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The use of porous scaffolds for repairing the damaged bone tissues has been increased in recent years. As exploration of the mechanical properties of the scaffolds on the basis of experiments is time consuming and uneconomic, mathematical models are increasingly being introduced into the field, but most of them rely on finite element method and theoretical studies are rarely found in the literature. In this paper, different micromechanical models are presented for obtaining the effective elastic properties of bone scaffolds. Using these models, the mechanical properties of different scaffolds, including ceramic and composite bone scaffolds, are investigated. Single scale and multi-scale modeling approaches are used to simulate the ceramic and composite scaffolds, respectively. Furthermore, because of the wide application of hydroxyapatite in fabrication of bone scaffolds, the mechanical properties of hydroxyapatite scaffolds in different porosities are obtained in the current study by means of the presented methods. Results show that Dewey, self-consistent and differential schemes are the best methods in calculation of the value of Young’s modulus of these scaffolds in porosity ranges of less than 30 %, 30 to 60 % and more than 60 %, respectively. Moreover, self-consistent scheme gives good estimation of the value of Poisson’s ratio of hydroxyapatite scaffolds in different porosities. By obtaining the values of the mechanical properties of the scaffolds in different porosities by these models and using the statistical analysis, the mathematical relationship between the porosity and the mechanical properties of this kind of scaffolds (Young’s modulus and Poisson’s ratio) is obtained.

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The main purpose of using scaffolds replacement tissues of the body. The most important part is to choose the type and steel scaffolding so that eventually will replace the damaged tissue. One of the mechanisms proposed to reshape the bone is based on its piezoelectric properties. It seems that the use of piezoelectric materials is an option for use in the body, is a unique privilege. Therefore, the ceramic barium titanate (BaTiO3) having good piezoelectric properties, Curie temperature of about 125˚C and laboratory observations that non-toxic in the body, as a candidate to replace and simulate the performance of bone tissue, has been proposed. In this study, the design and produce of barium titanate piezoelectric ceramic as a bone scaffold with foam casting method and become coated with gelatinous and nanostructured HA composite for bone tissue engineering. Then test its properties by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and mechanical properties were studied. In the end, it was concluded that the barium titanate scaffold produse with foam casting method coated with gelatin nano hydroxyapatite composite structure suitable for use in bone tissue engineering.

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The use of Additive Manufacturing (AM) techniques in medical science has resulted in a great change in this field, especially in bone tissue engineering. One of these techniques is the Fused Deposition Modeling (FDM) which is used to make bone scaffolds. From view point of bone tissue engineering, bone scaffolds must have acceptable mechanical properties in addition to the required biological properties. In this study, at first the printing parameters including layer height, printing speed and number of filaments in each row were determined and bone scaffolds were made with two different materials polylactic acid (PLA) and polycaprolactone (PCL) and were subjected to the compression tests. The results of Young’s modulus and yield stress analyzed in Design Expert software showed that increasing the layer height reduces the mechanical properties. Also, increasing the number of filaments in each row increases the elastic modulus of the scaffold. For example, for scaffolds made of PLA, the maximum modulus of elasticity belongs to 12 filament scaffolds with a layer height of 0.1, which is equal to 319 MPa, and the minimum elastic modulus belongs to 8 filament scaffolds with a layer height of 0.3, which is equal to 143 MPa. Printing speed for scaffolds made of PLA does not have a significant effect on the Young’s modulus and yield stress. But for scaffolds made of PCL, increasing the printing speed reduces the modulus of elasticity but it doesn’t have a significant effect on yield stress.