Qingyang Liu, Fei Wei, Melanie Coathup, Wen Shen, Dazhong Wu

Full text link : https://pubmed.ncbi.nlm.nih.gov/37689976/

Effect of Porosity and Pore Shape on the Mechanical and Biological Properties of Additively Manufactured Bone Scaffolds

1. Scientific Reference

• Study Title: Effect of Porosity and Pore Shape on the Mechanical and Biological Properties of Additively Manufactured Bone Scaffolds
• Authors: Qingyang Liu, Fei Wei, Melanie Coathup, Wen Shen, Dazhong Wu
• Journal: Advanced Healthcare Materials
• Year of Publication: 2023
• DOI: 10.1002/adhm.202301111

2. Scientific Background

Advances in additive manufacturing have significantly expanded the possibilities for designing bone scaffolds with highly controlled internal architectures. In bone tissue engineering, scaffold geometry is increasingly recognized as a critical design parameter because it influences both the mechanical stability of the construct and the biological environment that supports tissue regeneration.

For applications related to bone reconstruction and future implant rehabilitation, achieving an optimal balance between structural strength and cellular compatibility remains a major challenge. While biomaterial selection is essential, the organization of the scaffold’s pore network may also affect cell attachment, proliferation, and load-bearing capacity. This study explores how variations in porosity and pore geometry contribute to these properties, providing information that may assist in the design of next-generation scaffolds for regenerative medicine.

3. Study Objective

The purpose of this study was to investigate how scaffold porosity and pore geometry influence the biological and mechanical performance of additively manufactured bone scaffolds. The authors specifically evaluated whether different architectural designs affect cellular responses and compressive mechanical behavior, with the objective of identifying structural features that may improve scaffold performance for bone tissue engineering applications.

4. Methodology

This investigation was conducted as a preclinical in vitro study.

Polylactic acid (PLA) scaffolds were manufactured using fused filament fabrication with porosity levels ranging from 15% to 78%. Three different internal architectures were evaluated: a conventional regular structure with rectangular pores and two triply periodic minimal surface (TPMS) designs, namely gyroid and diamond.

Murine-derived macrophages and human bone marrow-derived mesenchymal stromal cells (hBMSCs) were cultured on the scaffolds to assess biological responses. Mechanical characterization included compression testing, while surface morphology was examined to evaluate structural characteristics that could influence cell behavior. Additional experimental details, including sample size and specific testing parameters, are not provided in the available abstract.

5. Main Findings

Both scaffold porosity and pore architecture influenced the biological and mechanical performance of the manufactured constructs.

Scaffolds with porosity levels of 15%, 30%, and 45% demonstrated the most favorable levels of macrophage and hBMSC growth. When comparing pore geometries, the gyroid and diamond architectures supported greater macrophage proliferation than the regular design, whereas the diamond structure produced the highest proliferation of human mesenchymal stromal cells.

Mechanical testing also demonstrated clear differences between scaffold configurations. Both TPMS architectures exhibited superior compressive performance compared with regular pore structures. Among all evaluated designs, the diamond scaffold achieved the highest compressive modulus and compressive strength. Surface characterization further revealed increased roughness in the gyroid and diamond scaffolds at equivalent porosity levels, a feature that was associated in this study with improved cellular attachment and proliferation.

6. Clinical Interpretation

This study highlights the importance of scaffold architecture as a design variable that extends beyond simple material selection. The findings suggest that modifying pore geometry can simultaneously influence structural integrity and the biological environment supporting bone-forming cells.

From the perspective of regenerative medicine and future bone reconstruction strategies, scaffolds must provide sufficient mechanical support while creating conditions favorable for cellular colonization and tissue formation. The observed performance of TPMS-based designs, particularly the diamond architecture, indicates that carefully engineered internal geometries may offer advantages when developing customized bone substitutes.

However, these findings should be interpreted within the context of the study design. The biological observations were generated under controlled laboratory conditions using cultured cells and synthetic scaffolds. Consequently, the results cannot be directly translated into clinical performance or implant success. Further validation in animal models and human clinical studies will be required before these architectural concepts can be incorporated into routine reconstructive procedures in implant dentistry or oral and maxillofacial surgery.

7. Clinical Applications

The results may support the future development of patient-specific bone scaffolds manufactured through additive manufacturing technologies.

Knowledge regarding the interaction between scaffold architecture, mechanical performance, and cellular behavior may contribute to the design of biomaterials intended for bone regeneration prior to implant placement or complex maxillofacial reconstruction. These findings may also be valuable for researchers developing digitally designed scaffolds within CAD/CAM-based regenerative workflows. Nevertheless, the available data do not establish clinical efficacy, and no direct therapeutic recommendations can be drawn from this preclinical investigation.

8. Level of Evidence, Limitations and Transparency

This publication represents a preclinical in vitro experimental study, corresponding to an early level of scientific evidence.

The investigation provides mechanistic insight into how scaffold architecture affects biological and mechanical properties but does not include animal experiments or clinical validation. Methodological limitations are not specifically discussed in the available abstract. Likewise, no long-term biological performance or clinical outcomes are reported.

The information provided does not mention any conflicts of interest or industry affiliations.

9. Key Study Highlights

• Study type: Preclinical in vitro study.
• Level of evidence: Preclinical.
• Population or samples: Not specified in the available information.
• Number of patients or implants: Not applicable.
• Follow-up period: Not specified.
• Primary outcome: Influence of porosity and pore geometry on scaffold mechanical and biological performance.
• Main finding: Diamond and gyroid architectures demonstrated improved compressive properties, while moderate porosity levels favored cellular proliferation.
• Scientific conclusion: Scaffold architecture plays a significant role in optimizing additively manufactured constructs intended for bone tissue engineering.
• Potential limitations: Laboratory-based study with no in vivo or clinical validation; additional methodological limitations are not detailed in the available abstract.

10. Scientific Impact

This study contributes to the growing body of research focused on the optimization of additively manufactured scaffolds for bone regeneration. Rather than concentrating solely on biomaterial composition, it emphasizes the importance of architectural design as a determinant of both mechanical competence and biological performance.

The work provides useful experimental evidence supporting the development of computationally designed scaffold geometries, particularly TPMS structures, for regenerative applications. Although the findings remain preclinical, they offer valuable guidance for future investigations exploring patient-specific scaffold manufacturing, advanced bone reconstruction strategies, and the integration of additive manufacturing into regenerative implant dentistry. Further translational research will be necessary to determine whether these laboratory observations translate into improved clinical outcomes.

11. Editorial Conclusion

This preclinical study demonstrates that scaffold porosity and pore geometry substantially influence both cellular responses and mechanical behavior in additively manufactured bone scaffolds. Among the evaluated designs, the diamond architecture showed the most favorable overall performance under the tested conditions. While these findings provide meaningful guidance for scaffold design in bone tissue engineering, additional in vivo and clinical investigations remain essential before their relevance to routine reconstructive or implant-related procedures can be fully established.