Enhanced Osteoinductivity of Porous Titanium Implant by Sodium Removal

The aim of this study was to optimize the surface treatment and to accelerate the osteoinductivity of porous bioactive titanium implant. Previous studies have reported that sodium removal with hot water treatment converts sodium titanate on the surface of an alkali-treated titanium plate into titania with a specific structure, which has better bioactivity than sodium titanate. We developed a dilute hydrochloric acid (HCl) treatment for porous titanium, which removed sodium from the complexly shaped porous structure more effectively than conventional hot water treatment. Three types of surface treatments were applied: (a) alkali and heat treatment, (b) alkali, hot water, and heat treatment (conventional treatment), and (c) alkali, dilute HCl, hot water, and heat treatment (Na-free treatment). The osteoinductivity of the materials implanted in the back muscles of adult beagle dogs was examined at three, six, and twelve months. Na-free porous bioactive titanium exhibited the highest osteoinductivity, and bone formation was observed within three months. This study showed that sodium removal has a significant positive effect on the osteoinductivity of the porous bioactive titanium implant.