Bone remodeling effect of a chitosan and calcium phosphate-based composite

Chitosan is a biocompatible polymer that has been widely studied for tissue engineering purposes.The aim of this research was to assess bone regenerative properties of an injectable chitosan and calcium phosphate-based composite and identify optimal degree of deacetylation(%DDA)of the chitosan polymer.Drill holes were generated on the left side of a mandible in Sprague-Dawley rats,and the hole was either left empty or filled with the implant.The animals were sacrificed at several time points after surgery(7–22 days)and bone was investigated using micro-CT and histology.No significant new bone formation was observed in the implants themselves at any time points.However,substantial new bone formation was observed in the rat mandible further away from the drill hole.Morphological changes indicating bone formation were found in specimens explanted on Day 7 in animals that received implant.Similar bone formation pattern was seen in control animals with an empty drill hole at later time points but not to the same extent.A second experiment was performed to examine if the%DDA of the chitosan polymer influenced the bone remodeling response.The results suggest that chitosan polymers with%DDA between 50 and 70%enhance the natural bone remodeling mechanism.

Micro computed tomography based finite element models for elastic and strength properties of 3D printed glass scaffolds

In this study,the mechanical properties of glass scaffolds manufactured by robocasting are investigated through micro computed tomography(/x-CT)based finite element modeling.The scaffolds are obtained by printing fibers along two perpendicular directions on parallel layers with a 90°tilting between two adjacent layers.A parametric study is first presented with the purpose to assess the effect of the major design parameters on the elastic and strength properties of the scaffold;the mechanical properties of the 3D printed scaffolds are eventually estimated by using the\i-CT data with the aim of assessing the effect of defects on the final geometry which are intrinsic in the manufacturing process.The macroscopic elastic modulus and strength of the scaffold are determined by simulating a uniaxial compressive test along the direction which is perpendicular to the layers of the printed fibers.An iterative approach has been used in order to determine the scaffold strength.A partial validation of the computational model has been obtained through comparison of the computed results with experimental values presented in[10]on a ceramic scaffold having the same geometry.All the results have been presented as non-dimensional values.The finite element analyses have shown which of the selected design parameters have the major effect on the stiffness and strength,being the porosity and fiber shifting between adjacent layers the most important ones.The analyses carried out on the basis of the/x-C7 data have shown elastic modulus and strength which are consistent with that found on ideal geometry at similar macroscopic porosity.