## 4 Discussion
These observations emphasize that scaffold design must be tailored to the unique biological and mechanical demands of critical defects, particularly when translating regenerative strategies from preclinical models to human applications [6,8,9]. Current bone reconstruction strategies rely on filling defects with autologous, allogenic, or xenogenic bone grafts, which promote healing through osteoinduction, osteoconduction, and osseointegration. However, autologous grafts are associated with higher donor site morbidity, while allogenic and xenogenic grafts face issues of availability, compatibility, and the risk of rejection or disease transmission. Furthermore, none of these grafts are tailored to the shape and size of the defect, which also hinders regeneration in extensive areas, increases surgical time and, consequently, operational costs [4,6,9,36,38,39,40,38]. Tissue engineering has focused on developing alternative biological substitutes with the structural properties of bone and the necessary mechanical properties to aid in regenerating large bone defects that do not spontaneously heal [9,37,39,40]. In this context, AM techniques, such as 3D printing, are considered innovative and promising for producing advanced materials, as they enable the printing of various biomaterials. Additionally, they offer several advantages over conventional techniques, including rapid prototyping, high repeatability, freeform fabrication, and precise fidelity to the shape and size of the defect [6,9]. These printing technologies have enabled the manufacturing of scaffolds with standardized geometric properties, including size, shape, pore distribution, and porosity, which directly influence vascularization and, consequently, the regeneration process [4,41]. The clinical success of scaffolds in tissue engineering depends on a complex combination of factors, including the biocompatibility of these materials, vascularization capacity, bone neoformation capacity, porosity and interconnectivity, mechanical stability, controlled degradability, and interaction with the host tissue [10,11,16,37]. Therefore, the careful design and manufacturing processes of these scaffolds are crucial for optimizing these factors and promoting effective bone regeneration, as both macro- and microarchitecture influence these properties and the performance of the scaffold [16,17]. Scaffolds serve as temporary support structures that mimic the extracellular matrix of bones, providing a framework for cells to attach, proliferate, and differentiate. In addition to structural support, scaffolds are designed to be biocompatible, meaning they do not cause an adverse immune response and can integrate well with the surrounding tissue [17,26]. Ideally, scaffolds degrade as new bone tissue forms, ensuring a gradual replacement by natural bone without requiring removal, while also promoting bone growth (osteoconductivity). Scaffolds can be functionalized with cells, growth factors, drugs, or other bioactive molecules to enhance their regenerative properties and guide tissue growth [6,17,42]. Theyare available in various forms, including porous structures, fibers, and meshes, each tailored to specific applications in bone regeneration [5; 41]. The selection and development of suitable biomaterials that mimic the properties of native bone and promote regeneration are complex. From a mechanical perspective, matching the characteristics of the scaffold with the tissue to be repaired is crucial to ensure the effectiveness of regeneration, structural stability, and long-term functional integration. Resembling the mechanical properties of the native tissue, such as elasticity modulus and strength, ensures that the scaffold can support physiological loads without excessive deformation or failure. This uniform load distribution minimizes stress points and promotes better integration and tissue regeneration.