Biomimetic bone-matching DLP-printed gradient TPMS ceramic implants.

The aim of this study is to develop a new type of bone implant that mimics the mechanical properties of natural bone through a gradient structure. The specific problem addressed is the mismatch between implant and bone stiffness, which can lead to stress-shielding and implant failure. The motivation is to improve long-term stability in dental and craniomaxillofacial repairs. To achieve this, the researchers designed TPMS scaffolds with porosity gradients. These scaffolds were printed using digital light processing (DLP) to ensure precise control over geometry and porosity. The study evaluates five different TPMS topologies to determine which offers the best mechanical and biological performance. The goal is to identify a scaffold that matches bone’s mechanical properties while supporting cell growth. This approach aims to bridge the gap between computational models and clinical applications in implant design.

The researchers designed five TPMS topologies—Gyroid, Schwarz, Diamond, Lidinoid, and Split-P—with both gradient and uniform porosity structures. These designs were fabricated using digital light processing (DLP) to create zirconia scaffolds. After printing, the scaffolds were sintered to enhance structural integrity. Mechanical properties, including compressive strength and elastic modulus, were measured using compression tests. Computational fluid dynamics (CFD) simulations were used to assess fluid flow and shear stress within the scaffolds. In vitro cytocompatibility was evaluated using CCK-8 assays and live-dead staining to measure cell viability and proliferation. Statistical analysis was performed using one-way ANOVA with a significance threshold of α = 0.05. This approach allowed the researchers to compare the performance of different topologies and porosity configurations. The results were analyzed to determine which design best mimicked natural bone mechanics while supporting cell growth.

The gradient Diamond scaffold achieved the highest compressive strength of 215.7 ± 8.3 MPa and an elastic modulus of 4.2 ± 0.2 GPa, significantly higher than other groups (P=0.002). This modulus closely matches that of natural bone, potentially reducing stress-shielding effects. The Diamond scaffold also showed 25% higher permeability compared to uniform designs, with optimal fluid shear stress in the range of 0.5–3 Pa. These findings suggest improved nutrient transport and cell adhesion. In vitro tests revealed cell proliferation reaching 150 ± 8% of the control group at day 7, with over 95% viability. Other topologies, such as Gyroid and Schwarz, showed lower mechanical performance and permeability. The gradient structure was found to be more effective than uniform porosity in balancing mechanical strength and biological function. These results indicate that the Diamond topology is a promising candidate for next-generation bone implants.

The study concludes that the Diamond topology with gradient porosity offers superior mechanical and biological performance compared to other TPMS designs. The elastic modulus of 4.2 GPa closely matches that of natural bone, addressing the issue of stress-shielding. The scaffold’s higher permeability and fluid shear stress suggest improved nutrient transport and cell adhesion. These findings support the potential of gradient TPMS scaffolds for dental and craniomaxillofacial applications. The authors propose that this design could enhance long-term implant stability. However, the study notes that further in-depth biological evaluation is needed before clinical translation. Mechanical fatigue testing is also recommended to assess long-term durability. The results suggest that biomimetic gradient structures can effectively bridge the gap between computational models and functional implants.