## 4 Discussion
The porous structure of the scaffolds not only promotes cell adhesion, proliferation, and differentiation but also allows cells to interact with the extracellular matrix, providing essential mechanical support for tissue growth. This porous structure facilitates rapid cell diffusion and offersa larger area for vascularization and bone growth, ultimately improving implant fixation and promoting bone integration [45]. In the study by [PERSON] et al. (2021) [27], the compressive strength of the regenerated bone with the HA/TCP scaffold was equivalent to that of native bone. The large size of the scaffold (30 mm in diameter) may have influenced the compressive strength, providing a robust structure to support compressive forces. This may have contributed to the equivalence in compressive strength with native bone. The pore size of 4 mm is relatively large, which may indicate that the scaffold favors vascularization and bone regeneration but could reduce mechanical strength. However, the scaffold successfully supported bone regeneration, suggesting that other factors, such as the quality of the regenerated bone, were also important [27]. [PERSON] et al. (2007) [35] showed that the BMSCs/b-TCP group had bending biomechanical properties similar to normal mandibles, suggesting that the scaffold provided adequate biomechanical support for bone regeneration. The scaffold's high porosity (70%) may have facilitated bone regeneration, but this could have compromised its mechanical strength. However, the combination with BMSCs may have compensated for this loss of strength, resulting in suitable biomechanical properties. The pore size of 450 \(\pm\) 750 \(\upmu\)m is relatively large, which may have favored cell regeneration but likely reduced the scaffold's strength compared to other materials with lower porosity. This indicates a trade-off between bone regeneration and mechanical strength. The size and cuboid shape (30 mm \(\times\) 15 mm \(\times\) 10 mm) of the BMSCs/b-TCP scaffold suggest that it was designed to support a significant load, which is important for testing bending mechanical properties. A larger and more robust scaffold may better withstand bending forces and stresses than smaller scaffolds, which could explain the results similar to native and autogenous bone in bending tests [35; 45]. Based on the results found by [PERSON] et al. (2019) [30], it can be concluded that a pore size of 300-400 \(\upmu\)m is suitable for mechanical fixation and bone regeneration, corroborating the findings of [PERSON] et al. (2021) [26] and [PERSON] et al. (2009) [33]. These correlations indicate that the geometry of the scaffold, including size, porosity, and pore size, has a significant impact on the material's mechanical properties, especially on bone regeneration and the scaffold's mechanical strength. However, other factors, such as the presence of BMPs or stem cells, may also modify mechanical outcomes independently of the geometric characteristics. Macroscopic features that provide a larger surface area of contact (such as granular and disc-shaped) [28; 31] or are adaptable to specific defects tend to favor better integration and bone formation. Additionally, combining macroscopic features with other characteristics, such as material composition and porosity, is crucial in determining the overall effectiveness of scaffolds in bone regeneration. Therefore, when designing scaffolds for specific applications, the consideration of macroscopic features is essential for optimizing bone regeneration outcomes [9; 13; 28; 39]. The preclinical studies analyzed in this review demonstrate significant advances in applying ceramic biomaterials for maxillofacial bone regeneration, particularly in critical-sized defects. A key factor influencing the translational relevance of these findings is the choice of animal model. Rodents, especially rats, have proven to be efficient for early-stage mechanistic studies in small defects, such as calvarial models.