A 3D printed TCP/HA structure as a new osteoconductive scaffold for vertical bone augmentation

Current bone grafting strategies often struggle to achieve consistent vertical bone augmentation. Traditional particulate grafts like Bio-Oss and Ceros have limitations in guiding new bone formation in specific directions. While porous scaffolds are known to support osteoconduction, their structure must be precisely engineered to optimize bone growth. Prior research has shown that interconnected porosity enhances cell migration and vascularization. However, the exact impact of scaffold architecture on vertical bone growth remains unclear. This gap motivated the development of a 3D-printed scaffold with defined porosity and interconnectivity. The sheep calvarial model is a well-established system for studying bone regeneration. It allows for controlled histomorphometric analysis of new bone formation. This study introduces a novel scaffold design aimed at improving vertical bone augmentation.

The goal was to evaluate a new 3D-printed scaffold for vertical bone growth in a controlled animal model. The scaffold, OsteoFlux(®), is made of tricalcium phosphate and hydroxyapatite. It features a layered, porous structure that can be shaped to fit bone defects. The study compared OF with two existing bone substitutes: Bio-Oss and Ceros. The primary outcome was new bone formation at specific distances from the bony bed. The secondary aim was to assess scaffold degradation over time. The sheep calvarial model was selected for its predictability in bone regeneration studies. The hypothesis was that OF would outperform standard grafts in promoting vertical bone growth.

The study used a sheep calvarial model with 12 adult sheep. Six titanium hemispheres were implanted per animal. Each hemisphere was filled with one of three materials: OF, Bio-Oss, or Ceros. The implants were placed on the calvaria and left for 8 or 16 weeks. Histomorphometric analysis was performed to measure new bone formation. The primary metric was the percentage of new bone relative to the total implant volume. A secondary measure was new bone formation at 3 mm above the bony bed. The study compared OF with Bio-Oss and Ceros at both time points. The 3D-printed OF scaffold was designed with controlled porosity and interconnectivity.

At 8 weeks, OF produced twice as much new bone as Bio-Oss and Ceros. OF yielded 22% ± 2.1 new bone, compared to 11.5% ± 1.9 for Bio-Oss and 12.9% ± 2.1 for Ceros. At 3 mm above the bony bed, OF showed four times more new bone than the other materials. This difference was statistically significant (n = 8, P < 0.002). By 16 weeks, all three materials showed similar levels of new bone synthesis. Moderate degradation was observed in all scaffolds by week 16. OF demonstrated superior early performance in vertical bone growth. The controlled porous structure of OF translated into enhanced osteoconductivity.

The study found that OF outperformed Bio-Oss and Ceros in promoting vertical bone growth during the first 8 weeks. The 3D-printed scaffold's controlled porosity and interconnectivity likely contributed to this effect. By 16 weeks, all materials showed similar new bone formation. The authors suggest that OF's architecture supports early osteoconductivity. The fourfold increase in new bone at 3 mm above the bony bed is a key finding. OF showed moderate degradation by week 16, which is consistent with other bone substitutes. The results indicate that OF could be a promising alternative for vertical bone augmentation. Further clinical testing is needed to confirm these findings in human subjects.