In tissue engineering, scaffolds can be obtained by means of 3D printing. Different structures are used in order to reduce the stiffness of the solid material. The present article analyzes the mechanical behavior of octet-truss microstructures. Three different octet structures with strut radii of 0.4, 0.5, and 0.6 mm were studied. The theoretical relative densities corresponding to these structures were 34.7%, 48.3%, and 61.8%, respectively. Two different values for the ratio of height (H) to width (W) were considered, H/W = 2 and H/W = 4. Several specimens of each structure were printed, which had the shape of a square base prism. Compression tests were performed and the elasticity modulus (E) of the octet-truss lattice-structured material was determined, both, experimentally and by means of Finite Element Methods (FEM). The greater the strut radius, the higher the modulus of elasticity and the compressive strength. Better agreement was found between the experimental and the simulated modulus of elasticity results for H/W = 4 than for H/W = 2. The octet-truss lattice can be considered to be a promising structure for printing in the field of tissue engineering.

In the literature, many researchers investigated static loading effects on an implant. However, dynamic loading under impact loading has not been investigated formally using numerical methods. This study aims to evaluate, with 3D finite element analysis (3D FEA), the stress transferred (maximum peak and variation in time) from a dynamic impact force applied to a single implant-supported prosthesis made from different materials. A 3D implant-supported prosthesis model was created on a digital model of a mandible section using CAD and reverse engineering. By setting different mechanical properties, six implant-supported prostheses made from different materials were simulated: metal (MET), metal-ceramic (MCER), metal-composite (MCOM), carbon fiber-composite (FCOM), PEEK-composite (PKCOM), and carbon fiber-ceramic (FCCER). Three-dimensional FEA was conducted to simulate the collision of 8.62 g implant-supported prosthesis models with a rigid plate at a speed of 1 m/s after a displacement of 0.01 mm. The stress peak transferred to the crown, titanium abutment, and cortical bone, and the stress variation in time, were assessed.

Statement of problem. Previous peri-implantitis, peri-implant bone regeneration, or immediate implant placement postextraction may be responsible for the absence of cortical bone. Single crown materials are then relevant when dynamic forces are transferred into bone tissue and, therefore, the presence (or absence) of cortical bone can affect the long-term survival of the implant. Purpose: the purpose of this study is to assess the biomechanical response of dental rehabilitation when selecting different crown materials in models with and without cortical bone. Methods: several crown materials were considered for modeling six types of crown rehabilitation: full metal (MET), metal-ceramic (MCER), metal-composite (MCOM), peek-composite (PKCOM), carbon fiber-composite (FCOM), and carbon fiber-ceramic (FCCER). An impact-load dynamic finite-element analysis was carried out on all the 3D models of crowns mentioned above to assess their mechanical behavior against dynamic excitation. Implant-crown rehabilitation models with and without cortical bone were analyzed to compare how the load-impact actions affect both type of models. Results: numerical simulation results showed important differences in bone tissue stresses. The results show that flexible restorative materials reduce the stress on the bone and would be especially recommendable in the absence of cortical bone. Conclusions: this study demonstrated that more stress is transferred to the bone when stiffer materials (metal and/or ceramic) are used in implant supported rehabilitations; conversely, more flexible materials transfer less stress to the implant connection. Also, in implant-supported rehabilitations, more stress is transferred to the bone by dynamic forces when cortical bone is absent.