ABSTRACT
@#The properties of adhesives and light-cured resin composites are closely related to the repair of dental defects. Therefore, improving the properties of adhesives and resins composite to increase the success rate of filling has been the focus of research in the field of prosthodontics in recent years. Current studies have confirmed that temperature can change the properties of adhesives and light-cured resin composites, affecting their repair effect. A proper storage temperature ensures the good performance of materials: the self-etching adhesive system should be refrigerated, and the light-cured resin composite should be refrigerated or stored at room temperature according to its composition, proportion and other properties; however, the appropriate storage temperature for the etch-and-rinse adhesive system is not clear. The appropriate application temperature could improve the fluidity, monomer conversion, bonding strength, compressive strength and other properties of the materials to improve the quality of filling restoration. However, there is a wide variety of adhesives and resin composites, and the effect of temperature on each material is different. Thus, it is still necessary to explore the temperature range for material storage, precooling and preheating. Few studies have been performed in vivo, and the clinical restorative effects of adhesives and resin composites stored and used at different temperatures need to be further studied.
ABSTRACT
At present, the modernization of Chinese medicine preparations (CMPs) is still a challenging task. The 3 typical Chinese medicine materials (CMMs) used for preparing CMPs are the powders, extracts, and components of Chinese medicine and their properties of CMMs are important for designing CMPs. Basing on our long term research, we have established a property system for CMMs according to the state of CMMs under an exactly condition and according to the interaction characteristics between substances. The property system could be divided into 5 categories: material composition, spatial structure, body property, surface property, physicochemical properties, and they could also be divided into 18 subcategories. Furthermore, we also established the corresponding index and characterization system, where the 61 indexes and characterization techniques were systematically summarized. At last, we hope that the article will promote the modernization of CMPs.
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BACKGROUND: Rapid development in tissue engineering research and technology makes dental pulp regeneration and revascularization possible. The interactions of stem cells, scaffolds and signaling factors in tissue engineering are particularly important. Whether stem cells can proliferate, differentiate and develop dental pulp-like tissue greatly depends on the choice of scaffolds OBJECTIVE: To review the widely studied and effective scaffold materials and two methods of scaffold preparation and analyze their applications in dental pulp reconstruction and their revascularization ability. METHODS: The first author searched PubMed, Wanfang and CNKI databases using a computer for relevant articles published between January 1, 2019 and September 30, 2019 with the search terms “pulp regeneration, pulp revascularization, scaffold” in English, and “pulp regeneration, pulp revascularization, revascularization, scaffold” in Chinese. A total of 421 English articles and 181 Chinese articles were retrieved. Finally, 61 articles were reviewed. RESULTS AND CONCLUSION: Platelet-derived scaffolds, extracellular-matrix-derived scaffolds, and self-assembling peptide take effect in pulp regeneration and revascularization. Composite materials combining natural and synthetic materials prepared by hydrogel and nanomaterial techniques exhibited advantages in cell proliferation, differentiation, migration, adherence, anti-inflammation, and factor delivery. The modified composite materials have a strong ability to promote vascularization. With the development of scaffold design and preparation technology based on hydrogels and nanomaterials, problems regarding insufficient scaffold source and unstable clinical effect will be solved in the future.
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Objective To investigate the effects of element size and type, material property distributions of vertebral cancellous bone and simulation methods of cortical bone structure on the finite element (FE) results during the finite element modeling of lumbar vertebral body. Methods Based on QCT images of lumbar spine, 22 FE models of L2 without posterior structure were built by 6 element sizes (0.5, 1.0, 1.5, 2.0, 2.5, 3.0 mm), 2 heterogeneous material distribution methods of cancellous bone (300, 150) and 2 cortical bone modeling methods. The maximum displacement, strain energy, average stress and axial stiffness of these models were obtained to analyze and verify the results. Results When the element size was 0.5 mm, the axial stiffness of models with 10, 150 and 300 kinds of heterogeneous materials showed obvious differences; for the vertebral cancellous bone with 150 kinds of materials, the variation of average stress was not distinct under different element sizes; the average stress of the model using the outermost hexahedral elements to simulate the cortical bone structure was larger than that appending the skin to the outmost of the model. Conclusions It is more reasonable and effective to build the FE model of lumbar vertebral body with the method by 0.5 mm element size, 8-noded hexahedral elements, 150 kinds of heterogeneous materials, and using the outermost hexahedral elements to simulate the cortical bone structure. The research findings will lay a foundation for building subject-specific FE models of lumbar vertebral body on a large scale in future.
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<b>Objective: </b>To optimize aluminum packaging used for medicinal products based on universal design (UD), the material properties of this packaging were evaluated. In addition, a questionnaire on the usability of this packaging was conducted for the same purpose.<br><b>Methods: </b>Tear resistances of the films used for both aluminum and polypropylene packaging were measured using a tensile tester. To evaluate tear linearity of both packaging types, gap widths from standard line to tear line were measured after the samples were torn 75 mm in length. A survey of 480 pharmacists was conducted on usability.<br><b>Results: </b>Regarding material properties, the maximum value of tear resistance for aluminum packaging was approximately 28 times higher than that for polypropylene packaging. The maximum gap width from standard line to tear line was approximately 10 mm for both types of packaging. Regarding the questionnaire, the total response rate was 41.0%. In valid responses, approximately 90% of pharmacists experienced frustration when opening aluminum packaging and requested improvements in usability. In addition, 88% of pharmacists opened packaging in the longitudinal direction by hands. For the important point in usability of aluminum packaging, the following answers were confirmed: “speed of opening (43%),” “ease of tearing (31%)” and “ease of taking blisters out (20%).”<br><b>Conclusion: </b>Our results suggest that current aluminum packaging is difficult to open and tear linearly based on the evaluation of material properties. These points are consistent with the concerns highlighted in the survey of pharmacists. We therefore conclude that the points to be improved when considering UD are the ease of opening and linear tearing for more efficient use of aluminum packaging in a clinical setting.