alloy, while neglecting factors like 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. The authors, employing a synthesis of experimental testing and finite element analysis, initially characterized 3D-printed Ti6Al4V dog-bone samples at various scales that reflected the key material components of the examined prostheses. Subsequently, the authors incorporated the determined material properties into finite element models, aiming to discern the implications of scale-dependent and conventional, scale-independent methodologies in predicting the experimental mechanical responses of the prostheses, including their overall stiffness and local strain distributions. The material characterization results indicated the importance of a scale-dependent reduction of the elastic modulus in thin samples as opposed to the conventional Ti6Al4V. This is crucial to accurately characterize both the overall stiffness and local strain distributions present in the prostheses. The presented work reveals the requirement for accurate material characterization and a scale-dependent material description to develop dependable finite element models of 3D-printed implants, marked by a complex distribution of materials across diverse scales.
Three-dimensional (3D) scaffolds are becoming increasingly important for applications in bone tissue engineering. Finding a material with the perfect blend of physical, chemical, and mechanical properties, however, constitutes a significant hurdle. Sustainable and eco-friendly procedures, coupled with textured construction, are vital for the green synthesis approach to effectively prevent the production of harmful by-products. The implementation of naturally synthesized, green metallic nanoparticles was the focus of this work, aiming to develop composite scaffolds for dental use. The present study focused on the synthesis of polyvinyl alcohol/alginate (PVA/Alg) composite hybrid scaffolds, specifically loaded with varied concentrations of green palladium nanoparticles (Pd NPs). To assess the properties of the synthesized composite scaffold, several methods of characteristic analysis were utilized. Scaffold microstructure, as revealed by SEM analysis, exhibited an impressive dependence on the concentration of incorporated Pd nanoparticles. Over time, the results corroborated the beneficial effect of Pd NPs doping on the sample's stability. The oriented lamellar porous structure characterized the synthesized scaffolds. The drying process, as confirmed by the results, preserved the shape's integrity, preventing any pore breakdown. Despite the addition of Pd NPs, the PVA/Alg hybrid scaffolds exhibited the same degree of crystallinity, as confirmed by XRD analysis. Demonstrably, the mechanical properties (up to 50 MPa) of the developed scaffolds were significantly affected by Pd nanoparticle doping and its concentration. Cell viability was augmented, as indicated by MTT assay results, due to the incorporation of Pd NPs within 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. Consequently, the synthesized composite scaffolds presented suitable characteristics for biodegradation, osteoconductivity, and the creation of 3D bone structures, implying their potential as a therapeutic approach for managing critical bone deficits.
This paper presents a mathematical dental prosthetic model using a single degree of freedom (SDOF) system to analyze micro-displacement under the influence of electromagnetic stimulation. Using Finite Element Analysis (FEA) and referencing published values, the stiffness and damping characteristics of the mathematical model were determined. Software for Bioimaging To guarantee the successful integration of a dental implant system, meticulous monitoring of initial stability, specifically micro-displacement, is essential. The Frequency Response Analysis (FRA) proves to be a popular methodology for determining stability. Evaluation of the resonant frequency of implant vibration, corresponding to the peak micro-displacement (micro-mobility), is achieved through this technique. The most frequent FRA technique amongst the diverse methods available is the electromagnetic FRA. Subsequent bone-implant displacement is assessed via vibrational equations. Vastus medialis obliquus To ascertain differences in resonance frequency and micro-displacement, a comparison of input frequencies varying from 1 Hz to 40 Hz was undertaken. The micro-displacement and its resonance frequency were graphically represented using MATLAB; the variation in the resonance frequency was found to be insignificant. An initial mathematical model is presented to explore micro-displacement variations resulting from electromagnetic excitation forces, and to determine the resonance frequency. This research supported the usage of input frequency ranges (1-30 Hz), exhibiting minimal fluctuation in micro-displacement and accompanying resonance frequency. Nevertheless, input frequencies exceeding the 31-40 Hz range are discouraged owing to substantial micromotion fluctuations and resultant resonance frequency discrepancies.
The fatigue properties of strength-graded zirconia polycrystals, utilized in monolithic three-unit implant-supported prostheses, were examined in this study. Additionally, characterization of the crystalline phase and micromorphology was performed. Dental restorations, fixed and supported by two implants, each containing three units, were created in distinct ways. The 3Y/5Y group involved monolithic structures of graded 3Y-TZP/5Y-TZP zirconia (IPS e.max ZirCAD PRIME). Meanwhile, the 4Y/5Y group utilized monolithic graded 4Y-TZP/5Y-TZP zirconia (IPS e.max ZirCAD MT Multi). The bilayer group involved a 3Y-TZP zirconia framework (Zenostar T) and a porcelain veneer (IPS e.max Ceram). The samples were subjected to step-stress analysis, which yielded data on their fatigue performance. A log of the fatigue failure load (FFL), the required cycles for failure (CFF), and the survival rate percentages for each cycle was kept. Fractography analysis followed the calculation of the Weibull module. Using Micro-Raman spectroscopy to evaluate crystalline structural content and Scanning Electron microscopy to measure crystalline grain size, graded structures were also analyzed. Based on the Weibull modulus, the 3Y/5Y cohort showed the highest levels of FFL, CFF, survival probability, and reliability. The bilayer group exhibited significantly lower FFL and survival probabilities compared to the 4Y/5Y group. Cohesive porcelain fractures in bilayer prostheses, originating from the occlusal contact point, were identified as catastrophic structural flaws by fractographic analysis in monolithic designs. Graded zirconia's grain size was exceptionally small, measuring 0.61 mm, with the minimum grain size at the cervical region. Grains in the tetragonal phase formed the primary component of the graded zirconia material. Monolithic zirconia, especially the 3Y-TZP and 5Y-TZP varieties, proved to be a promising candidate for use in implant-supported, three-unit prosthetic applications.
Medical imaging, limited to the calculation of tissue morphology, cannot directly reveal the mechanical characteristics of load-bearing musculoskeletal organs. Assessing spine kinematics and intervertebral disc strain in vivo offers vital information on spinal mechanics, enabling analysis of injury effects and evaluation of treatment effectiveness. Strains also function as a functional biomechanical gauge for distinguishing between normal and diseased tissues. It was our supposition that employing digital volume correlation (DVC) alongside 3T clinical MRI would yield direct insight into the mechanics of the human 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. The introduced tool allowed for the precise determination of spine kinematics and IVD strains, with measured errors not exceeding 0.17mm and 0.5%, respectively. The kinematics study determined that 3D translational movement of the lumbar spine in healthy subjects during extension spanned a range from 1 mm to 45 mm across different vertebral levels. anti-PD-1 inhibitor The average maximum tensile, compressive, and shear strains observed during lumbar extension across different spinal levels fell within a range of 35% to 72% as determined by the strain analysis. This tool, by providing baseline data on the mechanical environment of a healthy lumbar spine, allows clinicians to craft preventative strategies, to create patient-specific treatment plans, and to evaluate the success of surgical and non-surgical therapies.