In this study, a slurry foaming method was developed to fabricate porous titanium, and two different surface treatments were applied to investigate their effects on the osteoinduction of the implants. Three types of implants, that was porous titanium with no treatment, with chemical-thermal treatment (CTPT), and with acid-alkali treatment (AAPT), were implanted in the dorsal muscles of adult dogs for 3 and 5 months. After implantation for 3 months, new bone was only found in the inner pores of AAPT by histological analysis and field emission scanning electron microscopy observation. After implantation for 5 months, new bone was also found in CTPT, but it was absent in AAPT. This study not only confirmed that porous titanium with appropriate surface treatments could possess osteoinduction but also showed that its osteoinductive potential was tightly related to the surface treatment. As a simpler method, acid-alkali treatment could endow porous titanium with faster osteoinduction, and AAPT might have potential in clinical application.

Two‐layer TiO2 nanotube arrays were produced by stepping down the anodic voltage during which three nanotube interface structures between the top layer and the second layer were observed by SEM. We detected a polygonal ring structure on the top surface of the second layer and offer direct evidence of the growth of this second tube layer both at the cell boundary and right beneath the bottom of the first tube layer. For these processes, a possible growth mechanism is presented. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)