Three-dimension (3D) scaffolds for bone tissue regeneration were produced combining three different phases: nanometric hydroxyapatite (HA) was synthesized by precipitation method and the crystals nucleation took place directly within collagen fibrils following a biologically inspired mineralization process; polycaprolactone was employed to give the material a 3D structure. The chemico-physical analysis carried out to test the material's properties and composition revealed a high similarity in composition and morphology with biologically mineralized collagen fibrils and a scaffold degradation pattern suitable for physiological processes. The micro- computerized tomography (micro-CT) showed 53.53% porosity and a 97.86% mean interconnected pores. Computer-aided design and computer-aided manufacturing (CAD-CAM) technology was used for molding the scaffold's volume (design/shape) and for guiding the surgical procedure (cutting guides). The custom made scaffolds were implanted in sheep mandible using prototyped surgical guides and customized bone plates. After three months healing, scanning electron microscopy (SEM) analysis of the explanted scaffold revealed a massive cell seeding of the scaffold, with cell infiltration within the scaffold's interconnected pores. The micro-CT of the explanted construct showed a good match between the scaffold and the adjacent host's bone, to shield the implant primary stability. Histology confirmed cell penetration and widely documented neoangiogenesis within the entire scaffold's volume. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 723-734, 2017.

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The study of nanocrystalline calcium phosphate physical-chemical characteristics and, thereafter, the possibility to imitate bone mineral for the development of new advanced biomaterials is constantly growing. The availability to use synthetic biomimetic hydroxylapatites (HA), since they are the most important inorganic constituents of hard tissues in vertebrates, represents a great turning point in bone tissue engineering because of their chemical similarity to the biological mineral component. The ability to control the architecture and strength of a bone tissue engineering scaffold is critical to achieve a harmony between the scaffold and the host tissue. The scaffold attempts to mimic the function of the natural extracellular matrix, providing a temporary template for the growth of target tissues. Scaffolds should have suitable architecture and strength to serve their intended function. Rapid prototyping (RP) technique is applied to tissue engineering to satisfy this need and to create a scaffold with fully interconnected pore structure directly from the scanned and digitized image of the defect site. In this study, we developed a biomimetic mineralized collagen/Polycaprolactone composite by self-assembling process of collagen fibers and nucleation of a nanostructured HA mimicking the natural bone. This new solution provides a hybrid material, based on natural components of bone (collagen and HA) and the support of the widely-tested PCL (polycaprolactone) giving the scaffolds ideal characteristics such as resorption, biocompatibility and 3-D printability. CAD design of the microstructure and bioprinting fulfills the need to finely control the scaffold’s shape to best fit the anatomical defect, the possibility of customization and the ability to perfectly control spatial distribution of pores and their morphology. The results allowed the conclusion that these scaffolds are biocompatible and allow the colonization and proliferation of MSC (mesenchymal stem cell). The in vivo results confirm the scaffold’s biocompatibility and its composition and structure create the basis for bone tissue regeneration.