Adding mechanobiological cell features to finite element analysis of an immediately loaded dental implant.

Finite element analysis (FEA) has been used to analyze the behavior of dental materials, mainly in implantology. However, FEA is a mechanical analysis and few studies have tried to simulate the biological characteristics of the healing process of loaded implants. This study used the rule of mixtures to simulate the biological healing process of immediate implants in an alveolus socket and bone-implant junction interface through FEA. Three-dimensional geometric models of the structures were obtained, and material properties were derived from the literature. The rule of mixtures was used to simulate the healing periods-immediate and early loading, in which the concentration of each cell type, based on in vivo studies, influenced the final elastic moduli. A 100 N occlusal load was simulated in axial and oblique directions. The models were evaluated for maximum and minimum principal strains, and the bone overload was assessed through Frost's mechanostat. There was a higher strain concentration in the healing regions and cortical bone tissue near the cervical portion. The bone overload was higher in the immediate load condition. The method used in this study may help to simulate the biological healing process and could be useful to relate FEA results to clinical practice.

Tensile Strength and Elastic Modulus of Gutta-percha Cones Disinfected with Sodium Hypochlorite at Different Immersion Times: An In Vitro Comparative Study.

Aim: The tensile strength and modulus of elasticity of gutta-percha cones can be chemically altered due to disinfectant solutions. Therefore, the aim of the present study was to compare tensile strength and elastic modulus of gutta-percha cones subjected to sodium hypochlorite (NaOCl) disinfection at different times. Materials and Methods: This in vitro and longitudinal experimental study consisted of 45 gutta-percha cones, divided equally into three groups: Group 1 (disinfection with 2.5% NaOCl), Group 2 (disinfection with 5.25% NaOCl), and control group. All groups were subdivided according to immersion times for 1, 5, and 10 minutes. Tensile strength and elastic modulus were measured with a universal testing machine. For comparing more than two independent groups, parametric analysis of variance test with Sheffe's post hoc was used and for multivariate analysis, and multivariate analysis of variance test based on Pillai's Trace was used. In all statistical analysis, a significance level P ≤ 0.05 was considered. Results: When comparing the tensile strength of gutta-percha cones, no significant differences were observed after being immersed at 1, 5, and 10 minutes in NaOCl 2.5% (P = 0.715) and 5.25% (P = 0.585). Regarding the elastic modulus, a significant decrease (P < 0.05) was observed in those that were immersed in NaOCl 2.5% and 5.25% for 1, 5, and 10 minutes. Furthermore, increased NaOCl concentration significantly reduced the elastic modulus (P < 0.001). However, there were no significant differences in tensile strength (P > 0.05) and elastic modulus (P > 0.05), when evaluating the interaction between NaOCl concentration and time. Conclusion: Increasing NaOCl concentration significantly reduced the modulus of elasticity without affecting the tensile strength of gutta-percha cones, regardless of immersion time. Furthermore, the interaction of time and NaOCl concentration did not significantly affect the tensile strength and elastic modulus.

Investigation of the Chemical Composition, Microstructure, Density, Microhardness, and Elastic Modulus of the New ß Ti-50Nb-xMo Alloys for Biomedical Applications.

ß-type titanium alloys with a body-centered cubic structure are highly useful in orthopedics due to their low elastic modulus, lower than other commonly used alloys such as stainless steel and Co-Cr alloys. The formation of the ß phase in titanium alloys is achieved through ß-stabilizing elements such as Nb, Mo, and Ta. To produce new ß alloys with a low modulus of elasticity, this work aimed to produce our alloy system for biomedical applications (Ti-50Nb-Mo). The alloys were produced by arc-melting and have the following compositions Ti-50Nb-xMo (x = 0, 3, 5, 7, and 12 wt% Mo). The alloys were characterized by density, X-ray diffraction, scanning electron microscopy, microhardness, and elastic modulus. It is worth highlighting that this new set of alloys of the Ti-50Nb-Mo system produced in this study is unprecedented; due to this, there needs to be a report in the literature on the production and structural characterization, hardness, and elastic modulus analyses. The microstructure of the alloys has an exclusively ß phase (with bcc crystalline structure). The results show that adding molybdenum considerably increased the microhardness and decreased the elastic modulus, with values around 80 GPa, below the metallic materials used commercially for this type of application. From the produced alloys, Ti-50Nb-12Mo is highlighted due to its lower elastic modulus.

Alternative method of photopolymerization of composite resin specimen for flexural strength test / Método alternativo de fotopolimerização de resinas compostas para teste de flexão

The flexural resistence is one of the most used test in researchs of mechanical characterization of resin composites for dental restoration. ISO 4049 photopolymerization technique performed static application stages of light tip. To polymerize the entire area of the specimen some areas must receive extra radiation. These areas with extra radiation are called overlap areas. In an attempt to remedy this problem, this research compared the ISO method with a new method using constant movement (CM) during photopolymerization. Twenty specimens (SPs) were produced with 25 x 2 x 2 mm, for each group, 10 specimens being polymerized by the static technique recommended by the ISO-4049 and 10 specimens polymerized by the CM technique for each LED curing light used. After Tukey's statistical analysis, it was found that there was no statistical difference in relation to flexural strength (FS) and for the flexural modulus of elasticity (EF). However, the standard deviation of both FS and EF were much lower in MC than in ISO. Therefore, the photopolymerization by CM of the samples for the flexural strength test proved to be a possible solution to the problem of overlap of the technique proposed by ISO.

O teste de flexão é um dos mais utilizados em pesquisa de caracterização mecânica de compósitos resinosos para restauração dentária. A técnica ISO 4049 é feita em etapas com aplicação estática da luz. Para que toda a área do corpo de prova receba esta radiação é preciso que outras áreas recebam radiação extra. Na tentativa de sanar tal problema, esta pesquisa comparou o método da ISO com um método que utiliza um movimento constante (MC) durante a fotopolimerização. Foram produzidos 20 corpos de provas (CPs) com 25 x 2 x 2 mm, para cada grupo, sendo 10 polimerizados pela técnica estática recomendada pela normativa ISO-4049 e 10 polimerizados pela técnica de movimentação contínua (MC) para cada fotopolimerizador LED utilizado. Após análise estatística de Tukey apurou-se que não houve diferença estatística em relação à resistência à flexão (RF) e para o módulo de elasticidade em flexão. Porém, percebe-se, que o desvio padrão tanto da RF quanto do EF foram bem menores em MC do que em ISO. Sendo assim, a fotopolimerização em movimentação constante (MC) das amostras para o teste de resistência à flexão se mostrou como uma possível solução para o problema de sobreposição na técnica proposta pela ISO.

Simulation of the Influence of the Radial Graded Porosity Distribution on Elastic Modulus of γ/ß Phase Ti-Based Alloy Foams for Bone Implant.

This research aims to examine how a radial graded porosity distribution affects the elastic modulus by conducting simulations on Ti-based alloy foams with face-centered cubic and body-centered cubic crystal structures. Four types of foams were analyzed; commercially pure-Ti, Ti-13Ta-6Mn (TTM), Ti-13Ta-(TT) and Ti-13Ta-6Sn (TTS), (all in at.%). Four radial graded porosity distribution configurations were modeled and simulated using the finite element analysis (FEA). The radial graded porosity distribution configurations were generated using a Material Designer (Ansys) with a pore range of 200 to 600 µm. These radial graded porosity distributions had average porosity values of 0, 20, 30 and 40%. The consolidated samples that were obtained through a powder metallurgy technique in two step samples were synthesized using a powder metallurgy technique, with the elastic moduli values of the aforementioned Ti based alloys being measured by ultrasound using ~110, ~69, ~61 and ~65 GPa, respectively. The results showed that the modulus decreased as a function of porosity level in all simulated materials. The TTM, TT and TTS foams, with average porosities of 20, 30 and 40%, exhibited an modulus smaller than 30 GPa, which is a requirement to be used as a biomaterial in human bones. The TT foams showed the lowest modulus when compared to the other foams. Finally, certain theoretical models were used to obtain the modulus, the best being; the Gibson-Ashby model (α = 1 and n = 2.5) for the cp-Ti foams and Knudsen-Spriggs model (b = 3.06) for the TTM, TT and TTS foams.

Numerical Modeling of the Dynamic Elastic Modulus of Concrete.

This article introduces simulations of theoretical material with controlled properties for the evaluation of the effect of key parameters, as volumetric fractions, elastic properties of each phase and transition zone on the effective dynamic elastic modulus. The accuracy level of classical homogenization models was checked regarding the prediction of dynamic elastic modulus. Numerical simulations were performed with the finite element method for evaluations of the natural frequencies and their correlation with Ed through frequency equations. An acoustic test validated the numerical results and obtained the elastic modulus of concretes and mortars at 0.3, 0.5 and 0.7 water-cement ratios. Hirsch calibrated according to the numerical simulation (x = 0.27) exhibited a realistic behavior for concretes of w/c = 0.3 and 0.5, with a 5% error. However, when the water-to-cement ratio (w/c) was set to 0.7, Young's modulus displayed a resemblance to the Reuss model, akin to the simulated theoretical triphasic materials, considering matrix, coarse aggregate and a transition zone. Hashin-Shtrikman bounds is not perfectly applied to theoretical biphasic materials under dynamic situations.

Computational Study of the Influence of α/ß-Phase Ratio and Porosity on the Elastic Modulus of Ti-Based Alloy Foams.

This work aims to perform a computational analysis on the influence that microstructure and porosity have on the elastic modulus of Ti-6Al-4V foams used in biomedical applications with different α/ß-phase ratios. The work is divided into two analyses, first the influence that the α/ß-phase ratio has and second the effects that porosity and α/ß-phase ratio have on the elastic modulus. Two microstructures were analyzed: equiaxial α-phase grains + intergranular ß-phase (microstructure A) and equiaxial ß-phase grains + intergranular α-phase (microstructure B). The α/ß-phase ratio was variated from 10 to 90% and the porosity from 29 to 56%. The simulations of the elastic modulus were carried out using finite element analysis (FEA) using ANSYS software v19.3. The results were compared with experimental data reported by our group and those found in the literature. The ß-phase amount and porosity have a synergic effect on the elastic modulus, for example, when the foam has a porosity of 29 with 0% ß-phase, and it has an elastic modulus of ≈55 GPa, but when the ß-phase amount increases to 91%, the elastic modulus decreases as low as 38 GPa. The foams with 54% porosity have values smaller than 30 GPa for all the ß-phase amounts.

Viscoelastic Properties of Acellular Matrices of Porcine Esophageal Mucosa and Comparison with Acellular Matrices of Porcine Small Intestine Submucosa and Bovine Pericardium.

The aim of this study was to compare the viscoelastic properties of a decellularized mesh from the porcine esophagus, prepared by our group, with two commercial acellular tissues derived from porcine small intestine submucosa and bovine pericardium for use in medical devices. The tissues' viscoelastic properties were characterized by creep tests in tension, applying the load in the direction of the fibers or the transverse direction, and also by dynamic-shear mechanical tests between parallel plates or in tension at frequencies between 0.1 and 35 Hz. All the tests were performed in triplicate at a constant temperature of 37 °C immersed in distilled water. The tissues' surface and cross-sectional microstructure were observed by scanning electron microscopy (SEM) to characterize the orientation of the fibers. The matrices of the porcine esophagus present an elastic modulus in the order of 60 MPa when loaded in the longitudinal direction while those of the porcine intestine submucosa and bovine pericardium have an elastic modulus below 5 MPa. Nevertheless, the shear modulus of bovine pericardium nearly triplicates that of the esophageal matrix. The viscoelasticity of decellularized esophageal mucosa is characterized by a fast change in the creep compliance with time. The slope of the creep curve in the double logarithmic plot is twice that of the control samples. These results are consistent with the microstructure observed under electron microscopy regarding the orientation of the fibers that make up the matrices.

Adventitial Collagen Cross-Linking by Glutaraldehyde Reinforcing Human Saphenous Vein - Implication for Coronary Artery Bypass Grafting.

INTRODUCTION: A weak venous wall is one of the major reasons contributing to vein graft failure after coronary artery bypass grafting (CABG). We investigated whether adventitial collagen cross-linking by glutaraldehyde reinforces venous wall, preserving the endothelium of veins during high-pressure distention. METHODS: Human saphenous veins (SVs) were collected from 40 patients undergoing CABG, and adventitia cross-linking was performed with 0.3% glutaraldehyde for five minutes. The cross-linked SVs were accessed by biodegradation assay, immunofluorescent staining, and tensile test. Native SVs and cross-linked SVs from another 20 patients received the 200 mmHg pressure distention for two minutes. Pressure-induced injury of SVs were accessed by immunohistochemistry and electron microscopy. RESULTS: Time to digestion was 97±13 minutes for native SVs and 720±0 minutes for cross-linked SVs (P<0.05). After adventitial cross-linking, the collagen I fibres of the vein remarkably presented with compact and nonporous arrangement. In the high-stretch region (stretch ratio 1.4-1.8), the Young's elastic modulus of stress-stretch ratio curve in cross-linked SVs was larger than that in native SVs (13.88 vs. 5.83, P<0.05). The cross-linked SVs had a lower extent of endothelial denudation without fibre fracture during high-pressure distension than native SVs. Comparing with the non-cross-linked SVs, the percentage of endothelial nitric oxide synthase staining length on the endothelium of cross-linked SVs was significantly preserved after high-pressure distension (85.2% vs. 64.7%, P<0.05). CONCLUSION: Adventitial collagen cross-linking by glutaraldehyde reinforced venous wall by increasing stiffness and decreasing extensibility of SVs and mitigated the endothelial damage under high-pressure distension.

Adventitial Collagen Cross-Linking by Glutaraldehyde Reinforcing Human Saphenous Vein - Implication for Coronary Artery Bypass Grafting

ABSTRACT Introduction: A weak venous wall is one of the major reasons contributing to vein graft failure after coronary artery bypass grafting (CABG). We investigated whether adventitial collagen cross-linking by glutaraldehyde reinforces venous wall, preserving the endothelium of veins during high-pressure distention. Methods: Human saphenous veins (SVs) were collected from 40 patients undergoing CABG, and adventitia cross-linking was performed with 0.3% glutaraldehyde for five minutes. The cross-linked SVs were accessed by biodegradation assay, immunofluorescent staining, and tensile test. Native SVs and cross-linked SVs from another 20 patients received the 200 mmHg pressure distention for two minutes. Pressure-induced injury of SVs were accessed by immunohistochemistry and electron microscopy. Results: Time to digestion was 97±13 minutes for native SVs and 720±0 minutes for cross-linked SVs (P<0.05). After adventitial cross-linking, the collagen I fibres of the vein remarkably presented with compact and nonporous arrangement. In the high-stretch region (stretch ratio 1.4-1.8), the Young's elastic modulus of stress-stretch ratio curve in cross-linked SVs was larger than that in native SVs (13.88 vs. 5.83, P<0.05). The cross-linked SVs had a lower extent of endothelial denudation without fibre fracture during high-pressure distension than native SVs. Comparing with the non-cross-linked SVs, the percentage of endothelial nitric oxide synthase staining length on the endothelium of cross-linked SVs was significantly preserved after high-pressure distension (85.2% vs. 64.7%, P<0.05). Conclusion: Adventitial collagen cross-linking by glutaraldehyde reinforced venous wall by increasing stiffness and decreasing extensibility of SVs and mitigated the endothelial damage under high-pressure distension.

Strength, Elastic Properties and Fiber-Matrix Interaction Mechanism in Geopolymer Composites.

The current geopolymers have limited mechanical strength against the effect of tension, which makes them susceptible to brittle failure. However, owing to their potential as a sustainable construction material, there is growing interest in improving the poor mechanical properties of geopolymers. This study experimentally investigated crucial properties of polypropylene-fiber-reinforced fly ash-based geopolymer composites. The effects of polypropylene fibers (PPF) addition (0.5%, 1.0% and 1.5% by volume) on the mechanical properties of the geopolymer composites were investigated with respect to compressive and flexural strength, deformation behavior of Young's and shear moduli, and resilience capacity. In addition, scanning electron microscopy was performed to establish the morphology of the geopolymeric matrix and the fiber-matrix interfacial interaction. The addition of PPF significantly increased the flexural strength: compared with the control, at 7 days it was 27% greater for the 0.5% PPF composite and 65% greater for the 1.0% PPF composite. By 14 days it was 31% and 61% greater, respectively. By contrast, the 1.5% PPF composite had lower strength parameters compared with the control because the fiber dispersion increased the porosity. Similar trends were seen for resilience. The SEM observations showed the dispersion of the fibers and helped elucidate the fiber-matrix interaction mechanism.

The effect of whitening toothpastes on polyurethane and silicone orthodontic clear ligatures: A clinical study.

BACKGROUND: This study aimed to verify the effects of bleaching toothpaste on colour stability, elastic properties, surface topography between aesthetic polyurethane and silicone elastomeric ligatures from different brands. METHODS: Elastomeric ligatures tested were: 1-Mini Single Case Ligature Stick (RMO-polyurethane); 2-Ligature "S" Shaped Dispenser (RMO-Silicone); 3-Sany-tie (GAC-translucent polyurethane); and 4-Sili-tie (GAC-translucent silicone). The ligatures were randomly assigned from the brackets of canines and lower incisors of 40 patients. The study had two phases of 30 days in which a different toothpaste was used, followed by a washout period of 30 days. After each phase, ligatures were submitted to colour checking, tensile strength, and SEM. RESULTS: The average of the ultimate tensile strength (m = 2.59; DP = 0.014) was higher in the control ligatures if compared to the tested ones (m = 2.24; DP = 0.014). There were no statistically significant differences between toothpastes regarding the type of ligature. Also, no interaction was observed between toothpastes in ligature's ultimate tensile strength and strain. The type of toothpaste did not minimize colour changes. CONCLUSION: In conclusion, there was no difference in colour stability and elastic properties between polyurethane or silicone aesthetic elastomeric modules. Whitening toothpastes had no impact on ligatures performance after 30 days in the oral cavity.

Particle image velocimetry and digital image correlation for determining the elasticity modulus in wood

Several non-destructive testing techniques have been improved and tested in recent years. The non-destructive testing techniques using particle image velocimetry (PIV) and digital image correlation (DIC) differ from conventional testing techniques, as they allow making measurements indirectly. In this study, the elastic modulus in wood beams of Eucalyptus grandis and Pinus oocarpa were determined using PIV and DIC. The application of PIV and DIC techniques occurred during the static bending tests, when the displacements were also measured by the conventional method. The applied load values allowed calculating the elasticity modulus. In all regions of analysis, the mean values of the elasticity modulus found by the DIC, PIV and conventional method are statistically equivalent. It is concluded that the PIV and DIC testing techniques can be used to determine mechanical properties of wood.

Influence of photodynamic therapy and intracanal medication on Martens hardness, elastic modulus and bond strength of glass-fiber posts to endodontically treated root dentin.

BACKGROUND: The purpose of this in vitro study was to evaluate the influence of photodynamic therapy (PDT) with methylene blue photosensitizer (PS) and calcium hydroxide intracanal medication on Martens hardness (MH), elastic modulus (Eit) and adhesive bond strength of glass-fiber posts in different thirds of intraradicular dentin. METHODS: Ninety-six bovine teeth were distributed into the following 6 experimental groups: a negative control irrigated with deionized water; a positive control irrigated with deionized water and filled with calcium hydroxide intracanal medication (Ca[OH]2); Ca[OH]2 + methylene blue 50 mg/L without activation; Ca[OH]2 + methylene blue 100 mg/L without activation; Ca[OH]2 + methylene blue 50 mg/L activated by red laser; and Ca[OH]2 + methylene blue 100 mg/L activated by red laser (n = 16). MH and Eit were measured using an ultramicrodurometer under load action of 3 mN (n = 8). Adhesive bond strength was measured using the push-out test in a universal testing machine (n = 8), and representative samples underwent scanning electron microscopy. Data on MH, Eit, and bond strength were subjected to normality tests and analyzed by ANOVA and Tukey's test (α = 0.05). RESULTS: Methylene blue PS, activated or not by red laser, associated with calcium hydroxide medication did not promote significant difference as compared to the control groups irrigated with deionized water, associated or not with the use of intracanal medication, regarding mechanical properties and bond strength (p > 0.05). Experimental groups showed no difference between the thirds regarding root canal depth (p > 0.05), except for the positive control group, in which the apical third showed higher Eit values than the middle third (p = 0.0324). There was a predominance of mixed failure in all experimental groups, excepted the red laser-activated group treated with the highest concentration of methylene blue, which showed predominance of adhesive failure. CONCLUSIONS: PDT with methylene blue PS at 50 mg/L, associated with intracanal calcium hydroxide medication is a satisfactory alternative for endodontic treatment as there is no interference in the mechanical properties and bond strength among glass-fiber posts to intraradicular dentin at any depth of the root canal.

The Effect of Arabinoxylan and Wheat Bran Incorporation on Dough Rheology and Thermal Processing of Rotary-Moulded Biscuits.

Wheat bran incorporation into biscuits may increase their nutritional value, however, it may affect dough rheology and baking performance, due to the effect of bran particles on dough structure and an increase in water absorption. This study analyzed the enrichment effect of wheat bran and arabinoxylans, the most important non-starch polysaccharides found in whole wheat flour, on dough rheology and thermal behaviour during processing of rotary-moulded biscuits. The objective was to understand the contribution of arabinoxylans during biscuit-making and their impact when incorporated as wheat bran. Refined flour was replaced at 25, 50, 75, or 100% by whole flour with different bran particle sizes (fine: 4% > 500 µm; coarse: 72% > 500 µm). The isolated effect of arabinoxylans was examined by preparing model flours, where refined flour was enriched with water-extractable and water-unextractable arabinoxylans. Wheat bran had the greatest impact on dough firmness and arabinoxylans had the greatest impact on the elastic response. The degree of starch gelatinization increased from 24 to 36% in biscuits enriched with arabinoxylans or whole flour and coarse bran. The microstructural analysis (SEM, micro-CT) suggested that fibre micropores may retain water inside their capillaries which can be released in a controlled manner during baking.

Residual stresses explaining clinical fractures of bilayer zirconia and lithium disilicate crowns: A VFEM study.

OBJECTIVE: To understand the stress development in porcelain-veneered zirconia (PVZ) and porcelain-veneered lithium disilicate (PVLD) crowns with different veneer/core thickness ratios and cooling rates. To provide design guidelines for better performing bilayer restorations with the aid of Viscoelastic Finite Element Method (VFEM). METHODS: The VFEM was validated by comparing the predicted residual stresses with experimental measurements. Then, the model was used to predict transient and residual stresses in the two bilayer systems. Models with two different veneer/core thickness ratios were prepared (2:1 and 1:1) and two cooling protocols were simulated (Fast: ∼300 °C/min, Slow: ∼30 °C/min) using the heat transfer module, followed by stress analysis in ABAQUS. The physical properties of zirconia, lithium disilicate, and the porcelains used for the simulations were determined as a function of temperature. RESULTS: PVLD showed lower residual stresses than PVZ. The maximum tensile stresses in PVZ were observed in the cusp area, whereas those in PVLD were located in the central fossa. The 1:1 thickness ratio decreased stresses in both layers of PVZ. Slow cooling slightly decreased residual stresses in both systems. However, the cooling rate effect was more evident in transient stresses. SIGNIFICANCE: Slow cooling is preferable for both systems. A thinner porcelain layer over zirconia lowers stresses throughout the restoration. The different stress distributions between PVZ and PVLD may affect their failure modes. Smaller mismatches in modulus, CTE, and specific heat between the constituents, and the use of low Tg porcelains can effectively reduce the deleterious transient and residual tensile stresses in bilayer restorations.

Surface wave elastography is a reliable method to correlate muscle elasticity, torque, and electromyography activity level.

The shear elastic modulus is one of the most important parameters to characterize the mechanical behavior of soft tissues. In biomechanics, ultrasound elastography is the gold standard for measuring and mapping it locally in skeletal muscle in vivo. However, their applications are limited to the laboratory or clinic. Thus, low-frequency elastography methods have recently emerged as a novel alternative to ultrasound elastography. Avoiding the use of high frequencies, these methods allow obtaining a mean value of bulk shear elasticity. However, they are frequently susceptible to diffraction, guided waves, and near field effects, which introduces biases in the estimates. The goal of this work is to test the performance of the non-ultrasound surface wave elastography (NU-SWE), which is portable and is based on new algorithms designed to correct the incidence of such effects. Thus, we show its first application to muscle biomechanics. We performed two experiments to assess the relationships of muscle shear elasticity versus joint torque (experiment 1) and the electromyographic activity level (experiment 2). Our results were comparable regarding previous works using the reference ultrasonic methods. Thus, the NU-SWE showed its potentiality to get wide the biomechanical applications of elastography in many areas of health and sports sciences.

Assessing mechanical behavior of ostrich and equine trabecular and cortical bone based on depth sensing indentation measurements.

Guided bone regeneration surgeries are based on grafting a scaffold in the site to be repaired. The main focus of the scaffold is to provide mechanical support to newly formed blood vessels and cells that will colonize the grafted site, achiving bone regenertation. In this regards, the aim of this study was to characterize the anatomy, structular, surface morphologycal, chemical composition, and nanomechanical properties of ostrich and equine trabecular bone. Ostrich and equine specimens were obtained from a local abattoir and bone was obtained by blunt dissection, n = 5. Tissue bone anatomy and trabecular structure were measured using Computerized Axial Tomography (CAT). Atomic Force Microscopy (AFM) and Energy dispersion spectrometry of X-ray (EDS) were used to examine surface morphology and chemical composition of the trabecular ostrich and equine bone. Mechanical behavior was analysted by nanoindentation. Equine specimens were examined as control. CAT results suggest that in terms of anthropometry, ostrich tarsometatarsus bone is more suitable due to its length is 432.56 ± 3.12 mm vs. the highest human bone structures reported, which femur length is 533.66 ± 18.81 mm. Besides, the low radiodensity in the Hounsfield scale exhibits equine trabecular bone more brittle (Av = 1538.4 ± 0.9) than ostrich trabecular bone (Av = 462.1 ± 1.5). EDS showed a slight variation of the element Calcium (Ca2+) ranging from 20% to 25.5% wt in equine bone; the Ca2+ content variation is consistent with the ring-shaped morphology, while in ostrich bone the chemical composition is homogeneous. The elastic modulus, nanohardness (E = 5.3 ± 0.7 GPa, H = 220 ± 10 MPa) and average roughness (Ra = 207 nm) are similar to the human trabecular bone which could reduce the stress shielding, all of these findings suggest that ostrich bone can be promising for native tissue scaffolds for mechanically demanding applications. This research makes innovative contributions to science and provides a framework, which will allow us to address future biomedical tests, and rapidly identify promising organic and sustainable waste for tissue scaffold.

Effects of alternatively used thermal treatments on the mechanical and fracture behavior of dental resin composites with varying filler content.

The purpose of this study was two-fold: (i) to investigate whether the thermal treatment of direct dental resin composites (RCs) using microwave or autoclave heating cycles would modify the materials' strength as compared to the protocol without heating (control); and (ii) to compare the mechanical performance of direct and indirect RCs. Three RCs (from 3M ESPE) were tested: one indirect (Sinfony); and two direct materials (microhybrid - Filtek Z250; and nanofilled - Filtek Z350). Specimens from the direct RCs were prepared and randomly allocated into three groups according to the thermal treatment (n = 10): Control - no thermal treatment was performed; Microwave - the wet heating was performed using a microwave oven; and Autoclave - the wet heating was performed in an autoclave oven. The indirect RC was prepared following the instructions of the manufacturer. All materials were tested using flexural strength, elastic modulus, work of fracture (Wf), microhardness, and scanning electron microscopy (SEM) analyses. Data were analyzed with ANOVA and Tukey as well as Weibull analysis (α = 0.05). The thermal treatments tended to produce slight changes in the topography of direct RCs, especially by the autoclave' wet heating. Overall, the physico-mechanical properties changed after thermal treatment, although this effect was dependent on the type of RC and on the heating protocol. Sinfony showed the lowest modulus and hardness of the study, although it was the most compliant system (higher work of fracture). The load-deflection ability was also greater for the indirect RC. Reliability of the tested materials was similar among each other (p > 0.05). In conclusion, the alternative thermal treatments suggested here may significantly influence some aspects of the mechanical behavior of dental resin composites, with negative effects relying on both the chemical composition of the restorative material as well as on the wet heating protocol used. Clinicians should be aware of the possible effects that additional wet heating of direct resin composites using microwave or autoclave thermal protocols as performed here could have on the overall fracture and mechanical responses during loading circumstances.

Rheological properties of ethyl cellulose-monoglyceride-candelilla wax oleogel vis-a-vis edible shortenings.

The gelation process, elasticity, and mechanical recovery after shear were studied in mixed oleogels of ethylcellulose (EC), monoglycerides (MG), and candelilla wax (CW). EC oleogels produced without MG showed grainy texture due to incomplete dissolution of crystalline fractions of raw EC in the vegetable oil (150 °C). These fractions were eliminated by dissolving the raw EC/MG mixture in ethanol, evaporating the solvent, dispersing, and dissolving the solid residue in the vegetable oil (150 °C) prior gelation. The EC polymeric network, and MG, and CW crystals had a positive interaction on the elasticity of mixed oleogels. Mixed oleogels produced under static conditions showed a 100 % of elasticity recovery after shearing, a phenomenon associated with an EC interchain hydrogen bonding mediated by hydroxyl groups of MGs. This tentatively resulted from the formation of junction zones of the type EC-[MG]n-EC. The rheological behavior of these olegels was remarkably close to that of commercial shortenings.