## 4 Discussion
It facilitates the growth of human chondrocytes, preserving their cell morphology, viability, gene expression, and matrix production potency [44]. [PERSON] et al. [38] used a porcine antigen-free cartilage as a 3D scaffold. This type of scaffold falls within the category of natural polymers, specifically in the subgroup of gelatins. Gelatin has proven to be highly effective in the formulation of bioink for bioprinting materials due to its distinctive properties, such as high biocompatibility, biodegradability, significant cross-linking potential, and improved thermal stability in physiological environments [45]. However, despite the extensive advantages offered by advanced fabrication techniques, bioprinting currently faces numerous obstacles and challenges that limit its wide-ranging applications. Further studies are necessary to explore and identify the ideal type for optimal functionality. The potential to engineer anatomically accurate biomaterials holds tremendous promise for alveolar bone reconstructions. This systematic review uncovered that, across all the examined studies, a notable enhancement in bone augmentation and implant stability was observed with the utilization of multidimensional customized scaffolds. In general, each scaffold aims to mimic the natural extracellular matrix of bone tissue for a specific time period, both in terms of structure and mechanics. The limitations of all scaffolds are often associated with imaging resolution and, in most cases, inadequate mechanical properties. Moreover, the lack of cell viability for long time periods in these anatomic fields remains a problem to be solved. Subsequent investigations should leverage the insights gained from our analysis to formulate preclinical and clinical research protocols characterized by improved consistency. The combination of multiple components will result in a significant variability of materials, comprising various cell types, and an enhanced control over the delivery of bioactive agents. Future advancements may prioritize enhancing the accuracy and precision of 3D-printing development. High-resolution CT scanners will enable quantitative analysis of scaffolds and monitoring of the mineralization process. Improved CT scanners will also allow operators to thoroughly evaluate any failures and comprehend the overall micro- and macro-mechanical properties of the applied materials. Such an approach would facilitate more meaningful comparisons and enhance the overall quality of foundational data, thereby contributing to the strategic advancement of future clinical studies. In the future, enhancing custom-made scaffolds with stem cells or bioactive agents could expedite vascular invasion and promote bone regeneration. Conceptualization, L.T., D.T. and C.A. ; methodology, A.A., S.D. and P.K. ; software, P.K. and P.B. ; validation, P.K., L.B. and S.D. ; writing--original draft preparation, P.K. and S.D. ; writing--review and editing, S.D., L.B., D.T., P.B. and A.A.; supervision, C.A. and L.T. ; funding acquisition, L.T. All authors have read and agreed to the published version of the manuscript. This research has been cofinanced by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH-CREATE-INNOVATE (project code: T2 EDK-01641). Data Availability Statement: Data are contained within the article. The authors declare no conflicts of interest.