12 research outputs found
Changes in the Surface Texture of Thermoplastic (Monomer-Free) Dental Materials Due to Some Minor Alterations in the Laboratory Protocol—Preliminary Study
No full textContemporary thermoplastic monomer-free prosthetic materials are widely used nowadays, and there are a great variety available on the market. These materials are of interest in terms of the improvement of the quality features of the removable dentures. The aim of this study is to establish how minimal changes in the laboratory protocol of polyamide prosthetic base materials influence the surface texture. Two polyamide materials intended for the fabrication of removable dentures bases were used—Perflex Biosens (BS) and VertexTM ThermoSens (TS). A total number of 20 coin-shaped samples were prepared. They were injected under two different modes—regular, as provided by the manufacturer, and modified, proposed by the authors of this study. Scanning electronic microscopy (SEM) under four magnifications—×1000, ×3000, ×5000, and ×10,000—was conducted. With minimal alterations to the melting temperature (5 °C) and the pressure (0.5 Bar), in Biosens, no changes in terms of surface improvement were found, whereas in ThermoSens, the surface roughness of the material significantly changed in terms of roughness reduction. By modifying the technological mode during injection molding, a smoother surface was achieved in one of the studied materials
A 3D-simulation study of the deformation, tension, and stress of 3D-printed and conventional denture base materials after immersion in artificial saliva
Full text linkIntroduction: The worldwide application of digital technology has presented dentistry with transformative opportunities. The concept of digital dentures, incorporating computer-aided design (CAD) and computer-aided manufacturing (CAM) techniques, holds the promise of improved precision, customization, and overall patient satisfaction. However, the shift from traditional dentures to their digital counterparts should not be taken lightly, as the intricate interplay between oral physiology, patient comfort, and long-term durability requires thorough examination. Aim: The aim of the present study was to evaluate and compare the dimensional changes of 3D printed (NextDent, 3D Systems, The Netherlands) and conventional heat-cured (Vertex BasiQ 20, 3D Systems, The Netherlands) denture base resin after immersion in artificial saliva for different periods (7, 14, and 30 days) and then applying 3D simulated deformation, tensional strength, and stress, using the ANSYS software (ANSYS Inc., Pennsylvania, USA). Materials and methods: For the manufacturing of the test specimens, an STL file was created, using the Free CAD Version 0.19 (Free CAD, Stuttgart, Germany). The dimensions of each specimen were 20 mm in width, 20 mm in length, and 3 mm in thickness. Two hundred experimental bodies were created and divided into two groups (n=100), with half fabricated using a 3D printer (NextDent 5100, NextDent, 3D Systems, The Netherlands) and the other half prepared using the traditional method of heat-curing polymerization in metal flasks. The test samples were then weighed using an analytical balance, immersed in artificial saliva for three periods (7, 14, and 30 days), and reweighed after water absorption. After desiccation at 37°C for 24 hours and then at 23±1°C for 1 hour, the samples were weighed again. Then the data were entered into the specialized program ANSYS and the 3D simulation tests for deformation, tension, and stress were performed. Statistical analysis was performed using the IBM SPSS Statistics Version 0.26 statistical software, which includes descriptive statistics and one-way ANOVA analysis. Results: The findings weren’t statistically significant and indicated that the average metrics for the 3D-printed experimental test samples were marginally greater than those recorded for the conventional samples. Conclusions: Within the limitations of this study, it is possible to conclude that 3D-printed resin has a lower capacity to withstand deformation, tension, and stress under simulated conditions than conventional dental resin. However, they do not exceed the values accepted by the ISO standard for clinical application of this type of material
Advantage of Animal Models with Metabolic Flexibility for Space Research Beyond Low Earth Orbit
Full text linkAs the worlds space agencies and commercial entities continue to expand beyond Low Earth Orbit (LEO), novel approaches to carry out biomedical experiments with animals are required to address the challenge of adaptation to space flight and new planetary environments. The extended time and distance of space travel along with reduced involvement of Earth-based mission support increases the cumulative impact of the risks encountered in space. To respond to these challenges, it becomes increasingly important to develop the capability to manage an organisms self-regulatory control system, which would enable survival in extraterrestrial environments. To significantly reduce the risk to animals on future long duration space missions, we propose the use of metabolically flexible animal models as pathfinders, which are capable of tolerating the environmental extremes exhibited in spaceflight, including altered gravity, exposure to space radiation, chemically reactive planetary environments and temperature extremes.In this report we survey several of the pivotal metabolic flexibility studies and discuss the importance of utilizing animal models with metabolic flexibility with particular attention given to the ability to suppress the organism's metabolism in spaceflight experiments beyond LEO. The presented analysis demonstrates the adjuvant benefits of these factors to minimize damage caused by exposure to spaceflight and extreme planetary environments. Examples of microorganisms and animal models with dormancy capabilities suitable for space research are considered in the context of their survivability under hostile or deadly environments outside of Earth. Potential steps toward implementation of metabolic control technology in spaceflight architecture and its benefits for animal experiments and manned space exploration missions are discussed
Advantage of Animal Models with Metabolic Flexibility for Space Research Beyond Low Earth Orbit
No full textAdvantage of Animal Models with Metabolic Flexibility for Space Research Beyond Low Earth Orbit
Full text linkAs the world's space agencies and commercial entities continue to expand beyond Low Earth Orbit (LEO), novel approaches to carry out biomedical experiments with animals are required to address the challenge of adaptation to space flight and new planetary environments. The extended time and distance of space travel along with reduced involvement of Earth-based mission support increases the cumulative impact of the risks encountered in space. To respond to these challenges, it becomes increasingly important to develop the capability to manage an organism's self-regulatory control system, which would enable survival in extraterrestrial environments. To significantly reduce the risk to animals on future long duration space missions, we propose the use of metabolically flexible animal models as "pathfinders," which are capable of tolerating the environmental extremes exhibited in spaceflight, including altered gravity, exposure to space radiation, chemically reactive planetary environments and temperature extremes. In this report we survey several of the pivotal metabolic flexibility studies and discuss the importance of utilizing animal models with metabolic flexibility with particular attention given to the ability to suppress the organism's metabolism in spaceflight experiments beyond LEO. The presented analysis demonstrates the adjuvant benefits of these factors to minimize damage caused by exposure to spaceflight and extreme planetary environments. Examples of microorganisms and animal models with dormancy capabilities suitable for space research are considered in the context of their survivability under hostile or deadly environments outside of Earth. Potential steps toward implementation of metabolic control technology in spaceflight architecture and its benefits for animal experiments and manned space exploration missions are discussed
Crack Growth Modeling in CT Specimens: The Influence of Heat Treatment and Loading
No full textThis study provides a combined numerical and analytical investigation of fatigue crack growth in compact tension specimens made of 42CrMo4 steel. Through simulations in ANSYS Workbench (SMART Crack Growth module) and numerical modeling in MATLAB, the model is validated by comparing its results with the standard ASTM E399 and Paris’ law relationships. The effect of heat treatments and loading on crack growth rate was investigated. The results confirm the model’s applicability in predicting fatigue behavior in the linear–elastic region
