Bone regeneration over subperiosteal implants using 3D printed polycaprolactone scaffolds

Historical and contemporary subperiosteal implants continue to encounter issues with peri-implantitis, peri-implant mucositis and bacterial colonisation of the implant substructure, leading to failure of the entire implant. Combining Poly (ε-capro-lactone) (PCL) overlay scaffolds with subperiosteal implants could improve their success by encasing the implant in bone. A large animal study was undertaken with 4 groups (Titanium-only control, PCL Open, PCL Closed, and Nano PCL). Titanium subperiosteal implants were inserted with various overlying 3D printed PCL scaffold designs. Uncovered titanium was used as a control. Bony deposition was assessed at 3 months and 6 months via computed tomography, and histology at 6 months. PCL scaffolds reliably enabled bony deposition over the subperiosteal implants. A Mixed Model Analysis showed a statistically significant result both radiographically and histologically between the Titanium-only control group and the PCL Closed group, particularly surrounding the regenerated bone volumes and bone heights (maximum and mean). The PCL Open design was the next most reliable scaffold when compared against the Titanium-only group. This pilot study demonstrates that functionalised PCL scaffolds overlying subperiosteal implants can lead to bone deposition over titanium, with successful conversion into endosteal implants. PCL closed scaffold was the most effective design. This provides a basis for future clinical trials to improve the success rates of subperiosteal implants.