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SUMMARY: Tissue engineering aims to fabricate a scaffold that exhibits a suitable surface topography for a desired cellular response. Therefore, a study analyzing the characteristics of bone grafts is important for future research directions. This work aims to analyze the physical-chemical characteristics of commercially available bone grafts of human and bovine origin for dental use, using morphological analysis of the surface and chemical composition by variable pressure scanning electron microscope (VP-SEM) and energy-dispersive x-ray (EDX) spectrometry. In addition, pore diameter and surface area were analyzed by degassing method using a porosimeter, and particle size by laser diffraction. The analyzed allograft and xenograft particles differ in morphological characteristics and chemical composition. The allograft particles present a cuboidal and prismatic geometric morphology with angled edges and the absence of macropores. On the contrary, the xenograft particles present an irregular morphology with macropores in their structure. There is a statistically significant difference in C, P, and Ca between the xenograft and allografts (p < 0,05). The analyzed composition of allografts showed mainly the presence of C and O. In contrast, the composition of the xenograft was mainly Ca. These differences could influence the osteogenic properties of allografts and xenografts. This analysis provides basic information to understand the physicochemical properties of allografts and xenografts that facilitate cell-graft interaction.
La ingeniería de tejidos tiene como objetivo fabricar un andamio que muestre una topografía de superficie adecuada para una respuesta celular deseada. Por tanto, un estudio que analice las características de los injertos óseos es importante para futuros enfoques de investigación. Este trabajo tiene como objetivo analizar las características físico-químicas de injertos óseos de origen humano y bovino disponibles comercialmente para uso odontológico, mediante análisis morfológico de la superficie y composición química mediante microscopio electrónico de barrido de presión variable (VP-SEM) y x-dispersivo de energía. espectrometría de rayos (EDX). Además, el diámetro de los poros y el área superficial se analizaron mediante el método de desgasificación utilizando un porosímetro y el tamaño de las partículas mediante difracción láser. Las partículas de aloinjerto y xenoinjerto analizadas difieren en características morfológicas y composición química. Las partículas del aloinjerto presentan una morfología geométrica cúbica y prismática con bordes angulados y ausencia de macroporos. Por el contrario, las partículas de xenoinjerto presentan una morfología irregular con macroporos en su estructura. Existe una diferencia estadísticamente significativa en C, P y Ca entre el xenoinjerto y los aloinjertos (p < 0,05). La composición analizada de los aloinjertos mostró principalmente la presencia de C y O. Por el contrario, la composición del xenoinjerto fue principalmente Ca. Estas diferencias podrían influir en las propiedades osteogénicas de los aloinjertos y xenoinjertos. Este análisis proporciona información básica para comprender las propiedades fisicoquímicas de aloinjertos y xenoinjertos que facilitan la interacción célula-injerto.
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Humanos , Animais , Bovinos , Aloenxertos/anatomia & histologia , Aloenxertos/química , Espectrometria por Raios X , Regeneração Óssea , Microscopia Eletrônica de Varredura , Porosidade , Transplante Ósseo , Xenoenxertos/anatomia & histologia , Xenoenxertos/químicaRESUMO
BACKGROUND:In the treatment of skin trauma with active repair,tissue engineering techniques are needed to generate new tissue to replace necrotic tissue.Skin scaffolds have a good application prospect in the field of wound repair.Skin scaffolds need to present three-dimensional porous structures with certain mechanical strength to meet the needs of cell proliferation and division.However,the mechanical strength of the currently used gelatin-based biomaterials is weak and cannot meet the requirements of the use of skin scaffolds. OBJECTIVE:To study the 3D printing process used in the preparation of tissue engineering skin scaffolds by gelatin/oxidized nanocellulose composites,and focus on the relationship between the porosity and mechanical strength of the scaffolds prepared under different process parameters. METHODS:Oxidized nanocellulose whiskers at 10%concentration were extracted from Humulus scandens and then compounded with 5%gelatin to obtain gelatin/oxidized nanocellulose composites.The elastic modulus of gelatin and gelatin/oxidized nanocellulose composite was determined.Skin scaffolds were prepared by 3D printing extrusion molding using gelatin/oxidized nanocellulose composite as the base material.Mechanical and rheological properties of the composite were tested to determine extrusion molding parameters(filling gap 1.5-2.5 mm,uniform distribution of 0.1 mm;air pressure of 160-200 kPa),and the skin scaffold with a three-dimensional porous structure was prepared.The compressive performance of the skin scaffold was tested and compared with the finite element analysis results.The relationship between the filling gap and the porosity and mechanical strength of the scaffold was demonstrated. RESULTS AND CONCLUSION:(1)The elastic modulus of 5%gelatin was increased by 8.84 times by adding 10%oxidized nanocellulose whisker.A gel filament with a diameter of 1 mm was obtained by extrusion at the air pressure of 160 kPa.When the filling gap increased from 1.5 mm to 2.5 mm,the theoretical porosity of the scaffold increased from 33%to 60%,but the compressive strength decreased from 230 000 Pa to 95 000 Pa.(2)These findings showed that the skin scaffold with theoretical porosity of 50%and elastic modulus of 160 000 Pa was prepared by using 2 mm filling gap.The scaffold had a clear three-dimensional porous structure.
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BACKGROUND:At present,the traditional powder sintering method is easy to introduce impurities in the process of preparing porous titanium,and the manufacturing of porous titanium still faces two major problems:impurity pollution and difficult control of the material forming process. OBJECTIVE:To prepare pure porous titanium with certain porosity,and analyze the microstructure evolution and properties of the porous titanium. METHODS:Porous titanium was prepared at a low energy density by selective laser melting technology.The parameter range of porous titanium with large porosity was obtained by measuring the porosity of the formed specimen,and the evolution of the microstructure and mechanical properties of the specimen in the range were analyzed. RESULTS AND CONCLUSION:(1)With the increase in energy density,the porosity of the porous titanium specimen decreased gradually.When the energy density was between 10.61 and 27.78 J/mm3,porous titanium with a porosity of 11.23%-33.67%could be formed.When the energy density was between 27.78-37.88 J/mm3,the forming parts were relatively dense.(2)The phase composition of porous titanium formed was mainly α titanium.With the increase in energy density,the porosity gradually decreased,and the pore morphology changed from irregularly connected pores to closed nearly spherical pores.The powder particles changed from a slightly sintered neck to a continuous fuse.The CT scan results revealed that there were a large number of connected pores in the forming specimen with a large specific surface area and the pore radius was roughly distributed between 2-6 μm at the energy density of 10.61 J/mm3.Simultaneously,porous titanium with compressive strength of 188-1 000 MPa could be obtained at the energy density of 10.61-27.78 J/mm3,which could meet the requirements of biomedical applications.(3)These results have confirmed that the selective laser melting technology can overcome the problems of impurity pollution and long manufacturing cycle caused by the traditional preparation process,and provide an effective solution for the preparation of porous titanium with excellent mechanical properties.
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BACKGROUND:Medium-and large-diameter polytetrafluoroethylene artificial blood vessels have been widely used in clinical practice.However,most of the products were imported from other countries.Small-diameter porous polytetrafluoroethylene vessels are easy to form thrombosis and intimal hyperplasia,resulting in an extremely low long-term patency rate,which is difficult to fulfill clinical requirements. OBJECTIVE:To review and summarize the research progress of polytetrafluoroethylene in the field of artificial blood vessels,which can provide a reference for the functional modification of small-diameter polytetrafluoroethylene artificial blood vessels and the improvement of their long-term patency rate. METHODS:The relevant articles published from October 2022 to March 2023 in CNKI,Web of Science,Wiley Online Library,SpringerLink,Science Direct and IOP Science databases were searched by the first author.The search terms in Chinese were"porous polytetrafluoroethylene,vascular graft,electrospinning,medical application,functional modification".The search terms in English were"ePTFE,porous polytetrafluoroethylene,vascular graft,electrospinning,medical application,functional modification".All the articles about the preparation and modification of polytetrafluoroethylene artificial blood vessels were retrieved. RESULTS AND CONCLUSION:The preparation and functional modification of porous polytetrafluoroethylene artificial blood vessels were still research hotspots and difficult problems.From the research progress in and outside China in recent years,the preparation of porous polytetrafluoroethylene artificial blood vessels mainly adopted the rapid thermal stretching method,but the preparation of polytetrafluoroethylene artificial blood vessels by electrospinning was a promising new method.By analyzing and summarizing different functional modification methods,it was found that the long-term patency rate of porous polytetrafluoroethylene artificial blood vessels had been improved.However,the functional modification of small-diameter polytetrafluoroethylene artificial blood vessels still needed further exploration and optimization.
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BACKGROUND:With the increasing number of tendon transplantation surgeries for tendon injuries,the demand for tendon tissue engineering scaffolds is increasing.Research has found that good pore size and porosity of implants contribute to tissue healing. OBJECTIVE:To review the types of materials currently published for tendon tissue engineering scaffolds and investigate the correlation between various tendon tissue engineering scaffold materials and pores. METHODS:Articles were retrieved on PubMed,Embase,and Web of Science databases,using keywords"tendon"or"ligament"and"tissue scaffold"as well as"porosity"or"permeability".A total of 84 articles meeting the criteria were included to summarize,discuss and anticipate future development directions. RESULTS AND CONCLUSION:The materials used in the research of tendon tissue engineering are mainly divided into two categories:natural tendon scaffold materials and artificial synthetic tendon scaffold materials.Natural scaffold materials include autologous tendons,allogeneic tendons,and xenogeneic tendons.Autogenous tendons and allogeneic tendons have been used in clinical practice for many years.During the preparation of allogeneic tendons and animal experiments,it was found that the process of acellular disinfection resulted in an increase in the pore size and porosity of both types of tendons,but the specific reasons and mechanisms have not been further studied.There are many types of artificial tendon scaffold materials currently being studied,among which artificial ligament products such as Leeds Keio and LARS(Ligament Advanced Reinforcement System)are still in use in some countries.Other materials have not been promoted in clinical practice due to immature technology and other issues.The pores and porosity of artificial tendon scaffold materials also show different trends due to their different materials and preparation techniques.
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Abstract To assess the effect of cleaning protocols on dentin contaminated with blood in reparative endodontic materials, bovine root samples were divided: no contamination (N); contamination (P); contamination and cleaning with saline (S), 2.5% NaOCl+saline (Na) or 2.5% NaOCl+17% EDTA+saline (NaE) and filled with: mineral trioxide aggregate (MTA), calcium-aluminate-cement (C), or C+collagen (Ccol) (n=13). The samples were evaluated for porosity, chemical composition, and bond strength. MTA porosity was lower than C (p=0.02) and higher than Ccol (p<0.001). P and NaE were similar (p=1.00), but higher than the other groups (p<0.001). MTA bond strength was similar to Ccol (p=0.777) and lower than C (p=0.028). P presented lower bond strength than the N (p<0.001); S and Na were similar to each other (p=0.969), but higher than P and lower than N (p<0.001). It was observed a predominance of mixed and cohesive failures. None of the samples showed Ca/P ratio values similar to human hydroxyapatite. This study showed that contamination with blood increased the materials porosity, but dentin cleaning with 2.5% NaOCl reduced this effect, and the collagen additive reduced the material porosity. Furthermore, blood contamination reduced the materials bond strength, and cleaning with saline or 2.5% NaOCl diminished this effect.
Resumo As amostras de raízes bovinas foram divididas em: sem contaminação (N); contaminação sanguínea (P); contaminação sanguínea e limpeza com soro fisiológico (S), 2,5% NaOCl+soro fisiológico (Na) ou 2,5% NaOCl+17%EDTA+soro fisiológico (NaE) e preenchido com: agregado de trióxido mineral (MTA), cimento de aluminato de cálcio (C), ou C+colágeno (Ccol) (n=13). A porosidade do MTA foi menor que C (p=0,02) e maior que Ccol (p<0,001). P e NaE foram semelhantes (p=1,00), mas superiores aos demais grupos (p<0,001). A resistência de união do MTA foi semelhante ao Ccol (p=0,777) e inferior ao C (p=0,028). P apresentou menor resistência de união que o N (p<0,001); S e Na foram semelhantes entre si (p=0,969), porém maiores que P e menores que N (p<0,001). Este estudo mostrou que a contaminação com sangue aumentou a porosidade dos cimentos, mas a limpeza da dentina com NaOCl 2,5% reduziu esse efeito, e o aditivo de colágeno reduziu a porosidade dos cimentos. Além disso, a contaminação sanguínea reduziu a resistência de união dos cimentos e a limpeza com solução salina ou NaOCl 2,5% diminuiu esse efeito.
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OBJECTIVE@#To explore the influence of the thickness of mixed cardboard on the compressive strength of glass ionomer cement and the associated factors.@*METHODS@#Three different types of glass ionomer cements were mixed on the top of 60, 40, 20 and 1 pieces of paper (P60, P40, P20 and P1), respectively. The compressive strength of the materials was tested after solidification, and the bubble rate was calculated with the assistance of scanning electron microscope.@*RESULTS@#(1) Compressive strength: ① ChemFil Superior glass ionomer (CF): The average compressive strength of P1 group was the highest, which was significantly different from that of P40 and P60 groups (P values were 0.041 and 0.032 respectively); ② To Fuji IX GP glass ionomer (IX): The average compressive strength of P1 group was the highest, which was statistically different from that of P40 and P60 groups (P values were 0.042 and 0.038 respectively); ③ Glaslonomer FX-Ⅱ glass ionomer cement (FX): The average compressive strength of P1 group was the highest, which was statistically different from that of P20, P40 and P60 groups (P values were 0.031, 0.040 and 0.041 respectively), but there was no statistical difference among the other groups. All the three materials showed that the compressive strength of glass ions gradually increased with the decrease of the thickness of the blended paperboard, and the two materials had a highly linear negative correlation, the correlation coefficients of which were CF-0.927, IX-0.989, FX-0.892, respectively. (2) Scanning electron microscope: P1 group had the least bubbles among the three materials.@*CONCLUSION@#It indicates that the thickness of mixed cardboard has a negative correlation with the compressive strength of glass ions. The thicker the mixed cardboard is, the greater the elasticity is. Excessive elasticity will accelerate the mixing speed when the grinding glass ions. Studies have shown that the faster the speed of artificial mixing is, the more bubbles is produced.The thicker ther mixed cardboard is, the more bubblesn are generated by glass ionomer cement, and the higher the compressive strength is. Using one piece of paper board to mix glass ionomer cement has the least bubbles and can obtain higher compressive strength.
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Força Compressiva , Teste de Materiais , Cimentos de Ionômeros de Vidro , Dióxido de SilícioRESUMO
El objetivo de este estudio fue evaluar con microto-mografía los poros existentes entre el cemento de resina, poste de fibra y paredes del conducto en los distintos tercios radiculares en premolares inferio-res. Se utilizaron 15 premolares inferiores unirra-diculares humanos recientemente extraídos. Se les realizó el tratamiento endodóntico, y se obturó con conos de gutapercha y cemento endodóntico a base de resina. Una vez desobturados se procedió a la ce-mentación de los postes. Cada muestra se posicionó en un accesorio personalizado y se escaneó utilizan-do un Microtomógrafo. Con el software CTAn v.1.12 (Bruker-microCT) se analizaron las microtomografías para obtener el volumen de interés (VOI) que permi-tió calcular el área de superficie (mm2) y volumen de cada poro (mm3) entre la dentina y el poste a nivel co-ronal, medio y apical. Los datos fueron analizados me-diante las pruebas estadísticas de Friedman o ANOVA de medidas repetidas. El volumen de los poros entre los tres tercios radiculares mediante la prueba de Friedman, encontró una diferencia global significativa (F = 30,00; p < 0,05). El tercio en donde los poros presentaron un mayor volumen (mm3) fue el tercio coronal (mediana: 0,29250), seguido por los tercios medio (mediana: 0,03200), y apical (mediana: 0,00140). La comparación de la superficie de los poros entre los 3 tercios brindó un resultado análogo al de la comparación del volumen. La mayor superficie (mm2) correspondió al tercio coronal (media ± DE = 1,66377 ± 0,27175), seguido por los tercios medio (media ± DE = 1,16210 ± 0,20343) y apical (media ± DE = 0,41074 ± 0,12641). La microtomografía permitió realizar un análisis cuantitativo y cualitativo de los poros en toda la muestra, sin deterioro de la misma. Se puede concluir que el tercio coronal presenta más poros que el tercio apical con la técnica de cementación utilizada. En cuanto a la superficie y volumen de los poros, los resultados encontrados son similares a los reporta-dos por diversos autores (AU)
The aim of this study was to evaluate with microtomography the existing pores between the resin cement, fiber post and canal walls in the different in thirds of the canal, in single-root lower premolars. Fifteen recently extracted human single root lower premolars were used, endodontically treated, and filled with gutta-percha cones and resin-based endodontic cement. Once unfilled, the posts were cemented. Each sample was positioned on a custom fixture and scanned using a Microtomograph. Each sample was evaluated using CTAn v.1.12 software (Bruker-microCT) to obtain the surface area (mm2), volume of interest (mm3) of each pore between dentin and post at the coronal, middle and apical levels. Data were analyzed using Friedman's tests or repeated measures ANOVA. The volume of the pores between the three root thirds using the Friedman test, a significant global difference was found (F = 30.00; p < 0.05). The third in which the pores presented a greater volume (mm3) was the coronal third (means: 0.29250), followed by the middle (means: 0.03200) and apical (means: 0.00140) thirds. The comparison of the pore surface between the 3 thirds gave an analogous result to that of the volume comparison. The largest surface area (mm2) corresponded to the coronal third (mean ± SD 1.66377 ± 0.27175), followed by the middle (mean ± 1.16210 ± 0.20343) and apical (mean ± 0.41074 ± 0.12641) thirds.Microtomography allowed a quantitative and qualitative analysis of the pores in the entire sample without deterioration. It can be concluded that the coronal third has more pores than the apical third with the cementation technique used. Regarding the surface and volume of the pores, the results found are similar to those reported by various authors (AU)
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Porosidade , Técnica para Retentor Intrarradicular , Cimentação/instrumentação , Microtomografia por Raio-X , Dente Pré-Molar , Análise de Variância , Cimentos de Resina , Imageamento Tridimensional/métodos , Ácidos FíbricosRESUMO
Objective To study the effect of different materials and porosities on bone formation in the scaffold after implantation of the degradable bone scaffold into human body. Methods According to natural reaction mechanism of fracture healing, the finite element method was used, combined with geometry of the scaffold, to establish a computationally coupled model based on material degradation curve and bone reconstruction control equation. Through this platform, representative volume elements of the scaffold with five kinds of materials and four types of porosities were selected for calculation and analysis, and dynamic process was reflected by bone mineral density (BMD) and maximum stress of the scaffold. Results The elastic modulus of the materials had a greater influence on growth of bone tissues in the scaffold. The smaller elastic modulus of the materials would lead to the greater amount of bone formation, but it would also have a greater impact on mechanical properties of the scaffold. The scaffold with higher porosity had lower rigidity, which could better promote formation of bone tissues, meanwhile it would also destroy mechanical stability of the scaffold. Conclusions According to performance requirements for different age, gender and location of bone tissues, personalized reference and calculation basis for selection of materials and porosity, structural design and clinical application of degradable porous bone scaffolds can be provided.
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Abstract Introduction Personal protective equipment is mandatory to protect patients and professionals from diseases, especially in the dental environment. The risk of gloves micro-perforations is imminent when using sharp instruments or cleaning them up during lengthy clinical procedures. Objective This study evaluated the integrity of sterile and non-sterile gloves before clinical use and clarified whether friction with disinfectant solution modifies surface morphology and integrity. Material and method Samples of gloves from four different brands were divided into two groups: (1) Sterile surgical gloves (n=260) and (2) Non-sterile gloves (n=260). They were scissored and placed in Ostby's arch so that three solutions - distilled water, ethanol 70°, ethanol 96° - were rubbed with a cotton swab. After 30s, 5, 10, and 15 minutes of solution rubbing, samples were verified by a Scanning Electron Microscope. The pore sizes were measured by Image J software. Result Regardless of the brands, all gloves have been significantly affected by solutions and assessment periods. In general, remarkable changes were evident with ethanol 70° and 96°, and higher pore diameters were observed compared to distilled water. Conclusion Rubbing disinfectant solutions increases gloves' pores sizes, and time negatively influenced its quality.
Resumo Introdução Para proteger pacientes e profissionais de doenças, o uso de equipamentos de proteção individual é obrigatório, principalmente no ambiente odontológico. O risco de microperfurações das luvas é iminente ao usar instrumentos cortantes ou na tentativa de limpar as luvas durante longos procedimentos clínicos. Objetivo Este estudo avaliou a integridade das luvas cirúrgicas e de procedimento antes do uso clínico e esclareceu se o atrito com a solução desinfetante modifica a morfologia e integridade da superfície. Material e método Amostras de luvas de quatro marcas diferentes foram divididas em dois grupos: (1) Luvas cirúrgicas (n = 260) e (2) Luvas descartáveis não estéreis (n = 260). As luvas foram cortadas e colocadas em arco de Ostby, de modo que três soluções - água destilada, etanol 70 °, etanol 96 ° foram esfregadas com um cotonete. Após 30s, 5, 10 e 15 minutos de fricção das soluções, as amostras foram verificadas utilizando um microscópio eletrônico de varredura. Os tamanhos dos poros foram medidos pelo software Image J. Resultado Independentemente das marcas, todas as luvas foram significativamente afetadas por soluções e períodos de avaliação. Em geral, maiores alterações foram evidenciadas com o uso do etanol 70° e 96°, e maiores diâmetros dos poros foram observados quando comparados à água destilada. Conclusão Esfregar soluções desinfetantes aumenta o tamanho dos poros das luvas e o tempo influenciou negativamente sua qualidade.