Titanium implant functionalization with phosphate-containing polymers may favour in vivo osseointegration

Aim: Osseointegration of titanium implants is predictable, but can be improved via surface functionalization. Materials and Methods: One hundred and twenty implants were installed in parietal bone of 12 domestic pigs and left to heal for 1 or 3 months. Five groups were defined according surface treatments: immersion in water (H₂O), 10% polyphosphoric acid (PPA10), 1% phosphorylated pullulan (PPL1), 10% phosphorylated pullulan (PPL10) or 10% phosphorylated pullulan + 1 μg bone morphogenetic protein-2 (PPL10 BMP). As primary outcome, implant osseointegration was evaluated by quantitative histology, namely peri-implant bone formation (B/T in %) and bone-to-implant contact (BIC in %) for each healing period. The Wilcoxon signed-rank test and Mann–Whitney U-test with α = 0.05 were performed. Results: PPL10 and PPA10 groups showed significantly higher B/T and BIC results than the control (H₂O) group at 1-month (p <.05). No significant difference was found between PPL1 and H₂O or between PPL10 BMP and H₂O, irrespective of healing time (1 or 3 months) or investigated parameter (B/T and BIC; p >.05). After 3 months, no experimental group showed a significant difference compared to the control group (H₂O) for both investigated parameters (B/T and BIC; p >.05). Conclusion: Functionalizing titanium implants with inorganic or organic phosphate-containing polymers at 10 wt% concentration may stimulate peri-implant bone formation and implant osseointegration at early healing times.