Analysis of the Chemical Composition, Morphological Characterization, and Porosimetry of Allograft and Comparison with Xenograft for Dental Applications / Análisis de la Composición Química, Caracterización Morfológica y Porosimetría de Aloinjerto y Comparación con Xenoinjerto para Aplicaciones Odontológicas

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.

Effects of blood and root-dentin cleaning on the porosity and bond strength of a collagen bioceramic material

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.

3D printing process of gelatin/oxidized nanocellulose skin scaffold with high elastic modulus and high porosity / 中国组织工程研究

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.

Preparation and properties of selective laser melting of porous titanium at a low energy density / 中国组织工程研究

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.

Research advance in preparation and functional modification of porous polytetrafluoroethylene artificial blood vessels / 中国组织工程研究

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.

Biomaterials and pore characteristics of tendon tissue engineering scaffolds / 中国组织工程研究

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.

Influence of paper mixing pads thickness on the compressive strength of glass ionomer cement / 北京大学学报(医学版)

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.

Estudio microtomográfico de la porosidad en la cementación de postes de fibra / Microtomographic study of the porosity in the cementation of fiber posts

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)

The Effect of Materials and Porosity on Bone Formation of Degradable Scaffolds / 医用生物力学

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.

Rubbing ethanol and time of use: critical factors compromising latex gloves structure / Desinfecção com etanol e tempo de uso: fatores críticos que comprometem a estrutura das luvas de látex

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.

Physical properties of beans of the BRSMG majestoso cultivar during drying / Propriedades físicas de grãos de feijão cultivar BRSMG majestoso durante a secagem

Beans are the main source of protein of plant origin in the Brazilian diet, they also contain phenolic compounds, antioxidants, iron, fibers and vitamins. The BRSMG Majestoso cultivar belongs to the commercial group of carioca beans, displays high productivity, excellent health and a 90-day cycle, has high yield and is resistant to disease. The study of physical properties enables the prediction of agricultural products behavior relative to responses of physical and chemical treatments, in order to allow the maintenance of quality and safety of processed foods. The aim of the present study was to evaluate the effect of drying on the physical characteristics of beans of the BRSMG Majestoso cultivar. Beans with an initial moisture content of approximately 0.2660 d.b. (dry basis) were used, and dried at 40ºC. The following physical characteristics were determined: bulk density, unit density, intergranular porosity, 1000-grain weight, sphericity, circularity, geometric diameter, unit volume, projected area, surface area and the surface to volume ratio. Based on the results, a reduction in the moisture content of the beans promotes an increase in bulk density, unit density, porosity, sphericity, circularity and the surface to volume ratio. Conversely, the 1000-grain weight, geometric diameter, unit volume, projected area and surface area decreased as the moisture content of the beans was reduced.

Objetivou-se com o presente trabalho, avaliar o efeito da secagem sobre as características físicas de grãos de feijão cultivar BRSMG Majestoso. Foram utilizados grãos com teor de água inicial de aproximadamente 0,2660 b.s. (base seca), e submetidos à secagem com temperatura de 40 ºC. Foram determinadas as propriedades físicas: massa específica aparente, massa específica unitária, porosidade intergranular, massa de mil grãos, esfericidade, circularidade, diâmetro geométrico, volume unitário, área projetada, área superficial e a relação superfície/volume. Com base nos resultados obtidos conclui-se que a redução do teor de água dos grãos de feijão proporcionou aumento da massa específica aparente e unitária, porosidade, esfericidade, circularidade e relação superfície/volume. Em contrapartida, a massa de mil grãos, o diâmetro geométrico, o volume unitário, a área projetada e a área superficial diminuíram com a redução do teor de água dos grãos de feijão.

Formulation and stability studies of metformin hydrochloride in a controlled porosity osmotic pump system

This study was designed to formulate, for the first time, metformin hydrochloride (MH, 850 mg/tablet) as a controlledporosity osmotic pump (CPOP) system to achieve zero-order release pattern. MH core tablet was coated with celluloseacetate membrane containing PEG 400. The effect of different percentages and molecular weights of polyethyleneoxide (PEO, 900K and 4M) in tablet core was studied. The United States Pharmacopeia (USP) apparatus II andphosphate buffer pH 6.8 were used for the release studies; meanwhile, a promising formula was tested in biorelevantmedia. The stability of some selected formulations was carried out for 6 months, at bench and accelerated conditions.Evaluation included: MH content, Differential scanning calorimetry (DSC), Scanning electron microscopy (SEM),drug release, and kinetics. Results revealed that increasing PEO percentage within the core decreased MH release.SEM verified formation of pores in the membrane that accounts for MH release. Almost all stored tablets werestable for all studied parameters. MH endothermic peak maintained its position and energy of enthalpy on storageas confirmed by DSC. MH release rate from a promising formula, following zero-order release model, increased by28% in biorelevant media compared to phosphate buffer. Subsequently, in vitro release in biorelevant media could beemployed as a tool to anticipate in vivo tone of CPOP formulations

Ultrastructural changes of tibial subchondral bone in patients with knee osteoarthritis: CT evaluation / 中国组织工程研究

BACKGROUND: More and more attention has been paid to the role of subchondral bone changes in knee osteoarthritis. However, previous studies mainly focused on animal experiments. Animals and humans have certain differences, so it is very necessary to obtain relevant data directly in human joints. OBJECTIVE: To evaluate the difference of subchondral plate and subchondral bone ultrastructure between normal patients and patients with knee osteoarthritis by CT technique, so as to explore the role of subchondral bone in the occurrence and development of knee osteoarthritis. METHODS: CT scan data of 30 patients with knee osteoarthritis (knee osteoarthritis group) and 30 patients without knee osteoarthritis (non-knee osteoarthritis group) were collected from the Department of Imaging of Zhengzhou Orthopedic Hospital from July 2016 to July 2018. Subchondral plate and subchondral bone ultrastructure of medial and lateral tibial plateau was compared between the two groups using MIMICS software. This study was approved by the Ethics Committee of Zhengzhou Orthopedic Hospital on June 10, 2016 (approval No. 2016 004). RESULTS AND CONCLUSION: (1) Compared with the non-knee osteoarthritis group, bone density was significantly increased and porosity was significantly decreased in the subchondral bone plate in the knee osteoarthritis group in both the lateral and medial parts, while the medial part of subchondral bone plate thickness was significantly thicker than that in the non-knee osteoarthritis group. (2) There were also significant changes in subchondral trabeculae in the knee osteoarthritis group, which showed that the thickness of subchondral trabeculae in the lateral part and the medial part of the subchondral bone in the knee osteoarthritis group was significantly increased compared with the non-knee osteoarthritis group. Meanwhile, in the medial part, the degree of cancellous bone separation in the knee osteoarthritis group was significantly lower than that in the non-knee osteoarthritis group. Structure model index and connectivity density in the knee osteoarthritis group were significantly lower than those of the non-knee osteoarthritis group. (3) Results show that the change of tibial subchondral bone plate and subchondral cancellous bone in knee osteoarthritis patients mainly lies in the destruction of ultrastructure homeostasis. This change may be one of the causes of knee osteoarthritis.

In vitro biocompatibility of 3D printed polycaprolactone/nano-hydroxyapatite composite scaffold with bone marrow mesenchymal stem cells / 中国组织工程研究

BACKGROUND: Polycaprolactone/nano-hydroxyapatite composite is a new composite scaffold material prepared based on common bone tissue engineering materials using 3D printing technology. At present, little is reported on the in vitro biocompatibility of the composite material. OBJECTIVE: To investigate the cytocompatibility of 3D printed polycaprolactone/nano-hydroxyapatite composite scaffolds. METHODS: Polycaprolactone and polycaprolactone/nano-hydroxyapatite composite scaffolds were prepared by 3D printing technology to characterize the microstructure, porosity and mechanical properties of the two materials. Rat bone marrow mesenchymal stem cells were inoculated on the surface of the 3D-printed polycaprolactone and polycaprolactone/nano-hydroxyapatite composite scaffolds. Cell proliferation rate was detected by CCK-8 method. Cell growth on the scaffolds was observed by scanning electron microscopy and Live/Dead cell staining. RESULTS AND CONCLUSION: Two kinds of scaffolds had a three-dimensional network and interconnected structure. The fibers were arranged in a regular order and interlaced. There was no gap on the fiber surface, and the fiber spacing and diameter were relatively uniform. There was no significant difference in the porosity between two kinds of scaffolds (P > 0. 05). The elastic modulus of the composite scaffold was higher than that of the simple polycaprolactone scaffold (P < 0. 05). There was no significant difference in cell proliferation between two kinds of scaffolds after 1 day of culture. After 4 and 7 days of culture, cell proliferation on the composite scaffold was significantly faster than that on the simple polycaprolactone scaffold (P < 0. 05). Live/Dead cell staining showed that both polycaprolactone and polycaprolactone/nano-hydroxyapatite composite scaffolds had good cytocompatibility and high cell viability. A larger number of cells adhered to the polycaprolactone/nano-hydroxyapatite composite scaffolds. Scanning electron microscopy showed that cells grew well on two kinds of scaffolds and distributed on the surface and micropores of the scaffold. The secreted extracellular matrix appeared in filaments and surrounded the cells. These findings suggest that the polycaprolactone/nano-hydroxyapatite composite material prepared by 3D printing technology has abundant pores, exhibit good mechanical properties, and have good cytocompatibility and can be used as a scaffold material for tissue engineering.

Avaliação de matéria orgânica, densidade e porosidade do latossolo vermelho em contato com lixiviado de resíduos sólidos urbanos / Evaluation of organic matter, density and porosity of Oxisol in contact with leachate from urban solid waste

RESUMO O objetivo do trabalho é avaliar a densidade, a porosidade e a matéria orgânica do solo decorrentes da interação solo-lixiviado em um latossolo vermelho, em duas profundidades: 0,2 e 1,5 m. As amostras de solo foram coletadas indeformadas, e o lixiviado em aterro foi controlado. Utilizaram-se colunas de difusão, sem fluxo, onde o solo ficou submerso no lixiviado durante 90 dias. A matéria orgânica do solo (MOS) foi obtida por meio de determinação gravimétrica (IAPAR). Densidade, micro e macroporosidade foram obtidas de acordo com o ensaio de mesa de tensão (EMBRAPA). Foram realizadas análises de regressão para estudar os efeitos dos fatores e suas interações para o parâmetro da matéria orgânica. As principais conclusões foram: as maiores alterações nas propriedades físicas do solo ocorrem nos primeiros dias de contato; a densidade do solo a 0,2 m reduziu 5,9%, enquanto a 1,5 m aumentou 5,61%; a macroporosidade não se alterou a 0,2 m, mas foi reduzida em 11%, para 1,5 m; a microporosidade para as duas profundidades estudadas aumentou, respectivamente, em 4,25 e 21,14%. A MOS teve baixa correlação com a demanda bioquímica de oxigênio (DBO5) do lixiviado e uma correlação significativa com a sua demanda química de oxigênio (DQO); e seu aumento foi significativo no período de contato.

ABSTRACT The objective of this research is to evaluate soil density, porosity, and also the organic matter due to soil-leachate interaction in Oxisol, at two depths: 0.2 and 1.5 m. Soil samples were collected undisturbed and the leachate in a landfill. Diffusion columns, without any flow, were used, where the soil was submerged in the leachate for 90 days. The organic matter was obtained by gravimetric determination (IAPAR). Density, micro and macro porosity were obtained according to the stress table test (EMBRAPA). Regression analysis was performed to study the factors effects and their interactions for the organic matter parameter. The main conclusions were: major changes in physical soil properties occur in the first days of contact; soil bulk density at 0.2 m decreased by 5.9%, while at 1.5 m it increased by 5.61%; macroporosity did not changed to 0.2 m, but decreased by 11% for 1.5 m; microporosity for both depths studied increased, respectively, by 4.25 and 21,14%. The soil organic matter had a low correlation with the leachate BOD5 and a significant correlation with its COD; the increase of the soil organic matter was significant at the time of the contact.

An efficient method of Yarrowia lipolytica immobilization using oil- and emulsion-modified bacterial cellulose carriers

Background: Yarrowia lipolytica is a nonconventional, dimorphic yeast with multiple biotechnological applications. Considering the size of Y. lipolytica cells and a plethora of its morphological forms (spherical cells or hyphae and pseudohyphae), it is highly difficult to select a suitable carrier for this useful microorganism. Bacterial cellulose (BC) is currently considered one of the most promising immobilization carriers. In the current study, the usefulness of oil- and emulsion-modified BCs as a carrier for Y. lipolytica immobilization was investigated. Static and agitated cultures were conducted in media supplemented with oil or emulsion to improve carrier porosity. Results: It was found that the application of oil- and emulsion-modified BCs correlated with significantly higher efficiency of Y. lipolytica immobilization and hence higher yield than the yield achieved with an unmodified carrier. Increased efficiency of immobilization correlated with BC porosity-related parameters, which, in turn, depended on the size of oil droplets introduced into the culture medium. Moreover, changes in porosity-related parameters caused by the addition of oil or emulsion to the medium were observed when the cultures were conducted only under static conditions and not under agitated conditions. Conclusion: The application of oil- and emulsion-modified BCs as carriers significantly increased the efficiency of Y. lipolytica immobilization as compared to unmodified BC. The addition of oil or emulsion to the culture medium can be a simple but effective method to modify the porosity of BC-based carriers.

Evaluation and comparison of different polymerization techniques, curing cycles, and thicknesses of two denture base materials

Purpose: The study aimed to compare the effect of different materials, thicknesses, and polymerization methods and cycles, on the surface porosity of acrylic denture base resins. Materials and Methods: Conventional heat-polymerized polymethyl methacrylate (PMMA) and specially designed acrylic resin (Acron MC) were used to make 84 rectangular samples. They were divided into three groups to evaluate and compare the polymerization techniques, curing cycles, and thicknesses of the two denture base materials (28 samples each). Group A contained PMMA samples polymerized using water bath method (control group); Group B contained Acron MC samples polymerized by microwave method, and Group C contained PMMA samples polymerized by microwave method. Each group was further divided based on sample thickness and polymerization cycles. Each sample was scanned for surface porosity and area of each pore was measured using optical microscope. Data was analyzed using ANOVA, Bonferroni, and student t-tests. Unpaired student t-test was performed to compare the means of surface porosity with polymerization cycles and thicknesses among the groups. The power of study was kept at 80%. Results: Group C showed highest mean % of porosity depending on method of polymerization, different polymerization cycles (short and long) and polymerization cycles within the group. Group B showed the highest mean % of porosity depending on thickness and thickness within the groups. Conclusions: Microwavable acrylic resin polymerized by microwave energy exhibited statistically insignificant increase in porosity when compared to conventional heat cured acrylic resin by water bath method. Conventional acrylic resin polymerized by microwave energy exhibited high statistically significant porosity irrespective of sample thickness. There was statistically insignificant increase in porosity depending on sample thickness irrespective of material and method of polymerization.

Análise da performance mecânico-estrutural e resistência de união de diferentes técnicas de utilização de pinos de fibra de vidro / Analysis of the mechanical-structural performance and fatigue resistance of different techniques of fiberglass post

O objetivo deste trabalho foi avaliar "in vitro" e "in silico" a integridade estrutural da interface de cimentação, o comportamento biomecânico, e a resistência de união da interface dentina/cimento de diferentes técnicas de cimentação de pinos de fibra de vidro (PFV) em canais amplos. Para tanto, foram utilizados 33 incisivos bovinos. Após o tratamento endodôntico, os espécimes foram divididos aleatoriamente em três grupos (n=11): PCN- Pino convencional cimentado em dente com conduto normal; PCA- Pino convencional cimentado em dente com conduto amplo; PAA- Pino anatômico cimentado em dente com conduto amplo. Em seguida, foram executados os preparos intrarradiculares de acordo com cada grupo com brocas pré-estabelecidas, tratamento de superfície dos PFV (WhitePost nº3 DC, FGM) e cimentação dos mesmos com o cimento resinoso autoadesivo (Rely X U200, 3M ESPE). Então, 6 espécimes de cada grupo foram submetidos ao escaneamento em um microtomógrafo de alta resolução (SkyScan 1272) para avaliação da integridade, volume e presença de bolhas na interface de cimentação. Posteriormente, com base nos dados do µCT e imagens de microscopia (n=1), dois modelos tridimensionais de cada grupo foram confeccionados para a análise de elementos finitos, sendo que o primeiro foi considerado ideal (G1, G3 e G5), sem defeitos na interface, e o segundo continha as condições encontradas pela análise de µCT(G2, G4 e G6). Após o envelhecimento em estufa por 7 meses, todos os espécimes foram submetidos ao teste de resistência de união (n=10). Os dados foram submetidos à ANOVA com medidas repetidas e pós-teste de Tukey (p<0,05). O grupo PCA registrou os maiores valores médios de concentração de bolhas e fendas em relação aos grupos PCN e PAA (p< 0,05). Observou-se que a quantidade de fendas decresceu no terço apical para todos os grupos, especialmente para o grupo PAA, que registrou os menores valores médios, sendo localizadas predominantemente na face lingual entre o pino e a camada de cimento para os grupos PCN e PAA. No grupo PCA a maioria das fendas se localizaram na face vestibular entre a camada de cimento e a dentina intrarradicular. Na análise de resistência de união verificou-se diferença estatística entre os terços cervical e médio com terço apical do PCA (p< 0,05). Na comparação entre os grupos, observou-se diferença estatística na resistência de união nos PCA e PAA no terço cervical (p< 0,05), ambos sendo estatisticamente semelhantes com o PCN. Na análise "in silico" os níveis de tensão foram semelhantes na maioria das estruturas, sendo os picos de tensão observados na região cervical na face lingual. Concluiu-se que a presença de defeitos estruturais na camada da interface pode influenciar a resistência de união e o comportamento biomêcanico das diferentes técnicas de cimentação de pinos de fibra de vidro, sendo que a customização de pino de fibra de vidro com resina composta para cimentação em canais amplos proporcionou melhor desempenho de resistência de união e distribuição dos níveis de tensão na interface(AU)

The objective of this study was to evaluate "in vitro" and "in silico" the structural integrity of the cementation interface, the biomechanical behavior and the bond strength of different fiberglass post cementation techniques in flared root canal. To this end, 33 bovine incisors were used. After the endodontic treatment, the specimens were randomly divided into three groups (n = 11): PCN - conventional post cemented in tooth with normal canal lumen; PCA- Conventional fiberglass post cemented in flared root canal; PAA- Fiberglass post relined with composite resin and cemented in flared root canal; Then, the intra-radicular preparations were performed according to each group with pre-established drills, surface treatment of PFV (WhitePost Nº. 3DC, FGM) and cementation with self-adhesive resin cement (Rely X U200, 3M ESPE). Then, 6 specimens from each group were submitted to scanning in a high resolution microtomograph (SkyScan 1272) to evaluate the integrity, volume and presence of bubbles at the cementation interface. Then, based on the µCT data and the microscopic images (n = 1), two three-dimensional models of each group were made to analyze finite elements, the first one being considered ideal (G1, G3 and G5), without interface defects and the second contained the conditions found by µCT analysis (G2, G4 and G6). After being stored for 7 months, all specimens were submitted to the pushout bond strength test (n = 10). Data were submitted to ANOVA with repeated measures and Tukey post-test (p <0.05). The PCA group recorded the highest mean values of bubble and gap concentration in relation to PCN and PAA groups (p <0.05). It is observed that the number of gaps decreased in the apical third for all groups, especially for the PAA group that registered the lowest mean values, being located predominantly in the lingual face between the post and the cement layer for the PCN and PAA groups. In the PCA group, most of the gaps were located on the vestibular face between the cement layer and the intraradicular dentin. In the analysis of pushout bond strength, it was verified that statistical difference occurred between the cervical and middle thirds with apical third of the PCA (p <0.05). In the comparison between the groups, a statistical difference was observed in the bond strength in the PCA and PAA in the cervical third (p <0.05), both of which were statistically similar with the PCN. In the "in silico" analysis, the tension levels were similar in most structures, localized in the cervical region on the lingual surface. It was concluded that the presence of structural defects in the interface layer may influence the bond strength and the biomechanical behavior of the different fiberglass post cementation techniques, whereby the customization of fiberglass post with composite resin for cementation in flared root canals provided excellent bond strength performance and biomechanical behavior(AU)

Preparation and in vitro evaluation of pregabalin controlled porosity osmotic pump tablets / 中国药科大学学报

@#In this study, pregabalin controlled porosity osmotic pump tablets which are taken once a day were prepared. Single-factor tests were carried out to investigate the influence of excipients and manufacturing process. The formulation was optimized through orthogonal experiment on three levels of three significant factors including the amount of sodium citrate, and polyethylene glycol 400 and coating weight gain. On the basis of the results of the single-factor tests and the orthogonal experiment, optimal formulation and manufacturing process were obtained. The final tablet formulation contained pregabalin(82. 5 mg), microcrystalline cellulose(40%), sodium citrate(27. 5%), magnesium stearate(0. 5%)and 5% povidone K30 solution as the tablet binder; the coating formulation consisted of cellulose acetrate and 60% of polyethylene glycol 400 as a porogen; the coating weight gain was 3%. In vitro drug release kinetic study suggested that the drug release from controlled porosity osmotic pump tablets was mainly driven by osmotic pressure, which was barely affected by the pH of the release medium. The drug release behavior of the tablets within 12 hours complied with zero-order release rule and the linear correlation coefficient was 0. 991 6. The obtained porosity osmotic pump tablets could effectively slow the drug release rate, reduce concentration fluctuation and improve the safety and convenience for the patients, hence with broad prospects.

Preparation technology of oyster hydroxyapatite porous material for bone repair / 国际生物医学工程杂志

Objective To verify the feasibility of applying hydrothermal synthesis for preparing oyster hydroxyapatite(HA) and to develop a preparation method of oyster HA porous material for bone repair.Methods Hydrothermal synthesis was applied for preparing oyster HA,and the reaction condition was 220 ℃ for 6 h.Then,the prepared oyster HA was used as the raw material for porous scaffold preparation by sponge-soaking and sintering,successively.The porosity and compressive strength of the scaffold were adjusted by controlling the soaking time and absorbed HA slurry of the sponges.Results Hydrothermal synthesis was an effective method for preparing oyster HA.When the volume of the sponge cube was 1 cm3,the material absorbed by one to three times sponge-soaking were 0.184 8 g,0.318 1 g and 0.426 1 g,respectively,the corresponding porosity were 91.5％,82.9％ and 78.5％,and the compressive strength were 1.06 MPa,3.99 MPa and 8.49 MPa.Conclusion The oyster shell powder can be effectively converted into HA under the hydrothermal reaction condition of 220 ℃ for 6 h.The preparation of HA porous bone repair material by sponge-soaking method can obtain ideal porosity and mechanical strength.However,in this preparation process,the number of sponge-soaking and the weight of the absorbed HA slurry should be exactly controlled in order to obtain desired properties.