Bone induction of TiO₂ and Al₂O₃ ceramic

Protein absorption, release of calcium and phosphate ions, surface calcification are the possible material mechanisms of calcium phosphate-induced ectopic bone formation. We studied the bone induction of non-microporus hydroxyapatite ceramic (HA-S), microporous HA (HA-R), microporous bioinert ceramics (TiO₂ ceramic; Al₂O₃ ceramic; both incapable to release Ca/P ions and to get surface calcification). It was found that protein adsorption was material-specific. With almost no absorption of rhBMP-2, mirocporous TiO₂ ceramic and Al₂O₃ ceramic induced bone formation. The results indicate that release of calcium and phosphate ions, surface calcification do not play a key role in osteoinduction, and surface microstructure induces bone formation may not be through protein adsorption.