Synergistic effect of nanotopography and bioactive ions on peri-implant bone response

Both bioactive ion chemistry and nanoscale surface modifications are beneficial for enhanced osseointegration of endosseous implants. In this study, a facile synthesis approach to the incorporation of bioactive Ca²⁺ ions into the interlayers of nanoporous structures (Ca-nano) formed on a Ti6Al4V alloy surface was developed by sequential chemical and heat treatments. Samples with a machined surface and an Na⁺ ion-incorporated nanoporous surface (Na-nano) fabricated by concentrated alkali and heat treatment were used in parallel for comparison. The bone response was investigated by microcomputed tomography assessment, sequential fluorescent labeling analysis, and histological and histomorphometric evaluation after 8 weeks of implantation in rat femurs. No significant differences were found in the nanotopography, surface roughness, or crystalline properties of the Ca-nano and Na-nano surfaces. Bone-implant contact was better in the Ca-nano and Na-nano implants than in the machined implant. The Ca-nano implant was superior to the Na-nano implant in terms of enhancing the volume of new bone formation. The bone formation activity consistently increased for the Ca-nano implant but ceased for the Na-nano implant in the late healing stage. These results suggest that Ca-nano implants have promising potential for application in dentistry and orthopedics.